Lerback.pub 1 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2023 Utah Geological Association Publication 51 ABSTRACT Playa margin wetlands in the Bonneville basin are sustained by groundwater-fed brackish springs, which transport salts and other solutes into the playa basin. These wetlands are sensitive to changing water availabil- ity and quality, which are impacted by changing climate and land use, and whose sediments also provide im- portant records of changing environmental conditions. Gastropods building their shells in these springs provide important recorders of water chemistry and may reflect changing aqueous conditions. In this paper, we analyze spring water chemistry, gastropod ecology and gastropod shell chemistry of Blue Lake (BL) and Horseshoe Springs (HRS), two groundwater-fed wetlands in the Great Salt Lake watershed. We report the physical pa- rameters including pH, temperature, and specific conductivity across the spring pond at Horseshoe springs. There was a slight but statistically significant variation in these physical characteristics between the deeper and shallower parts of the pool, providing evidence that there are different subsite microclimates, which may im- pact the populations and the isotopic composition of gastropod shells. We measured gastropod population di- versity amongst nearly 12,000 shells sampled at Horseshoe springs, finding low population diversity (Shannon’s Diversity Index of 0.432), although the populations of shallow and deep snails are slightly differ- ent. The dominant snail at HRS is the Pyrgulopsis which is imperiled, and we also note that we did not find living snails here. We evaluated the bulk shell variation of stable carbonate isotopes (δ13C, and δ18O) across sites and genera. We show that there were no significant subsite-level differences in gastropod δ13C composi- tions, suggesting that water depth and productivity were not impacting the isotopic signal. We found subsite- and genera-specific differences in snail δ18O compositions, which we interpret to be more dependent on the geography and microclimate of where the snail lived rather than the genera’s physiology (pulmonate versus gil -breathing). We report concentrations of alkali metals (Li, Na, K, Rb, Cs), alkali earth metals (Be, Mg, Ca, Sr, Ba), and metals and metalloids (Al, Sc, Mn, Fe, Cu, Ni, Zn, As) at spring site waters and in bulk shells as po- tential baseline data for interpreting future or past environmental changes as recorded in shell material. We found trace element concentration and certain elemental ratio differences between genera at the same site (particularly of note were Li, Zn, Mn and Al) that will be important to constrain if these shells are to be applied as a paleoenvironmental proxy and are sometimes attributed to land use change. Keywords: hydrology, isotopes, carbon, groundwater, gastropod, critical zone Bonneville Basin Critical Zones: Spring Chemistry and Gastropod Ecology in Playa-Margin Wetlands Jory C. Lerback 1, Brenda B. Bowen2,4, Sam Bagge2, Mikelia Heberer2, Ryan Cocke2, and Hayley L. Bricker3 1Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California, lerback1@llnl.gov 2Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 3Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, California 4Global Change and Sustainability Center, University of Utah, Salt Lake City, Utah INTRODUCTION Earth’s critical zone encompasses the interactions between the biosphere, atmosphere, hydrosphere, and lithosphere from the top of vegetation to the bedrock (U.S. National Research Council, 2001; Anderson and others, 2007; White and others, 2015). The criti- cal zone is linked to anthropogenic activity, from soil formation’s relationship with agricultural production to landscape modifications impacting the hydrologic cycle and water resources (Brantley and others, 2007; Fan and others, 2019; Fovet and others, 2021; Minor and others, 2020). Groundwater-fed wetlands are, like many critical zone ecosystems, susceptible to changes in climate, water quality, air quality, and other effects of human impacts including recreation, agriculture and urbanization (Miguez-Macho & Fan, 2012; Singha & Navarre‐Sitchler, 2022; Torgeson and oth- ers, 2022). Groundwater-fed wetlands also provide sedimentary records of critical zone (particularly hy- drological) processes over time, termed paleo-critical zones by Ashley (2020), which help to calibrate and extend the temporal scales by which we understand the feedbacks between groundwater and climate. Playa margin wetlands in the Bonneville basin are sustained by brackish to saline springs, transporting salts into the playa basin (Lerback and others, 2019). Louderback and Rhode (2009) estimate the discharge rate of 1.6 cubic meters per second or 5x1010 L/yr at 10.31711/ugap.v51i.144 2 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones Blue Lake (BL), one of the two springs in this study. Lerback and others (2019) reported a slightly lower annual discharge rate of 1.3x1010 L/yr, and report measured Na concentration ranging between 1400- 1600 mg/L from 2016-2018. Using these values, and assuming no recirculation of playa solutes in these springs, we estimate that BL annually brings from 2.0�1013 - 7.5�10 13 mg of sodium to the playa sedi- ments annually (between 22,000-83,000 tons). Con- sidering these salt accumulation rates and long time- scales since glacial Lake Bonneville exposed these spring sites, brackish playa margin springs like BL may be an important component of Bonneville basin solute budgets. Thus, understanding the chemical his- tory and sustainability of these spring wetlands is use- ful in future work describing the dynamic solute and water budgets sustaining the ecosystems and indus- tries of the Bonneville basin. In this paper, we describe two spring-fed wetlands in the relatively under-studied western side of the Great Salt Lake watershed and describe their spring water chemistry by measuring their physical parame- ters (total dissolved solids, pH, dissolved oxygen, and temperature) and chemical compositions (alkali met- als, alkaline earth metals, select metals and metal- loids) (Figure 1). We use these parameters to estab- lish baseline chemistry for future monitoring of spring ecosystem functioning. Importantly, these wet- lands foster gastropod (snail) populations, including some endemic genera. Gastropod community diversi- ty can serve as a bioindicator of environmental chang- es, where an environmental change could lead to in- hospitable conditions for a relatively homogenous gastropod population (Magurran, 1988; Hershler and others, 2014). Thus, we survey the gastropod commu- nities in these two springs, and provide a baseline of population composition and diversity. Gastropod shell chemistry has been shown to record groundwater chemistry and changing aqueous conditions in the present, setting the stage for evaluating near-future environmental changes, and in the past to contextual- ize modern environmental change (Abell, 1985; Abell and Williams, 1989; Rosenthal and Katz, 1989; Ayliffe and others, 1996). We provide some context for using gastropod shells as proxies for environmental change by investi- gating the variability of modern shell chemistry, using δ13C and δ18O and the trace elemental composition of shells (alkali metals, alkaline earth metals, select met- als and metalloids) in comparison to water. δ13C has been used to reflect changes in the carbon cycle, such as changes in carbon inputs (land-plant versus aquatic humus), photosynthesis, dissolved oxygen content (Keith and others, 1964; Aravena and others, 1992; Jin and others, 2021). δ18O is often used to interpret the water temperatures at the time of carbonate for- mation (Anadon and others 2006; Immenhauser and others, 2016). While previous work highlights the complexities of using freshwater gastropods as direct stable isotopic proxies (Shanahan and others, 2005), we provide some additional context of differences by genera to understand differences in shell-building processes and potential disruptions to the isotopic utility as paleoenvironmental indicators. Shell chemi- cal compositions, particularly trace elements, also have potential conservation applications as the rapidly building shells incorporate trace elements being intro- duced to the environment. If new material (particularly if containing heavy metals) is introduced (deposited and bioavailable) to the springs due to land use change, urbanization, air quality, or industry, the shell chemistry and ecology may record these chang- es, serving as sentinels of environmental change (Rainbow, 2007; Baroudi and others, 2020). Addi- tionally, recent work highlights the potential for shells from gill-breathing gastropods preserved within spring sediments to record changes in groundwater chemistry through time using radiocarbon isotopes (Lerback and others, 2023). MATERIALS AND METHODS Site Description This study describes two perennial spring wetland sites in northwestern Utah, on traditional and ances- tral lands of the Newe/Western Shoshone, Goshute, and Ute peoples. The springs in this study are Blue Lake (BL) springs (40.502, -114.033) and Horseshoe Springs (HRS) (40.614, -112.709) in Toole County, Utah. As reported by Lerback and others (2023), BL and HRS spring systems are brackish (with specific conductance measurements above 7000 μS/cm) and mesothermal, with average