Responses of South Caspian Coastal Foraminifera to Warming: Spatial Patterns and Assemblage Shifts

Responses of South Caspian Coastal Foraminifera to Warming: Spatial Patterns and Assemblage Shifts | 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 Responses of South Caspian Coastal Foraminifera to Warming: Spatial Patterns and Assemblage Shifts Hossein Bagheri, Mehrshad Taheri This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7499422/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Feb, 2026 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract This study investigated the spatial distribution of coastal foraminifera at four stations, identifying seven distinct species representing five genera and three families, with Ammonia beccarii caspica as the dominant species. The Bandar Gaz station exhibited the highest density, species richness, evenness, and Shannon diversity. Consequently, Bandar Gaz was selected for a controlled field experiment examining benthic foraminiferal community responses to increased surface water temperature (20°C, 24°C, 27°C, and 30°C) over 60 days. While the highest total density and evenness were observed at 30°C, the total number of species and Margalef and Shannon indices did not significantly differ among treatments. Temperature changes significantly altered community structure through shifts in species dominance. Ammonia beccarii displayed resilience and increased dominance with higher temperatures, replacing other species. Elphidum advenum density decreased significantly at 30°C, while Ammonia tepida increased in dominance with rising temperatures. These findings highlight temperature-driven alterations in foraminiferal assemblages, with implications for coastal ecosystem monitoring in the context of climate change. Earth and environmental sciences/Climate sciences Biological sciences/Ecology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Ocean sciences Caspian Sea Temperature Foraminifera Sediments Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Global ocean warming, an undeniable outcome of climate change, poses a significant and increasing danger to marine ecosystems globally and even to isolated aquatic environments (Maslin., 2008;Venegas et al., 2023 ).The Caspian Sea, the world's largest inland water body, exemplifies this vulnerability, displaying elevated temperatures that contribute to sea level fall and substantial ecological instability(Bagheri et al., 2019; Arpe et al., 2020 ; Lahijani et al., 2024). Notably, the southern Caspian is undergoing rapid warming (Roshan et al., 2012 ; Azizpour and Ghaffari., 2023), resulting in shifts in species distribution, disrupted reproductive cycles, and altered migration patterns, all of which threaten the region's unique biodiversity (Taheri et al., 2025 ). Rising water temperatures threaten the ecological integrity of benthic coastal annimals as foraminifera, key sensitive organisms in marine ecosystems (Danovaro et al., 2001 , 2004 ; Moens et al., 2013 ). Climate models predict worsening conditions, with rising temperatures and diminishing rainfall compounding the Caspian Sea's recession and further endangering its delicate ecosystems. These changes are projected to significantly impact benthic foraminifera, crucial indicators of marine health, affecting their distribution, abundance, biodiversity, and community structure. Given the Caspian Sea's importance as a biodiversity hotspot, the current lack of research on foraminifera, particularly along its southeastern coasts, represents a critical deficiency in our understanding and ability to safeguard this vulnerable ecosystem. Foraminifera serve as valuable proxies in both modern and paleo-environmental reconstructions, as evidenced by numerous studies (Mojtahid et al., 2009 ; Bouchet et al., 2012 ; Dolven et al., 2013 ; Duffield et al., 2015 ; Nordberg et al., 2017 ; Polovodova Asteman and Nordberg, 2013 ). While field observations provide extensive data, laboratory experiments elucidating foraminiferal responses to environmental stressors remain relatively limited (Alve and Bernhard., 1995; Altenbach, 1992 ; Elderfield et al., 2006 ; Havach et al., 2001 ; Le Cadre and Debenay., 2006). These controlled studies, some simulating future global change scenarios and others exploring extreme conditions, are crucial for refining proxy calibrations and enhancing our understanding of foraminifera as environmental indicators (Wit et al., 2013 ). Limited research suggests that foraminiferal response to environmental change is either rapid or delayed by several years (Schönfeld & Mendes, 2021). Recent work has also explored temperature-induced shifts in entire benthic foraminiferal communities, documenting changes in species composition and diversity (Dong et al., 2019 ; Goldstein and Alve., 2011). in this study our microcosm experiment investigates how temperature variations influence benthic foraminifera communities, testing the hypothesis that warming significantly alters their structural composition and ecological functions. A controlled laboratory experiment was conducted to investigate the effects of elevated temperatures (24, 27, and 30°C) on benthic foraminiferal assemblages from a coastal Caspian Sea community over a 60-day period. This research provides novel experimental data on the response of foraminiferal communities and species richness to temperature stress within a microcosm environment. The findings offer crucial insights into the potential impacts of climate change on Caspian Sea biodiversity, contributing to a better understanding of warming's cascading ecological consequences. Furthermore, this laboratory culture-based study establishes a valuable reference point for both future field investigations and the refinement of paleotemperature reconstruction methodologies. Materials and Methods The Caspian Sea functions as a dynamic, non-tidal lake whose coastal and splash zones are shaped by powerful hydrodynamic processes, particularly wave action and rip currents. This ecologically sensitive region faces mounting pressures from multiple threats: anthropogenic disturbances (including physical habitat modification and pollution), natural stressors (such as coastal erosion and dramatic water level fluctuations), and the escalating impacts of climate change (Lahijani et al., 2023 ; Samant and Prange., 2023). These compounding factors have significantly heightened the ecosystem's vulnerability. Surface water temperatures exhibit extreme seasonal variability, fluctuating between 19.0°C in winter months and rarely reaching to 30.0°C during summer periods (Azizpour and Ghaffari., 2023), creating additional thermal stress on native species. Mazandaran and Golestan province are located in the south Caspian Sea, along the Iranian border.The southern Caspian coastal region supports over 3.5 million residents whose livelihoods depend primarily on agriculture, tourism, and fisheries. In March 2023, we conducted sampling across four stations (Fig. 1) in Mazandaran and Golestan provinces (Bandar Torkaman, Bandar Gaz, Sisangan, and Ramsar) to assess the spatial distribution of benthic foraminifera in this low-biodiversity zone (Taheri et al., 2014a ; Darvish Bastami et al., 2017 ; Taheri et al., 2017a ). The sediment temperature measured with spirit thermometer (precision: 1°C) in the surface sediment (top 1 cm) ranges from 18°C to 22°C, and the annual average temperature is 23°C. At each station, we collected three sediment samples using hand cores (5 cm diameter) from shallow waters (< 0.5 m depth), spaced 5 m apart along the shoreline. Each core penetrated 5 cm into the sediment to capture benthic communities. Samples were preserved in 4% buffered formaldehyde, stained with Rose Bengal(Bernhard, J. M., 2000 ), and analyzed for total density, species richness, Shannon diversity, and evenness. Bandar Gaz station, showing the highest foraminiferal density and species richness, was selected for subsequent experimental work. To investigate temperature effects on benthic foraminifera communities, we collected three replicate sediment samples from Bandar Gaz station using hand corer (5 cm inner diameter). Surface sediments (0–5 cm depth) were subsampled and total organic matter (TOM) determined through loss-on-ignition (550°C for 4 hours) after drying to constant weight at 90°C (Heiri et al., 2001). Sediment grain size distribution was analyzed using a HORIBA-LA950 Particle Size Analyzer (France & Japan). Resulting sediment fractions, categorized as gravel, sand, and silt + clay, were reported as percentage values and defined according to the Folk scale of particle size classification (Folk, 1980 ). Furthermore, dissolved oxygen and pH of the overlying water at each core sampling location were measured in situ utilizing a HACH HQ40d portable multimeter (HACH, USA). Subsequently, 100 mL aliquots of the overlying water were collected from each core for laboratory analysis of nitrate, ammonium, phosphate, and silicate concentrations. These nutrient concentrations were determined spectrophotometrically using an Analytik-jena SPECORD-210 spectrophotometer, adhering to standard analytical protocols outlined in APHA ( 2005 ). Sediment samples for biological analysis were collected along the coastal shoreline, maintaining a minimum distance of 5 meters between sampling points. Twelve hand corers (internal diameter: 5 cm) were extracted to a depth of 10 cm within the splash zone (water edge ± 0.5 m) at Bandar Gaz, where the water temperature was 22°C. Three cores were immediately processed in situ: these were sliced into 1 cm intervals down to a depth of 5 cm, and each slice was preserved in a buffered 4% formaldehyde solution. These field control (FC) samples were intended to preserve the characteristics of the foraminifera community at the time of collection (Taheri et al., 2014b ; Taheri et al., 2024 ). The remaining nine cores were sealed at the bottom with rubber stoppers, covered with perforated plastic lids, and transported to the laboratory within 30 minutes. In the laboratory, the cores were randomly assigned to three separate 70-liter tanks. Each tank was filled with filtered seawater (38 µm filter) collected from the sampling site and maintained at 20°C for five days (Gingold et al., 2013 ). During this period, the temperature within each tank was kept constant via a 200W aquarium heater, and water homogenization was achieved by bubbling airstones, placed above the heaters, using an air pump (Gingold et al., 2013 ). In On the initial day of the experiment, and again after a 60-day incubation period prior to sediment slicing, dissolved oxygen and pH levels in the overlying water of each core were assessed using a portable multimeter (HACH HQ40d, USA). Additionally, 100 ml water samples were extracted from each core for the quantification of nitrate, ammonium, phosphate, and silicate concentrations, employing previously established methodologies. Following the 60-day incubation, Foraminifera were picked up with a fine brush and stored on micropaleontological slides. Species were identified and counted with a stereomicroscope, in accordance with previously reported techniques (Lei et al., 2017a ; Lei and Li, 2014). Foraminifera were carefully extracted using a fine brush and mounted on micropaleontological slides.In addition, dead specimens in all samples were picked up and counted in order to explore the percentage of living specimens in the foraminiferal assemblages. 