Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring

Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring Djoeke F.B. Baelde Jansen, Marcelo González-Aravena, Francisco Santa Cruz, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6908361/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Apr, 2026 Read the published version in Scientific Reports → Version 1 posted 17 You are reading this latest preprint version Abstract The Antarctic Peninsula’s coastal benthic ecosystems are shaped by glacial meltwater-driven sedimentation and turbidity, yet high-resolution biodiversity studies across depth gradients remain scarce. Benthic megafauna and seaweeds were surveyed in Collins Bay, King George Island, using ROV video transects (10–80 m depth) and analysed for biodiversity and community composition in relation to environmental factors. Our results show that glacial proximity and bathymetry shape the benthic communities, with biodiversity increasing with both depth and distance from the glacier. Unexpectedly, species richness was high in shallow glacier-proximal areas, possibly due to a nutrient pump by wind-driven upwelling events enhancing local productivity and resource availability. Functional diversity followed a depth-related trend and interestingly showed sessile filter-feeders being dominant in deeper glacial-proximal habitats, while mobile taxa were more abundant further from the glacier. The prevalence of diverse seaweed assemblages highlights the role of primary productivity in structuring these communities. Site-specific differences in species composition suggest that small-scale environmental variability plays a stronger role than large-scale oceanographic processes. These findings highlight the need for continued monitoring, as glacial retreat will likely reshape these ecosystems, altering biodiversity patterns and functional composition in the coming decades. Biological sciences/Ecology/Biodiversity Biological sciences/Ecology Colar-water benthos environmental drivers habitat heterogeneity functional diversity community composition. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Benthic communities form the richest component of the Antarctic food web in terms of macrofaunal species diversity 1 and can potentially sequestrate 4.5k tonnes of carbon per year 2 . Yet despite their importance for ecosystem functioning and climate-altering properties, the structure and functioning of benthic ecosystems in the Southern Ocean remain poorly understood. This knowledge gap is especially concerning in the face of environmental change, which is particularly visible in the fast-heating Western Antarctic Peninsula 3 , 2 . A key driver of fjordic benthic community structure affected by climate change is glacial meltwater, where sedimentation, turbidity, and ice-scour influence habitat characteristics. Fjordic habitats further from glacial outflow typically experience lower sedimentation rates and have sandier substrates, whereas meltwater fjord habitats near glaciers are shaped by ice-scouring, high sedimentation, increased turbidity, and fine silty deposits interspersed with coarser glacially scoured substrates 4 . Ice-scour, one of the most impactful physical disturbances on Earth 5 , is especially influential in shallow zones and further contributes to the patchy and heterogeneous nature of these near-glacier habitats by scraping the seafloor and removing organisms in its path 6 – 9 . Alongside this mechanical disturbance, sedimentation also has a significant influence on benthic biodiversity (e.g. 10); for instance, high sedimentation can have negative effects on pelagic, sessile and non-sessile benthic organisms 11 – 14 . Additionally, it has been suggested that in deeper waters, where light availability diminishes, sedimentation becomes the dominant driver of benthic community structure 15 . These environmental conditions shape community complexity and functional trait dominance. In shallow waters, grazers and scavengers dominate, gradually transitioning to suspension feeders with increasing depth 16 , whereas in deeper waters, ascidians tend to be more abundant than sponges, which are otherwise dominant in Antarctic benthic communities 17 , 18 . However, while such studies describe clear depth-related patterns, others have reported more complex and variable community structures that are strongly influenced by habitat heterogeneity 19 , 20 . To better understand how these environmental gradients and physical disturbances interact to shape benthic communities, particularly across depth and glacial influence, it is necessary to study fjords with contrasting geomorphological features. Fjords along the Antarctic Peninsula, including those around King George Island (KGI), Maritime Antarctica, display complex seabed morphologies shaped by repeated glacial advance and retreat, supporting diverse and often highly localised benthic communities 7 , 20 . KGI, located in the South Shetland Islands off the northern tip of the Antarctic Peninsula, hosts several fjordic inlets, including Marian Cove and Collins Bay. The latter, located on the island’s western coast, is enclosed by a ~ 20 m sill that hinders the entrance of large icebergs, limiting deep ice-scouring. This provides a unique opportunity to study how glacial proximity and bathymetry shape benthic community structure without the confounding influence of icebergs from external sources. Despite the uniqueness of this opportunity, Collins Bay has not yet been the subject of studies that characterise its benthic biodiversity across a broad bathymetric gradient. In contrast, other areas such as Marian Cove have been extensively studied (see 21). Although the site has been included in previous work, it was only at low spatial or taxonomic resolution and without detailed bathymetric context 22 – 24 . More broadly, there is a general lack of high-resolution datasets that link biological communities with oceanographic conditions along the West Antarctic coast 4 . This is particularly important as environmental gradients in Antarctic fjords often vary gradually with depth and distance from glacial sources, potentially leading to transitional shifts in community composition rather than abrupt faunal zonation 25 contradicting earlier works describing clear zonation patterns. Addressing these knowledge gaps is critical for assessing the impacts of climate-driven glacial retreat on Antarctic benthic ecosystems. This study aims to provide a high-resolution characterisation of benthic community structure in Collins Bay, examining the influence of glacial proximity and bathymetry on species composition, relative abundance, and biodiversity patterns of macrofauna and seaweeds. Specifically, we hypothesise that environmental gradients lead to a continuous shift in species composition and functional traits with depth, rather than a strict zonation in Collins Bay 25 . We expect an increase in species abundance, species richness and functional diversity with depth and distance from the glacier 21 , 29 . Additionally, mobile species are expected to be more prevalent in areas subject to higher disturbance near the glacier, facilitating recolonisation after episodic sedimentation events. Hence, we anticipate identifying distinct community assemblages along the bathymetric gradient, shaped by the interplay of glacial influence and seabed depth. Results General patterns A total of 14,225 benthic individuals were counted, of which 12,350 corresponded to megafauna, representing 15 phyla and 157 unique taxa (Fig. 1 ). The most abundant animal taxon was morphologically identified as Nemertea, with 2,917 individuals recorded across 63.38% of all depths sampled. Two other abundant taxa included an unidentifiable small Polychaeta (1,394 individuals) and Newnesia sp. (1,066 individuals). Together, the five most abundant taxa covered 49.23% of all species counted. Three species, the bivalve Laternula elliptica and the polychaetes Newnesia sp., and a Terebellid , were present at all twelve sampled stations. The deepest and most versatile species were Terebellid s , which occurred at 78.87% of the sampled depths and eleven stations. The remaining 1,875 counts consisted of benthic algae and were counted in a presence-absence manner. The most abundant seaweed species, Ulothrix sp., was counted 399 times in 77.46% of the depth range. This was followed by Himantothallus grandifolius (n = 299) at 59.16% of the depth range, and diatomaceous films (n = 165), at 46.03%. At the phylum level, the seaweeds included members of Ochrophyta (738 presences), Chlorophyta (530), Rhodophyta (445), and CrCA (165). Biodiversity over the entire depth range Repeated sampling at station A4’s slope, combined with samples from nearby station A3 (Fig. 7 ), enabled a full vertical assessment of biodiversity while avoiding spatial overlap within an area of approximately 0.1 km² (Supplementary Tables 3 & 4). Shallow depths (0–10 m) supported relatively few fauna individuals, averaging 6.88 ± 4.10 (SD) individuals per frame, but both total species abundance (adj-R² = 0.55; p < 0.001) and species richness (adj-R² = 0.74; p < 0.001) increased markedly with depth (Supplementary Table 5). At depths greater than 50 m, an average of 13.0 species per frame was found (Fig. 1 a). In shallow waters, the community was dominated by Mollusca ( Nacella concinna and Newnesia sp.) and Holothuroidea ( Heterocucumis steineni) , which shifted to Ascidiacea (mainly Cnemidocarpa verrucosa) and Cnidaria ( Malacobelemnon sp.) in deeper waters. At the same depths, there was a notable shift in macroalgae occurrence (Fig. 1 b). Chlorophyta such as Ulothrix sp. and Monostroma hariotii appeared frequently in the shallower to mid-depth ranges (0–50 m), while Ochrophyta such as Desmarestia spp. and H. grandifolius were found across a broader depth range, occasionally as deep as 70–80 m. Rhodophyta displayed a similar broad distribution, although most occurrences were between 20 and 50 m depth. Diatom presence was highest at 20–40 m depth, with a peak of 19.37% (n = 37) near the glacier (< 0.75 km), followed by a marked decline with increasing distance, dropping to 4.85% (n = 20) beyond 1.75 km. At shallower depths (0–20 m), diatoms were less frequent and more variable, with low presence closest to the glacier (3.13%; n = 1) and a slight increase at intermediate distances. Diatoms were occasionally found at 40–60 m but were absent below 60 m. Overall, the algae presence declined significantly with depth (adj-R² = 0.34; p < 0.001; Supplementary Table 5). The difference in vertical gradients between flora and fauna underscores depth as a key structuring factor for benthic community structures (Fig. 1 c). Combined effects of glacier and bathymetry At near-glacier sites (< 0.75 km), the 0–20 m zone was dominated by Bivalvia (62.22%; n = 84) (Fig. 2 ). Their dominance persisted at 20–40 m (47.01%; n = 653), but deeper waters (60–80 m) showed a shift towards Polychaeta (61.02%; n = 160) and Cnidaria (20.54%; n = 53). At the same deepest depth further from the glacier, Porifera replaces Cnidaria as the second most abundant phylum (8.32%, n = 72). Furthest away from the glacier, the most abundant species were Nemertea (37.57%, n = 1956), Ascidiacea (20.98%, n = 1092) and Echinodermata (15.21%, n = 792). In terms of seaweed distribution, the shallow 0–20 m zone closest to the glacier was characterised by Chlorophyceae (46.59%, found in n frames = 89) and Desmarestiales (31.25%, n = 10). In the 40–60 m range, community complexity decreased to only five unique species. At deeper zones, only two species remained: CrCA (84.61%; n = 11) and Desmarestiales (15.38%; n = 2). At an intermediate distance of 0.75–1.25 km from the glacier, in the 60–80 m depth zone, five species were counted. Here, CrCA maintained a high relative abundance at 57.44% (n = 27), while Chlorophyceae and Desmarestiales were equally present (19.14%; n = 9). Further from the glacier, at distances of 1.25–1.75 km, a similar pattern emerged at 20–40 m depth, where Chlorophyceae comprised 35.60% (n = 94) and Desmarestiales 25.76% (n = 68). However, at 40–60 m, only five species persist, reflecting a clear depth-induced reduction in seaweed abundance. Furthest from the glacier (> 1.75 km), the 0–20 m zone exhibits high diversity with 13 species; the dominant taxon reaches 37.24% (n = 54), and community composition was more evenly distributed. The 20–40 m zone, total counts peaked, with Desmarestiales (26.70%, n = 110) and Chlorophyceae (16.02%, n = 66) as the most abundant groups. At the deepest interval, there were seven seaweed taxa present, with Desmarestiales prevailing at 53.85% (n = 63). Biodiversity measurements The interaction between depth and distance from the glacier was a significant driver of alpha diversity patterns, with prominent differences along the glacial distance gradient (Fig. 3 ; Tables 1 & 2 ). At stations closest to the glacier, total abundance, species richness, and Simpson’s diversity index all showed negative correlations with depth (Fig. 3 a). In contrast, stations furthest from the glacier, these biodiversity metrics displayed strong positive correlations with depth (R² = 0.75, 0.87, and 0.38, respectively; p < 0.001; Supplementary Tables 6 & 7). Stations at intermediate distances from the glacier exhibited transitional patterns between these two extremes. On the other hand, seaweed species richness showed a negative relationship with depth across all distances from the glacier, indicating that although glacial proximity affects the absolute species richness, it does not affect the bathymetric trend (Fig. 3 b). Table 1 Total abundance ( N ), species richness ( S′ ), and Simpson’s biodiversity index ( D ) ± SE, grouped by 10 m depth increments and distance from the glacier for faunal species studied at Collins Bay, King