A New Li/Mg Paleothermometer from Pteropod Shells

A New Li/Mg Paleothermometer from Pteropod Shells | 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 A New Li/Mg Paleothermometer from Pteropod Shells Keul Nina, Dieter Garbe-Schönberg, Vassilis Kitidis, Gerald Langer, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8425397/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Pteropods are promising proxy archives for paleoceanographic reconstructions but remain underexplored. Previous oxygen isotope analyses indicated that Heliconoides inflatus calcifies at shallow depths (50–75 m), suggesting its potential to record surface-ocean conditions. Here, we evaluate for the first time the applicability of Li/Mg thermometry in pteropod shells, a temperature proxy widely used in coral studies. We show that, in addition to recording environmental variability through shell carbon and oxygen isotopic composition, H. inflatus shells reliably track seawater temperature via their Li/Mg ratios. Li/Mg ratios decrease exponentially with increasing temperature, enabling temperature reconstructions with an average precision of ±1–2 °C. Pteropod shells (species Heliconoides inflatus , formerly known as Limacina inflata ) were collected along a latitudinal transect in the Atlantic Ocean (31° N to 38° S), covering a temperature range of nearly 15 °C. The global distribution and abundance of this annual species in sediments makes it a suitable alternative for palaeotemperature reconstruction. The utility of pteropod shells extends further to seasonal paleotemperature reconstruction, as seasonal temperature variability is captured in the elemental ratios from the embryonic to later (adult) sections of the shell. These results, in combination with a basin-scale distribution, make the Li/Mg thermometer in pteropods an exciting new tool in paleoceanography and further cement this group as new proxy archives. Earth and environmental sciences/Climate sciences Earth and environmental sciences/Ocean sciences Earth and environmental sciences/Solid earth sciences Heliconoides inflatus paleoceanography proxy development trace elemental composition paleothermometry Atlantic Ocean Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Assessing the future impact of anthropogenic CO 2 emissions and consequent temperature increase on marine ecosystems is difficult, as the complexity of ecosystems cannot be easily replicated in laboratory experiments. Geological records provide long-term evidence of global warming and ocean acidification, along with the responses of marine calcifiers. These records reveal past ocean temperatures and chemistry through fossilized calcium carbonate shells, as well as ecological indicators like species richness and net calcification. Multiple proxies have been developed to assess temperatures in the upper ocean, such as alkenones in sediments 1 , Mg/Ca and d 18 O in planktonic foraminifera 2,3 and Sr/Ca in corals 4 . Another prominent and relatively recent proxy for reconstructing seawater temperatures is the Li/Mg ratio in aragonitic corals and foraminifera 5-7 . This thermometer has evolved from an initial exponential calibration, in which skeletal Li/Mg shows a direct relationship with seawater temperature 7 ,8 to more refined multi-proxy approaches that combine Li/Mg with Sr/ Ca 9-11 . Compared with other geochemical proxies, Li/Mg is considered to be less influenced by organismal physiology or skeletal heterogeneity⁷, making it a promising candidate for application to pteropod shells using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Pteropods are holoplanktonic marine gastropods found in both epipelagic and mesopelagic zones, from the sea surface to depths exceeding 1000 meters 12 . While they have been studied less extensively than other calcifying plankton (e.g. foraminifera) as potential oceanographic proxy archives, various features of their biology make them promising candidates. Their approximately annual life cycle 13,14 may yield a more integrative proxy record across seasons compared to planktonic foraminifera, which are characterized by a shorter life span (ca. 1 month) 15 . Even though pteropods are known to carry out diel vertical migrations and some species are found at great depths 12 , the actual calcification depth of most species is probably much shallower (50- 250 m depth 14,16,17 ). In a previous study using the same samples that are investigated here, we were able to establish a shallow calcification depth of ca. 50- 75m for H. inflatus in the Atlantic 17 . In the same study we showed that pteropod shells are excellent recorders of climate change, as carbonate ion and temperature in the upper water column have dominant influences on pteropod shell carbon and oxygen isotopic composition 17 . Here we assess the potential of the Li/Mg thermometer in pteropod shells and present trace elemental ratios of Heliconoides inflatus (namely Li/Ca, Mg/Ca, and calibrations for the Li/Mg thermometer). Our material was collected along a meridional transect in the Atlantic Ocean, ranging from 31°N to 38°S, covering a temperature range of 15°C. The studied species, H. inflatus , occurs in high abundance in sediments worldwide, for instance, in the Atlantic (Caribbean Sea 18 , Cariaco Basin 19 ), Pacific (North West Shelf of Australia 20 ) and the Indian Ocean (off the Maldives 21 ). We expect that establishing a new temperature proxy for pteropods allows the disentanglement of temperature from secondary influences on the stable isotopic composition. Results Surface distribution of oceanographic parameters in the study area. Zooplankton, water samples and physical data were collected during the Atlantic Meridional Transect Cruise 22 (AMT22), which took place from October 19 to November 16 in 2012, between 31 °N and 38 °S. The warmest surface temperatures, up to 30°C, occurred in October/ November just north of the equator (around 10°N; Figs. S1d, 1a). Temperature decreased gradually both north and south of this maximum and reached approximately 12°C at 38°S, where our southernmost station was located (Fig. S1d). The surface salinity distribution mimicked this general latitudinal zonation (Fig. 1b), however, at the latitude of the temperature maximum, low salinities of (37) occurred around 25° N and 20° S west of 30° W. Trace elemental composition of pteropod shells (Li/Ca and Mg/Ca). Individual pteropods were manually sorted from bulk zooplankton net samples. The trace elemental (TE) composition of pteropod shells was determined by LA-ICP-MS (laser ablation inductively coupled mass spectrometry). Individual pteropod TE/Ca ratios vary over the latitudes (and temperatures) analyzed (see Tab. 1, Tab. S1 and Fig. S1a–c). Average pteropod Li/Ca values range from 3.55–6.36 µmol/mol (Tab. 1, Fig. S1a), with individual spot measurements ranging from 1.66–11.69 µmol/mol (Tab. S1). Variability in pteropod Li/Ca, expressed as the relative standard deviation (RSD; ratio of standard deviation to mean, in percent), is on average 23%. The highest values are found at the southernmost station (38.11°S) and the lowest values at the northernmost station. Pteropod Mg/Ca values (Tab. 1, Fig. S1b) vary on average from 0.20–0.84 mmol/mol, while individual spot measurements range from 0.13–3.93 mmol/mol (Tab. S1), with an average RSD of 37%. The comparatively high intra-shell variability observed for both Li/Ca and Mg/Ca warrants further investigation of within-shell compositional trends, which is addressed below. The Li/Mg thermometer in pteropod shells. Average pteropod Li/Mg values (Fig. S1c) range from 9.37–35.29 µmol/mmol, while individual spot measurements display a broader range of 2.05–52.64 µmol/mmol, with an average RSD of 38% (Tab. 1, Tab. S1, Fig. S1c). While Li/Ca ratios show a weak negative correlation with surface (50 m) temperature (p 0.05; Tab. S2b, Fig. 2b). In contrast, Li/Mg ratios display a significant positive relationship with surface (50 m) temperature, described by both a linear (p < 0.05, R² = 0.70) and an exponential fit (p < 0.05, R² = 0.73; Tab. 2, Fig. 2c). Our dataset does not allow discrimination between the two fits; therefore, both relationships are reported, although exponential relationships are more commonly reported in the literature for Li/Mg paleothermometry 7 . The following equations describe the linear and exponential correlations with temperature (T) at 50 m water depth: with p<0.05, R 2 =0.73. In addition, stable oxygen isotope ratios (δ¹⁸O) measured on the same set of pteropod samples have previously been shown to provide a reliable temperature proxy 17 . Temperatures derived from Li/Mg ratios are positively correlated with δ¹⁸O-derived temperatures (p < 0.05, R² = 0.57; Fig. 2d). Compositional variability of Mg/Ca, Li/Ca and Mg/Li ratios in pteropods. Trace elemental/ Ca ratios from LA-ICP-MS tend to have a much higher variability compared to traditional ICP-MS analysis of whole, acid-dissolved shells, where the intra-test inhomogeneity cannot be resolved. The average RSD of 23% for Li/Ca and 37% for Mg/Ca highlights pronounced compositional variability within individual pteropod shells and motivates a more detailed assessment of intra-shell trends. Laser ablation targets were placed at multiple positions across the shell, ranging from the innermost embryonic shell (spot 1; Fig. 3a) to progressively younger shell material formed later in ontogeny (spots 2–4; Fig. 3a). For clarity, laser spot 1 corresponds to the innermost, embryonic or very early juvenile shell material, while laser spots 2–4 represent progressively younger shell material formed later during ontogeny; this spatial framework is used throughout the Discussion when referring to shell growth stages. No statistically significant difference in median values was detected for Li/Ca ratios between measurements obtained from spot 1 and spot 4 (p > 0.05; Fig. 3b). In contrast, Mg/Ca ratios show a statistically