2-1-Statistical analyses Statistical analyses were performed using PRIMER v6 with the PERMANOVA + add-on. At each sampling station and for each experimental treatment, species richness, Shannon diversity (H', loge), and Pielou's evenness (J) were calculated. Differences in univariate measures (total Foraminifera density, species richness, H, J) and multivariate community structure across stations and treatments were assessed using one-way PERMANOVA (Taheri et al., 2014b ). Significant PERMANOVA results were followed by Monte Carlo pairwise comparisons (Anderson et al., 2008 ). Bray-Curtis similarity was used to construct Non-metric Multidimensional Scaling (nMDS) plots, visualizing total and vertical Foraminifera community structure. Dominant species were identified as those comprising ≥ 5% of the assemblage at their minimum abundance temperature. Results The presence of Foraminifera was confirmed across all sediment sampling locations. Subsequent analysis of collected samples identified seven distinct benthic species, belonging to five genera and three families, there by demonstrating the diversity of these organisms within the studied environment. Ammonia beccarii caspica, Ammonia tepida, Ammonia parkinsoniana, Elphidum advenum, Elphidium excavatum, Elphidum littorale caspicus, and Cornuspira sp which were subsequently analyzed to characterize the foraminiferal community. The highest and lowest of density of foraminifera respectively observed at station Bandar Gaz (2497.5 individual /0.1m 2 ) and (7.33 individual /0.1m 2 ) at Sisangan station. Ammonia beccarii caspica was the dominant species in all sampling stations. Ammonia tepida and Ammonia parkinsoniana were not very abundance such as Ammonia beccarii . Elphidium littoraleca spicus was observed in all stations and had the most abundance after Ammonia beccarii caspica in the sampling area. Elphidium excuavatum and Ammonia parkinsoniana . were rarely to compare with Elphidium littorale . Cornuspira sp only was observed in Bandar Torkaman. Principal Component Analysis of environmental analysis revealed that the first two principal components (PC1 and PC2) accounted for 84.90% of the total variance. Within PC1, silt and salinity exhibited notable negative loadings (-0.422), while temperature showed a significant positive loading (0.46). In PC2, dissolved oxygen (0.593) and depth (0.625) emerged as the most influential parameters in differentiating stations (Fig. 2). Total density vareid amon stations (Pseudo-F = 5.31, p = 0.025). the lowest density was observed in Sisangan while there were not significant differences among the other stations. There was no difference in total numer of species (Pseudo-F = 1.33, p = 0.80), eveness index (Pseudo-F = 0.77, p = 0.54) and shanon index (Pseudo-F = 0.84, p = 0.53) among stations. In total all three species from genus Ammonia did not show any significant differences among stations (all p valuses > 0.05) while there were dominant in total density. The densiy of Elphidium littorale caspicus varied among stations (Pseudo-F = 8.29, p = 0.01). the lowest densit ywas observed in Sisangan while there were not significant differences among the other stations.Density of Elphidium excavatum also shows significant differences among stations (Pseudo-F = 5.88, p = 0.02). the lowest densit ywas observed in Sisangan stations. The density of Elphidium advenum revealed a variation among stations (Pseudo-F = 56.25, p = 0.001). the highest density was observed at Bandar Torkeman station while the lowest was at Sisangan station (Table .1) Ramsar Sisangan Bandar Gaz Bandar Torkaman Total Density 4783 ± 1593.2 A 1111 ± 190.47 B 5560 ± 3632.38 A 5160 ± 1659.7 A Number of Spicies 6.00 ± 00 A 5.66 ± 0.57 A 6.00 ± 00 A 6.33 ± 0.57 A Eveness Index 0.76 ± 0.15 A 0.62 ± 0.02 A 0.62 ± 0.02 A 0.70 ± 0.02 A Shanoon Index 1.35 ± 0.27 A 1.09 ± 0.27 A 1.11 ± 0.04 A 1.03 ± 0.08 A Ammonia Beccarii Caspica 2497.5 ± 1957.6 A 726.67 ± 71.3 A 2442.22 ± 1928.87 A 1885 ± 86.63 A Ammonia Tepida 352.92 ± 234.52 A 101.61 ± 20.95 A 332.78 ± 262.71 A 280.83 ± 232.99 A Ammonia Parkinsoniana 126.67 ± 7156 A 60.00 ± 32.8 A 97.78 ± 53.7 A 93.33 ± 63.68 A Elphidium Littorale Caspicus 373.33 ± 211.36 A 116.67 ± 63.42 B 312.22 ± 195.89 A 3.1.67 ± 217.52 A Elphidium Excavatum 677.5 ± 495.32 A 80.00 ± 24.49 B 652.22 ± 562.3 AB 430.00 ± 377.56 A Elphidium Advenum sp1 150 ± 115.54 B 26.67 ± 17 D 38.89 ± 13.34 C 173.33 ± 147.95 A Table.1.Total foraminiferal density, number of sSpicies, Eveness Index, Shannon Index at all stations.Different capital letters above the columns indicate statistically significant results(A > B > C > D) of pairwise test(p < 0.05) According nMDS plot similarity there were significant differences on total foraminifera density at different stations (Fig. 3). 3-1-Experimental Study Environmental parameters were carefully monitored throughout the experiment(Table 2). Statistical analysis revealed no significant temporal variations in dissolved oxygen, pH, phosphate, or silicate concentrations across all treatments (PERMANOVA, p > 0.05). However, a marginally significant difference was detected in nitrate and ammonium levels between treatments (PERMANOVA, p < 0.05), with Treatment 1 exhibiting the lowest observed concentrations of these compounds. Table 2 Mean environmental variable measured after 60 days of experiment. Different capital letters above the numbers indicate statistically significant results (A > B > C) of pairwise test (p < 0.05). Treatments Do (mg/l) pH Nitrate (µg/l) Ammonium (µg/l) Phosphate (µg/l) Silicate (µg/l) T1, First 8.53 ± 0.21 8.08 ± 0.05 68.06 ± 3.00 B 89.00 ± 19.31 B 11.66 ± 2.08 176.00 ± 20.29 T1, Last 8.42 ± 0.21 8.22 ± 0.04 74.33 ± 3.05 B 91.00 ± 16.09 B 15.33 ± 0.04 169.05 ± 11.78 T2, First 8.52 ± 0.23 8.08 ± 0.04 92.66 ± 18.23 A 97.33 ± 9.29 A 13.66 ± 3.78 168.66 ± 19.55 T2, Last 8.56 ± 0.18 8.18 ± 0.06 98.66 ± 16.25 A 101.66 ± 9.45 A 15.56 ± 2.08 163.33 ± 20.10 T3, First 8.25 ± 0.11 8.11 ± 0.11 94.36 ± 9.50 A 112.33 ± 4.93 A 17.66 ± 3.51 178.33 ± 19.30 T3, Last 8.43 ± 0.20 8.23 ± 0.20 96.00 ± 5.29 A 115.00 ± 4.58 A 18.33 ± 1.52 170.33 ± 12.34 Overall, five foraminifera species were identified in the experimental study (Table.3). The species Ammonia beccarii was the most abundant groups in all treatments. However, Significant differences in density index were observed across treatments (Pseudo-F = 9.68, p = 0.005), with the highest density recorded at 30°C and the lowest at 27°C. The density of Ammonia beccari also showed significant variation among treatments (Pseudo-F = 12.53, p = 0.032), peaking at 30°C, while the other two treatments exhibited no discernible difference. Ammonia tepida density displayed significant differences across all treatments (Pseudo-F = 215.53, p = 0.006), with the highest density at 30°C and the lowest in the initial treatment. The density of Elphidium excavatum significantly differed among treatments (Pseudo-F = 37.16, p = 0.003), with the highest density observed at 24°C and the lowest at 30°C (Table.3).Significant differences in Elphidium advenum densities were observed between the first and second, and first and third treatment groups (Pseudo-F = 31.553, p = 0.042), with overall significant differences between treatments.The highest density was recorded in the 24°C treatment, while the lowest was observed at 30°C. Similarly, Elphidium incertum exhibited significant differences between treatments (Pseudo-F = 7.21, p = 0.04), with treatment 3 displaying the highest abundance and treatment 1 the lowest (Table 3), and a lower abundance observed at 30°C (Table.3). The eveness index exhibited a statistically significant difference among treatments (Pseudo-F = 22.84, p = 0.012). While treatments 2 and 3 were not significantly different from each other, treatment 1 differed significantly from both. Shannon's diversity index also revealed no significant difference between treatments 2 and 3 (Pseudo-F = 16.50 p = 0.036), but treatment 24 degrees differed significantly from treatments 27 and 30 degrees. No significant difference was observed among treatments with respect to Margalef's index (Pseudo-F = .049, p = 0.663). Analysis of the community structure revealed a statistically significant difference between treatments and environmental controls (Pseudo-F = 5.52, p = 0.002). Multidimensional scaling (nMDS) plot clearly distinguishes the three temperature treatments (Fig. 4). The analysis reveals temperature-driven shifts in species dominance. Ammonia beccarii exhibits resilience and prevalence across treatments, increasing in dominance with higher temperatures and replacing other species. While Elphidum advenum is also a dominant species, its density decreases significantly at 30°C. Conversely, Ammonia tepida , initially less prevalent, increases its dominance as temperature rises, suggesting a preference for warmer conditions. These findings, detailed in Table 3, demonstrate the impact of temperature fluctuations on species composition. Table 3 Mean density of various species at temperatures of 24, 27, and 30 C. and biotic indices. (Different capital letters above the columns indicate statistically significant results(A > B > C > D) of pairwise test(p < 0.05. Temperature T1 T2 T3 Ammonia. Beccari 743.33 ± 60.27 a 713.33 ± 165.02 a 1150 ± 43.58 b Ammonia. tepida 13.33 ± 2.88 a 23.33 ± 5.77 b 153.3 ± 16.07 c Elphidum. excavatum 135 ± 21.79 a 40 ± 21.78 b 6.66 ± 2.88 c Elphidum. advenum 230 ± 10 a 23.33 ± 20.2 b 13.33 ± 5.77 b Elphidum. incertum 1.66 ± 2.88 a 6.66 ± 5.77 ab 26.66 ± + 10.4 b Margalef index 0.56 ± 0.07 a 0.58 ± 0.13 a 0.63 ± 0.00 a Eveness Index 0.69 ± 0.04 a 0.56 ± 0.03 ab 0.53 ± 0.01 bc Shanoon Index 1.15 ± 0.00 a 0.92 ± 0.08 ab 0.96 ± 0.02 bc Discussion The results of this study provide significant insights into the composition and distribution of foraminiferal communities across various sediment sampling locations in the south Caspian sea. The presence of seven identified species demonstrates notable biodiversity, emphasizing the ecological richness of these environments. Ammonia beccarii caspica was consistently the dominant species, while the relative abundance of other species varied significantly among the sampling sites. Such dominance has been observed in other studies, where Ammonia species are recognized for their resilience and adaptability to fluctuating environmental conditions (Gooday, 2003; Murray, 2006 ). In the present study, The presence of foraminifera across all sediment sampling locations indicates a widespread distribution of these organisms within the studied environment. Identification of seven distinct benthic species, belonging to five genera and three families, confirms notable diversity despite the relatively limited geographic scope of the study. The observed species composition, dominated by Ammonia beccarii caspica , suggests specific environmental preferences within the study area. Variation in foraminiferal density, ranging from high concentrations at Bandar Gaz to sparse populations at Sisangan, highlights the influence of localized environmental factors on their distribution. Also the relative scarcity of Ammonia tepida and Ammonia parkinsoniana , contrasted with the prevalence of Elphidium littorale caspicus , indicates niche differentiation or differential sensitivity to environmental factors. The restricted distribution of Cornuspira sp. to Bandar Torkaman warrants further investigation into localized habitat suitability. The highest density, number of species, and Shannon diversity were recorded at Bandar Gaz station. Additionally, significant differences were observed in the foraminifera community structure across the various stations. Consequently, Bandar Gaz station was selected for further experimentation. Previous studies have demonstrated that foraminiferal communities can respond to environmental changes within just a few weeks (Dong et al., 2019 ; Goldstein and Alve, 2011 ). Given this rapid responsiveness, our 60-day experimental period was sufficient to assess the effects of temperature on the benthic foraminiferal community in the south Caspian sea.Species diversity and environmental correlates principal component analysis highlighted key environmental drivers affecting foraminiferal distribution. The negative loadings of silt and salinity in PC1 suggest that finer sediments may be less favorable for certain foraminiferal species, while the positive association with temperature points to its crucial role in community structuring. Temperature is a well-documented factor influencing foraminiferal assemblages (Dubey et al., 2018 ), and our findings reinforce the concept that increasing temperatures can affect species dominance, as noted by the experimental results where Ammonia beccarii and Ammonia tepida exhibited increased densities at higher temperatures.These findings suggest that a complex interplay of sedimentological, thermal, and oxygen-related factors governs the distribution and abundance of foraminifera in this environment. In addition the experiment meticulously monitored environmental parameters, revealing a stable environment with no significant temporal variations in dissolved oxygen, pH, phosphate, or silicate concentrations across treatments. Notably, nitrate and ammonium levels showed marginal differences between treatments, with Treatment 1 exhibiting the lowest concentrations. While Ammonia beccarii was the most abundant foraminifera species across all treatments, significant variations in density index, species densities, and community structure were observed among