George Island. Data from four replicate frames are averaged per depth bin. Distance (km) 1.75 Depth (m) N S’ D N S’ D N S’ D N S’ D 0–10 39.00 ± 0.00 7.00 ± 0.00 0.53 ± 0.00 10–20 105.00 ± 0.00 8.00 ± 0.00 0.43 ± 0.00 44.50 ± 8.83 8.10 ± 1.13 0.62 ± 0.16 37.00 ± 0.00 13.00 ± 0.00 0.88 ± 0.00 23.25 ± 5.90 7.00 ± 2.92 0.74 ± 0.113 20–30 81.30 ± 12.76 6.70 ± 0.81 0.39 ± 0.00 51.00 ± 16.20 10.40 ± 4.55 0.62 ± 0.22 27.57 ± 2.02 8.43 ± 0.19 0.76 ± 0.02 26.93 ± 0.93 9.93 ± 0.39 0.79 ± 0.04 30–40 46.60 ± 16.66 8.10 ± 2.21 0.75 ± 0.06 82.80 ± 0.00 12.30 ± 0.00 0.55 ± 0.00 58.14 ± 17.62 12.93 ± 3.81 0.72 ± 0.04 53.00 ± 0.00 11.00 ± 0.00 0.60 ± 0.00 40–50 17.00 ± 0.00 5.50 ± 0.00 0.65 ± 0.0 74.00 ± 0.00 8.50 ± 0.00 0.68 ± 0.00 43.25 ± 0.00 13.00 ± 0.00 0.83 ± 0.00 42.00 ± 0.00 12.00 ± 0.00 0.76 ± 0.00 50–60 132.86 ± 55.09 7.43 ± 3.81 0.52 ± 0.04 77.75 ± 0.00 7.50 ± 0.00 0.52 ± 0.00 102.00 ± 0.00 24.67 ± 0.00 0.90 ± 0.00 299.00 ± 0.00 32.50 ± 0.00 0.87 ± 0.00 60–70 30.57 ± 0.00 5.71 ± 0.00 0.60 ± 0.00 192.80 ± 0.00 32.30 ± 0.00 0.90 ± 0.00 70–80 6.50 ± 0.00 0.50 ± 0.00 0.00 ± 0.00 462.50 ± 0.00 36.17 ± 0.00 0.69 ± 0.00 Table 2 Species richness ± SE grouped by 10 m depth increments and distance from the glacier for seaweed species studied at Collins Bay, King George Island. Data from four replicate frames are averaged per depth bin. Distance (km) Depth (m) 1.75 0–10 10.83 ± 2.57 10–20 10.00 ± 0.00 8.31 ± 0.67 6.00 ± 0.00 12.70 ± 1.47 20–30 7.83 ± 4.48 9.17 ± 2.36 4.33 ± 0.47 11.50 ± 0.00 30–40 2.60 ± 0.85 6.90 ± 0.00 3.13 ± 2.40 8.50 ± 0.00 40–50 2.50 ± 0.00 2.00 ± 0.00 1.75 ± 0.00 1.50 ± 0.00 50–60 1.20 ± 1.13 2.25 ± 0.00 3.33 ± 0.00 2.50 ± 0.00 60–70 1.00 ± 0.00 8.00 ± 0.00 6.17 ± 0.00 70–80 0.00 ± 0.00 Canonical Component Analysis The Canonical Component Analysis 30 (CCA; Supplementary Tables 8 to 10) revealed that environmental drivers collectively explained 86.89% of the variation in benthic community structure (scaled χ² = 1.60) across the stations (Fig. 4 ). The first two constrained axes accounted for 71.10% of the total inertia, effectively fitting taxa along the environmental gradients. Notably, Polychaeta displayed a strong negative loading on CCA1 (–1.70), suggesting an affinity for deeper, denser, more saline waters. In contrast, Annelida, Nemertea, and Echinodermata showed positive loadings on CCA1 (0.55, 0.54, and 0.51, respectively), indicative of a preference for shallower, algae-rich environments (mostly Rhodophytes) further from the glacier. These three taxa have high adult mobility. Furthermore, Mollusca scored positively on both axes (CCA1: 0.45; CCA2: 0.93), reflecting an association with warmer nearshore habitats with high algae presence. Conversely, Perciformes (CCA1: − 0.52; CCA2: − 0.57) and Arthropoda (CCA1: 0.30; CCA2: − 0.74) were more characteristic of distal, glacially influenced conditions. Three station clusters were identified based on community composition. The first comprised stations C1, B2, and C2, representing deep sites near the glacier dominated by Polychaeta. The second included stations B1, A1, and C3, which were shallower sites near the glacier, characterised by Bivalvia. The third cluster encompassed all remaining stations, spanning a broad depth range further from the glacier. Mobility and functional traits In shallow waters (10–20 m), animals at sites further from the glacier consistently exhibit significantly higher mobility compared to those at sites closest to the glacier. For example, between < 0.75 km and 0.75 to 1.25 km, adult mobility differs by 1.49 (p < 0.001; Supplementary Table 11). Tukey post-hoc comparisons reveal a complex pattern of adult mobility variation across depth and distance from the glacier. Similar patterns were observed within the upper 40 m; however, at deeper sites, only animals located more than 1.25 km from the glacier show increased mobility compared to proximity to the glacier, although overall mobility remains lower than in shallower areas (Fig. 5 left). This significant depth–distance interaction (Two-Way ANOVA; F 260,7 = 12.09; p < 0.001; Supplementary Table 11) underscores that both depth and distance from the glacier jointly shape adult mobility patterns. A shift in larval developmental strategies was also observed along these gradients. Larval types transition from lecithotrophic to planktotrophic with increasing depth and greater distances from the glacier, a pattern that reversed at near-glacier sites (Fig. 5 , right). This interaction was statistically significant (Two-Way ANOVA; F 237,14 = 5.59, p < 0.001; Supplementary Table 11), indicating that glacial influence modulates how depth affects larval strategy. Notably, none of the samples approach a value of 1, which indicates a general absence of direct development (egg laying and/or brooding taxa) throughout the faunal dataset. Functional feeding modes varied significantly with depth and distance from the glacier (PERMANOVA; F 260,7 = 10.329; p < 0.001; Supplementary Table 12). Close to the glacier, filter and suspension feeders dominated the benthic community, together accounting for at least 77.13% of feeding modes within each depth bin. However, their numbers declined sharply with increasing distance, encompassing only 9.52% of feeding modes in shallow waters at > 1.75 km from the glacier (Fig. 6 ). In the same sample, predators (41.04%) and grazers (32.38%) were the most prominent functional groups. Notably, the relative abundance of deposit feeders and opportunists increased farther from the glacier. For instance, deposit feeders increased from approximately 3.70% in near-glacier shallow waters to about 6.89% at > 1.75 km, while opportunists increased from 1.84–4.01%. These patterns suggest that communities located farther from the glacier exhibit a more even and functionally diverse distribution of feeding modes compared to those closer to glacial influence. Discussion This study provides the first detailed assessment of benthic biodiversity in Collins Bay, a site located in one of the most logistically and touristically active areas in the Antarctic 32 but which has remained relatively understudied 33 , 22 – 24 . Our results showed how bathymetry and glacial proximity are the main factors influencing species composition and functional traits. Species richness increased with depth and distance from the glacier, but no strict zonation was observed, supporting the hypothesis that environmental gradients drive continuous rather than discrete zones in benthic community structures 25 . Despite the relatively small spatial extent of the surveyed area in Collins Bay, we found considerable heterogeneity, supporting the hypothesis that local environmental conditions shape the benthos rather than large-scale processes 34 – 36 . The patterns observed in this study align with broader regional findings while offering new insights into fine-scale biodiversity dynamics. A similar study by Kim et al. 21 documented spatial variation in benthic megafauna structure and function across Marian Cove, adjacent to Collins Bay, driven by depth and distance from the glacier. Although their results reflect comparable patterns, the degree of heterogeneity reported there was somewhat less pronounced. This difference may stem from spatial design, as sampling stations were primarily concentrated within the same sector of the cove. Such spatial clustering, despite the study’s depth gradient, focused more on local glacial retreat instead of broader glacial influences. Another study that incorporates Collins Bay as well as other areas of Maxwell Bay by Valdivia et al. 24 has documented biodiversity patterns across the region but lacked the fine-scale depth resolution achieved in this study. Their sampling at a single station within Collins Bay found lower species richness than elsewhere in Maxwell Bay, consistent with our findings that biodiversity declines with increasing proximity to the glacier. However, differences in methodology, such as their use of dredge sampling versus the video-based approach, may explain some differences in species richness, particularly for taxa living in crevices or beneath seaweed canopies, which are not visible through imaging. Notably, our survey revealed three times the number of seaweed taxa reported by Valdivia et al. 24 , and double the number reported by Newcombe & Cárdenas 22 in the same area, underscoring the strength of video surveys in capturing algal diversity. Valdivia et al. 24 reported water turbidity to be higher near the surface and concluded it as a potential explanation for the observed increased biodiversity at greater depths. Several studies have shown that sedimentation exerts multiple stressors on benthic communities 37 , 38 , including increased mineral discharge, which can induce oxidative stress and metal accumulation in filter feeders (e.g. 39 ), as well as reduce food availability and clog feeding structures 40 , 41 . Our findings are in accordance with these previous observations, as higher species richness and abundance were found in deeper waters and further from the glacier. This pattern was similarly noted as an explainable factor by Kim et al. 21 in Marian Cove, an area which is adjacent to Collins Bay. However, an opposite trend close to the glacier was also observed in our study, with species richness peaking in shallow waters. This pattern was primarily driven by the presence of molluscs ( L. elliptica and N. concinna ), ascidians and echinoderms ( O. validus and Neosmilaster sp.). The dominance of pioneer species such as molluscs is expected, as they can bury themselves and thus avoid ice impact, as noted in Potter Cove by Sahade et al. 17 . Furthermore, the mobility of echinoderms may allow them to actively seek favourable conditions. Similarly, the high relative abundance of ascidians near the glacier reflects findings by Kim et al. 42 and Sahade et al. 17 who reported peak ascidian densities at around 30 m depth in Marian Cove and Potter Cove, respectively. Although Antarctic coastal waters are generally well mixed, subglacial discharge from the marine-terminating Collins Glacier may locally alter circulation and enhance nutrient availability 43 . Such discharge may carry nutrients, like iron, organic matter, and sediments from beneath the ice sheet 44 , 45 , which interacts with intrusions of relatively warmer subsurface waters during the flood time in the head of the bay 46 , increasing phytoplankton biomass and primary production in nearshore areas 47 and supporting unexpectedly high biodiversity close to glacier fronts due to pelagic-benthic coupling 48 . However, it is also plausible that the discharge itself is driven by meteorological and oceanographic forcing, including wind and offshore intrusions of warm deep water 49 , rather than acting as a primary driver of circulation. Further investigations into nutrient fluxes, chlorophyll concentrations and water column structure are needed to better understand the underlying processes. The significance of primary producers in shaping benthic communities cannot be underestimated. Larger macroalgal species can facilitate the establishment of benthic organisms in highly disturbed areas 50 , whereas diatoms and filamentous algal aggregates serve as essential food sources in Antarctic ecosystems, impacting energy transfer throughout the benthic food web 51 . In addition to their ecological function, diatoms are increasingly recognised as sensitive indicators of environmental change, particularly concerning glacial influence 52 . In Collins Bay, their abundance peaked at intermediate depths (20–40 m) near the glacier (< 0.75 km) and declined both with increasing depth and distance, mirroring patterns reported in Marian Cove, King George Island 53 and South Bay, Doumer Island 54 . These studies describe massive blooms of filamentous colonial diatoms at similar depths, where environmental conditions are favourable for growth. The higher diatom presence in glacially influenced zones of Collins Bay may likewise reflect nutrient pulses or stabilised substrates in areas of moderate disturbance. Such blooms are thought to be linked to changing salinity, temperature, and stratification caused by ice melt 53 , 54 , 52 . Their rapid response to environmental variability highlights benthic diatoms as valuable indicators of ecosystem change, with future shifts in primary production and food-web structure likely to follow patterns of glacial retreat. The widespread distribution of diverse algal assemblages, particularly Desmarestiales and Chlorophyceae, suggests that primary productivity remains relatively high despite glacial influence. This aligns with the findings of Quartino et al. 55 , who observed that macroalgal community structure in Antarctic coastal environments is primarily shaped by depth, substrate type, and irradiance, with salinity and nutrient availability playing a lesser role. Ice scouring further contributes to spatial patchiness in these communities. In Collins Bay, species richness generally declined with increasing depth, consistent with reduced irradiance as a limiting factor (e.g. 56 ). Interestingly, further from the glacier, a slight increase in algal richness was observed at greater depths, possibly reflecting reduced ice disturbance, which is similar to what was found by Quartino et al. 55 in Potter Cove, the eastern part of KGI. Despite this, no clear trend emerged concerning glacial distance, suggesting that spatial heterogeneity and patchiness play a significant role in structuring local algal biodiversity. For example, shallow stations near the glacier (A1, B1, and C3) hosted diverse communities, including Desmarestiales, Chlorophyceae, and diatomaceous films. However, P. decipiens , a known glacial opportunist found in Marian Cove 57 , 58 , Half Moon Island 59 , and Potter Cove 55 , and even found in deep waters 60 , was relatively scarce (relative abundance: < 5%) in our study. This challenges expectations that pioneer species would dominate these extreme environments and suggests that local conditions may favour a broader range of algal ecological baselines for future shifts in benthic community structure. Notably, recent observations by Amsler et al. 52 revealed rapid shifts in macroalgal cover in the Palmer Archipelago over just four years, emphasising that Antarctic seaweed communities are highly dynamic. Beyond species richness, functional diversity exhibited a clear depth gradient, with mobile taxa becoming increasingly present farther from the glacier. Previous studies suggest that high-disturbance environments near glaciers should favour mobile species capable of recolonising after episodic sedimentation events 16 ; however, our CCA results revealed an opposite pattern. Sessile filter feeders dominated deeper glacial-proximal habitats, while mobile taxa – including arthropods, echinoderms, and nemerteans – were more abundant at stations further away from the glacier. One possible explanation is that dominant filter feeders in deep glacial sites exhibit low adult mobility and limited larval dispersal, leading to a reliance on self-recruitment and local population stability 61 . Filter-feeders are found in deeper sites all around KGI 62 , and are often a cause for an increase in local heterogeneity by increasing the available surface 17 . The latter is particularly significant in habitats like Collins Bay, where over 83% of samples consist of mud and show no significant correlation between species distribution and substrate type. The high number of filter feeders thus reinforces the high patchiness found in Collins Bay, which is often seen in Antarctic fjord ecosystems 25 , 63 . To continue, the increase in mobile taxa with glacier distance corresponds to a rise in functional group diversity, as observed in Marian Cove by Kim et al. 21 , suggesting a consistent trend across Antarctic fjord systems. Disturbance and bathymetry can also influence reproductive and feeding strategies. In many systems, fauna typically declined with increasing disturbance, while scavengers and species with high dispersal potential became dominant in shallow, high-disturbance areas. In Collins Bay, however, sessile taxa remained dominant even in deeper glacial-proximal habitats, suggesting site-specific differences in disturbance regimes or resource availability. While highly disturbed environments are often associated with species exhibiting pelagic larval development due to their rapid recolonisation potential 61 , 64 , our findings indicate a mix of reproductive strategies across depths, possibly reflecting local adaptations to environmental conditions. Additionally, the increasing relative abundance of deposit feeders and opportunists with distance from the glacier suggests a shift in resource use and trophic structuring, reinforcing the importance of functional diversity in shaping benthic community composition in glacial fjords. Notably, most functional diversity studies to date have focused on terrestrial vegetation, leaving research gaps in our understanding of marine ecosystems 65 . While some studies have examined broad-scale patterns such as the latitudinal gradient 66 , the influence of substrate on functional groups 29 , 65 , or large-scale patterns in Arctic regions 31 , high-resolution studies that compare functional diversity along depth and glacier gradients remain largely absent. The findings presented here thus provide a valuable baseline for understanding functional diversity in Antarctic benthic communities. Despite similar depths and distances from the glacier, stations C4 (fjord inflow) and A3 (fjord outflow) exhibited no significant differences in species composition. This contrasts with observations from other polar regions, where strong hydrodynamic forcing influences larval transport and community connectivity 67 , 68 . Instead, our results suggest that in Collins Bay, local habitat conditions and heterogeneity probably exert a stronger influence on community structure than broader oceanographic processes, reinforcing the need for high-resolution ecological and oceanographic assessments. Conclusions This study provides the first fine-scale assessment of benthic biodiversity in Collins Bay, revealing how bathymetry and proximity to the glacier are key drivers of species composition and functional diversity. While species richness increased with depth and distance from the glacier, localised heterogeneity and environmental complexity disrupted clear zonation patterns. The site-specific differences in species composition suggest that small-scale environmental variability plays a stronger role than large-scale oceanographic processes, which was reconfirmed with unexpectedly high biodiversity in shallow, glacial proximal sites and diverse seaweed assemblage presence. Interestingly, functional diversity followed a depth-related trend, with sessile filter-feeders dominant in deeper glacial-proximal habitats and mobile taxa more abundant further from the glacier. Given the rapid pace of glacial retreat in the Antarctic Peninsula 69 , 70 , continued monitoring of benthic communities in Collins Bay is essential for tracking ecosystem responses to climate-driven environmental change, especially in areas with a high human footprint 33 , 71 . High-resolution biodiversity assessments such as this provide a crucial baseline for future conservation efforts and improve our understanding of how Antarctic benthic ecosystems will adapt to a changing climate. All data processing and statistical analyses were performed in r (RStudio 2023.06.2, build 561). Methods Study site Sampling was conducted in Collins Bay (62.177°S, 58.826°W), a semi-enclosed cove approximately 3 × 3 km in size, located within Maxwell Bay, one of the two major fjords systems on KGI, South Shetland Islands (Fig. 7 ). The bay reaches depths of up to 190 metres at the central part of its mouth. Collins Glacier, a small ice dome covering approximately 15 km² with a maximum elevation of 270 metres, influences the southeastern region of the bay 74 . The glacier’s catchment area spans roughly 50 km², and it directly influences the adjacent coastal zone through both land-terminating and tidewater-terminating fronts 74 , 75 . Stations were selected in Collins Bay to ensure that each depth profile (0–80 m depth) overlapped with each distance from the glacier (ranging from 0 to 3 km), creating a completely crossed design. ROV surveying procedures To assess biodiversity non-invasively, twelve ROV video surveys were conducted in December 2024 in Collins Bay using the FIFISH V6 EXPERT and FIFISH V6 PRO by QYSEA & FiFish. Both ROVs were equipped with a UHK 4K underwater camera (12-megapixel resolution, 166° ultra-wide field of view) flanked by two 6000-lumen LED lights to ensure consistent illumination. Each transect included at least 35 frames, captured with the ROV positioned at a stable 0.5 m height above the seafloor to avoid disturbing the sediment. Each transect followed a butterfly pattern with a maximum radius of 50 m from a central starting point where the Zodiac was anchored, or in deeper waters, kept at the same coordinates. Video analysis A total of 678 frames were distinguished from the video-transects of 12 stations in Collins Bay (Fig. 7 ). For each frame, depth from the ROV screen and substrate type (mud, pebble, cobble, or boulder) were noted. Depth ranged from 6.6 to 78.8 m. All recognisable epibenthic megafauna (approximately > 1 cm) were counted and identified to the lowest possible taxonomic level using standard flora and fauna guides 76 – 79 and online databases (e.g. www.marinespecies.org , www.fishbase.se ). Colonial species were counted as one, except when physically separated by sediment or other organisms. Due to the inability to distinguish individual thalli in video imagery, seaweeds were not quantified as discrete individuals. Instead, we use the term seaweed as an overarching term including macroalgae, diatoms (film/mats), and encrusting coralline algae (CrCa), enabling comparison with faunal groups in subsequent analyses. Environmental data Conductivity–temperature–depth (CTD) profiles were recorded using a DST CTD by Star Oddi while the ROV conducted transects to capture in-situ water characteristics. Measurements were taken every ten seconds during descent. Sensor accuracies for conductivity, temperature, and salinity were ± 1.5 mS/cm, ± 0.1°C, and ± 0.1 PSU, respectively, while the depth accuracy, determined via pressure, was ± 0.6% over the entire range. Consequently, the first 0.5 m of measurements (from the bottom) were removed from the dataset. Salinity was calculated as practical salinity (PSS-78) from conductivity, and similarly, potential density anomaly (σ in kg/m³) and potential temperature (θ in °C) were derived from the CTD data. To capture water characteristics unaffected by daily fluctuations, all stations were sampled in a clockwise sequence, using a SonTek CastAway® CTD. This device offers an accuracy of ± 0.05°C and ± 0.1 PSU, operates at a 5 Hz sampling rate, and includes an integrated GPS for georeferenced casts. Data analysis To represent the local communities furthest from the glacier at a small scale over the sampled range, faunal counts were summed by order/phylum in 10 m depth intervals, covering the entire water column within an area of approximately 0.1 km². To understand the proportions of flora and fauna over the entire Collins Bay, data from all stations were combined and categorised into 20 m depth bins and four distance ranges from the glacier. Faunal abundance was summed within each depth–distance bin, while seaweeds were merged to represent presence/absence within each depth-distance range. To accurately calculate the alpha-biodiversity index, data from four frames within a similar 10 m depth range were combined per station to create replicates. For each replicate, mean depth was calculated and used for subsequent analysis. Total abundance, species richness, and Simpson’s diversity index were derived from these replicates. A Principal Component Analysis (PCA) and further ANOVA tests were used to evaluate significant substrate type effect. Subsequently, two-way ANOVAs were performed using depth and distance as categorical variables to test their effects on biodiversity metrics 80 . The best‐fitting models were selected based on the lowest Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) values. These models were then used to predict biodiversity response across the range of observed depths and distances from the glacier. A Canonical Correspondence Analysis (CCA 30 ) was conducted to investigate environmental drivers of community composition across the twelve sampling stations. Relative abundance data were used for 35 samples to ensure balanced sampling effort, as some stations had up to 50 samples. Initial tests indicated that the model fit improved when seaweed presence/absence data were included as environmental explanatory variables alongside CTD measurements of December 21st, 2024. For each station, the deepest CTD values were used to represent environmental benthic conditions, incorporating temperature (°C), salinity (PSU), potential density (kg/m³), and depth (m) 24 . Distance from Collins Glacier (km) was also added as an environmental explanatory variable. Building on the above approaches, functional traits of organisms (e.g. adult mobility and larval type) were incorporated to further clarify community structure. The mean trait value per community ( \(\:mT\) ) was computed as a weighted average of species-specific trait values, with the species’ relative abundances serving as weights: $$\:mT\:=\sum\:_{i=1}^{S}{p}_{i}{x}_{i}$$ Here, \(\:{x}_{i}\) represents the trait value of the \(\:i\) -th species. For binary traits, \(\:{x}_{i}\) takes on values of 0 or 1. For categorical traits, a fuzzy coding method was used 81 (Supplementary Table 1), where each taxon was assigned an affinity score ( \(\:{a}_{k}\) ) for each category ( \(\:1\:\le\:k\le\:h\) ), with \(\:h\) being the total number of categories for the given trait. Affinity scores ranged from 0 (no affinity) to 3 (high affinity). These scores were converted into a frequency distribution by dividing each \(\:{a}_{k}\) by the total sum of the affinity scores for that taxon (see 31 for further details. Trait information for faunal species was collected from Robinson et al. 60 and adjusted to fit the observed taxa (Supplementary Tables 1 & 2). When analysing \(\:mT\) , the depth range 0–10 m was excluded due to a lack of replicates. Two-way ANOVAs were used to analyse adult mobility and larval type across depth and distance gradients, and feeding modes were analysed with a PERMANOVA based on Bray-Curtis dissimilarity with 9,999 permutations 82 . Declarations Ethics statement The report presents research on animals that do not require ethical approval for their study. Competing interests statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Funding INACH ‘Marine Protected Areas’ Program (2409052) and ANID/Millennium Science Initiative Program – ICN2021_002. Author Contribution D.B.J., C.A.C conceived the study. D.B.J. and A.H.S. conducted field sampling. D.B.J performed the video analysis, numerical analysis, creation of figures and tables and writing the manuscript. C.A.C., M.G.A., F.S.C., and M.L. reviewed and edited the overall content of the manuscript. All the authors have been involved with the work and have approved the manuscript for submission. Acknowledgement The authors acknowledge the expert support and aid of the team at the Chilean Professor Julio Escudero Base and INACH. 