significant difference between spot 1 and spot 4 (Wilcoxon test, p < 0.05; Fig. 3c), indicating systematic changes in Mg incorporation across shell growth. Similarly, Li/Mg ratios differ significantly between spot 1 and spot 4 (Welch’s t-test, p < 0.05; Fig. 3d). Discussion Apart from an early study investigating trace elemental incorporation in pteropods 24 , there has been no study looking at a suite of trace metals since. However, several studies have investigated the relationship between environmental signals and trace elemental signature in shells of various other groups. For example , Jurikova and colleagues 25 examined Li/Ca and Mg/Ca ratios in modern brachiopod shells and reported a moderate variability in Li/Ca (34– 39.1 μmol/mol) and Mg/Ca ( 5.79 to 7.39 mmol/mol).Another study assessed elemental ratios in the aragonitic gastropod Turbo torquatus from multiple locations in Western Australia 26 . Their results yielded an average Li/Ca ratio of 7.1 μmol/mol, but they noted that the Li concentrations were too variable to serve as reliable environmental indicators. Average Mg/Ca values were with ca. 0.4 mmol/mol markedly lower than in brachiopods and more similar to the values we measured on pteropods (0.2 – 0.8 mmol/mol, Tab. 1). Another study analyzed elemental composition on another gastropod species, Patella caerulea, and reported even lower Li/Ca ratios of 0.0031 - 0.0052 mmol/mmol, associated with low Mg/Ca values of 0.52 – 0.78 mmol/mol 27 . It is noteworthy that all three gastropods, Turbo, Patella (aragonite shell parts ) , and Heliconoides , display similar Li/Ca and Mg/Ca values 26,27 . This suggests similar Li and Mg incorporation mechanisms across the Gastropoda. These similarities among mollusks seem to be mirrored in their suitability as proxy archives, e.g. Heliconoides (this study) and Mytilus 28 . It remains to be studied which fractionation processes underpin the robust Li/Mg vs temperature relationships in gastropods. Marriott and coworkers 29 compared Li/Ca ratios and lithium isotopic compositions in abiotic and foraminiferal CaCO₃, concluding that biological control is generally limited but not absent. They highlighted the importance of mineralogy, temperature, and salinity, while also recognizing the influence of species-specific physiological factors in modifying trace elemental uptake. A strong association between Mg and Li in biogenic carbonates was pointed out, suggesting similar transport mechanisms of these two elements in mollusks as identified by Dellinger an colleagues 28 . The Li/Ca and Mg/Ca values we report here fit well into their overall correlation of Li/Ca versus Mg/Ca 28 , aligning well with values from other calcifiers, including mollusks (Fig. 4). Our data from pteropods can be found on the lower end of the range of trace elemental/ calcium ratios along with values reported by Langer and colleagues 27 for the gastropod Patella . While recent studies have advanced our understanding of pteropod shell ultrastructure 41 the mechanisms of their biomineralisation remain poorly understood. However, extensive research on other mollusks provides useful insights that may inform hypotheses about pteropod shell formation 42 . In mollusks, calcification was traditionally assumed to occur within the extrapallial fluid (EPF)—a semi-isolated compartment located between the shell and mantle epithelium. The EPF is generally assumed to be similar in ionic composition to seawater, but enriched with organic macromolecules such as proteins and polysaccharides that are believed to modulate crystal nucleation and growth 43-47 . The precipitation of shell calcium carbonate directly from the EPF, however, has become increasingly unlikely since multiple avenues of research have shown that the mantle epithelium most likely is in close contact with the shell surface at the site of crystallization 48-52 . Based on this idea, a distinction between two ion transport scenarios, the “EPF scenario” and the “mantle scenario” was proposed by Langer and colleagues 27 . The latter authors suggested that in the EPF scenario the fractionation of trace elements should be explicable in terms of inorganic precipitation from seawater, whereas in the mantle scenario no such simple explanation is expected because selective ion transport can, and likely will, lead to fractionation patterns markedly different from fractionation in inorganic precipitation experiments. Fractionation patterns can be analysed from different perspectives. A useful parameter to look at in this regard is the partitioning coefficient (K D ) which is defined as: where (TE/Ca) CC refers to the measured molar ratio of the trace element (TE) and Ca in calcium carbonate and (TE/Ca) SW to that in the seawater or culture media. The K D shows if the element is enriched (K D >1) or depleted (K D <1) in the biomineral relative to seawater. Assuming average Mg/Ca ratio of surface Atlantic seawater (~upper 200 m) of approximately 5.1 mol/mol 53 , the calculated K DMg for our pteropod values falls between 0.04 – 0.17 x 10 -3 (Tab. S3), whereas inorganic K DMg for aragonite of ca. 1-2 x 10 -3 have been reported 54 . Little information on seawater Li/Ca variability has been reported, so we assume a seawater Li/Ca ratio of 0.0025 mol/mol here 8 , resulting in a range of K DLi for our Li/Ca values of ca. 1.4 – 2.5 x 10 -3 (Tab. S3). In comparison, inorganic K DLi for aragonite have been reported on the order of 3-4 x 10 -3 29 . Interestingly, our average values for K DMg and K DLi (0.1 and 1.9 x 10 -3 , Tab. S3), align well with those observed in Patella, another gastropod species (0.1 and 2.2 x 10 -3 ) 27 . Our calculated partitioning coefficients (K D ), namely 0.04 – 0.17 x 10 -3 for K DMg and 1.4 – 2.5 x 10 -3 (Tab. S3) for K DLi show that the K DLi is explicable in the EPF scenario, since the K DLi close to values reported for inorganically precipitated aragonite (3 – 4 x 10 -3 ) 29 whereas the KD Mg is not (inorganic values: 1-2 x 10 -3 ) 54 . The same holds for Patella , where also the K D s of Sr, B, and U were inexplicable in the EPF scenario 27 . It would be helpful to analyze K D s of Sr, B, and U in pteropods as well to uncover how far similarities in absolute fractionation (K D ) between mollusks go. At any rate, it can be tentatively concluded that pteropods do not calcify according to the EPF scenario, because for this to be so, the K D of every trace element should be seawater-like. Another similarity in the fractionation behavior of Heliconoides and Patella is the apparent sensitivity of K DLi to environmental and physiological parameters. In Patella , K DLi shows a negative correlation with calcification rate 27 . In Heliconoides , K DLi exhibits a negative correlation with temperature (Fig. 2a), which may indirectly reflect changes in calcification rate, as temperature and calcification rate are generally positively correlated in pteropods (up to a thermal optimum) 55 . By contrast, inorganic precipitation experiments show a positive relationship between K DLi and precipitation rate 56 This is another indication that the mantle scenario is operative in pteropods, as it most likely is in other mollusks. The positive K DMg rate dependence in Patella and the insignificant temperature dependence in Heliconoides are the only difference in fractionation patterns between these two gastropods. It is clearly warranted to analyze more trace elements and more aspects of their fractionation patterns (such as dependence on seawater chemistry) in pteropods. These data would help to understand whether pteropods follow the general mollusk biomineralization mechanism. Li/Mg ratios were highest in the innermost part of the shell, corresponding to the embryonic or very early juvenile (veliger) stage (laser spot 1; Fig. 3d), and decreased progressively with increasing shell growth (laser spots 2–4). Applying the exponential (linear) Li/Mg–temperature calibration (Eq. 2) yields a reconstructed temperature of approximately 18.5 (19.1) °C for the median Li/Mg ratio of laser spot 1 (23.6 µmol/mmol), whereas median values from laser spot 4 (8.9 µmol/mmol) correspond to markedly higher temperatures of approximately 32.4 (29.6) °C. In addition to seasonal variability in ambient temperature, these ontogenetic differences in Li/Mg ratios may reflect changes in biomineralization processes during early shell formation, shifts in habitat depth occupied over the life cycle, or a combination of these factors. Shells of the genus Heliconoides have been reported to exhibit pronounced microstructural heterogeneity. Most of the shell consists of fibrous material arranged in a helical structure, corresponding to laser spots 1–3 (Fig. 3). In contrast, more external shell regions, represented by laser spot 4, display a crossed-lamellar microstructure 41 . Such ontogenetically controlled variations in shell microstructure and mineralization pathways during pteropod shell growth may influence trace-element incorporation and could therefore partly explain the differences in Li/Mg ratios between earlier-formed shell portions (laser spots 1–3) and later formed shell material (laser spot 4), independent of external environmental conditions. However, these microstructural differences cannot account for the variations observed within laser spots 1–3 themselves, where a distinct decreasing trend in Li/Mg ratios is already evident (Fig. 3d). Consequently, additional explanations must be considered. Heliconoides inflatus exhibits brooding brooding behaviour 57 , whereby embryos are retained within the mantle cavity until they are released as veligers (approximately 70 µm in diameter). If initial shell formation occurs while embryos or veligers are still brooded by the adult, the resulting Li/Mg signature may reflect the environmental conditions experienced by the brooding individual rather than those encountered by free-living early life stages. This process would primarily