treatments, particularly driven by temperature. Specifically, higher temperatures (30°C) promoted the dominance of Ammonia beccarii and Ammonia tepida , while depressing the density of Elphidium advenum .Conversely, Elphidium excavatum and Elphidium advenum thrived at lower temperatures (24°C). These temperature- driven shifts in species dominance are further supported by differences in evenness and Shannon's diversity indices between treatments, and are visually represented in the MDS plot demonstrating distinct community structures. Margalef's index, however, remained consistent across treatments, suggesting that while species evenness and relative abundance shifted, overall species richness was unaffected by the experimental conditions. In contrast, the fluctuating densities of species like Elphidium advenum across different temperature treatments highlight the sensitivity of certain species to environmental changes. This phenomenon aligns with findings by Taheri et al ( 2025 ) and Lei et al (2019), who documented shifts in benthic foraminifera populations in response to thermal stress. Finally,observed trends suggest a general correlation between rising temperatures and increased density and biological indices in natural communities (Hale et al., 2011 ; Meadows et al., 2015 ; Ingels et al., 2018 ). However, the impact of temperature is multifaceted and context-dependent. Community adaptation (Vafeiadou et al., 2024 ), the magnitude of temperature change, and concurrent environmental factors such as pH, salinity (Moens and Vincx, 2000 ), and existing faunal composition. all modulate the observed response. Further research is needed to disentangle the complex interactions driving these shifts. Conclusions The study confirms the presence and diversity of benthic foraminifera in the coastal environment under investigation, with Ammonia beccarii caspica emerging as the dominant species. The distribution patterns of foraminifera are shaped by multiple environmental factors, including silt content, salinity, temperature, dissolved oxygen, and water depth. Notably, experimental results highlight temperature as a key regulator of foraminiferal density, suggesting its critical role in influencing community dynamics under shifting environmental conditions. These findings enhance our understanding of foraminiferal ecology in coastal ecosystems and establish a valuable baseline for future monitoring and research. Declarations 6-Funding This work is based upon research founded by Iranian National Science Foundation (INSF) under project NO. 40266240. 7-Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 8- Author Contribution Hossein Bagheri: writing—original draft preparation, methodology, writing-review and editing. Mehrshad Taheri: methodology, software, writing-review and editing, visualization. All authors have read and agreed to the published version of the manuscript. 9-Acknowledgements We thank the anonymous reviewers for their constructive comments that improved the quality of the manuscript . 10-Data availability The datasets during and/or analyzed during the current study available from the corresponding author on reasonable request . References Altenbach, A. V. (1992). Short term processes influencing the vertical distribution of foraminifera in a sublittoral habitat. Marine Micropaleontology, 20(1), 21-29. Alve, E., & Bernhard, J. M. (1995). Vertical migratory response of benthic foraminifera to controlled oxygen perturbations in an experimental marine ecosystem. Marine Ecology Progress Series, 116, 137-151. Anderson, M.J., Gorley, R.N., & Clarke, K.R. (2008). PERMANOVA+ for PRIMER. Guide to software and statistical methods. PRIMER-E Ltd., Plymouth, UK. APHA. (2005). Standard Methods for the Examination of Water and Wastewater. American Public Health Association. Arpe, K., Molavi-Arabshahi, M. and Leroy, S.A.G. (2020). Wind variability over the Caspian Sea, its impact on Caspian seawater level and link with ENSO. International Journal of Climatology 40(14), 6039-6054. https://doi.org/10.1002/joc.6564. Azizpour, J., Ghaffari, P. 2023. Low-frequency sea level changes in the Caspian Sea: long-term and seasonal trends. Climate Dynamics. 61, 2753–2763. https://doi.org/10.1007/s00382-023-06715-9. Bagheri, H., Mahmudy Gharaei, M., Mousavi Harami, R., Khanebad, M. ) 2019 ( . Reconstruction of Caspian Sea level changes using magnetic susceptibility during the last millennium. IJMS Vol.48 (09), 1452-1459. Bernhard, J. M., 2000, Distinguishing live from dead foraminifera: methods review and proper applications. Micropaleontology 46, suppl. 1, 38-46). Bouchet, V. M. P., Koho, K. A., McCarthy, F. M. G., Martin, R. A., & Martin, J. B. (2012). Benthic foraminiferal distribution in Bonne Bay, Newfoundland: Assessing environmental gradients and proxy potential. Marine Micropaleontology , 96 , 38-54. Danovaro, R., Company, J., Carreja, J. M., Duineveld, G., Kuklinski, P., & Van Wezel, R. (2004). Deep-sea biodiversity in the Mediterranean Sea: Which is the role of food availability?. Deep Sea Research Part I: Oceanographic Research Papers , 51 (11), 1529-1542. doi:10.1016/S0169-5347(01)02215-7. Danovaro, R., Gambi, C., & Della Croce, N. (2001). Meiofauna response to organic matter enrichment in a Mediterranean coastal lagoon. Hydrobiologia , 445 (1-3), 131-139. Darvish Bastami, K., Taheri, M., Yazdani Foshtomi, M., Haghparast, S., Bagheri, H., Hamzehpoor, A., Esmaeilzadeh, M., & Molamohyeddin, N. (2017). Nematode community structure in relation to metals in the southern of Caspian Sea. Acta Oceanologica Sinica. 36 (10), 1–8. Dolven, J. K., McCarthy, F. M. G., Collins, E. S., Chmura, G. L., & Patterson, R. T. (2013). Salt-marsh foraminifera as proxies for relative sea-level change: statistical (transfer function) vs. indicator zone approaches. Journal of Quaternary Science , 28 (4), 369-380. Dong, B., Kong, L., Guo, W., Zhan, B., & Li, X. (2019). Benthic foraminiferal response to environmental changes in the Pearl River Estuary, China. Journal of Marine Systems , 195 , 1-13. Duffield, A., Patterson, R. T., Reinhardt, E. G., McKillop, I. K., & Roe, H. M. (2015). Distribution of intertidal foraminifera in the Pachena River salt marsh, British Columbia, Canada: Assessing their utility as sea-level indicators. Marine Micropaleontology , 119 , 22-36. Dubey, R., Saraswat, R., Nigam, R., 2018. Mudbank off Alleppey, India: a bane for foraminifera but not so for carbon burial. Sci. Total Environ. 634, 459–470 Elderfield, H., Vautravers, M., & Cooper, M. (2006). The relationship between benthic foraminiferal magnesium and seawater temperature. Earth and Planetary Science Letters , 250 (1-2), 208-223. Folk, R. L. (1980). Petrology of Sedimentary Rocks. Hemphill Publishing Company Gingold, R., Moens, T., Rocha-Olivares, A. (2013). Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment. PLoS ONE, 8(6): e66653. Goldstein, S. T., & Alve, E. (2011). Effect of increased bottom-water temperature on foraminiferal assemblages in a Norwegian Fjord. Journal of Foraminiferal Research , 41 (1), 1-11. Goody, A.j. (2003). Benthic foraminifera (Protista) as tools in deep-water palaeoceanography: environmental influences on faunal characteristics. Advance Marrine Biology:46:1-90. doi: 10.1016/s0065-2881(03)46002-1. Hale, R., Calos, P., Mcneill, L., Mieszkowska, N., & Widdicombe, S. (2011). Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities. Oikos, 120, 661–674. Havach, S., Frontalini, F., & Coccioni, R. (2001). Benthic foraminifera as indicators of heavy-metal pollution in the Lagoon of Venice, Italy. Journal of Foraminiferal Research , 31 (3), 194-201Heiri, O., Lotter, A. F., & Lemcke, G. (2001). Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results. Journal of Paleolimnology, 25(1), 101-110. Ingels, J., dos Santos, G., Hicks, N., Valdes Vazquez, Y., Fernandes Neres, P., Pereira Pontes, L., Nataly Amorim, M., Roman, S., Du, Y., Stahl, H., Somerfield, P. J., & Widdicombe, S. (2018). Short-term CO2 exposure and temperature rise effects on metazoan meiofauna and free-living nematodes in sandy and muddy sediments: Results from a flume experiment. Journal of Experimental Marine Biology and Ecology, 502, 211. Lahijani, H., Azizpour,J., Arpe, K., Abtahi, B., Rahnama, R., Ghafarian, P., Hamzeh, M.A., Hamzehpour, A., Mohammadpour Penchah, M., & Mahmoudof, S.M. (2023). Tracking of sea level impact on Caspian Ramsar sites and potential restoration of the Gorgan Bay on the southeast Caspian coast. Science of the Total Environment. 857 (1), 158833. Lahijani, H., Ghaffari, P., Leroy, S., Naderi Beni, A., Yakushev, E., Abtahi, B., Saleh, S., Behravesh, M., 2024. A note on the silent decline of the Caspian environment, Marine Pollution Bulletin, Volume 205, 116551, https://doi.org/10.1016/j.marpolbul.2024.116551. Le Cadre, V., Debenay, J. P. (2006). Morphological abnormalities in foraminifera: one tool for pollution assessment?. Marine Micropaleontology , 61 (3), 178-196. Lei, Y., Li, T., Jian, Z., Nigam, R., 2017a. Taxonomy and distribution of benthic foraminifera in an intertidal zone of the Yellow Sea, PR China: correlations with sediment temperature and salinity. Mar. Micropaleontol. 133, 1–20. Lei, Y.-L., Stumm, K., Wickham, S.A., Berninger, U.-G., 2014. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments. J. Eukaryot. Microbiol. 61, 493–508. Maslin, M. (2008). Global warming: A very short introduction. Oxford University Press. Meadows, A.S., Ingels, J., Widdicombe, S., Hale, R., & Rundle, S.D. (2015). Effects of elevated CO2 and temperature on an intertidal meiobenthic community. Journal of Experimental Marine Biology and Ecology, 469, 44–56. Moens T, Vincx M. (2000). Temperature, salinity and food thresholds in two brackishwater bacterivorous nematode species: assessing niches from food absorption and respiration experiments. Journal of Experimental Marine Biology and Ecology 243:137–154 DOI 10.1016/S0022-0981(99)00114-8. Moens, T., Artois, T., De Meyer, T., Gillardin, V., Goethals, P., & Van Steenkiste, N. (2013). Nematode taxonomic diversity in the Southern Ocean: a test of the latitudinal gradient hypothesis in remote, relatively unexplored habitats. PLoS One, 8(11), e80134. Mojtahid, M., Nercessian, A., Debenay, J. P., & Buoncristiani, J. F. (2009). Modern benthic foraminifera distribution in the Arcachon Lagoon, French Atlantic Coast: Environmental significance. Estuarine, Coastal and Shelf Science, 81(1), 81-93. Murray, J. W. (2006). Ecology and Applications of Benthic Foraminifera. Cambridge University Press. Nordberg, K., Eichler, P. P. B., Volkov, I. A., & Asteman, I. P. (2017). Modern benthic foraminifera in the Sea of Azov: distribution in relation to salinity, organic matter, and pollution. Journal of Foraminiferal Research , 47 (2), 167-181. Polovodova Asteman, I., & Nordberg, K. (2013). The influence of different ecological factors on benthic foraminiferal distribution in the Himmerfjärden Estuary, northern Baltic Sea. Journal of Micropalaeontology , 32 (2), 173-187. Roshan, G., Moghbel, M. & Grab, S. Modeling Caspian Sea water level oscillations under different scenarios of increasing atmospheric carbon dioxide concentrations. J Environ Health Sci Engineer 9, 24 (2012). https://doi.org/10.1186/1735-2746-9-24. Samant, R., & Prange, M. (2023). Climate-driven 21st century Caspian Sea level decline estimated from CMIP6 projections. Communications Earth & Environment, 4, 357. Schönfeld, J. (2018). Living foraminifera in shelf seas . Cambridge University Press. Taheri, M., Darvish Bastami, K., Yazdani Foshtomi, M., 2014a. Meiofauna-sediment relationships in shallow water of the south Caspian Sea. In: INOC-International Congress“Estuaries & Coastal Protected Areas” ECPA 2014, 04–06 November 2014, Izmir–TURKEY. Taheri, M., Braeckman, U., Vincx, M., Vanaverbeke, J., 2014b. Effect of short-term hypoxia on marine nematode community structure and vertical distribution pattern in three different sediment types of the North Sea. Mar. Environ. Res. 99, 149–159. Taheri, M., Grego, M., Riedel, B., Vincx, M., Vanaverbeke, J., 2015. Patterns in nematode community during and after experimentally induced anoxia in the northern Adriatic Sea. Mar. Environ. Res. 110, 110–123. Taheri, M., Darvish Bastami, K., Yazdani Foshtomi, M., 2017a. The role of the sediment conditions in shaping meiofauna spatial distribution in the shallow water of the south Caspian Sea. In: First International Conference on Oceanography for West Asia 30–31 October 2017. Taheri, M., Giunio, M., De Troch, M., Vincx, M., Vanaverbeke, J., 2017b. Effect of short- term hypoxia on the feeding activity of abundant nematode genera from an intertidal mudflat. Nematology 19, 1–13. Taheri, M., Yazdani Foshtami,m M. Manbohi., A. Mira., M.