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Landaeta","email":"","orcid":"","institution":"Universidad de Valparaíso","correspondingAuthor":false,"prefix":"","firstName":"Mauricio","middleName":"F.","lastName":"Landaeta","suffix":""},{"id":473007992,"identity":"5b418ba3-bf45-49c9-95e1-18f017af0404","order_by":4,"name":"Antonia Hinojosa Saez","email":"","orcid":"","institution":"Pontificia Universidad Católica de Valparaíso","correspondingAuthor":false,"prefix":"","firstName":"Antonia","middleName":"Hinojosa","lastName":"Saez","suffix":""},{"id":473007993,"identity":"c3d8db84-b13c-4330-a2e2-f474e64e4ce9","order_by":5,"name":"César A. Cárdenas","email":"","orcid":"","institution":"Instituto Antártico Chileno","correspondingAuthor":false,"prefix":"","firstName":"César","middleName":"A.","lastName":"Cárdenas","suffix":""}],"badges":[],"createdAt":"2025-06-16 20:08:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6908361/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6908361/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-49555-3","type":"published","date":"2026-04-30T15:58:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":85292759,"identity":"1b9e822f-7b67-45d4-911d-7b6b1737acdd","added_by":"auto","created_at":"2025-06-24 10:22:14","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":905554,"visible":true,"origin":"","legend":"\u003cp\u003eProportions of faunal phyla (a) and seaweed orders (b) across the depth ranges of stations A3 and A4 (Fig. 7). Depths are binned in 10 m intervals. Numbers to the right of the bars represent the average number of individuals frame ± SD in that depth-bin. Randomly selected screenshots representing each depth (c).\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/d2e99f48f55cdb10846fbedf.png"},{"id":85292757,"identity":"b5e09147-d643-40e5-9b75-3d9d1b392824","added_by":"auto","created_at":"2025-06-24 10:22:14","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":351856,"visible":true,"origin":"","legend":"\u003cp\u003eProportions of faunal phyla (a) and seaweed orders (b) across depth ranges of all stations (Fig. 7). Depths are binned at 20 m intervals and divided over distance from glaciers surrounding Collins Bay, King George Island.\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/cea3ed945d90b18a73c26924.jpeg"},{"id":85293627,"identity":"8f1d5b31-6524-4308-8931-b6d646b2d2b1","added_by":"auto","created_at":"2025-06-24 10:30:14","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":288937,"visible":true,"origin":"","legend":"\u003cp\u003eGenerated predictions of total abundance, species richness and Simpson’s diversity index for faunal data (a) and species richness for seaweed data (b). Predictions and 95% confidence intervals are modelled from observed biodiversity results over depth and distance from the glacier surrounding Collins Bay (Supplementary Tables 6 \u0026amp; 7).\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/7e85a74e0b0b5a241565577d.jpeg"},{"id":85292763,"identity":"8852d394-c3a4-4aa3-9b0e-e1e6793045ca","added_by":"auto","created_at":"2025-06-24 10:22:14","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":146762,"visible":true,"origin":"","legend":"\u003cp\u003eCanonical Component Analysis (CCA) of mobile and sessile taxa and variables studied at Collins Bay, King George Island. Vectors represent environmental and biological variables (Supplementary Tables 8 to 10).\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/f6a0b3311dcf3b93022187b0.jpeg"},{"id":85292761,"identity":"4c0ab1eb-1575-4119-92d5-a605b262236e","added_by":"auto","created_at":"2025-06-24 10:22:14","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":212722,"visible":true,"origin":"","legend":"\u003cp\u003eBoxplots showing adult mobility (left) and larval type (right) by depth, categorised into four glacial distance groups. Mobility and larval type values were derived using fuzzy coding, following Vandewalle et al.\u003csup\u003e31\u003c/sup\u003e Letters indicate statistically distinct groups (p \u0026lt; 0.05) based on Tukey post hoc tests following a two-way ANOVA with interaction.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/b271cecfc5dcbdbf09c9e507.jpeg"},{"id":85293635,"identity":"33709939-f824-40e7-af1c-ee838b86bc18","added_by":"auto","created_at":"2025-06-24 10:30:14","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":144608,"visible":true,"origin":"","legend":"\u003cp\u003eFunctional feeding modes in benthic organisms over distance from the glacier and depth based on trait data from Vandewalle et al.\u003csup\u003e31\u003c/sup\u003e\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/86bd905fd735aea87bfe63d1.jpeg"},{"id":85292779,"identity":"ae63d9f6-5d43-4bbd-86dc-93ba2127fd9c","added_by":"auto","created_at":"2025-06-24 10:22:14","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":438443,"visible":true,"origin":"","legend":"\u003cp\u003eSampling area of Collins Bay, King George Island (KGI) in the Western Antarctic Peninsula (WAP) with Collins Glacier (CG) in the South-East of Maxwell Bay. Antarctic coastline via Gerrish et al. \u003csup\u003e72\u003c/sup\u003e and bathymetry of South Shetland Islands via Fremand\u003csup\u003e73\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/6677719c4c3b2b558c39c8ac.png"},{"id":108437969,"identity":"36da3d67-f7cb-482b-a0a1-abb717413e3b","added_by":"auto","created_at":"2026-05-04 16:05:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3211190,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/40966379-74b1-4f1c-b992-fca734697662.pdf"},{"id":85293628,"identity":"6247fbe7-6070-4f80-a5e5-b116fa21ce3d","added_by":"auto","created_at":"2025-06-24 10:30:14","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":83132,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-6908361/v1/2b4db3946a5f42bd80133e62.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring","fulltext":[{"header":"Introduction","content":"\u003cp\u003eBenthic communities form the richest component of the Antarctic food web in terms of macrofaunal species diversity\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e and can potentially sequestrate 4.5k tonnes of carbon per year\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Yet despite their importance for ecosystem functioning and climate-altering properties, the structure and functioning of benthic ecosystems in the Southern Ocean remain poorly understood.\u003c/p\u003e \u003cp\u003eThis knowledge gap is especially concerning in the face of environmental change, which is particularly visible in the fast-heating Western Antarctic Peninsula\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. A key driver of fjordic benthic community structure affected by climate change is glacial meltwater, where sedimentation, turbidity, and ice-scour influence habitat characteristics. Fjordic habitats further from glacial outflow typically experience lower sedimentation rates and have sandier substrates, whereas meltwater fjord habitats near glaciers are shaped by ice-scouring, high sedimentation, increased turbidity, and fine silty deposits interspersed with coarser glacially scoured substrates\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Ice-scour, one of the most impactful physical disturbances on Earth\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e, is especially influential in shallow zones and further contributes to the patchy and heterogeneous nature of these near-glacier habitats by scraping the seafloor and removing organisms in its path\u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAlongside this mechanical disturbance, sedimentation also has a significant influence on benthic biodiversity (e.g. 10); for instance, high sedimentation can have negative effects on pelagic, sessile and non-sessile benthic organisms\u003csup\u003e\u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Additionally, it has been suggested that in deeper waters, where light availability diminishes, sedimentation becomes the dominant driver of benthic community structure\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. These environmental conditions shape community complexity and functional trait dominance. In shallow waters, grazers and scavengers dominate, gradually transitioning to suspension feeders with increasing depth\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, whereas in deeper waters, ascidians tend to be more abundant than sponges, which are otherwise dominant in Antarctic benthic communities\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. However, while such studies describe clear depth-related patterns, others have reported more complex and variable community structures that are strongly influenced by habitat heterogeneity\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTo better understand how these environmental gradients and physical disturbances interact to shape benthic communities, particularly across depth and glacial influence, it is necessary to study fjords with contrasting geomorphological features. Fjords along the Antarctic Peninsula, including those around King George Island (KGI), Maritime Antarctica, display complex seabed morphologies shaped by repeated glacial advance and retreat, supporting diverse and often highly localised benthic communities\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. KGI, located in the South Shetland Islands off the northern tip of the Antarctic Peninsula, hosts several fjordic inlets, including Marian Cove and Collins Bay. The latter, located on the island\u0026rsquo;s western coast, is enclosed by a\u0026thinsp;~\u0026thinsp;20 m sill that hinders the entrance of large icebergs, limiting deep ice-scouring. This provides a unique opportunity to study how glacial proximity and bathymetry shape benthic community structure without the confounding influence of icebergs from external sources. Despite the uniqueness of this opportunity, Collins Bay has not yet been the subject of studies that characterise its benthic biodiversity across a broad bathymetric gradient. In contrast, other areas such as Marian Cove have been extensively studied (see 21). Although the site has been included in previous work, it was only at low spatial or taxonomic resolution and without detailed bathymetric context\u003csup\u003e\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. More broadly, there is a general lack of high-resolution datasets that link biological communities with oceanographic conditions along the West Antarctic coast\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. This is particularly important as environmental gradients in Antarctic fjords often vary gradually with depth and distance from glacial sources, potentially leading to transitional shifts in community composition rather than abrupt faunal zonation\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e contradicting earlier works describing clear zonation patterns. Addressing these knowledge gaps is critical for assessing the impacts of climate-driven glacial retreat on Antarctic benthic ecosystems.\u003c/p\u003e \u003cp\u003eThis study aims to provide a high-resolution characterisation of benthic community structure in Collins Bay, examining the influence of glacial proximity and bathymetry on species composition, relative abundance, and biodiversity patterns of macrofauna and seaweeds. Specifically, we hypothesise that environmental gradients lead to a continuous shift in species composition and functional traits with depth, rather than a strict zonation in Collins Bay\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. We expect an increase in species abundance, species richness and functional diversity with depth and distance from the glacier\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Additionally, mobile species are expected to be more prevalent in areas subject to higher disturbance near the glacier, facilitating recolonisation after episodic sedimentation events. Hence, we anticipate identifying distinct community assemblages along the bathymetric gradient, shaped by the interplay of glacial influence and seabed depth.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eGeneral patterns\u003c/h2\u003e \u003cp\u003eA total of 14,225 benthic individuals were counted, of which 12,350 corresponded to megafauna, representing 15 phyla and 157 unique taxa (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The most abundant animal taxon was morphologically identified as Nemertea, with 2,917 individuals recorded across 63.38% of all depths sampled. Two other abundant taxa included an unidentifiable small \u003cem\u003ePolychaeta\u003c/em\u003e (1,394 individuals) and \u003cem\u003eNewnesia\u003c/em\u003e sp. (1,066 individuals). Together, the five most abundant taxa covered 49.23% of all species counted. Three species, the bivalve \u003cem\u003eLaternula elliptica\u003c/em\u003e and the polychaetes \u003cem\u003eNewnesia\u003c/em\u003e sp., and a \u003cem\u003eTerebellid\u003c/em\u003e, were present at all twelve sampled stations. The deepest and most versatile species were Terebellid\u003cem\u003es\u003c/em\u003e, which occurred at 78.87% of the sampled depths and eleven stations. The remaining 1,875 counts consisted of benthic algae and were counted in a presence-absence manner. The most abundant seaweed species, \u003cem\u003eUlothrix\u003c/em\u003e sp., was counted 399 times in 77.46% of the depth range. This was followed by \u003cem\u003eHimantothallus grandifolius\u003c/em\u003e (n\u0026thinsp;=\u0026thinsp;299) at 59.16% of the depth range, and diatomaceous films (n\u0026thinsp;=\u0026thinsp;165), at 46.03%. At the phylum level, the seaweeds included members of Ochrophyta (738 presences), Chlorophyta (530), Rhodophyta (445), and CrCA (165).