temperatures between 20° C and 30°C depending on measurement location within the spring pools. These temperatures are high- er than mean annual air temperatures of 12°C (Lerback and others, 2023). Gastropod Physiology Gastropod genera sampled in this study include Melanoides, Pyrgulopsis, Physella, Tryonia, Planor- bella, and Succineidae (Figure 2). Melanoides Melanoides shells found in this study are of the species tuberculate. This paper will refer to Mela- 3 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 Figure 1. Site Description. A) Location map of spring wetland sites. B) Satellite image of Blue Lake (BL) wetland at the playa margin. C) Satellite image of Horseshoe Springs (HRS) wetland at the playa margin with the southwest part of the Great Salt Lake. D) Sche- matic of Blue Lake (BL) from a top- down view with subsites marked. E) Schematic of Horseshoe Springs (HRS) from a top-down view (left) and cross- sectional schematic view (right, not to scale) with subsites marked. 4 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones noides tuberculate as the genus only for consistency with the other genera described here. Melanoides is a prosobranch (gill-breathing), fully aquatic freshwater spring snail native to tropical Africa and Asia. Mela- noides was first introduced to North America via the aquatic trade during the 1930s and has continued to spread across the continent into warm regions such as the Great Basin (Murray, 1971). Melanoides is an in- vasive species (Dudgeon, 1986; Facon and others, 2003; Raw and others, 2016). This species likes to burrow into the spring substrate during daylight hours and can therefore be difficult to detect in locations where it has recently been introduced (Subda Rao and Mitra, 1982). They may vary in size from 20 to 40 mm with a lifespan of about 2 – 3.5 years (Berry and Kadri, 1974; Dudgeon, 1982; Livshits and Fishelson, 1983; Pointier, 1989). Melanoides is less sensitive to salinity conditions than it is to temperature range, with an optimal growth range of 18 – 31oC (Murray, 1971; Russo, 1973; Roessler and others, 1977; Neck, 1985; Bolaji and others, 2011). When optimal condi- tions are consistent and abundant, Melanoides may reach population densities of up to 6452 m-2, as was found in a study conducted at Fish Springs National Wildlife Refuge by Rader et al. 2003. This is attribut- ed to the species reproducing asexually (parthenogenetic), reproducing more than once in its lifetime as well as early in the life cycle (iteroparous), and by developing offspring internally (viviparous). Pyrgulopsis Pyrgulopsis sp. are one of the largest genera in the family Hydrobiidae, which are a family of proso- branch (gill-breathing) snails. They are the second most common Hydrobiidae genera in North America, specifically in Utah, Nevada, and Idaho, and are typi- cally found in moist wetland areas such as the ben- thos of lakes and springs (Hershler, 1994). Measuring about 1 – 8 mm in shell length, individuals typically cluster with densities greater than 1000 m-2 (Hershler, 1994). They may grow to a length of 2.5 mm (Hershler and Sada, 1987). The temperature range of living specimens falls between 22 – 35oC (Hershler, 1994). Individuals are typically found near spring groundwater discharge areas (Hershler and others, 2014). Pyrgulopsis sp. are very sensitive to climatic and environmental changes, which stem from mem- bers of this genus diversifying due to their regional separation and isolation; although individual species may live in a range of environments (e.g. tempera- tures, salinities, CO2 concentrations), perturbations to these constant conditions can greatly disturb popula- tions (Pearson and others, 2014). They are considered imperiled (Turgeon and others, 1998). Figure 2. Gastropod genera found in this study. A) Mela- noides, B) Pyrgulopsis, C) Physella, D) Planorbella, E) Succineidae, and F) Tyronia. 5 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 Tyronia Tyronia sp. is another genera part of the Hydrobi- idae family and is restricted to North America. Like its fellow Hydrobiid genera, Tyronia sp. are fully aquatic and typically prefer to inhabit thermal springs. Their dispersion is slow and may be linked to drain- age history, making them key biogeographical indica- tor genera (Hershler and others, 1999). Some species may be quite salinity tolerant (Hershler and others, 1999). Shells can range between 1.2 – 7 mm in length (Hershler and Sada, 1987). Physella Physella sp. are part of subfamily Physinae, which are pulmonated (lung-breathing) freshwater spring snails. They are difficult to identify based on morphology alone (Young et al., 2021). Physella sp. are capable of self-fertilization (parthenogenesis), which may contribute to rapid evolution amplified by isolation or thermally different habitats (Perrin, 1986). They typically reproduce annually (Russell- Hunter, 1978). Observationally, Physella sp. have been known to inhabit waters with temperatures of 8 – 35oC. Shell length can grow to 14 mm in very warm water temperatures, indicating that growth is tempera- ture-dependent (McMahon, 1975). Planorbella Planorbella sp. are part of family Planorbidae and is a freshwater gastropod genus restricted to North America (Baker, 1945). Members of this genera are hermaphroditic and may rely on self-fertilization for reproduction (Martin and others, 2020). They have been shown in studies to be optimally active between 26 - 28oC, with minimum and maximum optimal thresholds appearing to occur at 18oC and 33oC, re- spectively. (El-Emam and Madsen, 1982). Succineidae Succineidae are a family of minute taxa of pulmo- nated (lung-breathing) land snails that typically in- habit wetland areas worldwide (Pilsbry, 1948; Patter- son, 1971). Genera are typically found on vegetations near streams or marshes, or where dew might be pre- sent. There may be extreme differences in morpho- logical features such as size and shell shape, between genera within Succineidae. They are hermaphroditic and can reproduce through mutual fertilization or self -fertilization. Experimental Design We measured physical and chemical parameters using a multiparameter probe in the spring to under- stand circulation within the spring pond. We meas- ured probe depth (m), Total Dissolved Solids (TDS in ppt), pH, Dissolved Oxygen (DO in mg/L) and tem- perature (°C) using an Aqua TROLL 600 Multipa- rameter Sonde. We recorded these basic physical and chemical parameters of the spring water along a NW- SE transect at HRS to understand the structure of flow and potential circulation within the northern spring pool and stream outlet (Figure 3). The probe recorded the time, which we marked and calibrated to locations marked at 0, 150s, 200s, 250s, 300s, and 345s. Time is used as a proxy for the distance along the transect, as it is not a linear transect. Water sam- ples were collected at the water surface for trace ele- ment analyses in High-Density Polyethylene (HDPE) bottles that were washed with 5% HCl and rinsed three times with deionized water. Samples were fil- tered with a 0.45 μm polypropylene syringe filter and stored with minimal headspace. At HRS, we sampled bulk sediment at sites HRS- 1, HRS-2, HRS-3, and HRS-4 to measure the diversi- ty and density of snail populations. At these four sub- sites in shallow and deeper waters, we filled one 0.25 L container with bulk sediment. Samples were cleaned at the University of Utah by sieving and rins- ing bulk samples with deionized water and soaking the shells in 3% hydrogen peroxide for one hour which served to separate the sediment and organic material from the shells. Snails in sediment samples at each site were identified to the genus level and counted to understand the diversity of taxa across subsites at HRS. Gastropods were collected under a research agreement with the Utah Division of Wild- life Resources (4COLL10642). We used Shannon’s Diversity Index to test the diversity of gastropods at HRS, which is a common metric of ecological diver- sity that takes into consideration the richness and evenness of each of the genera or species collected (Clarke and others, 2014). The equation from Shan- non (1948) is Shells prepared for chemical analysis were cleaned with 3% hydrogen peroxide for one hour to remove organic material, rinsed with deionized water, and then sonicated to further remove organic matter and sediment. Bulk shells were homogenized individ- ually using a mortar and pestle. Four shells were se- lected to be subsampled along transects from tip to (1) 6 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones aperture (“intrashell transects”) to assess variation in shell chemistry over the snail’s lifetime. Intrashell transects were collected at four evenly spaced sub- sites along the long axis of the shell using a micro- drill. Melanoides shells from BL-Spring were select- ed for the intrashell transects due to their relatively larger size. A total of sixty-four whole gastropod shells (37 from BL and from 27 HRS) and four sub-sampled shells from BL were analyzed at the SIRFER labora- tory at the University of Utah. Samples were reacted with orthophosphoric acid and analyzed as CO2 after cryogenic purification. Samples were analyzed on a Finnigan MAT 252 mass spectrometer. Data are re- ported using delta notation relative to the Vienna Pee Dee belemnite (VPDB) standard for carbonates and water δ13C and the Vienna