(2025). Spatial distribution and effects of temperature rise on coastal free-living nematode community in the South Caspian Sea. Marine Pollution Bulletin 214. 117806. https://doi.org/10.1016/j.marpolbul.2025.117806 Taheri, M., Yazdani Foshtomi, M., Hamzeh, M.A., Manbohi, A., Rahnama Haratbar, R., 2024. Effects of discarded garbage bags on intertidal free living nematode community. Aquat. Ecol. 58, 853–863. Venegas, R.M., Acevedo, J., Treml, E.A., 2023. Three decades of ocean warming impacts on marine ecosystems: a review and perspective. Deep-Sea Res. II Top. Stud. Oceanogr. 212, 105318. Wit, J. C., Filipsson, H. L., & Platzman, D. J. (2013). Interactive effects of hypoxia and pH on the benthic foraminifera Ammonia tepida: growth rate, survival, and shell characteristics. Biogeosciences , 10 (11), 7479-7496. Vafeiadou, A.M., Geldhof, K., Barhdadi, W., Baetens, J., De Baets, B., Moens, T., & Daly, A. (2024). Temperature-driven dynamics : unraveling the impact of climate change on cryptic species interactions within the Litoditis marina complex. PEERJ, 12. https://doi.org/10.7717/peerj.17324. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Feb, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 03 Oct, 2025 Reviews received at journal 29 Sep, 2025 Reviews received at journal 29 Sep, 2025 Reviewers agreed at journal 09 Sep, 2025 Reviewers agreed at journal 09 Sep, 2025 Reviewers invited by journal 09 Sep, 2025 Editor invited by journal 09 Sep, 2025 Editor assigned by journal 08 Sep, 2025 Submission checks completed at journal 05 Sep, 2025 First submitted to journal 31 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7499422","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":512581957,"identity":"675851a4-d77f-450b-bd4b-07d6d2a6f5d0","order_by":0,"name":"Hossein Bagheri","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4klEQVRIiWNgGAWjYBACewYGNhDNww8iEwqI0GLYANEiI9kA0mJAhBaDAxAtNkAGiEuMLe3Hrz34uOcwj/H51YkfHhgwyPOLHcCvxZ4np9xwxrPDPGY33m6WADrMcObsBAK2NOSkSfMcAGk5uwGkJcHgNgEtBuffpEn/AWoxnnF28w/itNxIPybNANRiwN+7jThbDGe8YZPsOZDOI3GDd5tFgoEEYb/Y86c/k/hxwNqev//s5ps/Kmzk+aUJaAHGOygumhkYJMAqJQgpBwH2B0CijoGB/wAxqkfBKBgFo2AkAgCxbEhIOE9w0QAAAABJRU5ErkJggg==","orcid":"","institution":"Iranian National Institute for Oceanography and Atmospheric Sciences","correspondingAuthor":true,"prefix":"","firstName":"Hossein","middleName":"","lastName":"Bagheri","suffix":""},{"id":512581958,"identity":"bffd283c-4549-4161-9df3-0fe2cb87e6c4","order_by":1,"name":"Mehrshad Taheri","email":"","orcid":"","institution":"Iranian National Institute for Oceanography and Atmospheric Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mehrshad","middleName":"","lastName":"Taheri","suffix":""}],"badges":[],"createdAt":"2025-08-31 08:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7499422/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7499422/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-38207-1","type":"published","date":"2026-02-01T15:59:25+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":91434017,"identity":"de074b18-e5f1-4a39-a3c0-c0613b52c0b6","added_by":"auto","created_at":"2025-09-16 12:45:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":293359,"visible":true,"origin":"","legend":"\u003cp\u003eSampling station in Mazandaran and Golestan provinces in the south Caspian Sea\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7499422/v1/cfded0fe804ef060433b0802.png"},{"id":91434568,"identity":"928dca4e-0608-4314-9ba8-ed2245d8c40e","added_by":"auto","created_at":"2025-09-16 12:53:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":94859,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePrincipal Component Analysis of environmental parameters sepereated stations\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7499422/v1/02a2baca958d9b385eebddc2.png"},{"id":91435252,"identity":"f29a60c2-ede0-4860-91c6-8388951ae458","added_by":"auto","created_at":"2025-09-16 13:01:30","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":129012,"visible":true,"origin":"","legend":"\u003cp\u003enMDS plot based on Bray-Curtis similarity on total foraminifera density data in different stations\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7499422/v1/4468e0e30eaa11268e8d08da.png"},{"id":91434018,"identity":"1115d7dc-497b-4466-8d04-a77a42626c99","added_by":"auto","created_at":"2025-09-16 12:45:30","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":34722,"visible":true,"origin":"","legend":"\u003cp\u003emultidimensional scaling (nMDS) plot illustrating the overall community structure of foraminifera\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7499422/v1/68500ec080b6f7e15bbab575.png"},{"id":101690676,"identity":"d84be623-2254-4fee-949e-4106e118b7cc","added_by":"auto","created_at":"2026-02-02 16:07:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1199605,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7499422/v1/52d6637c-ada4-48b3-88fd-379c6867e823.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Responses of South Caspian Coastal Foraminifera to Warming: Spatial Patterns and Assemblage Shifts","fulltext":[{"header":"Introduction","content":"\u003cp\u003eGlobal ocean warming, an undeniable outcome of climate change, poses a significant and increasing danger to marine ecosystems globally and even to isolated aquatic environments (Maslin., 2008;Venegas et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).The Caspian Sea, the world's largest inland water body, exemplifies this vulnerability, displaying elevated temperatures that contribute to sea level fall and substantial ecological instability(Bagheri et al., 2019; Arpe et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Lahijani et al., 2024). Notably, the southern Caspian is undergoing rapid warming (Roshan et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Azizpour and Ghaffari., 2023), resulting in shifts in species distribution, disrupted reproductive cycles, and altered migration patterns, all of which threaten the region's unique biodiversity (Taheri et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Rising water temperatures threaten the ecological integrity of benthic coastal annimals as foraminifera, key sensitive organisms in marine ecosystems (Danovaro et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2001\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Moens et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Climate models predict worsening conditions, with rising temperatures and diminishing rainfall compounding the Caspian Sea's recession and further endangering its delicate ecosystems. These changes are projected to significantly impact benthic foraminifera, crucial indicators of marine health, affecting their distribution, abundance, biodiversity, and community structure. Given the Caspian Sea's importance as a biodiversity hotspot, the current lack of research on foraminifera, particularly along its southeastern coasts, represents a critical deficiency in our understanding and ability to safeguard this vulnerable ecosystem. Foraminifera serve as valuable proxies in both modern and paleo-environmental reconstructions, as evidenced by numerous studies (Mojtahid et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Bouchet et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Dolven et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Duffield et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Nordberg et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Polovodova Asteman and Nordberg, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). While field observations provide extensive data, laboratory experiments elucidating foraminiferal responses to environmental stressors remain relatively limited (Alve and Bernhard., 1995; Altenbach, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Elderfield et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Havach et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Le Cadre and Debenay., 2006). These controlled studies, some simulating future global change scenarios and others exploring extreme conditions, are crucial for refining proxy calibrations and enhancing our understanding of foraminifera as environmental indicators (Wit et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Limited research suggests that foraminiferal response to environmental change is either rapid or delayed by several years (Sch\u0026ouml;nfeld \u0026amp; Mendes, 2021). Recent work has also explored temperature-induced shifts in entire benthic foraminiferal communities, documenting changes in species composition and diversity (Dong et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Goldstein and Alve., 2011). in this study our microcosm experiment investigates how temperature variations influence benthic foraminifera communities, testing the hypothesis that warming significantly alters their structural composition and ecological functions. A controlled laboratory experiment was conducted to investigate the effects of elevated temperatures (24, 27, and 30\u0026deg;C) on benthic foraminiferal assemblages from a coastal Caspian Sea community over a 60-day period. This research provides novel experimental data on the response of foraminiferal communities and species richness to temperature stress within a microcosm environment. The findings offer crucial insights into the potential impacts of climate change on Caspian Sea biodiversity, contributing to a better understanding of warming's cascading ecological consequences. Furthermore, this laboratory culture-based study establishes a valuable reference point for both future field investigations and the refinement of paleotemperature reconstruction methodologies.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThe Caspian Sea functions as a dynamic, non-tidal lake whose coastal and splash zones are shaped by powerful hydrodynamic processes, particularly wave action and rip currents. This ecologically sensitive region faces mounting pressures from multiple threats: anthropogenic disturbances (including physical habitat modification and pollution), natural stressors (such as coastal erosion and dramatic water level fluctuations), and the escalating impacts of climate change (Lahijani et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Samant and Prange., 2023). These compounding factors have significantly heightened the ecosystem's vulnerability. Surface water temperatures exhibit extreme seasonal variability, fluctuating between 19.0\u0026deg;C in winter months and rarely reaching to 30.0\u0026deg;C during summer periods (Azizpour and Ghaffari., 2023), creating additional thermal stress on native species. Mazandaran and Golestan province are located in the south Caspian Sea, along the Iranian border.The southern Caspian coastal region supports over 3.5\u0026nbsp;million residents whose livelihoods depend primarily on agriculture, tourism, and fisheries. In March 2023, we conducted sampling across four stations (Fig.\u0026nbsp;1) in Mazandaran and Golestan provinces (Bandar Torkaman, Bandar Gaz, Sisangan, and Ramsar) to assess the spatial distribution of benthic foraminifera in this low-biodiversity zone (Taheri et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2014a\u003c/span\u003e; Darvish Bastami et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Taheri et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2017a\u003c/span\u003e). The sediment temperature measured with spirit thermometer (precision: 1\u0026deg;C) in the surface sediment (top 1 cm) ranges from 18\u0026deg;C to 22\u0026deg;C, and the annual average temperature is 23\u0026deg;C. At each station, we collected three sediment samples using hand cores (5 cm diameter) from shallow waters (\u0026lt;\u0026thinsp;0.5 m depth), spaced 5 m apart along the shoreline. Each core penetrated 5 cm into the sediment to capture benthic communities. Samples were preserved in 4% buffered formaldehyde, stained with Rose Bengal(Bernhard, J. M., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), and analyzed for total density, species richness, Shannon diversity, and evenness. Bandar Gaz station, showing the highest foraminiferal density and species richness, was selected for subsequent experimental work.