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eBiodiversity over the entire depth range\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003eRepeated sampling at station A4\u0026rsquo;s slope, combined with samples from nearby station A3 (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), enabled a full vertical assessment of biodiversity while avoiding spatial overlap within an area of approximately 0.1 km\u0026sup2; (Supplementary Tables\u0026nbsp;3 \u0026amp; 4).\u003c/p\u003e \u003cp\u003eShallow depths (0\u0026ndash;10 m) supported relatively few fauna individuals, averaging 6.88\u0026thinsp;\u0026plusmn;\u0026thinsp;4.10 (SD) individuals per frame, but both total species abundance (adj-R\u0026sup2; = 0.55; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and species richness (adj-R\u0026sup2; = 0.74; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) increased markedly with depth (Supplementary Table\u0026nbsp;5). At depths greater than 50 m, an average of 13.0 species per frame was found (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). In shallow waters, the community was dominated by Mollusca (\u003cem\u003eNacella concinna\u003c/em\u003e and \u003cem\u003eNewnesia\u003c/em\u003e sp.) and Holothuroidea (\u003cem\u003eHeterocucumis steineni)\u003c/em\u003e, which shifted to Ascidiacea (mainly \u003cem\u003eCnemidocarpa verrucosa)\u003c/em\u003e and Cnidaria (\u003cem\u003eMalacobelemnon\u003c/em\u003e sp.) in deeper waters.\u003c/p\u003e \u003cp\u003eAt the same depths, there was a notable shift in macroalgae occurrence (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). Chlorophyta such as \u003cem\u003eUlothrix\u003c/em\u003e sp. and \u003cem\u003eMonostroma hariotii\u003c/em\u003e appeared frequently in the shallower to mid-depth ranges (0\u0026ndash;50 m), while Ochrophyta such as \u003cem\u003eDesmarestia\u003c/em\u003e spp. and \u003cem\u003eH. grandifolius\u003c/em\u003e were found across a broader depth range, occasionally as deep as 70\u0026ndash;80 m. Rhodophyta displayed a similar broad distribution, although most occurrences were between 20 and 50 m depth. Diatom presence was highest at 20\u0026ndash;40 m depth, with a peak of 19.37% (n\u0026thinsp;=\u0026thinsp;37) near the glacier (\u0026lt;\u0026thinsp;0.75 km), followed by a marked decline with increasing distance, dropping to 4.85% (n\u0026thinsp;=\u0026thinsp;20) beyond 1.75 km. At shallower depths (0\u0026ndash;20 m), diatoms were less frequent and more variable, with low presence closest to the glacier (3.13%; n\u0026thinsp;=\u0026thinsp;1) and a slight increase at intermediate distances. Diatoms were occasionally found at 40\u0026ndash;60 m but were absent below 60 m. Overall, the algae presence declined significantly with depth (adj-R\u0026sup2; = 0.34; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Table\u0026nbsp;5). The difference in vertical gradients between flora and fauna underscores depth as a key structuring factor for benthic community structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec).\u003c/p\u003e\n\u003ch3\u003eCombined effects of glacier and bathymetry\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003eAt near-glacier sites (\u0026lt;\u0026thinsp;0.75 km), the 0\u0026ndash;20 m zone was dominated by Bivalvia (62.22%; n\u0026thinsp;=\u0026thinsp;84) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Their dominance persisted at 20\u0026ndash;40 m (47.01%; n\u0026thinsp;=\u0026thinsp;653), but deeper waters (60\u0026ndash;80 m) showed a shift towards Polychaeta (61.02%; n\u0026thinsp;=\u0026thinsp;160) and Cnidaria (20.54%; n\u0026thinsp;=\u0026thinsp;53). At the same deepest depth further from the glacier, Porifera replaces Cnidaria as the second most abundant phylum (8.32%, n\u0026thinsp;=\u0026thinsp;72). Furthest away from the glacier, the most abundant species were Nemertea (37.57%, n\u0026thinsp;=\u0026thinsp;1956), Ascidiacea (20.98%, n\u0026thinsp;=\u0026thinsp;1092) and Echinodermata (15.21%, n\u0026thinsp;=\u0026thinsp;792).\u003c/p\u003e \u003cp\u003eIn terms of seaweed distribution, the shallow 0\u0026ndash;20 m zone closest to the glacier was characterised by Chlorophyceae (46.59%, found in n frames\u0026thinsp;=\u0026thinsp;89) and Desmarestiales (31.25%, n\u0026thinsp;=\u0026thinsp;10). In the 40\u0026ndash;60 m range, community complexity decreased to only five unique species. At deeper zones, only two species remained: CrCA (84.61%; n\u0026thinsp;=\u0026thinsp;11) and Desmarestiales (15.38%; n\u0026thinsp;=\u0026thinsp;2). At an intermediate distance of 0.75\u0026ndash;1.25 km from the glacier, in the 60\u0026ndash;80 m depth zone, five species were counted. Here, CrCA maintained a high relative abundance at 57.44% (n\u0026thinsp;=\u0026thinsp;27), while Chlorophyceae and Desmarestiales were equally present (19.14%; n\u0026thinsp;=\u0026thinsp;9). Further from the glacier, at distances of 1.25\u0026ndash;1.75 km, a similar pattern emerged at 20\u0026ndash;40 m depth, where Chlorophyceae comprised 35.60% (n\u0026thinsp;=\u0026thinsp;94) and Desmarestiales 25.76% (n\u0026thinsp;=\u0026thinsp;68). However, at 40\u0026ndash;60 m, only five species persist, reflecting a clear depth-induced reduction in seaweed abundance. Furthest from the glacier (\u0026gt;\u0026thinsp;1.75 km), the 0\u0026ndash;20 m zone exhibits high diversity with 13 species; the dominant taxon reaches 37.24% (n\u0026thinsp;=\u0026thinsp;54), and community composition was more evenly distributed. The 20\u0026ndash;40 m zone, total counts peaked, with Desmarestiales (26.70%, n\u0026thinsp;=\u0026thinsp;110) and Chlorophyceae (16.02%, n\u0026thinsp;=\u0026thinsp;66) as the most abundant groups. At the deepest interval, there were seven seaweed taxa present, with Desmarestiales prevailing at 53.85% (n\u0026thinsp;=\u0026thinsp;63).\u003c/p\u003e\n\u003ch3\u003eBiodiversity measurements\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003eThe interaction between depth and distance from the glacier was a significant driver of alpha diversity patterns, with prominent differences along the glacial distance gradient (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u0026amp; \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). At stations closest to the glacier, total abundance, species richness, and Simpson\u0026rsquo;s diversity index all showed negative correlations with depth (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). In contrast, stations furthest from the glacier, these biodiversity metrics displayed strong positive correlations with depth (R\u0026sup2; = 0.75, 0.87, and 0.38, respectively; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Tables\u0026nbsp;6 \u0026amp; 7). Stations at intermediate distances from the glacier exhibited transitional patterns between these two extremes. On the other hand, seaweed species richness showed a negative relationship with depth across all distances from the glacier, indicating that although glacial proximity affects the absolute species richness, it does not affect the bathymetric trend (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTotal abundance (\u003cem\u003eN\u003c/em\u003e), species richness (\u003cem\u003eS\u0026prime;\u003c/em\u003e), and Simpson\u0026rsquo;s biodiversity index (\u003cem\u003eD\u003c/em\u003e)\u0026thinsp;\u0026plusmn;\u0026thinsp;SE, grouped by 10 m depth increments and distance from the glacier for faunal species studied at Collins Bay, King George Island. Data from four replicate frames are averaged per depth bin.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"24\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c17\" colnum=\"17\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c18\" colnum=\"18\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c19\" colnum=\"19\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c20\" colnum=\"20\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c21\" colnum=\"21\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c22\" colnum=\"22\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c23\" colnum=\"23\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c24\" colnum=\"24\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"23\" nameend=\"c24\" namest=\"c2\"\u003e \u003cp\u003eDistance (km)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.75\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"7\" nameend=\"c13\" namest=\"c7\"\u003e \u003cp\u003e0.75\u0026ndash;1.25\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c18\" namest=\"c14\"\u003e \u003cp\u003e1.25\u0026ndash;1.75\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c24\" namest=\"c19\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;1.75\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepth (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e\u003cem\u003eS\u0026rsquo;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c9\" namest=\"c7\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003e\u003cem\u003eS\u0026rsquo;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c15\" namest=\"c14\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c17\" namest=\"c16\"\u003e \u003cp\u003e\u003cem\u003eS\u0026rsquo;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c18\"\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c21\" namest=\"c19\"\u003e \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c23\" namest=\"c22\"\u003e \u003cp\u003e\u003cem\u003eS\u0026rsquo;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c24\"\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e0\u0026ndash;10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e39.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e7.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e10\u0026ndash;20\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e105.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e8.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e44.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;8.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e8.10\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;1.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e37.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003e13.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e23.25\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;5.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e7.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;2.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.113\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e20\u0026ndash;30\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e81.30\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;12.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e6.70\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.39\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e51.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;16.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e10.40\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;4.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e27.57\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;2.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003e8.43\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e26.93\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e9.93\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.79\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e30\u0026ndash;40\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e46.60\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;16.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e8.10\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e82.80\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e12.30\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e58.14\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;17.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003e12.93\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;3.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e \u003cp\u003e0.72\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e53.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e11.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e40\u0026ndash;50\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e17.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e5.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e74.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e8.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e0.68\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e43.25\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003e13.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e \u003cp\u003e0.83\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e42.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e12.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e50\u0026ndash;60\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e132.86\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;55.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e7.43\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;3.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.52\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e77.75\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e7.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e0.52\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e102.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e \u003cp\u003e24.67\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e299.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e32.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e60\u0026ndash;70\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e30.57\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e5.71\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e192.80\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e32.30\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e70\u0026ndash;80\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e6.