affect the earliest shell material (laser spot 1), providing a potential explanation for the difference in Li/Mg ratios—and consequently reconstructed temperatures—between embryonic shell portions and those formed during later ontogenetic stages. However, this mechanism alone cannot explain the progressive decrease in Li/Mg ratios observed from laser spots 2 to 4 (Fig. 3d). The most important external factor to consider is temperature. Although the timing and environmental conditions of egg release in H. inflatus remain poorly constrained, sediment trap observations 19 and the intra-shell geochemical data presented here (Tab. S1; Fig. 3d) provide insight into aspects of its life cycle. Interpreting the data in terms of a discrete seasonal spawning period is challenging due to opposing seasons encountered along the transect, the generally weak seasonality of tropical and subtropical waters, and the widespread occurrence of veligers, juveniles, and adults throughout the study area (K. Peijnenburg, pers. obs.). These observations suggest that the life cycle of H. inflatus differs from that of higher-latitude pteropod species and is unlikely to be tightly coupled to strong seasonal environmental variability. Nevertheless, temperature remains the most plausible external control on Li/Mg incorporation. The relatively low reconstructed temperatures recorded in embryonic and juvenile shell portions are therefore most likely the result of shell formation during cooler phases of the annual temperature cycle, potentially amplified by ontogenetically controlled processes, and/ or brooding effects. Further research is needed to fully decipher the life-cycle information archived within different sections of pteropod shells. The geological record contains a wealth of information about past climate change events, as past ocean temperature and chemistry can be derived from fossil calcium carbonate shells 58,59 . The present study shows that the studied species here, H. inflatus, is nicely suited for paleo-reconstructions, as the Li/Mg thermometer works well in pteropod shells. Additionally, the fact that these proxies cannot be only measured simultaneously on a single pteropod shell but also along the whorl of a pteropod renders them promising new proxy carriers, as this offers the potential to assess seasonal variation within one specimen. The material comprising a single pteropod shell may, in theory, be precipitated at different depths and over multiple seasons. This is consistent with reports indicating that the average lifespan of several pteropod species is approximately one year 13 . In the case of H. inflatus , the lifespan is likely shorter, on the order of ~7–9 months 14 . Because H. inflatus preferentially inhabits surface waters 14,16 , where environmental parameters influencing shell trace-element incorporation (e.g., temperature and salinity) vary seasonally, the resulting shell geochemistry may integrate signals from changing conditions throughout the year. Sediment-trap studies would therefore be well suited to assess the influence of seasonality on the trace-element composition of pteropod shells. In addition, culturing experiments could be used to investigate the effects of other environmental parameters, such as carbonate chemistry, on trace-element incorporation, analogous to approaches commonly employed in foraminiferal studies 60-63 . Correlations between trace elemental composition of pteropod shells and upper ocean water temperature show that indeed the Mg/Li paleothermometer can be applied in pteropods with the following regression (assuming an exponential relationship between Li/Mg and temperature, equation 2) : with p<0.05, R 2 =0.73. Comparing the average standard deviation of the Li/Mg measurements (≈4.0 µmol/mmol) with the the temperature sensitivity of the linear and exponential paleothermometry calibrations (equation 4) provides an estimate of the magnitude of temperature changes that can be reliably reconstructed. For H. inflatus , the exponential calibration (equation 4) resolves ~1–2 °C of temperature change for station averages with typical to high Li/Mg values (~0.37–35.3 µmol/mmol). These results indicate that pteropod-derived Li/Mg ratios are sufficiently sensitive to reconstruct glacial–interglacial temperature variations across the study transect Heliconoides inflatus is a pteropod species that has a global distribution in tropical and subtropical waters (including the Caribbean, Mediterranean and Indo-Pacific). Therefore, it is a good proxy carrier to assess surface water variations over paleo timescales worldwide. One limitation is the occurrence of well-preserved pteropod shells in sediments confined to waters above the lysocline of aragonite. However, there are plenty of sediment cores available in which H. inflatus is abundant, well preserved and where the calibrations reported here can be applied 18,20,64 21,65,66 . Methods Pteropod collection. Bulk zooplankton samples were collected during the Atlantic Meridional Transect Cruise 22 (AMT22), which took place from October 19 to November 16, 2012. Oblique bongo net tows (200 µm and 333 µm mesh sizes) were conducted from an average depth of 361 meters up to the sea surface. Pteropods were sampled at 11 stations spanning latitudes from 31°N to 38°S, primarily during the pre-dawn hours (see Tab. S1). Following collection, specimens were immediately preserved in 96–99% ethanol, with the ethanol replaced within 12–24 hours. Samples were then stored at –20°C until further analysis. Seawater parameters: temperature and salinity. Seawater temperature and salinity in the upper 500 m of the water column were obtained by conductivity-temperature-depth (CTD) casts (Sea-Bird Electronics, models: ocean logger, SBE45, 9plus). Sensors were calibrated and data archived by the British Oceanographic Data Centre (BODC). Furthermore data from the World Ocean Database (WOD) 22 were used to generate surface distribution maps of the Atlantic for temperature and salinity (Fig. 1). Plots present average values from October through November in order to obtain a representation of the typical surface distribution of these parameters during the period of the cruise (10/13/2012 to 11/19/2012). The WOD data collection contained all surface data available from 1986 to 2011. Elemental composition of pteropod shells. The LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) system at Kiel University was used to determine elemental concentrations of pteropod shells. The LA-ICP-MS system consisted of a quadrupole mass spectrometer (Agilent 7500s) connected to a 193nm excimer laser ablation system (Coherent GeoLas HD), equipped with a Zurich-type two-volume ablation cell. Helium @ ~1L/min was used as the carrier gas with 14 mL/min H 2 added to increase sensitivity. The pulse repetition rate was set to 6 Hz, and energy density was ~3 J cm -2 while using an ablation beam diameter of 60mm. Assuming standard natural abundance ratios 67 , counts of 7 Li, 24 Mg, 27 Al, 43 Ca 44 Ca, 57 Fe were used to calculate elemental concentrations. A complete measurement cycle through all masses took 0.5s. The ablation profiles were checked for potential surface contaminations using 27 Al and 57 Fe. A glass reference material (SRM NIST 612) 67 was ablated three times and a pressed-powder nanopellet 68 of JCt-1 (aragonitic giant clam Tridacna gigas ) 69 was used as a consistency standard between every 10 samples. The glass standard was ablated at a higher energy density (~13 J cm -2 ). Assuming 40wt% (m/m) calcium in calcite, 43 Ca was chosen as an internal standard, while counts for 44 Ca were used to check for consistency. Using the software Glitter (software for LA data reduction) 70 , time resolved isotopic counts during ablation of the shell were integrated and the background substracted. Then the isotopic counts were normalised to 43 Ca and converted to concentrations using the signals obtained on the NIST standards. Three individual specimens were analyzed per station and between three to four individual laser spot measurements were carried out per shell, summing up to 104 single spot measurements on pteropod shells in total. During the measurements, the laser ablated sequentially deeper parts of the test, and measurements were stopped once the laser had protruded through the test. Statistical analyses. On each specimen 3–4 laser spots were placed (Tab. S1), and the resulting measurements were averaged to obtain a single value per specimen. Station-level means were calculated from the three specimen averages. The standard error (SE) for each station was calculated from the standard deviation of the three specimen averages divided by the square root of the number of specimens (n = 3). Single spot measurements from different specimens were averaged per station and regression analyses (linear and exponential) were performed to analyze correlation between pteropod trace elemental ratios (namely Li/Ca, Mg/Ca, Li/Mg) and environmental parameters (temperature, salinity) at several depths (2, 25, 50, 75, 100, 200, 250, 300 m). Furthermore, we performed regressions against d 18 O, as this has been found on the same set of plankton samples to be a good temperature proxy 17 . Data was tested for normality using Shapiro test, normal distributed data was compared using Welch’s t-test, if not, Wilcoxon test was performed. All analyses were performed in R ( version 4.4.1 71 ). Declarations Acknowledgements We thank the scientists participating in the Atlantic Meridional Transect (AMT) programme and the crew of the RRS James Cook for their support during zooplankton sampling. We also acknowledge the assistance of Matthis Frey and Ulrike Westernströer with LA-ICP-MS measurements, and thank Mathieu Dellinger for sharing his compilation of Li/Ca and Mg/Ca data across different phyla. This study contributes to the international IMBeR project and represents contribution number ### of the AMT programme. Author Contributions N.K. and K.T.C.A.P. designed the study, K.T.C.A.P. and V.K. carried out sampling, N.K. and D.G.S analyzed the data and N.K. compiled the manuscript with the help of all co-authors. Funding N.K. was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number 522414573 and by BONITOS Project (International programme DFG–AEI 2023 – Project number 541693727; PCI2025-163190) during the writing of the manuscript. NK received funding for the laboratory work by a scholarship from the Daimler Benz Stiftung and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 80 – 24122362.KP was supported by the Netherlands Organisation for Scientific Research (NWO) cruise participation grant, and the NWO Vidi grant 016.161.351. The Atlantic Meridional Transect is funded by the UK Natural Environment Research Council through its National Capability Long-term Single Centre Science Programme, Atlantic Climate and Environment Strategic Science – AtlantiS (Grant No. NE/Y005589/1). Data availability All Li/Mg, Mg/Ca, and Li/Ca ratios measured in this study are provided in the Supplementary Information. Shell stable carbon and oxygen isotope data can be found in our previous publication: Keul, N. et al., Scientific Reports 7, 12645 (2017). Any additional information or analysis scripts are available from the corresponding author upon reasonable request. 