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo investigate temperature effects on benthic foraminifera communities, we collected three replicate sediment samples from Bandar Gaz station using hand corer (5 cm inner diameter). Surface sediments (0\u0026ndash;5 cm depth) were subsampled and total organic matter (TOM) determined through loss-on-ignition (550\u0026deg;C for 4 hours) after drying to constant weight at 90\u0026deg;C (Heiri et al., 2001). Sediment grain size distribution was analyzed using a HORIBA-LA950 Particle Size Analyzer (France \u0026amp; Japan). Resulting sediment fractions, categorized as gravel, sand, and silt\u0026thinsp;+\u0026thinsp;clay, were reported as percentage values and defined according to the Folk scale of particle size classification (Folk, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1980\u003c/span\u003e). Furthermore, dissolved oxygen and pH of the overlying water at each core sampling location were measured in situ utilizing a HACH HQ40d portable multimeter (HACH, USA). Subsequently, 100 mL aliquots of the overlying water were collected from each core for laboratory analysis of nitrate, ammonium, phosphate, and silicate concentrations. These nutrient concentrations were determined spectrophotometrically using an Analytik-jena SPECORD-210 spectrophotometer, adhering to standard analytical protocols outlined in APHA (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSediment samples for biological analysis were collected along the coastal shoreline, maintaining a minimum distance of 5 meters between sampling points. Twelve hand corers (internal diameter: 5 cm) were extracted to a depth of 10 cm within the splash zone (water edge\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 m) at Bandar Gaz, where the water temperature was 22\u0026deg;C. Three cores were immediately processed in situ: these were sliced into 1 cm intervals down to a depth of 5 cm, and each slice was preserved in a buffered 4% formaldehyde solution. These field control (FC) samples were intended to preserve the characteristics of the foraminifera community at the time of collection (Taheri et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014b\u003c/span\u003e; Taheri et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The remaining nine cores were sealed at the bottom with rubber stoppers, covered with perforated plastic lids, and transported to the laboratory within 30 minutes. In the laboratory, the cores were randomly assigned to three separate 70-liter tanks. Each tank was filled with filtered seawater (38 \u0026micro;m filter) collected from the sampling site and maintained at 20\u0026deg;C for five days (Gingold et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). During this period, the temperature within each tank was kept constant via a 200W aquarium heater, and water homogenization was achieved by bubbling airstones, placed above the heaters, using an air pump (Gingold et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). In On the initial day of the experiment, and again after a 60-day incubation period prior to sediment slicing, dissolved oxygen and pH levels in the overlying water of each core were assessed using a portable multimeter (HACH HQ40d, USA). Additionally, 100 ml water samples were extracted from each core for the quantification of nitrate, ammonium, phosphate, and silicate concentrations, employing previously established methodologies. Following the 60-day incubation, Foraminifera were picked up with a fine brush and stored on micropaleontological slides. Species were identified and counted with a stereomicroscope, in accordance with previously reported techniques (Lei et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017a\u003c/span\u003e; Lei and Li, 2014). Foraminifera were carefully extracted using a fine brush and mounted on micropaleontological slides.In addition, dead specimens in all samples were picked up and counted in order to explore the percentage of living specimens in the foraminiferal assemblages.\u003c/p\u003e\n\u003ch3\u003e2-1-Statistical analyses\u003c/h3\u003e\n\u003cp\u003eStatistical analyses were performed using PRIMER v6 with the PERMANOVA\u0026thinsp;+\u0026thinsp;add-on. At each sampling station and for each experimental treatment, species richness, Shannon diversity (H', loge), and Pielou's evenness (J) were calculated. Differences in univariate measures (total Foraminifera density, species richness, H, J) and multivariate community structure across stations and treatments were assessed using one-way PERMANOVA (Taheri et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014b\u003c/span\u003e). Significant PERMANOVA results were followed by Monte Carlo pairwise comparisons (Anderson et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Bray-Curtis similarity was used to construct Non-metric Multidimensional Scaling (nMDS) plots, visualizing total and vertical Foraminifera community structure. Dominant species were identified as those comprising\u0026thinsp;\u0026ge;\u0026thinsp;5% of the assemblage at their minimum abundance temperature.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe presence of Foraminifera was confirmed across all sediment sampling locations. Subsequent analysis of collected samples identified seven distinct benthic species, belonging to five genera and three families, there by demonstrating the diversity of these organisms within the studied environment. \u003cem\u003eAmmonia beccarii caspica, Ammonia tepida, Ammonia parkinsoniana, Elphidum advenum, Elphidium excavatum, Elphidum littorale caspicus, and Cornuspira\u003c/em\u003e sp which were subsequently analyzed to characterize the foraminiferal community. The highest and lowest of density of foraminifera respectively observed at station Bandar Gaz (2497.5 individual /0.1m\u003csup\u003e2\u003c/sup\u003e) and (7.33 individual /0.1m\u003csup\u003e2\u003c/sup\u003e) at Sisangan station. \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e was the dominant species in all sampling stations. \u003cem\u003eAmmonia tepida\u003c/em\u003e and \u003cem\u003eAmmonia parkinsoniana\u003c/em\u003e were not very abundance such as \u003cem\u003eAmmonia beccarii\u003c/em\u003e. \u003cem\u003eElphidium littoraleca\u003c/em\u003e spicus was observed in all stations and had the most abundance after \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e in the sampling area. \u003cem\u003eElphidium excuavatum\u003c/em\u003e and \u003cem\u003eAmmonia parkinsoniana\u003c/em\u003e. were rarely to compare with \u003cem\u003eElphidium littorale\u003c/em\u003e. Cornuspira sp only was observed in Bandar Torkaman.\u003c/p\u003e\u003cp\u003ePrincipal Component Analysis of environmental analysis revealed that the first two principal components (PC1 and PC2) accounted for 84.90% of the total variance. Within PC1, silt and salinity exhibited notable negative loadings (-0.422), while temperature showed a significant positive loading (0.46). In PC2, dissolved oxygen (0.593) and depth (0.625) emerged as the most influential parameters in differentiating stations (Fig.\u0026nbsp;2).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTotal density vareid amon stations (Pseudo-F\u0026thinsp;=\u0026thinsp;5.31, p\u0026thinsp;=\u0026thinsp;0.025). the lowest density was observed in Sisangan while there were not significant differences among the other stations. There was no difference in total numer of species (Pseudo-F\u0026thinsp;=\u0026thinsp;1.33, p\u0026thinsp;=\u0026thinsp;0.80), eveness index (Pseudo-F\u0026thinsp;=\u0026thinsp;0.77, p\u0026thinsp;=\u0026thinsp;0.54) and shanon index (Pseudo-F\u0026thinsp;=\u0026thinsp;0.84, p\u0026thinsp;=\u0026thinsp;0.53) among stations. In total all three species from genus \u003cem\u003eAmmonia\u003c/em\u003e did not show any significant differences among stations (all p valuses\u0026thinsp;\u0026gt;\u0026thinsp;0.05) while there were dominant in total density. The densiy of \u003cem\u003eElphidium littorale caspicus\u003c/em\u003e varied among stations (Pseudo-F\u0026thinsp;=\u0026thinsp;8.29, p\u0026thinsp;=\u0026thinsp;0.01). the lowest densit ywas observed in Sisangan while there were not significant differences among the other stations.Density of \u003cem\u003eElphidium excavatum\u003c/em\u003e also shows significant differences among stations (Pseudo-F\u0026thinsp;=\u0026thinsp;5.88, p\u0026thinsp;=\u0026thinsp;0.02). the lowest densit ywas observed in Sisangan stations. The density of \u003cem\u003eElphidium advenum\u003c/em\u003e revealed a variation among stations (Pseudo-F\u0026thinsp;=\u0026thinsp;56.25, p\u0026thinsp;=\u0026thinsp;0.001). the highest density was observed at Bandar Torkeman station while the lowest was at Sisangan station (Table .1)\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"5\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRamsar\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSisangan\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBandar Gaz\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eBandar Torkaman\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal Density\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4783\u0026thinsp;\u0026plusmn;\u0026thinsp;1593.2\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1111\u0026thinsp;\u0026plusmn;\u0026thinsp;190.47\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5560\u0026thinsp;\u0026plusmn;\u0026thinsp;3632.38 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5160\u0026thinsp;\u0026plusmn;\u0026thinsp;1659.7 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNumber of Spicies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.00\u0026thinsp;\u0026plusmn;\u0026thinsp;00\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.00\u0026thinsp;\u0026plusmn;\u0026thinsp;00\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEveness Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShanoon Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmmonia Beccarii Caspica\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2497.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1957.6\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e726.67\u0026thinsp;\u0026plusmn;\u0026thinsp;71.3\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2442.22\u0026thinsp;\u0026plusmn;\u0026thinsp;1928.87\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1885\u0026thinsp;\u0026plusmn;\u0026thinsp;86.63\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmmonia Tepida\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e352.92\u0026thinsp;\u0026plusmn;\u0026thinsp;234.52\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e101.61\u0026thinsp;\u0026plusmn;\u0026thinsp;20.95\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e332.78\u0026thinsp;\u0026plusmn;\u0026thinsp;262.71\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e280.83\u0026thinsp;\u0026plusmn;\u0026thinsp;232.99\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmmonia Parkinsoniana\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e126.67\u0026thinsp;\u0026plusmn;\u0026thinsp;7156\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60.00\u0026thinsp;\u0026plusmn;\u0026thinsp;32.8\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e97.78\u0026thinsp;\u0026plusmn;\u0026thinsp;53.7\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e93.33\u0026thinsp;\u0026plusmn;\u0026thinsp;63.68\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidium Littorale Caspicus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e373.33\u0026thinsp;\u0026plusmn;\u0026thinsp;211.36 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e116.67\u0026thinsp;\u0026plusmn;\u0026thinsp;63.42\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e312.22\u0026thinsp;\u0026plusmn;\u0026thinsp;195.89 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.1.67\u0026thinsp;\u0026plusmn;\u0026thinsp;217.52 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidium Excavatum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e677.5\u0026thinsp;\u0026plusmn;\u0026thinsp;495.32\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e80.00\u0026thinsp;\u0026plusmn;\u0026thinsp;24.49 \u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e652.22\u0026thinsp;\u0026plusmn;\u0026thinsp;562.3\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e430.00\u0026thinsp;\u0026plusmn;\u0026thinsp;377.56\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidium Advenum sp1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e150\u0026thinsp;\u0026plusmn;\u0026thinsp;115.54\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e26.67\u0026thinsp;\u0026plusmn;\u0026thinsp;17\u003csup\u003eD\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e38.89\u0026thinsp;\u0026plusmn;\u0026thinsp;13.34\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e173.33\u0026thinsp;\u0026plusmn;\u0026thinsp;147.95\u003csup\u003eA\u003c/sup\u003e\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\u003eTable.1.Total foraminiferal density, number of sSpicies, Eveness Index, Shannon Index at all stations.Different capital letters above the columns indicate statistically significant results(A\u0026thinsp;\u0026gt;\u0026thinsp;B\u0026thinsp;\u0026gt;\u0026thinsp;C\u0026thinsp;\u0026gt;\u0026thinsp;D) of pairwise test(p\u0026thinsp;\u0026lt;\u0026thinsp;0.05)\u003c/p\u003e\u003cp\u003eAccording nMDS plot similarity there were significant differences on total foraminifera density at different stations (Fig.