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c16\" namest=\"c15\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c19\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c20\"\u003e \u003cp\u003e462.50\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c22\" namest=\"c21\"\u003e \u003cp\u003e36.17\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c24\" namest=\"c23\"\u003e \u003cp\u003e0.69\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSpecies richness\u0026thinsp;\u0026plusmn;\u0026thinsp;SE grouped by 10 m depth increments and distance from the glacier for seaweed species studied at Collins Bay, King George Island. Data from four replicate frames are averaged per depth bin.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"7\" nameend=\"c8\" namest=\"c2\"\u003e \u003cp\u003eDistance (km)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepth (m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.75\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e0.75\u0026ndash;1.25\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e1.25\u0026ndash;1.75\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;1.75\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e0\u0026ndash;10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10.83\u0026thinsp;\u0026plusmn;\u0026thinsp;2.57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e10\u0026ndash;20\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e8.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e6.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e12.70\u0026thinsp;\u0026plusmn;\u0026thinsp;1.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e20\u0026ndash;30\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.83\u0026thinsp;\u0026plusmn;\u0026thinsp;4.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e9.17\u0026thinsp;\u0026plusmn;\u0026thinsp;2.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e4.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e11.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e30\u0026ndash;40\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e6.90\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e3.13\u0026thinsp;\u0026plusmn;\u0026thinsp;2.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e8.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e40\u0026ndash;50\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e2.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e1.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e50\u0026ndash;60\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.20\u0026thinsp;\u0026plusmn;\u0026thinsp;1.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e2.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e3.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e60\u0026ndash;70\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003e8.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e6.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e70\u0026ndash;80\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e0.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eCanonical Component Analysis\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003eThe Canonical Component Analysis\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e (CCA; Supplementary Tables\u0026nbsp;8 to 10) revealed that environmental drivers collectively explained 86.89% of the variation in benthic community structure (scaled χ\u0026sup2; = 1.60) across the stations (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The first two constrained axes accounted for 71.10% of the total inertia, effectively fitting taxa along the environmental gradients. Notably, Polychaeta displayed a strong negative loading on CCA1 (\u0026ndash;1.70), suggesting an affinity for deeper, denser, more saline waters. In contrast, Annelida, Nemertea, and Echinodermata showed positive loadings on CCA1 (0.55, 0.54, and 0.51, respectively), indicative of a preference for shallower, algae-rich environments (mostly Rhodophytes) further from the glacier. These three taxa have high adult mobility.\u003c/p\u003e \u003cp\u003eFurthermore, Mollusca scored positively on both axes (CCA1: 0.45; CCA2: 0.93), reflecting an association with warmer nearshore habitats with high algae presence. Conversely, Perciformes (CCA1: \u0026minus;\u0026thinsp;0.52; CCA2: \u0026minus;\u0026thinsp;0.57) and Arthropoda (CCA1: 0.30; CCA2: \u0026minus;\u0026thinsp;0.74) were more characteristic of distal, glacially influenced conditions.\u003c/p\u003e \u003cp\u003eThree station clusters were identified based on community composition. The first comprised stations C1, B2, and C2, representing deep sites near the glacier dominated by Polychaeta. The second included stations B1, A1, and C3, which were shallower sites near the glacier, characterised by Bivalvia. The third cluster encompassed all remaining stations, spanning a broad depth range further from the glacier.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMobility and functional traits\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn shallow waters (10\u0026ndash;20 m), animals at sites further from the glacier consistently exhibit significantly higher mobility compared to those at sites closest to the glacier. For example, between \u0026lt;\u0026thinsp;0.75 km and 0.75 to 1.25 km, adult mobility differs by 1.49 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Table\u0026nbsp;11). Tukey post-hoc comparisons reveal a complex pattern of adult mobility variation across depth and distance from the glacier. Similar patterns were observed within the upper 40 m; however, at deeper sites, only animals located more than 1.25 km from the glacier show increased mobility compared to proximity to the glacier, although overall mobility remains lower than in shallower areas (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e left). This significant depth\u0026ndash;distance interaction (Two-Way ANOVA; F\u003csub\u003e260,7\u003c/sub\u003e = 12.09; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Table\u0026nbsp;11) underscores that both depth and distance from the glacier jointly shape adult mobility patterns.\u003c/p\u003e \u003cp\u003eA shift in larval developmental strategies was also observed along these gradients. Larval types transition from lecithotrophic to planktotrophic with increasing depth and greater distances from the glacier, a pattern that reversed at near-glacier sites (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, right). This interaction was statistically significant (Two-Way ANOVA; F\u003csub\u003e237,14\u003c/sub\u003e = 5.59, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Table\u0026nbsp;11), indicating that glacial influence modulates how depth affects larval strategy. Notably, none of the samples approach a value of 1, which indicates a general absence of direct development (egg laying and/or brooding taxa) throughout the faunal dataset.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFunctional feeding modes varied significantly with depth and distance from the glacier (PERMANOVA; F\u003csub\u003e260,7\u003c/sub\u003e = 10.329; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; Supplementary Table\u0026nbsp;12). Close to the glacier, filter and suspension feeders dominated the benthic community, together accounting for at least 77.13% of feeding modes within each depth bin. However, their numbers declined sharply with increasing distance, encompassing only 9.52% of feeding modes in shallow waters at \u0026gt;\u0026thinsp;1.75 km from the glacier (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). In the same sample, predators (41.04%) and grazers (32.38%) were the most prominent functional groups. Notably, the relative abundance of deposit feeders and opportunists increased farther from the glacier. For instance, deposit feeders increased from approximately 3.70% in near-glacier shallow waters to about 6.89% at \u0026gt;\u0026thinsp;1.75 km, while opportunists increased from 1.84\u0026ndash;4.01%. These patterns suggest that communities located farther from the glacier exhibit a more even and functionally diverse distribution of feeding modes compared to those closer to glacial influence.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study provides the first detailed assessment of benthic biodiversity in Collins Bay, a site located in one of the most logistically and touristically active areas in the Antarctic\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e but which has remained relatively understudied\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Our results showed how bathymetry and glacial proximity are the main factors influencing species composition and functional traits. Species richness increased with depth and distance from the glacier, but no strict zonation was observed, supporting the hypothesis that environmental gradients drive continuous rather than discrete zones in benthic community structures\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. Despite the relatively small spatial extent of the surveyed area in Collins Bay, we found considerable heterogeneity, supporting the hypothesis that local environmental conditions shape the benthos rather than large-scale processes\u003csup\u003e\u003cspan additionalcitationids=\"CR35\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe patterns observed in this study align with broader regional findings while offering new insights into fine-scale biodiversity dynamics. A similar study by Kim et al.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e documented spatial variation in benthic megafauna structure and function across Marian Cove, adjacent to Collins Bay, driven by depth and distance from the glacier. Although their results reflect comparable patterns, the degree of heterogeneity reported there was somewhat less pronounced. This difference may stem from spatial design, as sampling stations were primarily concentrated within the same sector of the cove. Such spatial clustering, despite the study\u0026rsquo;s depth gradient, focused more on local glacial retreat instead of broader glacial influences. Another study that incorporates Collins Bay as well as other areas of Maxwell Bay by Valdivia et al.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e has documented biodiversity patterns across the region but lacked the fine-scale depth resolution achieved in this study. Their sampling at a single station within Collins Bay found lower species richness than elsewhere in Maxwell Bay, consistent with our findings that biodiversity declines with increasing proximity to the glacier. However, differences in methodology, such as their use of dredge sampling versus the video-based approach, may explain some differences in species richness, particularly for taxa living in crevices or beneath seaweed canopies, which are not visible through imaging. Notably, our survey revealed three times the number of seaweed taxa reported by Valdivia et al.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e, and double the number reported by Newcombe \u0026amp; C\u0026aacute;rdenas\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e in the same area, underscoring the strength of video surveys in capturing algal diversity.\u003c/p\u003e \u003cp\u003eValdivia et al.\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e reported water turbidity to be higher near the surface and concluded it as a potential explanation for the observed increased biodiversity at greater depths. Several studies have shown that sedimentation exerts multiple stressors on benthic communities\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e, including increased mineral discharge, which can induce oxidative stress and metal accumulation in filter feeders (e.g. \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e), as well as reduce food availability and clog feeding structures\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. Our findings are in accordance with these previous observations, as higher species richness and abundance were found in deeper waters and further from the glacier. This pattern was similarly noted as an explainable factor by Kim et al.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e in Marian Cove, an area which is adjacent to Collins Bay. However, an opposite trend close to the glacier was also observed in our study, with species richness peaking in shallow waters. This pattern was primarily driven by the presence of molluscs (\u003cem\u003eL. elliptica\u003c/em\u003e and \u003cem\u003eN. concinna\u003c/em\u003e), ascidians and echinoderms (\u003cem\u003eO. validus\u003c/em\u003e and \u003cem\u003eNeosmilaster\u003c/em\u003e sp.). The dominance of pioneer species such as molluscs is expected, as they can bury themselves and thus avoid ice impact, as noted in Potter Cove by Sahade et al.\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Furthermore, the mobility of echinoderms may allow them to actively seek favourable conditions. Similarly, the high relative abundance of ascidians near the glacier reflects findings by Kim et al.\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e and Sahade et al.\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e who reported peak ascidian densities at around 30 m depth in Marian Cove and Potter Cove, respectively.