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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-8425397","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":571177376,"identity":"8178b186-ed5a-41f4-8bea-8428fcd7af04","order_by":0,"name":"Keul Nina","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABE0lEQVRIie2Pv0vEMBTHv+UgXWrniBb/hUDAH3j4tzQc6CaCy40Nhd4idK2T/4L/gSkBXQqut8oNrhkcOgia9Dx0Sb1RMJ+Q5CW8D+89IBD4i0zcoYA0loVxMbFL4QpR8ZtCklY23wobUbBRaB416xexe0Q5indag24qqt2VlG/QlymIUIYhqz3KSZnOKJbnotoTstyHvraNqbZh4LeeMkwnjMJopyxWFDY4eC3sJ8S98iq8h/mwjbWyHBTEhX63yoNfObSNKVHRSEozKERpuCqeWZxynHczXiV2FrALp+TtDaO88VV57vjSPJ5ldfz0Ivv5qbgrCDf9fJrVnvEH8q97YqfeQEfyfxD12+UFAoHAP+MTmdpd+f9fwdgAAAAASUVORK5CYII=","orcid":"","institution":"Kiel University","correspondingAuthor":true,"prefix":"","firstName":"Keul","middleName":"","lastName":"Nina","suffix":""},{"id":571177377,"identity":"6e1beb52-f355-472a-a6c2-a756559ce609","order_by":1,"name":"Dieter Garbe-Schönberg","email":"","orcid":"","institution":"Kiel University","correspondingAuthor":false,"prefix":"","firstName":"Dieter","middleName":"","lastName":"Garbe-Schönberg","suffix":""},{"id":571177379,"identity":"7c5332a1-bbaf-4dff-931c-106f7a85b096","order_by":2,"name":"Vassilis Kitidis","email":"","orcid":"","institution":"Plymouth Marine Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Vassilis","middleName":"","lastName":"Kitidis","suffix":""},{"id":571177380,"identity":"bcae2042-6e31-4880-8d20-2bf083c90bc1","order_by":3,"name":"Gerald Langer","email":"","orcid":"","institution":"Alfred Wegener Institute for Polar and Marine Research","correspondingAuthor":false,"prefix":"","firstName":"Gerald","middleName":"","lastName":"Langer","suffix":""},{"id":571177381,"identity":"f9977ae3-938b-49b6-8d5a-d78778f3055a","order_by":4,"name":"Katja T.C.A. Peijnenburg","email":"","orcid":"","institution":"Naturalis Biodiversity Center","correspondingAuthor":false,"prefix":"","firstName":"Katja","middleName":"T.C.A.","lastName":"Peijnenburg","suffix":""}],"badges":[],"createdAt":"2025-12-22 14:07:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8425397/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8425397/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":100100987,"identity":"4f9ff775-3435-4118-9f34-ca18f3e28667","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":29582300,"visible":true,"origin":"","legend":"","description":"","filename":"TECAAMTfinal2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/669783b28d47b331feab5abe.docx"},{"id":100100984,"identity":"3bb2d07c-50ec-4877-8251-54f2835e4c23","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8085,"visible":true,"origin":"","legend":"","description":"","filename":"51c279dfc6324827bd504a3b29c97c11.json","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/6748ae60bafa0b3f67fda512.json"},{"id":100100986,"identity":"4ccf0e94-a79a-486e-b411-4189b7c74217","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":923228,"visible":true,"origin":"","legend":"","description":"","filename":"SOMv1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/91e3c5f039062853b7f0aac5.pdf"},{"id":100100979,"identity":"065a8c83-b20a-4791-9ef7-6f0d34a8d5eb","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":251739,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution plots of (\u003cstrong\u003ea\u003c/strong\u003e) temperature (° Celsius) and (\u003cstrong\u003eb\u003c/strong\u003e) salinity (psu) in surface waters in the Atlantic Ocean. Only cruise stations from which pteropods were sampled for this study are shown. Data are derived from the World Ocean Database\u003csup\u003e22\u003c/sup\u003e and represent average values during the months of the cruise (October and November) between 1986 and 2011. The software Ocean Data View (v. 4.6.3, http://odv.awi.de) was used to generate these maps\u003csup\u003e23\u003c/sup\u003e. Modified after Fig. 1 in Keul et al., 2017\u003csup\u003e17\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/deaaaad16b473ce7be590969.jpg"},{"id":100100982,"identity":"d2051853-295a-4316-9040-e7c2a395280d","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1059643,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation plots of (\u003cstrong\u003ea\u003c/strong\u003e) Li/Ca ((mmol/mol), (\u003cstrong\u003eb\u003c/strong\u003e) Mg/Ca (mmol/mol) and (\u003cstrong\u003ec\u003c/strong\u003e) Li/Mg (mmol/mmol) versus temperature at 50m depth and (\u003cstrong\u003ed\u003c/strong\u003e) temperature derived from Li/Mg versus temperature derived from d\u003csup\u003e18\u003c/sup\u003eO\u003csup\u003e17\u003c/sup\u003e. Depicted are average values per station, error bars represent the standard errors, please note: in some instances error bars are smaller than closed squares.\u0026nbsp; Dashed lines in (\u003cstrong\u003ea\u003c/strong\u003e) and (\u003cstrong\u003ec\u003c/strong\u003e) depict statistically significant (p\u0026lt;0.05) linear regressions, dot-dashed line in (\u003cstrong\u003ec\u003c/strong\u003e) depicts exponential regression. Dashed line in (\u003cstrong\u003ed\u003c/strong\u003e) represents the 1:1 line where calculated Li/Mg temperatures would exactly equal δ¹⁸Oₐ-derived temperatures (data can be found in Keul et al., 2017\u003csup\u003e17\u003c/sup\u003e). Data can be found in Tab. 1 and 2.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/ce5114b9fa1b2e5346572410.jpg"},{"id":100364996,"identity":"f56183cc-7c90-4c5b-b926-3807fccd786d","added_by":"auto","created_at":"2026-01-16 07:54:33","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1423741,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003eSketch depicting the location on the pteropod shell, where spots for LA-ICP-MS were placed (laser spots). Box and whisker’s plots of (\u003cstrong\u003eb\u003c/strong\u003e) Li/Ca ((mmol/mol), (\u003cstrong\u003ec\u003c/strong\u003e) Mg/Ca (mmol/mol) and (\u003cstrong\u003ed\u003c/strong\u003e) Li/Mg (mmol/mmol) versus different laser spot positions (laser spot 1–4). Each box represents the interquartile range (IQR) with the median indicated by a horizontal line. Whiskers extend to 1.5× the IQR, and individual data points outside this range (if any) are plotted as potential outliers. Data can be found in Tab. S1.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/1129dfb0c2998f2df8d2efe9.jpg"},{"id":100100981,"identity":"48480527-7f8d-4cbc-9ac1-2ebf7b749dfe","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":185709,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between Li/Ca (mmol/mol) and Mg/Ca (mmol/mol) across different groups of organisms. Purple indicates results from this study, with purple squares indicating average values (Tab. 1), purple crosses indicating individual laser spots (Tab. S1). Data from various published datasets are represented in black. Black squares indicate data from other mollusks \u003csup\u003e26-28,30,31\u003c/sup\u003e, crosses indicate data from corals\u003csup\u003e7,8,29,32,33\u003c/sup\u003e, planktic and benthic foraminifera\u003csup\u003e34,35-37\u003c/sup\u003e, red algae\u003csup\u003e38\u003c/sup\u003e, and brachiopods \u003csup\u003e25,28,39,40\u003c/sup\u003e. Note logarithmic scales.\u003c/p\u003e","description":"","filename":"Figure4jpg.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/4a94847f336aeb276f6fab39.jpg"},{"id":100382057,"identity":"4d60456c-b1fb-4290-8403-e8ddd795bca6","added_by":"auto","created_at":"2026-01-16 10:40:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3778262,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/e90f643f-e7ae-46b0-a9ca-9f245c22f7d2.pdf"},{"id":100365558,"identity":"5b9c3b7e-866b-48b6-a70a-716ec3fe16c9","added_by":"auto","created_at":"2026-01-16 07:55:22","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":923228,"visible":true,"origin":"","legend":"","description":"","filename":"SOMv1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/e3ae15604df4ea7925f633a2.pdf"},{"id":100100980,"identity":"9e4f0359-2762-424c-a28a-7867bebe6896","added_by":"auto","created_at":"2026-01-13 03:32:09","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":19465,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8425397/v1/e9240757deb9e878bc7642be.