\u0026nbsp;3).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003e3-1-Experimental Study\u003c/h3\u003e\n\u003cp\u003eEnvironmental parameters were carefully monitored throughout the experiment(Table\u0026nbsp;2). Statistical analysis revealed no significant temporal variations in dissolved oxygen, pH, phosphate, or silicate concentrations across all treatments (PERMANOVA, p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, a marginally significant difference was detected in nitrate and ammonium levels between treatments (PERMANOVA, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), with Treatment 1 exhibiting the lowest observed concentrations of these compounds.\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 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMean environmental variable measured after 60 days of experiment. Different capital letters above the numbers indicate statistically significant results (A\u0026thinsp;\u0026gt;\u0026thinsp;B\u0026thinsp;\u0026gt;\u0026thinsp;C) of pairwise test (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" 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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDo (mg/l)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003epH\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNitrate (\u0026micro;g/l)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAmmonium (\u0026micro;g/l)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003ePhosphate (\u0026micro;g/l)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSilicate (\u0026micro;g/l)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT1, First\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e68.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.00 \u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e89.00\u0026thinsp;\u0026plusmn;\u0026thinsp;19.31 \u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e11.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e176.00\u0026thinsp;\u0026plusmn;\u0026thinsp;20.29\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT1, Last\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e74.33\u0026thinsp;\u0026plusmn;\u0026thinsp;3.05 \u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e91.00\u0026thinsp;\u0026plusmn;\u0026thinsp;16.09 \u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e15.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e169.05\u0026thinsp;\u0026plusmn;\u0026thinsp;11.78\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT2, First\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e92.66\u0026thinsp;\u0026plusmn;\u0026thinsp;18.23 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e97.33\u0026thinsp;\u0026plusmn;\u0026thinsp;9.29 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e13.66\u0026thinsp;\u0026plusmn;\u0026thinsp;3.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e168.66\u0026thinsp;\u0026plusmn;\u0026thinsp;19.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT2, Last\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e98.66\u0026thinsp;\u0026plusmn;\u0026thinsp;16.25 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e101.66\u0026thinsp;\u0026plusmn;\u0026thinsp;9.45 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e15.56\u0026thinsp;\u0026plusmn;\u0026thinsp;2.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e163.33\u0026thinsp;\u0026plusmn;\u0026thinsp;20.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT3, First\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e94.36\u0026thinsp;\u0026plusmn;\u0026thinsp;9.50 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e112.33\u0026thinsp;\u0026plusmn;\u0026thinsp;4.93 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e17.66\u0026thinsp;\u0026plusmn;\u0026thinsp;3.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e178.33\u0026thinsp;\u0026plusmn;\u0026thinsp;19.30\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eT3, Last\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e8.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e96.00\u0026thinsp;\u0026plusmn;\u0026thinsp;5.29 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e115.00\u0026thinsp;\u0026plusmn;\u0026thinsp;4.58 \u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e18.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e170.33\u0026thinsp;\u0026plusmn;\u0026thinsp;12.34\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\u003eOverall, five foraminifera species were identified in the experimental study (Table.3). The species \u003cem\u003eAmmonia beccarii\u003c/em\u003e was the most abundant groups in all treatments. However, Significant differences in density index were observed across treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;9.68, p\u0026thinsp;=\u0026thinsp;0.005), with the highest density recorded at 30\u0026deg;C and the lowest at 27\u0026deg;C. The density of \u003cem\u003eAmmonia beccari\u003c/em\u003e also showed significant variation among treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;12.53, p\u0026thinsp;=\u0026thinsp;0.032), peaking at 30\u0026deg;C, while the other two treatments exhibited no discernible difference. \u003cem\u003eAmmonia tepida\u003c/em\u003e density displayed significant differences across all treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;215.53, p\u0026thinsp;=\u0026thinsp;0.006), with the highest density at 30\u0026deg;C and the lowest in the initial treatment. The density of \u003cem\u003eElphidium excavatum\u003c/em\u003e significantly differed among treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;37.16, p\u0026thinsp;=\u0026thinsp;0.003), with the highest density observed at 24\u0026deg;C and the lowest at 30\u0026deg;C (Table.3).Significant differences in \u003cem\u003eElphidium advenum\u003c/em\u003e densities were observed between the first and second, and first and third treatment groups (Pseudo-F\u0026thinsp;=\u0026thinsp;31.553, p\u0026thinsp;=\u0026thinsp;0.042), with overall significant differences between treatments.The highest density was recorded in the 24\u0026deg;C treatment, while the lowest was observed at 30\u0026deg;C. Similarly, \u003cem\u003eElphidium incertum\u003c/em\u003e exhibited significant differences between treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;7.21, p\u0026thinsp;=\u0026thinsp;0.04), with treatment 3 displaying the highest abundance and treatment 1 the lowest (Table\u0026nbsp;3), and a lower abundance observed at 30\u0026deg;C (Table.3).\u003c/p\u003e\u003cp\u003eThe eveness index exhibited a statistically significant difference among treatments (Pseudo-F\u0026thinsp;=\u0026thinsp;22.84, p\u0026thinsp;=\u0026thinsp;0.012). While treatments 2 and 3 were not significantly different from each other, treatment 1 differed significantly from both. Shannon's diversity index also revealed no significant difference between treatments 2 and 3 (Pseudo-F\u0026thinsp;=\u0026thinsp;16.50 p\u0026thinsp;=\u0026thinsp;0.036), but treatment 24 degrees differed significantly from treatments 27 and 30 degrees. No significant difference was observed among treatments with respect to Margalef's index (Pseudo-F\u0026thinsp;=\u0026thinsp;.049, p\u0026thinsp;=\u0026thinsp;0.663). Analysis of the community structure revealed a statistically significant difference between treatments and environmental controls (Pseudo-F\u0026thinsp;=\u0026thinsp;5.52, p\u0026thinsp;=\u0026thinsp;0.002). Multidimensional scaling (nMDS) plot clearly distinguishes the three temperature treatments (Fig.\u0026nbsp;4).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe analysis reveals temperature-driven shifts in species dominance. \u003cem\u003eAmmonia beccarii\u003c/em\u003e exhibits resilience and prevalence across treatments, increasing in dominance with higher temperatures and replacing other species. While \u003cem\u003eElphidum advenum\u003c/em\u003e is also a dominant species, its density decreases significantly at 30\u0026deg;C. Conversely, \u003cem\u003eAmmonia tepida\u003c/em\u003e, initially less prevalent, increases its dominance as temperature rises, suggesting a preference for warmer conditions. These findings, detailed in Table\u0026nbsp;3, demonstrate the impact of temperature fluctuations on species composition.\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 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMean density of various species at temperatures of 24, 27, and 30 C. and biotic indices. (Different capital letters above the columns indicate statistically significant results(A\u0026thinsp;\u0026gt;\u0026thinsp;B\u0026thinsp;\u0026gt;\u0026thinsp;C\u0026thinsp;\u0026gt;\u0026thinsp;D) of pairwise test(p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTemperature\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eT1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eT2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eT3\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmmonia. Beccari\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e743.33\u0026thinsp;\u0026plusmn;\u0026thinsp;60.27\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e713.33\u0026thinsp;\u0026plusmn;\u0026thinsp;165.02 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1150\u0026thinsp;\u0026plusmn;\u0026thinsp;43.58\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAmmonia. tepida\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13.33\u0026thinsp;\u0026plusmn;\u0026thinsp;2.88 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23.33\u0026thinsp;\u0026plusmn;\u0026thinsp;5.77 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e153.3\u0026thinsp;\u0026plusmn;\u0026thinsp;16.07\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidum. excavatum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e135\u0026thinsp;\u0026plusmn;\u0026thinsp;21.79 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40\u0026thinsp;\u0026plusmn;\u0026thinsp;21.78 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.88\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidum. advenum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e230\u0026thinsp;\u0026plusmn;\u0026thinsp;10 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23.33\u0026thinsp;\u0026plusmn;\u0026thinsp;20.2 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e13.33\u0026thinsp;\u0026plusmn;\u0026thinsp;5.77\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElphidum. incertum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.88 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.66\u0026thinsp;\u0026plusmn;\u0026thinsp;5.77\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26.66\u0026thinsp;\u0026plusmn;\u0026thinsp;+\u0026thinsp;10.4 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMargalef index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEveness Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShanoon Index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.00\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe results of this study provide significant insights into the composition and distribution of foraminiferal communities across various sediment sampling locations in the south Caspian sea. The presence of seven identified species demonstrates notable biodiversity, emphasizing the ecological richness of these environments. \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e was consistently the dominant species, while the relative abundance of other species varied significantly among the sampling sites. Such dominance has been observed in other studies, where \u003cem\u003eAmmonia\u003c/em\u003e