\u003c/p\u003e \u003cp\u003eAlthough Antarctic coastal waters are generally well mixed, subglacial discharge from the marine-terminating Collins Glacier may locally alter circulation and enhance nutrient availability\u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. Such discharge may carry nutrients, like iron, organic matter, and sediments from beneath the ice sheet\u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e, which interacts with intrusions of relatively warmer subsurface waters during the flood time in the head of the bay\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e, increasing phytoplankton biomass and primary production in nearshore areas\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e and supporting unexpectedly high biodiversity close to glacier fronts due to pelagic-benthic coupling\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. However, it is also plausible that the discharge itself is driven by meteorological and oceanographic forcing, including wind and offshore intrusions of warm deep water\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e, rather than acting as a primary driver of circulation. Further investigations into nutrient fluxes, chlorophyll concentrations and water column structure are needed to better understand the underlying processes.\u003c/p\u003e \u003cp\u003eThe significance of primary producers in shaping benthic communities cannot be underestimated. Larger macroalgal species can facilitate the establishment of benthic organisms in highly disturbed areas\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e, whereas diatoms and filamentous algal aggregates serve as essential food sources in Antarctic ecosystems, impacting energy transfer throughout the benthic food web\u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. In addition to their ecological function, diatoms are increasingly recognised as sensitive indicators of environmental change, particularly concerning glacial influence\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. In Collins Bay, their abundance peaked at intermediate depths (20\u0026ndash;40 m) near the glacier (\u0026lt;\u0026thinsp;0.75 km) and declined both with increasing depth and distance, mirroring patterns reported in Marian Cove, King George Island\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e and South Bay, Doumer Island\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. These studies describe massive blooms of filamentous colonial diatoms at similar depths, where environmental conditions are favourable for growth. The higher diatom presence in glacially influenced zones of Collins Bay may likewise reflect nutrient pulses or stabilised substrates in areas of moderate disturbance. Such blooms are thought to be linked to changing salinity, temperature, and stratification caused by ice melt\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e,\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. Their rapid response to environmental variability highlights benthic diatoms as valuable indicators of ecosystem change, with future shifts in primary production and food-web structure likely to follow patterns of glacial retreat.\u003c/p\u003e \u003cp\u003eThe widespread distribution of diverse algal assemblages, particularly Desmarestiales and Chlorophyceae, suggests that primary productivity remains relatively high despite glacial influence. This aligns with the findings of Quartino et al.\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e, who observed that macroalgal community structure in Antarctic coastal environments is primarily shaped by depth, substrate type, and irradiance, with salinity and nutrient availability playing a lesser role. Ice scouring further contributes to spatial patchiness in these communities. In Collins Bay, species richness generally declined with increasing depth, consistent with reduced irradiance as a limiting factor (e.g. \u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e). Interestingly, further from the glacier, a slight increase in algal richness was observed at greater depths, possibly reflecting reduced ice disturbance, which is similar to what was found by Quartino et al.\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e in Potter Cove, the eastern part of KGI. Despite this, no clear trend emerged concerning glacial distance, suggesting that spatial heterogeneity and patchiness play a significant role in structuring local algal biodiversity. For example, shallow stations near the glacier (A1, B1, and C3) hosted diverse communities, including Desmarestiales, Chlorophyceae, and diatomaceous films. However, \u003cem\u003eP. decipiens\u003c/em\u003e, a known glacial opportunist found in Marian Cove\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e,\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e, Half Moon Island\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e, and Potter Cove\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e, and even found in deep waters\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e, was relatively scarce (relative abundance: \u0026lt; 5%) in our study. This challenges expectations that pioneer species would dominate these extreme environments and suggests that local conditions may favour a broader range of algal ecological baselines for future shifts in benthic community structure. Notably, recent observations by Amsler et al.\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e revealed rapid shifts in macroalgal cover in the Palmer Archipelago over just four years, emphasising that Antarctic seaweed communities are highly dynamic.\u003c/p\u003e \u003cp\u003eBeyond species richness, functional diversity exhibited a clear depth gradient, with mobile taxa becoming increasingly present farther from the glacier. Previous studies suggest that high-disturbance environments near glaciers should favour mobile species capable of recolonising after episodic sedimentation events\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e; however, our CCA results revealed an opposite pattern. Sessile filter feeders dominated deeper glacial-proximal habitats, while mobile taxa \u0026ndash; including arthropods, echinoderms, and nemerteans \u0026ndash; were more abundant at stations further away from the glacier. One possible explanation is that dominant filter feeders in deep glacial sites exhibit low adult mobility and limited larval dispersal, leading to a reliance on self-recruitment and local population stability\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e. Filter-feeders are found in deeper sites all around KGI\u003csup\u003e\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e\u003c/sup\u003e, and are often a cause for an increase in local heterogeneity by increasing the available surface\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. The latter is particularly significant in habitats like Collins Bay, where over 83% of samples consist of mud and show no significant correlation between species distribution and substrate type. The high number of filter feeders thus reinforces the high patchiness found in Collins Bay, which is often seen in Antarctic fjord ecosystems\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. To continue, the increase in mobile taxa with glacier distance corresponds to a rise in functional group diversity, as observed in Marian Cove by Kim et al.\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, suggesting a consistent trend across Antarctic fjord systems.\u003c/p\u003e \u003cp\u003eDisturbance and bathymetry can also influence reproductive and feeding strategies. In many systems, fauna typically declined with increasing disturbance, while scavengers and species with high dispersal potential became dominant in shallow, high-disturbance areas. In Collins Bay, however, sessile taxa remained dominant even in deeper glacial-proximal habitats, suggesting site-specific differences in disturbance regimes or resource availability. While highly disturbed environments are often associated with species exhibiting pelagic larval development due to their rapid recolonisation potential\u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e,\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e\u003c/sup\u003e, our findings indicate a mix of reproductive strategies across depths, possibly reflecting local adaptations to environmental conditions. Additionally, the increasing relative abundance of deposit feeders and opportunists with distance from the glacier suggests a shift in resource use and trophic structuring, reinforcing the importance of functional diversity in shaping benthic community composition in glacial fjords.\u003c/p\u003e \u003cp\u003eNotably, most functional diversity studies to date have focused on terrestrial vegetation, leaving research gaps in our understanding of marine ecosystems\u003csup\u003e\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e. While some studies have examined broad-scale patterns such as the latitudinal gradient\u003csup\u003e\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e\u003c/sup\u003e, the influence of substrate on functional groups\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e, or large-scale patterns in Arctic regions\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e, high-resolution studies that compare functional diversity along depth and glacier gradients remain largely absent. The findings presented here thus provide a valuable baseline for understanding functional diversity in Antarctic benthic communities.\u003c/p\u003e \u003cp\u003eDespite similar depths and distances from the glacier, stations C4 (fjord inflow) and A3 (fjord outflow) exhibited no significant differences in species composition. This contrasts with observations from other polar regions, where strong hydrodynamic forcing influences larval transport and community connectivity\u003csup\u003e\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e,\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e\u003c/sup\u003e. Instead, our results suggest that in Collins Bay, local habitat conditions and heterogeneity probably exert a stronger influence on community structure than broader oceanographic processes, reinforcing the need for high-resolution ecological and oceanographic assessments.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study provides the first fine-scale assessment of benthic biodiversity in Collins Bay, revealing how bathymetry and proximity to the glacier are key drivers of species composition and functional diversity. While species richness increased with depth and distance from the glacier, localised heterogeneity and environmental complexity disrupted clear zonation patterns. The site-specific differences in species composition suggest that small-scale environmental variability plays a stronger role than large-scale oceanographic processes, which was reconfirmed with unexpectedly high biodiversity in shallow, glacial proximal sites and diverse seaweed assemblage presence. Interestingly, functional diversity followed a depth-related trend, with sessile filter-feeders dominant in deeper glacial-proximal habitats and mobile taxa more abundant further from the glacier. Given the rapid pace of glacial retreat in the Antarctic Peninsula\u003csup\u003e\u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e,\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e\u003c/sup\u003e, continued monitoring of benthic communities in Collins Bay is essential for tracking ecosystem responses to climate-driven environmental change, especially in areas with a high human footprint\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e\u003c/sup\u003e. High-resolution biodiversity assessments such as this provide a crucial baseline for future conservation efforts and improve our understanding of how Antarctic benthic ecosystems will adapt to a changing climate.\u003c/p\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003cp\u003eAll data processing and statistical analyses were performed in r (RStudio 2023.06.2, build 561).\u003c/p\u003e \u003c/div\u003e"},{"header":"Methods","content":"\u003ch2\u003eStudy site\u003c/h2\u003e\n\u003cp\u003eSampling was conducted in Collins Bay (62.177\u0026deg;S, 58.826\u0026deg;W), a semi-enclosed cove approximately 3 \u0026times; 3 km in size, located within Maxwell Bay, one of the two major fjords systems on KGI, South Shetland Islands (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e). The bay reaches depths of up to 190 metres at the central part of its mouth. Collins Glacier, a small ice dome covering approximately 15 km\u0026sup2; with a maximum elevation of 270 metres, influences the southeastern region of the bay\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e74\u003c/span\u003e\u003c/sup\u003e. The glacier\u0026rsquo;s catchment area spans roughly 50 km\u0026sup2;, and it directly influences the adjacent coastal zone through both land-terminating and tidewater-terminating fronts\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e74\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e75\u003c/span\u003e\u003c/sup\u003e. Stations were selected in Collins Bay to ensure that each depth profile (0\u0026ndash;80 m depth) overlapped with each distance from the glacier (ranging from 0 to 3 km), creating a completely crossed design.\u003c/p\u003e\n\u003ch2\u003eROV surveying procedures\u003c/h2\u003e\n\u003cp\u003eTo assess biodiversity non-invasively, twelve ROV video surveys were conducted in December 2024 in Collins Bay using the FIFISH V6 EXPERT and FIFISH V6 PRO by QYSEA \u0026amp; FiFish. Both ROVs were equipped with a UHK 4K underwater camera (12-megapixel resolution, 166\u0026deg; ultra-wide field of view) flanked by two 6000-lumen LED lights to ensure consistent illumination. Each transect included at least 35 frames, captured with the ROV positioned at a stable 0.5 m height above the seafloor to avoid disturbing the sediment. Each transect followed a butterfly pattern with a maximum radius of 50 m from a central starting point where the Zodiac was anchored, or in deeper waters, kept at the same coordinates.