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"A New Li/Mg Paleothermometer from Pteropod Shells","fulltext":[{"header":"Introduction ","content":"\u003cp\u003eAssessing the future impact of anthropogenic CO\u003csub\u003e2\u003c/sub\u003e emissions and consequent temperature increase on marine ecosystems is difficult, as the complexity of ecosystems cannot be easily replicated in laboratory experiments. Geological records provide long-term evidence of global warming and ocean acidification, along with the responses of marine calcifiers. These records reveal past ocean temperatures and chemistry through fossilized calcium carbonate shells, as well as ecological indicators like species richness and net calcification. Multiple proxies have been developed to assess temperatures in the upper ocean, such as alkenones in sediments \u003csup\u003e1\u003c/sup\u003e, Mg/Ca and\u0026nbsp;d\u003csup\u003e18\u003c/sup\u003eO in planktonic foraminifera\u003csup\u003e2,3\u003c/sup\u003e and Sr/Ca in corals\u003csup\u003e4\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAnother prominent and relatively recent proxy for reconstructing seawater temperatures is the Li/Mg ratio in aragonitic corals and foraminifera\u003csup\u003e5-7\u003c/sup\u003e. This thermometer has evolved from an initial exponential calibration, in which skeletal Li/Mg shows a direct relationship with seawater temperature\u003csup\u003e7\u003c/sup\u003e\u003csup\u003e,8\u003c/sup\u003e to more refined multi-proxy approaches that combine Li/Mg with Sr/\u0026nbsp;Ca\u003csup\u003e9-11\u003c/sup\u003e.\u0026nbsp;Compared with other geochemical proxies, Li/Mg is considered to be less influenced by organismal physiology or skeletal heterogeneity⁷, making it a promising candidate for application to pteropod shells using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).\u003c/p\u003e\n\u003cp\u003ePteropods are holoplanktonic marine gastropods found in both epipelagic and mesopelagic zones, from the sea surface to \u0026nbsp;depths exceeding 1000 meters\u003csup\u003e12\u003c/sup\u003e.\u0026nbsp;While they have been studied less extensively than other calcifying plankton (e.g. foraminifera) as potential oceanographic proxy archives, various features of their biology make them promising candidates. Their approximately annual life cycle\u003csup\u003e13,14\u003c/sup\u003e may yield a more integrative proxy record across seasons compared to planktonic foraminifera, which are characterized by a shorter life span (ca. 1 month)\u003csup\u003e15\u003c/sup\u003e. Even though pteropods are known to carry out diel vertical migrations and some species are found at great depths\u003csup\u003e12\u003c/sup\u003e, the actual calcification depth of most species is probably much shallower (50- 250 m depth\u003csup\u003e14,16,17\u003c/sup\u003e). In a previous study using the same samples that are investigated here, we were able to establish a shallow calcification depth of ca. 50- 75m for \u003cem\u003eH. inflatus\u003c/em\u003e in the Atlantic\u003csup\u003e17\u003c/sup\u003e. In the same study we showed that pteropod shells are excellent recorders of climate change, as carbonate ion and temperature in the upper water column have dominant influences on pteropod shell carbon and oxygen isotopic composition\u003csup\u003e17\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eHere we assess the potential of the Li/Mg thermometer in pteropod shells and present trace elemental ratios of \u003cem\u003eHeliconoides inflatus\u003c/em\u003e (namely Li/Ca, Mg/Ca, and calibrations for the Li/Mg thermometer). Our material was collected along a meridional transect in the Atlantic Ocean, ranging from 31°N to 38°S, covering a temperature range of 15°C. The studied species, \u003cem\u003eH. inflatus\u003c/em\u003e, occurs in high abundance in sediments worldwide, for instance, in the Atlantic (Caribbean Sea\u003csup\u003e18\u003c/sup\u003e, Cariaco Basin\u003csup\u003e19\u003c/sup\u003e), Pacific (North West Shelf of Australia\u003csup\u003e20\u003c/sup\u003e) and the Indian Ocean (off the Maldives\u003csup\u003e21\u003c/sup\u003e). We expect that establishing a new temperature proxy for pteropods allows the disentanglement of temperature from secondary influences on the stable isotopic composition.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eSurface distribution of oceanographic parameters in the study area.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZooplankton, water samples and physical data were collected during the Atlantic Meridional Transect Cruise 22 (AMT22), which took place from October 19 to November 16 in 2012, between 31 \u0026deg;N and 38 \u0026deg;S. The warmest surface temperatures, up to 30\u0026deg;C, occurred in October/ November just north of the equator (around 10\u0026deg;N; Figs. S1d, 1a). Temperature decreased gradually both north and south of this maximum and reached approximately 12\u0026deg;C at 38\u0026deg;S, where our southernmost station was located (Fig. S1d). The surface salinity distribution mimicked this general latitudinal zonation (Fig. 1b), however, at the latitude of the temperature maximum, low salinities of (\u0026lt;36) prevailed. Highest surface salinities (\u0026gt;37) occurred around 25\u0026deg; N and 20\u0026deg; S west of 30\u0026deg; W.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrace elemental composition of pteropod shells (Li/Ca and Mg/Ca).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIndividual pteropods were manually sorted from bulk zooplankton net samples. The trace elemental (TE) composition of pteropod shells was determined by LA-ICP-MS (laser ablation inductively coupled mass spectrometry). Individual pteropod TE/Ca ratios vary over the latitudes (and temperatures) analyzed (see Tab. 1, Tab. S1 and Fig. S1a\u0026ndash;c). Average pteropod Li/Ca values range from 3.55\u0026ndash;6.36 \u0026micro;mol/mol (Tab. 1, Fig. S1a), with individual spot measurements ranging from 1.66\u0026ndash;11.69 \u0026micro;mol/mol (Tab. S1). Variability in pteropod Li/Ca, expressed as the relative standard deviation (RSD; ratio of standard deviation to mean, in percent), is on average 23%. The highest values are found at the southernmost station (38.11\u0026deg;S) and the lowest values at the northernmost station.\u003c/p\u003e\n\u003cp\u003ePteropod Mg/Ca values (Tab. 1, Fig. S1b) vary on average from 0.20\u0026ndash;0.84 mmol/mol, while individual spot measurements range from 0.13\u0026ndash;3.93 mmol/mol (Tab. S1), with an average RSD of 37%. The comparatively high intra-shell variability observed for both Li/Ca and Mg/Ca warrants further investigation of within-shell compositional trends, which is addressed below.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe Li/Mg thermometer in pteropod shells.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAverage pteropod Li/Mg values (Fig. S1c) range from 9.37\u0026ndash;35.29 \u0026micro;mol/mmol, while individual spot measurements display a broader range of 2.05\u0026ndash;52.64 \u0026micro;mol/mmol, with an average RSD of 38% (Tab. 1, Tab. S1, Fig. S1c). While Li/Ca ratios show a weak negative correlation with surface (50 m) temperature (p \u0026lt; 0.05, R\u0026sup2; = 0.42; Tab. S2a, Fig. 2a), no significant relationship is observed between Mg/Ca and surface temperature (p \u0026gt; 0.05; Tab. S2b, Fig. 2b).\u003c/p\u003e\n\u003cp\u003eIn contrast, Li/Mg ratios display a significant positive relationship with surface (50 m) temperature, described by both a linear (p \u0026lt; 0.05, R\u0026sup2; = 0.70) and an exponential fit (p \u0026lt; 0.05, R\u0026sup2; = 0.73; Tab. 2, Fig. 2c). Our dataset does not allow discrimination between the two fits; therefore, both relationships are reported, although exponential relationships are more commonly reported in the literature for Li/Mg\u0026nbsp;paleothermometry\u003csup\u003e7\u003c/sup\u003e.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe following equations describe the linear and exponential correlations with temperature (T) at 50 m water depth:\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003ewith p\u0026lt;0.05, R\u003csup\u003e2\u003c/sup\u003e=0.73.\u003c/p\u003e\n\u003cp\u003eIn addition, stable oxygen isotope ratios (\u0026delta;\u0026sup1;⁸O) measured on the same set of pteropod samples have previously been shown to provide a reliable temperature proxy\u003csup\u003e17\u003c/sup\u003e. Temperatures derived from Li/Mg ratios are positively correlated with \u0026delta;\u0026sup1;⁸O-derived temperatures (p \u0026lt; 0.05, R\u0026sup2; = 0.57; Fig. 2d).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompositional variability of Mg/Ca, Li/Ca and Mg/Li ratios in pteropods.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTrace elemental/ Ca ratios from LA-ICP-MS tend to have a much higher variability compared to traditional ICP-MS analysis of whole, acid-dissolved shells, where the intra-test inhomogeneity cannot be resolved. The average RSD of 23% for Li/Ca and 37% for Mg/Ca highlights pronounced compositional variability within individual pteropod shells and motivates a more detailed assessment of intra-shell trends. Laser ablation targets were placed at multiple positions across the shell, ranging from the innermost embryonic shell (spot 1; Fig. 3a) to progressively younger shell material formed later in ontogeny (spots 2\u0026ndash;4; Fig. 3a).\u0026nbsp;For clarity, laser spot 1 corresponds to the innermost, embryonic or very early juvenile shell material, while laser spots 2\u0026ndash;4 represent progressively younger shell material formed later during ontogeny; this spatial framework is used throughout the Discussion when referring to shell growth stages.\u0026nbsp;No statistically significant difference in median values was detected for Li/Ca ratios between measurements obtained from spot 1 and spot 4 (p \u0026gt; 0.05; Fig. 3b).\u003c/p\u003e\n\u003cp\u003eIn contrast, Mg/Ca ratios show a statistically significant difference between spot 1 and spot 4 (Wilcoxon test, p \u0026lt; 0.05; Fig. 3c), indicating systematic changes in Mg incorporation across shell growth. Similarly, Li/Mg ratios differ significantly between spot 1 and spot 4 (Welch\u0026rsquo;s t-test, p \u0026lt; 0.05; Fig. 3d).