species are recognized for their resilience and adaptability to fluctuating environmental conditions (Gooday, 2003; Murray, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). In the present study, The presence of foraminifera across all sediment sampling locations indicates a widespread distribution of these organisms within the studied environment. Identification of seven distinct benthic species, belonging to five genera and three families, confirms notable diversity despite the relatively limited geographic scope of the study. The observed species composition, dominated by \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e, suggests specific environmental preferences within the study area. Variation in foraminiferal density, ranging from high concentrations at Bandar Gaz to sparse populations at Sisangan, highlights the influence of localized environmental factors on their distribution. Also the relative scarcity of \u003cem\u003eAmmonia tepida\u003c/em\u003e and \u003cem\u003eAmmonia parkinsoniana\u003c/em\u003e, contrasted with the prevalence of \u003cem\u003eElphidium littorale caspicus\u003c/em\u003e, indicates niche differentiation or differential sensitivity to environmental factors. The restricted distribution of \u003cem\u003eCornuspira\u003c/em\u003e sp. to Bandar Torkaman warrants further investigation into localized habitat suitability. The highest density, number of species, and Shannon diversity were recorded at Bandar Gaz station. Additionally, significant differences were observed in the foraminifera community structure across the various stations. Consequently, Bandar Gaz station was selected for further experimentation. Previous studies have demonstrated that foraminiferal communities can respond to environmental changes within just a few weeks (Dong et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Goldstein and Alve, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Given this rapid responsiveness, our 60-day experimental period was sufficient to assess the effects of temperature on the benthic foraminiferal community in the south Caspian sea.Species diversity and environmental correlates principal component analysis highlighted key environmental drivers affecting foraminiferal distribution. The negative loadings of silt and salinity in PC1 suggest that finer sediments may be less favorable for certain foraminiferal species, while the positive association with temperature points to its crucial role in community structuring. Temperature is a well-documented factor influencing foraminiferal assemblages (Dubey et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), and our findings reinforce the concept that increasing temperatures can affect species dominance, as noted by the experimental results where \u003cem\u003eAmmonia beccarii\u003c/em\u003e and \u003cem\u003eAmmonia tepida\u003c/em\u003e exhibited increased densities at higher temperatures.These findings suggest that a complex interplay of sedimentological, thermal, and oxygen-related factors governs the distribution and abundance of foraminifera in this environment. In addition the experiment meticulously monitored environmental parameters, revealing a stable environment with no significant temporal variations in dissolved oxygen, pH, phosphate, or silicate concentrations across treatments. Notably, nitrate and ammonium levels showed marginal differences between treatments, with Treatment 1 exhibiting the lowest concentrations. While \u003cem\u003eAmmonia beccarii\u003c/em\u003e was the most abundant foraminifera species across all treatments, significant variations in density index, species densities, and community structure were observed among treatments, particularly driven by temperature. Specifically, higher temperatures (30\u0026deg;C) promoted the dominance of \u003cem\u003eAmmonia beccarii\u003c/em\u003e and \u003cem\u003eAmmonia tepida\u003c/em\u003e, while depressing the density of \u003cem\u003eElphidium advenum\u003c/em\u003e.Conversely, \u003cem\u003eElphidium excavatum\u003c/em\u003e and \u003cem\u003eElphidium advenum\u003c/em\u003e thrived at lower temperatures (24\u0026deg;C). These temperature- driven shifts in species dominance are further supported by differences in evenness and Shannon's diversity indices between treatments, and are visually represented in the MDS plot demonstrating distinct community structures. Margalef's index, however, remained consistent across treatments, suggesting that while species evenness and relative abundance shifted, overall species richness was unaffected by the experimental conditions. In contrast, the fluctuating densities of species like \u003cem\u003eElphidium advenum\u003c/em\u003e across different temperature treatments highlight the sensitivity of certain species to environmental changes. This phenomenon aligns with findings by Taheri et al (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) and Lei et al (2019), who documented shifts in benthic foraminifera populations in response to thermal stress. Finally,observed trends suggest a general correlation between rising temperatures and increased density and biological indices in natural communities (Hale et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Meadows et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Ingels et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). However, the impact of temperature is multifaceted and context-dependent. Community adaptation (Vafeiadou et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), the magnitude of temperature change, and concurrent environmental factors such as pH, salinity (Moens and Vincx, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), and existing faunal composition. all modulate the observed response. Further research is needed to disentangle the complex interactions driving these shifts.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe study confirms the presence and diversity of benthic foraminifera in the coastal environment under investigation, with \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e emerging as the dominant species. The distribution patterns of foraminifera are shaped by multiple environmental factors, including silt content, salinity, temperature, dissolved oxygen, and water depth. Notably, experimental results highlight temperature as a key regulator of foraminiferal density, suggesting its critical role in influencing community dynamics under shifting environmental conditions. These findings enhance our understanding of foraminiferal ecology in coastal ecosystems and establish a valuable baseline for future monitoring and research.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e6-Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is based upon research founded by Iranian National Science Foundation (INSF) under project NO. 40266240.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e7-Declaration of competing interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e8- Author Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHossein Bagheri: writing\u0026mdash;original draft preparation, methodology, writing-review and editing. Mehrshad Taheri: methodology, software, writing-review and editing, visualization. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e9-Acknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the anonymous reviewers for their constructive comments that improved the quality of the manuscript\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e10-Data availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets during and/or analyzed during the current study available from the corresponding author on reasonable request\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAltenbach, A. V. (1992). Short term processes influencing the vertical distribution of foraminifera in a sublittoral habitat. Marine Micropaleontology, 20(1), 21-29.\u003c/li\u003e\n\u003cli\u003eAlve, E., \u0026amp; Bernhard, J. M. (1995). Vertical migratory response of benthic foraminifera to controlled oxygen perturbations in an experimental marine ecosystem. Marine Ecology Progress Series, 116, 137-151.\u003c/li\u003e\n\u003cli\u003eAnderson, M.J., Gorley, R.N., \u0026amp; Clarke, K.R. (2008). PERMANOVA+ for PRIMER. Guide to software and statistical methods. PRIMER-E Ltd., Plymouth, UK.\u003c/li\u003e\n\u003cli\u003eAPHA. (2005). Standard Methods for the Examination of Water and Wastewater. American Public Health Association.\u003c/li\u003e\n\u003cli\u003eArpe, K., Molavi-Arabshahi, M. and Leroy, S.A.G. (2020). Wind variability over the Caspian Sea, its impact on Caspian seawater level and link with ENSO. International Journal of Climatology 40(14), 6039-6054. https://doi.org/10.1002/joc.6564. \u003c/li\u003e\n\u003cli\u003eAzizpour, J., Ghaffari, P. 2023. Low-frequency sea level changes in the Caspian Sea: long-term and seasonal trends. Climate Dynamics. 61, 2753\u0026ndash;2763. https://doi.org/10.1007/s00382-023-06715-9.\u003c/li\u003e\n\u003cli\u003eBagheri, H., Mahmudy Gharaei, M., Mousavi Harami, R., Khanebad, M. \u003cspan dir=\"RTL\"\u003e)\u003c/span\u003e2019\u003cspan dir=\"RTL\"\u003e(\u003c/span\u003e. Reconstruction of Caspian Sea level changes using magnetic susceptibility during the last millennium. IJMS Vol.48 (09), 1452-1459.\u003c/li\u003e\n\u003cli\u003eBernhard, J. M., 2000, Distinguishing live from dead foraminifera: methods review and proper applications. Micropaleontology 46, suppl. 1, 38-46).\u003c/li\u003e\n\u003cli\u003eBouchet, V. M. P., Koho, K. A., McCarthy, F. M. G., Martin, R. A., \u0026amp; Martin, J. B. (2012). Benthic foraminiferal distribution in Bonne Bay, Newfoundland: Assessing environmental gradients and proxy potential. \u003cem\u003eMarine Micropaleontology\u003c/em\u003e, \u003cem\u003e96\u003c/em\u003e, 38-54.\u003c/li\u003e\n\u003cli\u003eDanovaro, R., Company, J., Carreja, J. M., Duineveld, G., Kuklinski, P., \u0026amp; Van Wezel, R. (2004). Deep-sea biodiversity in the Mediterranean Sea: Which is the role of food availability?. \u003cem\u003eDeep Sea Research Part I: Oceanographic Research Papers\u003c/em\u003e, \u003cem\u003e51\u003c/em\u003e(11), 1529-1542. doi:10.1016/S0169-5347(01)02215-7.\u003c/li\u003e\n\u003cli\u003eDanovaro, R., Gambi, C., \u0026amp; Della Croce, N. (2001). Meiofauna response to organic matter enrichment in a Mediterranean coastal lagoon. \u003cem\u003eHydrobiologia\u003c/em\u003e, \u003cem\u003e445\u003c/em\u003e(1-3), 131-139.\u003c/li\u003e\n\u003cli\u003eDarvish Bastami, K., Taheri, M., Yazdani Foshtomi, M., Haghparast, S., Bagheri, H., Hamzehpoor, A., Esmaeilzadeh, M., \u0026amp; Molamohyeddin, N. (2017). Nematode community structure in relation to metals in the southern of Caspian Sea. Acta Oceanologica Sinica. 36 (10), 1\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eDolven, J. K., McCarthy, F. M. G., Collins, E. S., Chmura, G. L., \u0026amp; Patterson, R. T. (2013). Salt-marsh foraminifera as proxies for relative sea-level change: statistical (transfer function) vs. indicator zone approaches. \u003cem\u003eJournal of Quaternary Science\u003c/em\u003e, \u003cem\u003e28\u003c/em\u003e(4), 369-380.\u003c/li\u003e\n\u003cli\u003eDong, B., Kong, L., Guo, W., Zhan, B., \u0026amp; Li, X. (2019). Benthic foraminiferal response to environmental changes in the Pearl River Estuary, China. \u003cem\u003eJournal of Marine Systems\u003c/em\u003e, \u003cem\u003e195\u003c/em\u003e, 1-13.\u003c/li\u003e\n\u003cli\u003eDuffield, A., Patterson, R. T., Reinhardt, E. G., McKillop, I. K., \u0026amp; Roe, H. M. (2015). Distribution of intertidal foraminifera in the Pachena River salt marsh, British Columbia, Canada: Assessing their utility as sea-level indicators. \u003cem\u003eMarine Micropaleontology\u003c/em\u003e, \u003cem\u003e119\u003c/em\u003e, 22-36.\u003c/li\u003e\n\u003cli\u003eDubey, R., Saraswat, R., Nigam, R., 2018. Mudbank off Alleppey, India: a bane for foraminifera but not so for carbon burial. Sci. Total Environ. 634, 459\u0026ndash;470\u003c/li\u003e\n\u003cli\u003eElderfield, H., Vautravers, M., \u0026amp; Cooper, M. (2006). The relationship between benthic foraminiferal magnesium and seawater temperature. \u003cem\u003eEarth and Planetary Science Letters\u003c/em\u003e, \u003cem\u003e250\u003c/em\u003e(1-2), 208-223.\u003c/li\u003e\n\u003cli\u003eFolk, R. L. (1980). Petrology of Sedimentary Rocks. Hemphill Publishing Company\u003c/li\u003e\n\u003cli\u003eGingold, R., Moens, T., Rocha-Olivares, A. (2013). Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment. PLoS ONE, 8(6): e66653.\u003c/li\u003e\n\u003cli\u003eGoldstein, S. T., \u0026amp; Alve, E. (2011). Effect of increased bottom-water temperature on foraminiferal assemblages in a Norwegian Fjord. \u003cem\u003eJournal of Foraminiferal Research\u003c/em\u003e, \u003cem\u003e41\u003c/em\u003e(1), 1-11.\u003c/li\u003e\n\u003cli\u003eGoody, A.j. (2003). Benthic foraminifera (Protista) as tools in deep-water palaeoceanography: environmental influences on faunal characteristics. Advance Marrine Biology:46:1-90. doi: 10.1016/s0065-2881(03)46002-1.\u003c/li\u003e\n\u003cli\u003eHale, R., Calos, P., Mcneill, L., Mieszkowska, N., \u0026amp; Widdicombe, S. (2011). Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities. Oikos, 120, 661\u0026ndash;674.\u003c/li\u003e\n\u003cli\u003eHavach, S., Frontalini, F., \u0026amp; Coccioni, R. (2001). Benthic foraminifera as indicators of heavy-metal pollution in the Lagoon of Venice, Italy. \u003cem\u003eJournal of Foraminiferal Research\u003c/em\u003e, \u003cem\u003e31\u003c/em\u003e(3), 194-201Heiri, O., Lotter, A. F., \u0026amp; Lemcke, G. (2001). Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results. Journal of Paleolimnology, 25(1), 101-110.\u003c/li\u003e\n\u003cli\u003eIngels, J., dos Santos, G., Hicks, N., Valdes Vazquez, Y., Fernandes Neres, P., Pereira Pontes, L., Nataly Amorim, M., Roman, S., Du, Y., Stahl, H., Somerfield, P. J., \u0026amp; Widdicombe, S. (2018). Short-term CO2 exposure and temperature rise effects on metazoan meiofauna and free-living nematodes in sandy and muddy sediments: Results from a flume experiment. Journal of Experimental Marine Biology and Ecology, 502, 211.\u003c/li\u003e\n\u003cli\u003eLahijani, H., Azizpour,J., Arpe, K., Abtahi, B., Rahnama, R., Ghafarian, P., Hamzeh, M.A., Hamzehpour, A., Mohammadpour Penchah, M., \u0026amp; Mahmoudof, S.M. (2023). Tracking of sea level impact on Caspian Ramsar sites and potential restoration of the Gorgan Bay on the southeast Caspian coast. Science of the Total Environment. 857 (1), 158833.\u003c/li\u003e\n\u003cli\u003eLahijani, H., Ghaffari, P., Leroy, S., Naderi Beni, A., Yakushev, E., Abtahi, B., Saleh, S., Behravesh, M., 2024. A note on the silent decline of the Caspian environment, Marine Pollution Bulletin, Volume 205, 116551, https://doi.org/10.1016/j.marpolbul.2024.116551.\u003c/li\u003e\n\u003cli\u003eLe Cadre, V., Debenay, J. P. (2006). Morphological abnormalities in foraminifera: one tool for pollution assessment?. \u003cem\u003eMarine Micropaleontology\u003c/em\u003e, \u003cem\u003e61\u003c/em\u003e(3), 178-196.\u003c/li\u003e\n\u003cli\u003eLei, Y., Li, T., Jian, Z., Nigam, R., 2017a. Taxonomy and distribution of benthic foraminifera in an intertidal zone of the Yellow Sea, PR China: correlations with sediment temperature and salinity. Mar. Micropaleontol. 133, 1\u0026ndash;20.\u003c/li\u003e\n\u003cli\u003eLei, Y.-L., Stumm, K., Wickham, S.A., Berninger, U.-G., 2014. Distributions and biomass of benthic ciliates, foraminifera and amoeboid protists in marine, brackish, and freshwater sediments. J. Eukaryot. Microbiol. 61, 493\u0026ndash;508.\u003c/li\u003e\n\u003cli\u003eMaslin, M. (2008). Global warming: A very short introduction. Oxford University Press.\u003c/li\u003e\n\u003cli\u003eMeadows, A.S., Ingels, J., Widdicombe, S., Hale, R., \u0026amp; Rundle, S.D. (2015). Effects of elevated CO2 and temperature on an intertidal meiobenthic community. Journal of Experimental Marine Biology and Ecology, 469, 44\u0026ndash;56.\u003c/li\u003e\n\u003cli\u003eMoens T, Vincx M. (2000). Temperature, salinity and food thresholds in two brackishwater bacterivorous nematode species: assessing niches from food absorption and respiration experiments. Journal of Experimental Marine Biology and Ecology 243:137\u0026ndash;154 DOI 10.1016/S0022-0981(99)00114-8. \u003c/li\u003e\n\u003cli\u003eMoens, T., Artois, T., De Meyer, T., Gillardin, V., Goethals, P., \u0026amp; Van Steenkiste, N. (2013). Nematode taxonomic diversity in the Southern Ocean: a test of the latitudinal gradient hypothesis in remote, relatively unexplored habitats. PLoS One, 8(11), e80134.\u003c/li\u003e\n\u003cli\u003eMojtahid, M., Nercessian, A., Debenay, J. P., \u0026amp; Buoncristiani, J. F. (2009). Modern benthic foraminifera distribution in the Arcachon Lagoon, French Atlantic Coast: Environmental significance. Estuarine, Coastal and Shelf Science, 81(1), 81-93.\u003c/li\u003e\n\u003cli\u003eMurray, J. W. (2006). Ecology and Applications of Benthic Foraminifera. Cambridge University Press.\u003c/li\u003e\n\u003cli\u003eNordberg, K., Eichler, P. P. B., Volkov, I. A., \u0026amp; Asteman, I. P. (2017). Modern benthic foraminifera in the Sea of Azov: distribution in relation to salinity, organic matter, and pollution. \u003cem\u003eJournal of Foraminiferal Research\u003c/em\u003e, \u003cem\u003e47\u003c/em\u003e(2), 167-181.\u003c/li\u003e\n\u003cli\u003ePolovodova Asteman, I., \u0026amp; Nordberg, K. (2013). The influence of different ecological factors on benthic foraminiferal distribution in the Himmerfj\u0026auml;rden Estuary, northern Baltic Sea. \u003cem\u003eJournal of Micropalaeontology\u003c/em\u003e, \u003cem\u003e32\u003c/em\u003e(2), 173-187.\u003c/li\u003e\n\u003cli\u003eRoshan, G., Moghbel, M. \u0026amp; Grab, S. Modeling Caspian Sea water level oscillations under different scenarios of increasing atmospheric carbon dioxide concentrations. J Environ Health Sci Engineer 9, 24 (2012). https://doi.org/10.1186/1735-2746-9-24.\u003c/li\u003e\n\u003cli\u003eSamant, R., \u0026amp; Prange, M. (2023). Climate-driven 21st century Caspian Sea level decline estimated from CMIP6 projections. Communications Earth \u0026amp; Environment, 4, 357. \u003c/li\u003e\n\u003cli\u003eSch\u0026ouml;nfeld, J. (2018). \u003cem\u003eLiving foraminifera in shelf seas\u003c/em\u003e. Cambridge University Press.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Darvish Bastami, K., Yazdani Foshtomi, M., 2014a. Meiofauna-sediment relationships in shallow water of the south Caspian Sea. In: INOC-International Congress\u0026ldquo;Estuaries \u0026amp; Coastal Protected Areas\u0026rdquo; ECPA 2014, 04\u0026ndash;06 November 2014, Izmir\u0026ndash;TURKEY.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Braeckman, U., Vincx, M., Vanaverbeke, J., 2014b. Effect of short-term hypoxia on marine nematode community structure and vertical distribution pattern in three different sediment types of the North Sea. Mar. Environ. Res. 99, 149\u0026ndash;159.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Grego, M., Riedel, B., Vincx, M., Vanaverbeke, J., 2015. Patterns in nematode community during and after experimentally induced anoxia in the northern Adriatic Sea. Mar. Environ. Res. 110, 110\u0026ndash;123.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Darvish Bastami, K., Yazdani Foshtomi, M., 2017a. The role of the sediment conditions in shaping meiofauna spatial distribution in the shallow water of the south Caspian Sea. In: First International Conference on Oceanography for West Asia 30\u0026ndash;31 October 2017.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Giunio, M., De Troch, M., Vincx, M., Vanaverbeke, J., 2017b. Effect of short- term hypoxia on the feeding activity of abundant nematode genera from an intertidal mudflat. Nematology 19, 1\u0026ndash;13.\u003c/li\u003e\n\u003cli\u003eTaheri, M., Yazdani Foshtami,m M. Manbohi., A. Mira., M.(2025). Spatial distribution and effects of temperature rise on coastal free-living nematode community in the South Caspian Sea. Marine Pollution Bulletin 214. 117806. https://doi.org/10.1016/j.marpolbul.2025.117806\u003c/li\u003e\n\u003cli\u003eTaheri, M., Yazdani Foshtomi, M., Hamzeh, M.A., Manbohi, A., Rahnama Haratbar, R., 2024. Effects of discarded garbage bags on intertidal free living nematode community. Aquat. Ecol. 58, 853\u0026ndash;863.\u003c/li\u003e\n\u003cli\u003eVenegas, R.M., Acevedo, J., Treml, E.A., 2023. Three decades of ocean warming impacts on marine ecosystems: a review and perspective. Deep-Sea Res. II Top. Stud. Oceanogr. 212, 105318.\u003c/li\u003e\n\u003cli\u003eWit, J. C., Filipsson, H. L., \u0026amp; Platzman, D. J. (2013). Interactive effects of hypoxia and pH on the benthic foraminifera Ammonia tepida: growth rate, survival, and shell characteristics. \u003cem\u003eBiogeosciences\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e(11), 7479-7496.\u003c/li\u003e\n\u003cli\u003eVafeiadou, A.M., Geldhof, K., Barhdadi, W., Baetens, J., De Baets, B., Moens, T., \u0026amp; Daly, A. (2024). Temperature-driven dynamics : unraveling the impact of climate change on cryptic species interactions within the Litoditis marina complex. PEERJ, 12. https://doi.org/10.7717/peerj.17324.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Caspian Sea, Temperature, Foraminifera, Sediments","lastPublishedDoi":"10.21203/rs.3.rs-7499422/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7499422/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigated the spatial distribution of coastal foraminifera at four stations, identifying seven distinct species representing five genera and three families, with \u003cem\u003eAmmonia beccarii caspica\u003c/em\u003e as the dominant species. The Bandar Gaz station exhibited the highest density, species richness, evenness, and Shannon diversity. Consequently, Bandar Gaz was selected for a controlled field experiment examining benthic foraminiferal community responses to increased surface water temperature (20\u0026deg;C, 24\u0026deg;C, 27\u0026deg;C, and 30\u0026deg;C) over 60 days. While the highest total density and evenness were observed at 30\u0026deg;C, the total number of species and Margalef and Shannon indices did not significantly differ among treatments. Temperature changes significantly altered community structure through shifts in species dominance. \u003cem\u003eAmmonia beccarii\u003c/em\u003e displayed resilience and increased dominance with higher temperatures, replacing other species. \u003cem\u003eElphidum advenum\u003c/em\u003e density decreased significantly at 30\u0026deg;C, while \u003cem\u003eAmmonia tepida\u003c/em\u003e increased in dominance with rising temperatures. These findings highlight temperature-driven alterations in foraminiferal assemblages, with implications for coastal ecosystem monitoring in the context of climate change.\u003c/p\u003e","manuscriptTitle":"Responses of South Caspian Coastal Foraminifera to Warming: Spatial Patterns and Assemblage Shifts","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-16 12:45:25","doi":"10.21203/rs.3.rs-7499422/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-03T12:35:18+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-30T00:16:19+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-29T12:06:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"67384622775101524576690888253044694792","date":"2025-09-09T14:16:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"5344021445790444901974145174883428270","date":"2025-09-09T14:08:35+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-09T12:47:33+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-09T12:36:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-08T16:30:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-06T01:20:07+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-08-31T08:44:11+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":"bf903e55-0881-4799-b53e-cc3c852a8627","owner":[],"postedDate":"September 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":54447860,"name":"Earth and environmental sciences/Climate sciences"},{"id":54447861,"name":"Biological sciences/Ecology"},{"id":54447862,"name":"Earth and environmental sciences/Ecology"},{"id":54447863,"name":"Earth and environmental sciences/Environmental sciences"},{"id":54447864,"name":"Earth and environmental sciences/Ocean sciences"}],"tags":[],"updatedAt":"2026-02-02T16:03:58+00:00","versionOfRecord":{"articleIdentity":"rs-7499422","link":"https://doi.org/10.1038/s41598-026-38207-1","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-02-01 15:59:25","publishedOnDateReadable":"February 1st, 2026"},"versionCreatedAt":"2025-09-16 12:45:25","video":"","vorDoi":"10.1038/s41598-026-38207-1","vorDoiUrl":"https://doi.org/10.1038/s41598-026-38207-1","workflowStages":[]},"version":"v1","identity":"rs-7499422","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7499422","identity":"rs-7499422","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}