\u003c/p\u003e\n\u003ch2\u003eVideo analysis\u003c/h2\u003e\n\u003cp\u003eA total of 678 frames were distinguished from the video-transects of 12 stations in Collins Bay (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e ). For each frame, depth from the ROV screen and substrate type (mud, pebble, cobble, or boulder) were noted. Depth ranged from 6.6 to 78.8 m. All recognisable epibenthic megafauna (approximately\u0026thinsp;\u0026gt;\u0026thinsp;1 cm) were counted and identified to the lowest possible taxonomic level using standard flora and fauna guides\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e76\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e79\u003c/span\u003e\u003c/sup\u003e and online databases (e.g. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.marinespecies.org\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.fishbase.se\u003c/span\u003e\u003c/span\u003e). Colonial species were counted as one, except when physically separated by sediment or other organisms. Due to the inability to distinguish individual thalli in video imagery, seaweeds were not quantified as discrete individuals. Instead, we use the term seaweed as an overarching term including macroalgae, diatoms (film/mats), and encrusting coralline algae (CrCa), enabling comparison with faunal groups in subsequent analyses.\u003c/p\u003e\n\u003ch2\u003eEnvironmental data\u003c/h2\u003e\n\u003cp\u003eConductivity\u0026ndash;temperature\u0026ndash;depth (CTD) profiles were recorded using a DST CTD by Star Oddi while the ROV conducted transects to capture \u003cem\u003ein-situ\u003c/em\u003e water characteristics. Measurements were taken every ten seconds during descent. Sensor accuracies for conductivity, temperature, and salinity were \u0026plusmn;\u0026thinsp;1.5 mS/cm, \u0026plusmn;\u0026thinsp;0.1\u0026deg;C, and \u0026plusmn;\u0026thinsp;0.1 PSU, respectively, while the depth accuracy, determined via pressure, was \u0026plusmn;\u0026thinsp;0.6% over the entire range. Consequently, the first 0.5 m of measurements (from the bottom) were removed from the dataset. Salinity was calculated as practical salinity (PSS-78) from conductivity, and similarly, potential density anomaly (\u0026sigma; in kg/m\u0026sup3;) and potential temperature (\u0026theta; in \u0026deg;C) were derived from the CTD data.\u003c/p\u003e\n\u003cp\u003eTo capture water characteristics unaffected by daily fluctuations, all stations were sampled in a clockwise sequence, using a SonTek CastAway\u0026reg; CTD. This device offers an accuracy of \u0026plusmn;\u0026thinsp;0.05\u0026deg;C and \u0026plusmn;\u0026thinsp;0.1 PSU, operates at a 5 Hz sampling rate, and includes an integrated GPS for georeferenced casts.\u003c/p\u003e\n\u003ch2\u003eData analysis\u003c/h2\u003e\n\u003cp\u003eTo represent the local communities furthest from the glacier at a small scale over the sampled range, faunal counts were summed by order/phylum in 10 m depth intervals, covering the entire water column within an area of approximately 0.1 km\u0026sup2;.\u003c/p\u003e\n\u003cp\u003eTo understand the proportions of flora and fauna over the entire Collins Bay, data from all stations were combined and categorised into 20 m depth bins and four distance ranges from the glacier. Faunal abundance was summed within each depth\u0026ndash;distance bin, while seaweeds were merged to represent presence/absence within each depth-distance range.\u003c/p\u003e\n\u003cp\u003eTo accurately calculate the alpha-biodiversity index, data from four frames within a similar 10 m depth range were combined per station to create replicates. For each replicate, mean depth was calculated and used for subsequent analysis. Total abundance, species richness, and Simpson\u0026rsquo;s diversity index were derived from these replicates. A Principal Component Analysis (PCA) and further ANOVA tests were used to evaluate significant substrate type effect. Subsequently, two-way ANOVAs were performed using depth and distance as categorical variables to test their effects on biodiversity metrics\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e80\u003c/span\u003e\u003c/sup\u003e. The best‐fitting models were selected based on the lowest Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) values. These models were then used to predict biodiversity response across the range of observed depths and distances from the glacier.\u003c/p\u003e\n\u003cp\u003eA Canonical Correspondence Analysis (CCA\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e) was conducted to investigate environmental drivers of community composition across the twelve sampling stations. Relative abundance data were used for 35 samples to ensure balanced sampling effort, as some stations had up to 50 samples. Initial tests indicated that the model fit improved when seaweed presence/absence data were included as environmental explanatory variables alongside CTD measurements of December 21st, 2024. For each station, the deepest CTD values were used to represent environmental benthic conditions, incorporating temperature (\u0026deg;C), salinity (PSU), potential density (kg/m\u0026sup3;), and depth (m)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Distance from Collins Glacier (km) was also added as an environmental explanatory variable.\u003c/p\u003e\n\u003cp\u003eBuilding on the above approaches, functional traits of organisms (e.g. adult mobility and larval type) were incorporated to further clarify community structure. The mean trait value per community (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:mT\\)\u003c/span\u003e\u003c/span\u003e) was computed as a weighted average of species-specific trait values, with the species\u0026rsquo; relative abundances serving as weights:\u003c/p\u003e\n\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equa\" class=\"mathdisplay\"\u003e$$\\:mT\\:=\\sum\\:_{i=1}^{S}{p}_{i}{x}_{i}$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eHere, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{x}_{i}\\)\u003c/span\u003e\u003c/span\u003e represents the trait value of the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:i\\)\u003c/span\u003e\u003c/span\u003e-th species. For binary traits, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{x}_{i}\\)\u003c/span\u003e\u003c/span\u003e takes on values of 0 or 1. For categorical traits, a fuzzy coding method was used\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e81\u003c/span\u003e\u003c/sup\u003e (Supplementary Table\u0026nbsp;1), where each taxon was assigned an affinity score (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{a}_{k}\\)\u003c/span\u003e\u003c/span\u003e) for each category (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:1\\:\\le\\:k\\le\\:h\\)\u003c/span\u003e\u003c/span\u003e), with \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:h\\)\u003c/span\u003e\u003c/span\u003e being the total number of categories for the given trait. Affinity scores ranged from 0 (no affinity) to 3 (high affinity). These scores were converted into a frequency distribution by dividing each \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{a}_{k}\\)\u003c/span\u003e\u003c/span\u003e by the total sum of the affinity scores for that taxon (see 31 for further details. Trait information for faunal species was collected from Robinson et al.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e and adjusted to fit the observed taxa (Supplementary Tables\u0026nbsp;1 \u0026amp; 2).\u003c/p\u003e\n\u003cp\u003eWhen analysing \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:mT\\)\u003c/span\u003e\u003c/span\u003e, the depth range 0\u0026ndash;10 m was excluded due to a lack of replicates. Two-way ANOVAs were used to analyse adult mobility and larval type across depth and distance gradients, and feeding modes were analysed with a PERMANOVA based on Bray-Curtis dissimilarity with 9,999 permutations\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e82\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics statement\u003c/h2\u003e \u003cp\u003eThe report presents research on animals that do not require ethical approval for their study.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests statement\u003c/h2\u003e \u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eINACH \u0026lsquo;Marine Protected Areas\u0026rsquo; Program (2409052) and ANID/Millennium Science Initiative Program \u0026ndash; ICN2021_002.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eD.B.J., C.A.C conceived the study. D.B.J. and A.H.S. conducted field sampling. D.B.J performed the video analysis, numerical analysis, creation of figures and tables and writing the manuscript. C.A.C., M.G.A., F.S.C., and M.L. reviewed and edited the overall content of the manuscript. All the authors have been involved with the work and have approved the manuscript for submission.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors acknowledge the expert support and aid of the team at the Chilean Professor Julio Escudero Base and INACH.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data are available in the main text or the Supplementary Information.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGriffiths, H. J. 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A fuzzy coding approach for the analysis of long-term ecological data. \u003cem\u003eFreshw. Biol.\u003c/em\u003e \u003cb\u003e31\u003c/b\u003e, 295\u0026ndash;309 (1994).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson, M. J. A new method for non-parametric multivariate analysis of variance. \u003cem\u003eAustral Ecol.\u003c/em\u003e \u003cb\u003e26\u003c/b\u003e, 32\u0026ndash;46 (2001).\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Colar-water benthos, environmental drivers, habitat heterogeneity, functional diversity, community composition.","lastPublishedDoi":"10.21203/rs.3.rs-6908361/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6908361/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Antarctic Peninsula\u0026rsquo;s coastal benthic ecosystems are shaped by glacial meltwater-driven sedimentation and turbidity, yet high-resolution biodiversity studies across depth gradients remain scarce. Benthic megafauna and seaweeds were surveyed in Collins Bay, King George Island, using ROV video transects (10\u0026ndash;80 m depth) and analysed for biodiversity and community composition in relation to environmental factors. Our results show that glacial proximity and bathymetry shape the benthic communities, with biodiversity increasing with both depth and distance from the glacier. Unexpectedly, species richness was high in shallow glacier-proximal areas, possibly due to a nutrient pump by wind-driven upwelling events enhancing local productivity and resource availability. Functional diversity followed a depth-related trend and interestingly showed sessile filter-feeders being dominant in deeper glacial-proximal habitats, while mobile taxa were more abundant further from the glacier. The prevalence of diverse seaweed assemblages highlights the role of primary productivity in structuring these communities. Site-specific differences in species composition suggest that small-scale environmental variability plays a stronger role than large-scale oceanographic processes. These findings highlight the need for continued monitoring, as glacial retreat will likely reshape these ecosystems, altering biodiversity patterns and functional composition in the coming decades.\u003c/p\u003e","manuscriptTitle":"Environmental drivers of benthic biodiversity in Collins Bay (King George Island), Antarctica: evidence for small- scale community structuring","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-24 10:22:09","doi":"10.21203/rs.3.rs-6908361/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-07T04:55:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-20T14:04:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-19T15:43:12+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-16T11:49:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"256578725948194811516726836919749948388","date":"2025-11-25T13:05:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"331304242849447832089595263930183922371","date":"2025-11-24T09:18:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"94511094331381500692731324658772947382","date":"2025-11-23T19:44:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"259468332298601351044050658571500011959","date":"2025-11-23T01:52:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"25487892711616183050436627378720249319","date":"2025-11-11T07:57:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"148064549280163775954014878993588760339","date":"2025-08-07T11:21:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-07T11:32:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"325906573951607578301125517034963696548","date":"2025-06-25T19:36:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-24T15:01:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-24T14:59:47+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-18T09:36:45+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-18T03:56:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-06-16T20:06:18+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5e4b53f5-5354-4859-94d7-00feeecd2130","owner":[],"postedDate":"June 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":50231826,"name":"Biological sciences/Ecology/Biodiversity"},{"id":50231827,"name":"Biological sciences/Ecology"}],"tags":[],"updatedAt":"2026-05-04T16:04:54+00:00","versionOfRecord":{"articleIdentity":"rs-6908361","link":"https://doi.org/10.1038/s41598-026-49555-3","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-04-30 15:58:37","publishedOnDateReadable":"April 30th, 2026"},"versionCreatedAt":"2025-06-24 10:22:09","video":"","vorDoi":"10.1038/s41598-026-49555-3","vorDoiUrl":"https://doi.org/10.1038/s41598-026-49555-3","workflowStages":[]},"version":"v1","identity":"rs-6908361","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6908361","identity":"rs-6908361","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}