\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eApart from an early study investigating trace elemental incorporation in pteropods\u003csup\u003e24\u003c/sup\u003e, there has been no study looking at a suite of trace metals since. However, several studies have investigated the relationship between environmental signals and trace elemental signature in shells of various other groups.\u0026nbsp;For example\u003cstrong\u003e,\u0026nbsp;\u003c/strong\u003eJurikova and colleagues\u003csup\u003e25\u003c/sup\u003e examined Li/Ca and Mg/Ca ratios in modern brachiopod shells and reported a moderate variability in Li/Ca (34\u0026ndash; 39.1 \u0026mu;mol/mol) and Mg/Ca ( 5.79 to 7.39 mmol/mol).Another study assessed elemental ratios in the aragonitic gastropod Turbo torquatus from multiple locations in Western Australia\u003csup\u003e26\u003c/sup\u003e. Their results yielded an average Li/Ca ratio of 7.1 \u0026mu;mol/mol, but they noted that the Li concentrations were too variable to serve as reliable environmental indicators. Average Mg/Ca values were with ca. 0.4 mmol/mol markedly lower than in brachiopods and more similar to the values we measured on pteropods (0.2 \u0026ndash; 0.8 mmol/mol, Tab. 1). Another study analyzed elemental composition on another gastropod species, Patella caerulea, and reported even lower Li/Ca ratios of 0.0031 - 0.0052 mmol/mmol, associated with low Mg/Ca values of 0.52 \u0026ndash; 0.78 mmol/mol\u003csup\u003e27\u003c/sup\u003e. It is noteworthy that all three gastropods, \u003cem\u003eTurbo, Patella\u0026nbsp;\u003c/em\u003e(aragonite shell parts\u003cem\u003e)\u003c/em\u003e, and \u003cem\u003eHeliconoides\u003c/em\u003e, display similar Li/Ca and Mg/Ca values\u003csup\u003e26,27\u003c/sup\u003e. This suggests similar Li and Mg incorporation mechanisms across the Gastropoda. These similarities among mollusks seem to be mirrored in their suitability as proxy archives, e.g. \u003cem\u003eHeliconoides\u003c/em\u003e (this study) and \u003cem\u003eMytilus\u003c/em\u003e\u003csup\u003e28\u003c/sup\u003e. It remains to be studied which fractionation processes underpin the robust Li/Mg vs temperature relationships in gastropods.\u003c/p\u003e\n\u003cp\u003eMarriott and coworkers\u003csup\u003e29\u003c/sup\u003e compared Li/Ca ratios and lithium isotopic compositions in abiotic and foraminiferal CaCO₃, concluding that biological control is generally limited but not absent. They highlighted the importance of mineralogy, temperature, and salinity, while also recognizing the influence of species-specific physiological factors in modifying trace elemental uptake. A strong association between Mg and Li in biogenic carbonates was pointed out, suggesting similar transport mechanisms of these two elements in mollusks as identified by Dellinger an colleagues\u003csup\u003e28\u003c/sup\u003e. The Li/Ca and Mg/Ca values we report here fit well into their overall correlation of Li/Ca versus Mg/Ca\u003csup\u003e28\u003c/sup\u003e, aligning well with values from other calcifiers, including mollusks (Fig. 4). Our data from pteropods can be found on the lower end of the range of trace elemental/ calcium ratios along with values reported by Langer and colleagues \u003csup\u003e27\u003c/sup\u003e for the gastropod \u003cem\u003ePatella\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eWhile recent studies have advanced our understanding of pteropod shell ultrastructure\u003csup\u003e41\u003c/sup\u003e the mechanisms of their biomineralisation remain poorly understood. However, extensive research on other mollusks provides useful insights that may inform hypotheses about pteropod shell formation\u003csup\u003e42\u003c/sup\u003e. In mollusks, calcification was traditionally assumed to occur within the extrapallial fluid (EPF)\u0026mdash;a semi-isolated compartment located between the shell and mantle epithelium. The EPF is generally assumed to be similar in ionic composition to seawater, but enriched with organic macromolecules such as proteins and polysaccharides that are believed to modulate crystal nucleation and growth\u003csup\u003e43-47\u003c/sup\u003e. The precipitation of shell calcium carbonate directly from the EPF, however, has become increasingly unlikely since multiple avenues of research have shown that the mantle epithelium most likely is in close contact with the shell surface at the site of crystallization\u003csup\u003e48-52\u003c/sup\u003e. Based on this idea, a distinction between two ion transport scenarios, the \u0026ldquo;EPF scenario\u0026rdquo; and the \u0026ldquo;mantle scenario\u0026rdquo; was proposed by Langer and colleagues\u003csup\u003e27\u003c/sup\u003e. The latter authors suggested that in the EPF scenario the fractionation of trace elements should be explicable in terms of inorganic precipitation from seawater, whereas in the mantle scenario no such simple explanation is expected because selective ion transport can, and likely will, lead to fractionation patterns markedly different from fractionation in inorganic precipitation experiments. Fractionation patterns can be analysed from different perspectives.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA useful parameter to look at in this regard is the partitioning coefficient (K\u003csub\u003eD\u003c/sub\u003e) which is defined as:\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003ewhere (TE/Ca)\u003csub\u003eCC\u003c/sub\u003e refers to the measured molar ratio of the trace element (TE) and Ca in calcium carbonate and (TE/Ca)\u003csub\u003eSW\u003c/sub\u003e to that in the seawater or culture media.\u003c/p\u003e\n\u003cp\u003eThe K\u003csub\u003eD\u003c/sub\u003e shows if the element is enriched (K\u003csub\u003eD\u003c/sub\u003e\u0026gt;1) or depleted (K\u003csub\u003eD\u003c/sub\u003e\u0026lt;1) in the biomineral relative to seawater. Assuming average Mg/Ca ratio of surface Atlantic seawater (~upper 200 m) of approximately 5.1 mol/mol\u003csup\u003e53\u003c/sup\u003e, the calculated K\u003csub\u003eDMg\u0026nbsp;\u003c/sub\u003efor our pteropod values falls between 0.04 \u0026ndash; 0.17 x 10\u003csup\u003e-3\u003c/sup\u003e (Tab. S3), whereas inorganic K\u003csub\u003eDMg\u003c/sub\u003e for aragonite of ca. 1-2 x 10\u003csup\u003e-3\u003c/sup\u003e have been reported\u003csup\u003e54\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eLittle information on seawater Li/Ca variability has been reported, so we assume a seawater Li/Ca ratio of 0.0025 mol/mol here\u003csup\u003e8\u003c/sup\u003e, resulting in a range of K\u003csub\u003eDLi\u003c/sub\u003e for our Li/Ca values of ca. 1.4 \u0026ndash; 2.5 x 10\u003csup\u003e-3\u003c/sup\u003e (Tab. S3). In comparison, inorganic K\u003csub\u003eDLi\u003c/sub\u003e for aragonite have been reported on the order of 3-4 x 10\u003csup\u003e-3 29\u003c/sup\u003e. Interestingly, our average values for K\u003csub\u003eDMg\u003c/sub\u003e and K\u003csub\u003eDLi\u003c/sub\u003e (0.1 and 1.9 x 10\u003csup\u003e-3\u003c/sup\u003e, Tab. S3), align well with those observed in Patella, another gastropod species (0.1 and 2.2 x 10\u003csup\u003e-3\u003c/sup\u003e)\u003csup\u003e27\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eOur calculated partitioning coefficients (K\u003csub\u003eD\u003c/sub\u003e), namely 0.04 \u0026ndash; 0.17 x 10\u003csup\u003e-3\u003c/sup\u003e for K\u003csub\u003eDMg\u003c/sub\u003e and 1.4 \u0026ndash; 2.5 x 10\u003csup\u003e-3\u0026nbsp;\u003c/sup\u003e(Tab. S3)\u003csup\u003e\u0026nbsp;\u003c/sup\u003efor K\u003csub\u003eDLi\u003c/sub\u003e show that the K\u003csub\u003eDLi\u0026nbsp;\u003c/sub\u003eis explicable in the EPF scenario, since the K\u003csub\u003eDLi\u003c/sub\u003e close to values reported for inorganically precipitated aragonite (3 \u0026ndash; 4 x 10\u003csup\u003e-3\u003c/sup\u003e)\u003csup\u003e29\u003c/sup\u003e whereas the KD\u003csub\u003eMg\u003c/sub\u003e is not (inorganic values: 1-2 x 10\u003csup\u003e-3\u003c/sup\u003e)\u003csup\u003e54\u003c/sup\u003e. The same holds for \u003cem\u003ePatella\u003c/em\u003e, where also the K\u003csub\u003eD\u003c/sub\u003es of Sr, B, and U were inexplicable in the EPF scenario\u003csup\u003e27\u003c/sup\u003e. It would be helpful to analyze K\u003csub\u003eD\u003c/sub\u003es of Sr, B, and U in pteropods as well to uncover how far similarities in absolute fractionation (K\u003csub\u003eD\u003c/sub\u003e) between mollusks go. At any rate, it can be tentatively concluded that pteropods do not calcify according to the EPF scenario, because for this to be so, the K\u003csub\u003eD\u003c/sub\u003e of every trace element should be seawater-like.\u003c/p\u003e\n\u003cp\u003eAnother similarity in the fractionation behavior of \u003cem\u003eHeliconoides\u003c/em\u003e and \u003cem\u003ePatella\u003c/em\u003e is the apparent sensitivity of K\u003csub\u003eDLi\u003c/sub\u003e to environmental and physiological parameters. In \u003cem\u003ePatella\u003c/em\u003e, K\u003csub\u003eDLi\u003c/sub\u003e shows a negative correlation with calcification rate\u003csup\u003e27\u003c/sup\u003e. In \u003cem\u003eHeliconoides\u003c/em\u003e, K\u003csub\u003eDLi\u003c/sub\u003e exhibits a negative correlation with temperature (Fig. 2a), which may indirectly reflect changes in calcification rate, as temperature and calcification rate are generally positively correlated in pteropods (up to a thermal optimum)\u003csup\u003e55\u003c/sup\u003e. By contrast, inorganic precipitation experiments show a positive relationship between K\u003csub\u003eDLi\u003c/sub\u003e and precipitation rate\u003csup\u003e56\u003c/sup\u003e This is another indication that the mantle scenario is operative in pteropods, as it most likely is in other mollusks. The positive K\u003csub\u003eDMg\u003c/sub\u003e rate dependence in \u003cem\u003ePatella\u003c/em\u003e and the insignificant temperature dependence in \u003cem\u003eHeliconoides\u003c/em\u003e are the only difference in fractionation patterns between these two gastropods. It is clearly warranted to analyze more trace elements and more aspects of their fractionation patterns (such as dependence on seawater chemistry) in pteropods. These data would help to understand whether pteropods follow the general mollusk biomineralization mechanism.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLi/Mg ratios were highest in the innermost part of the shell, corresponding to the embryonic or very early juvenile (veliger) stage (laser spot 1; Fig. 3d), and decreased progressively with increasing shell growth (laser spots 2\u0026ndash;4). Applying the exponential (linear) Li/Mg\u0026ndash;temperature calibration (Eq. 2) yields a reconstructed temperature of approximately 18.5 (19.1) \u0026deg;C for the median Li/Mg ratio of laser spot 1 (23.6 \u0026micro;mol/mmol), whereas median values from laser spot 4 (8.9 \u0026micro;mol/mmol) correspond to markedly higher temperatures of approximately 32.4 (29.6) \u0026deg;C. In addition to seasonal variability in ambient temperature, these ontogenetic differences in Li/Mg ratios may reflect changes in biomineralization processes during early shell formation, shifts in habitat depth occupied over the life cycle, or a combination of these factors.\u003c/p\u003e\n\u003cp\u003eShells of the genus \u003cem\u003eHeliconoides\u003c/em\u003e have been reported to exhibit pronounced microstructural heterogeneity. Most of the shell consists of fibrous material arranged in a helical structure, corresponding to laser spots 1\u0026ndash;3 (Fig. 3). In contrast, more external shell regions, represented by laser spot 4, display a crossed-lamellar microstructure\u003csup\u003e41\u003c/sup\u003e. Such ontogenetically controlled variations in shell microstructure and mineralization pathways during pteropod shell growth may influence trace-element incorporation and could therefore partly explain the differences in Li/Mg ratios between earlier-formed shell portions (laser spots 1\u0026ndash;3) and later formed shell material (laser spot 4), independent of external environmental conditions. However, these microstructural differences cannot account for the variations observed within laser spots 1\u0026ndash;3 themselves, where a distinct decreasing trend in Li/Mg ratios is already evident (Fig. 3d). Consequently, additional explanations must be considered.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eHeliconoides inflatus\u003c/em\u003e exhibits brooding brooding behaviour\u003csup\u003e57\u003c/sup\u003e, whereby embryos are retained within the mantle cavity until they are released as veligers (approximately 70 \u0026micro;m in diameter). If initial shell formation occurs while embryos or veligers are still brooded by the adult, the resulting Li/Mg signature may reflect the environmental conditions experienced by the brooding individual rather than those encountered by free-living early life stages. This process would primarily affect the earliest shell material (laser spot 1), providing a potential explanation for the difference in Li/Mg ratios\u0026mdash;and consequently reconstructed temperatures\u0026mdash;between embryonic shell portions and those formed during later ontogenetic stages. However, this mechanism alone cannot explain the progressive decrease in Li/Mg ratios observed from laser spots 2 to 4 (Fig. 3d).\u003c/p\u003e\n\u003cp\u003eThe most important external factor to consider is temperature. Although the timing and environmental conditions of egg release in \u003cem\u003eH. inflatus\u003c/em\u003e remain poorly constrained, sediment trap observations\u003csup\u003e19\u003c/sup\u003e and the intra-shell geochemical data presented here (Tab. S1; Fig. 3d) provide insight into aspects of its life cycle. Interpreting the data in terms of a discrete seasonal spawning period is challenging due to opposing seasons encountered along the transect, the generally weak seasonality of tropical and subtropical waters, and the widespread occurrence of veligers, juveniles, and adults throughout the study area (K. Peijnenburg, pers. obs.). These observations suggest that the life cycle of \u003cem\u003eH. inflatus\u003c/em\u003e differs from that of higher-latitude pteropod species and is unlikely to be tightly coupled to strong seasonal environmental variability. Nevertheless, temperature remains the most plausible external control on Li/Mg incorporation. The relatively low reconstructed temperatures recorded in embryonic and juvenile shell portions are therefore most likely the result of shell formation during cooler phases of the annual temperature cycle, potentially amplified by ontogenetically controlled processes, and/ or brooding effects. Further research is needed to fully decipher the life-cycle information archived within different sections of pteropod shells.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe geological record contains a wealth of information about past climate change events, as past ocean temperature and chemistry can be derived from fossil calcium carbonate shells\u003csup\u003e58,59\u003c/sup\u003e. The present study shows that the studied species here, \u003cem\u003eH. inflatus,\u0026nbsp;\u003c/em\u003eis nicely suited for paleo-reconstructions, as the Li/Mg thermometer works well in pteropod shells. Additionally, the fact that these proxies cannot be only measured simultaneously on a single pteropod shell but also along the whorl of a pteropod renders them promising new proxy carriers, as this offers the potential to assess seasonal variation within one specimen.\u003c/p\u003e\n\u003cp\u003eThe material comprising a single pteropod shell may, in theory, be precipitated at different depths and over multiple seasons. This is consistent with reports indicating that the average lifespan of several pteropod species is approximately one year\u003csup\u003e13\u003c/sup\u003e. In the case of \u003cem\u003eH. inflatus\u003c/em\u003e, the lifespan is likely shorter, on the order of ~7\u0026ndash;9 months\u003csup\u003e14\u003c/sup\u003e. Because \u003cem\u003eH. inflatus\u003c/em\u003e preferentially inhabits surface waters\u003csup\u003e14,16\u003c/sup\u003e, where environmental parameters influencing shell trace-element incorporation (e.g., temperature and salinity) vary seasonally, the resulting shell geochemistry may integrate signals from changing conditions throughout the year. Sediment-trap studies would therefore be well suited to assess the influence of seasonality on the trace-element composition of pteropod shells. In addition, culturing experiments could be used to investigate the effects of other environmental parameters, such as carbonate chemistry, on trace-element incorporation, analogous to approaches commonly employed in foraminiferal studies\u003csup\u003e60-63\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eCorrelations between trace elemental composition of pteropod shells and upper ocean water temperature show that indeed the Mg/Li paleothermometer can be applied in pteropods with the following regression (assuming an exponential relationship between Li/Mg and temperature, equation 2) :\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003ewith p\u0026lt;0.05, R\u003csup\u003e2\u003c/sup\u003e=0.73.\u003c/p\u003e\n\u003cp\u003eComparing the average standard deviation of the Li/Mg measurements (\u0026asymp;4.0 \u0026micro;mol/mmol) with the the temperature sensitivity of the linear and exponential paleothermometry calibrations (equation 4) provides an estimate of the magnitude of temperature changes that can be reliably reconstructed. For \u003cem\u003eH. inflatus\u003c/em\u003e, the exponential calibration (equation 4) resolves ~1\u0026ndash;2 \u0026deg;C of temperature change for station averages with typical to high Li/Mg values (~0.37\u0026ndash;35.3 \u0026micro;mol/mmol). These results indicate that pteropod-derived Li/Mg ratios are sufficiently sensitive to reconstruct glacial\u0026ndash;interglacial temperature variations across the study transect\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eHeliconoides inflatus\u003c/em\u003e is a pteropod species that has a global distribution in tropical and subtropical waters (including the Caribbean, Mediterranean and Indo-Pacific). Therefore, it is a good proxy carrier to assess surface water variations over paleo timescales worldwide. One limitation is the occurrence of well-preserved pteropod shells in sediments confined to waters above the lysocline of aragonite. However, there are plenty of sediment cores available in which \u003cem\u003eH. inflatus\u003c/em\u003e is abundant, well preserved and where the calibrations reported here can be applied\u003csup\u003e18,20,64\u003c/sup\u003e \u003csup\u003e21,65,66\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003ePteropod collection.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBulk zooplankton samples were collected during the Atlantic Meridional Transect Cruise 22 (AMT22), which took place from October 19 to November 16, 2012. Oblique bongo net tows (200 µm and 333 µm mesh sizes) were conducted from an average depth of 361 meters up to the sea surface. Pteropods were sampled at 11 stations spanning latitudes from 31°N to 38°S, primarily during the pre-dawn hours (see Tab. S1). Following collection, specimens were immediately preserved in 96–99% ethanol, with the ethanol replaced within 12–24 hours. Samples were then stored at –20°C until further analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSeawater parameters: temperature and salinity.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSeawater temperature and salinity in the upper 500 m of the water column were obtained by conductivity-temperature-depth (CTD) casts (Sea-Bird Electronics, models: ocean logger, SBE45, 9plus). Sensors were calibrated and data archived by the British Oceanographic Data Centre (BODC). Furthermore data from the World Ocean Database (WOD)\u003csup\u003e22\u003c/sup\u003e were used to generate surface distribution maps of the Atlantic for temperature and salinity (Fig. 1). Plots present average values from October through November in order to obtain a representation of the typical surface distribution of these parameters during the period of the cruise (10/13/2012 to 11/19/2012). The WOD data collection contained all surface data available from 1986 to 2011.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElemental composition of pteropod shells.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) system at Kiel University was used to determine elemental concentrations of pteropod shells. The LA-ICP-MS system consisted of a quadrupole mass spectrometer (Agilent 7500s) connected to a 193nm excimer laser ablation system (Coherent GeoLas HD), equipped with a Zurich-type two-volume ablation cell. Helium @ ~1L/min was used as the carrier gas with 14 mL/min H\u003csub\u003e2\u003c/sub\u003e added to increase sensitivity. The pulse repetition rate was set to 6 Hz, and energy density was ~3 J cm\u003csup\u003e-2\u0026nbsp;\u003c/sup\u003ewhile using an ablation beam diameter of 60mm. Assuming standard natural abundance ratios \u003csup\u003e67\u003c/sup\u003e, counts of \u003csup\u003e7\u003c/sup\u003eLi,\u003csup\u003e\u0026nbsp;24\u003c/sup\u003eMg, \u003csup\u003e27\u003c/sup\u003eAl, \u003csup\u003e43\u003c/sup\u003eCa \u003csup\u003e44\u003c/sup\u003eCa, \u003csup\u003e57\u003c/sup\u003eFe were used to calculate elemental concentrations. A complete measurement cycle through all masses took 0.5s. The ablation profiles were checked for potential surface contaminations using \u003csup\u003e27\u003c/sup\u003eAl and \u003csup\u003e57\u003c/sup\u003eFe. A glass reference material (SRM NIST 612)\u003csup\u003e67\u003c/sup\u003e was ablated three times and a pressed-powder nanopellet\u003csup\u003e68\u003c/sup\u003e of JCt-1 (aragonitic giant clam \u003cem\u003eTridacna gigas\u003c/em\u003e)\u003csup\u003e69\u003c/sup\u003e was used as a consistency standard between every 10 samples. The glass standard was ablated at a higher energy density (~13 J cm\u003csup\u003e-2\u003c/sup\u003e). Assuming 40wt% (m/m) calcium in calcite, \u003csup\u003e43\u003c/sup\u003eCa was chosen as an internal standard, while counts for \u003csup\u003e44\u003c/sup\u003eCa were used to check for consistency. Using the software Glitter (software for LA data reduction)\u003csup\u003e70\u003c/sup\u003e, time resolved isotopic counts during ablation of the shell were integrated and the background substracted. Then the isotopic counts were normalised to \u003csup\u003e43\u003c/sup\u003eCa and converted to concentrations using the signals obtained on the NIST standards. Three individual specimens were analyzed per station and between three to four individual laser spot measurements were carried out per shell, summing up to 104 single spot measurements on pteropod shells in total. During the measurements, the laser ablated sequentially deeper parts of the test, and measurements were stopped once the laser had protruded through the test.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analyses.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn each specimen 3–4 laser spots were placed (Tab. S1), and the resulting measurements were averaged to obtain a single value per specimen. Station-level means were calculated from the three specimen averages. The standard error (SE) for each station was calculated from the standard deviation of the three specimen averages divided by the square root of the number of specimens (n = 3). Single spot measurements from different specimens were averaged per station and regression analyses (linear and exponential) were performed to analyze correlation between pteropod trace elemental ratios (namely Li/Ca, Mg/Ca, Li/Mg) and environmental parameters (temperature, salinity) at several depths (2, 25, 50, 75, 100, 200, 250, 300 m). Furthermore, we performed regressions against d\u003csup\u003e18\u003c/sup\u003eO, as this has been found on the same set of plankton samples to be a good temperature proxy\u003csup\u003e17\u003c/sup\u003e. Data was tested for normality using Shapiro test, normal distributed data was compared using Welch’s t-test, if not, Wilcoxon test was performed. All analyses were performed in R ( version 4.4.1\u003csup\u003e71\u003c/sup\u003e).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the scientists participating in the Atlantic Meridional Transect (AMT) programme and the crew of the RRS \u003cem\u003eJames Cook\u003c/em\u003e for their support during zooplankton sampling. We also acknowledge the assistance of Matthis Frey and Ulrike Westernströer with LA-ICP-MS measurements, and thank Mathieu Dellinger for sharing his compilation of Li/Ca and Mg/Ca data across different phyla. This study contributes to the international IMBeR project and represents contribution number ### of the AMT programme.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eN.K. and K.T.C.A.P. designed the study, K.T.C.A.P. and V.K. carried out sampling, N.K. and D.G.S analyzed the data and N.K. compiled the manuscript with the help of all co-authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eN.K. was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number 522414573 and by BONITOS Project (International programme DFG–AEI 2023 – Project number 541693727; PCI2025-163190) during the writing of the manuscript. NK received funding for the laboratory work by a scholarship from the Daimler Benz Stiftung and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 80 – 24122362.KP was supported by the Netherlands Organisation for Scientific Research (NWO) cruise participation grant, and the NWO Vidi grant 016.161.351. The Atlantic Meridional Transect is funded by the UK Natural Environment Research Council through its National Capability Long-term Single Centre Science Programme, Atlantic Climate and Environment Strategic Science – AtlantiS (Grant No. NE/Y005589/1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll Li/Mg, Mg/Ca, and Li/Ca ratios measured in this study are provided in the Supplementary Information. Shell stable carbon and oxygen isotope data can be found in our previous publication: Keul, N. et al., \u003cem\u003eScientific Reports\u003c/em\u003e 7, 12645 (2017). Any additional information or analysis scripts are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCompeting Interests: The authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eM\u0026uuml;ller, P. J., Kirst, G., Ruhland, G., von Storch, I. \u0026amp; Rosell-Mel\u0026eacute;, A. 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Y. in \u003cem\u003eLaser Ablation ICP-MS in the Earth Sciences: Current Practices and Outstanding Issues\u003c/em\u003e Vol. 40 (ed Paul Sylvester) 0 (Mineralogical Association of Canada, 2008).\u003c/li\u003e\n \u003cli\u003eR: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, Vienna, Austria, 2012).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 and 2 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":true,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"Heliconoides inflatus, paleoceanography, proxy development, trace elemental composition, paleothermometry, Atlantic Ocean","lastPublishedDoi":"10.21203/rs.3.rs-8425397/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8425397/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePteropods are promising proxy archives for paleoceanographic reconstructions but remain underexplored. Previous oxygen isotope analyses indicated that \u003cem\u003eHeliconoides inflatus\u003c/em\u003e calcifies at shallow depths (50–75 m), suggesting its potential to record surface-ocean conditions. Here, we evaluate for the first time the applicability of Li/Mg thermometry in pteropod shells, a temperature proxy widely used in coral studies. We show that, in addition to recording environmental variability through shell carbon and oxygen isotopic composition, \u003cem\u003eH. inflatus\u003c/em\u003e shells reliably track seawater temperature via their Li/Mg ratios. Li/Mg ratios decrease exponentially with increasing temperature, enabling temperature reconstructions with an average precision of ±1–2 °C. Pteropod shells (species \u003cem\u003eHeliconoides inflatus\u003c/em\u003e, formerly known as \u003cem\u003eLimacina inflata\u003c/em\u003e) were collected along a latitudinal transect in the Atlantic Ocean (31° N to 38° S), covering a temperature range of nearly 15 °C. The global distribution and abundance of this annual species in sediments makes it a suitable alternative for palaeotemperature reconstruction. The utility of pteropod shells extends further to seasonal paleotemperature reconstruction, as seasonal temperature variability is captured in the elemental ratios from the embryonic to later (adult) sections of the shell. These results, in combination with a basin-scale distribution, make the Li/Mg thermometer in pteropods an exciting new tool in paleoceanography and further cement this group as new proxy archives.\u003c/p\u003e","manuscriptTitle":"A New Li/Mg Paleothermometer from Pteropod Shells","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-13 03:32:04","doi":"10.21203/rs.3.rs-8425397/v1","editorialEvents":[{"type":"communityComments","content":0}],"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":"cb1196f9-5c63-4ee9-a30a-0f3b668819a9","owner":[],"postedDate":"January 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":60780973,"name":"Earth and environmental sciences/Climate sciences"},{"id":60780974,"name":"Earth and environmental sciences/Ocean sciences"},{"id":60780975,"name":"Earth and environmental sciences/Solid earth sciences"}],"tags":[],"updatedAt":"2026-05-19T07:38:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-13 03:32:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8425397","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8425397","identity":"rs-8425397","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}