standard mean ocean water (VSMOW) for water δ18O, where analytical precision for δ13C and δ18O was ~0.1‰. δ18O-VSMOW values were converted to δ18O-VPDB to directly compare δ18O of water and shells. An additional 22 shell sam- ples (17 from BL and from five HRS) were added to the dataset here from Lerback and others (2023), where their data were made using the same methods. Analyses including calculation of mean and standard deviations (SD), and statistical tests including analy- Figure 3. Physical parameters of water along a transect at HRS. A) Schematic maps of HRS with probe transect loca- tions and select times marked in the left panel, and the bathy- metric distinction made be- tween shallow and deep areas of the spring pool on the cross- sectional view in the right pan- el. B) Probe depth along tran- sect. C) Total Dissolved Solids (TDS) along transect, D) pH along transect. E) Dissolved Oxygen (DO) along transect. F) Water temperature along transect. 7 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 sis of variance (ANOVA) and Tukey’s Honestly Sig- nificant Difference (HSD) were performed in R v3.6 in RStudio. Comparisons between water and shell iso- tope values evaluated the fractionation (ε), which is the difference between shell and water isotope values. Eight shells (four Succineidae from BL, three Pyrgulopsis and one Tryonia from HRS) and four wa- ter samples (two from BL and two from HRS) were analyzed for trace element concentrations at the Uni- versity of Utah's Strontium Isotopes Laboratory using an Agilent 7500ce quadrupole inductively coupled plasma mass spectrometer (ICP-MS). RESULTS AND DISCUSSION Spring Water We evaluated the multiparameter probe data from HRS to understand how the aquatic environment var- ies within the spring system. We divided the HRS multiparameter probe data from HRS into shallow and deep sections of the pond at time 150s (of a total of 345s recorded) due to the relatively steady depth of the probe measurements (0.5 m depth in the NW sec- tion, and 1-1.5 m depth in the SE part of the transect where the shore edge became steep) and the variable depths of the spring pond (Table 1). Over the transect, TDS ranged from 1.7 in the shallow pool to 5.0 ppt in the deeper pool. Average TDS values were 3.6 ppt (SD = 1.2) for the shallow pool and 4.8 ppt (SD = 0.1) for the deeper pool. This difference was signifi- cant where (t (151) = 12.6; p < 0.01). The decrease in TDS values downstream (from shallower to deeper) within the spring may result from fresh water dis- charging to the shallower spring pool or evapocon- centration in the deep pool. The water pH increased through the transect, with a total mean of 7.8 (SD = 0.08), ranging from a low of 7.7 in the deep section to a high of 8.2 in the shallow areas. The average of the deep section was 7.8 (SD = 0.01), and the shallow section was 7.9 (SD = 0.07), with a significant differ- ence (t(162) = -22.5; p < 0.01). DO content gradually increased from 7.45 mg/L (SD = 0.22) to 8.1 (SD = 0.78) as the water flowed into the shallower region. This difference was significant where (t (170) = - 15.5; p < 0.01). The temperature was relatively ele- vated through the transect around 19.5℃ (SD = 1.19). The water temperature in the shallow section of the spring was an average of 18.8℃ (SD= 1.59. The deep section of the pond water 20.0℃ (SD = 0.08), which is warmer than the shallower section (t(148) = 9.0; p < 0.001). Data for these measurements are provided in Appendix 1. We measured alkali metals (Li, Na, K, Rb, and Cs), alkaline earth metals (Be, Mg, Ca, Sr, and Ba), and select metals and metalloids (Al, Mn, Fe, Zn) in spring waters (Figure 4 and Appendix 2). Overall, al- kali metal concentrations were more abundant at BL than at HRS and were highest at the BL-Marsh site, which is likely due to evapoconcentration in the shal- low standing water. Al, Mn, and Fe concentrations in HRS and BL were the 0.04 mg/L detection limit. Alt- hough this water is not designated for human con- sumption, it is worth contextualizing these values as below the National Secondary Drinking Water Stand- ards of 0.05-0.2 mg/L, 0.05 and 0.3 mg/L, respective- ly (U.S. Environmental Protection Agency, 2009). Although these natural brackish springs are not used for drinking water, we note that these analyses did not have high enough resolution to detect whether the concentrations were below the National Primary Drinking Water Regulations maximum contaminant level for As of 0.01 mg/L (U.S. Environmental Pro- tection Agency, 2009). Gastropods Ecological Diversity Biodiversity is important for protecting the stabil- ity of the community which can aid in the overall re- covery time from ecological harm that may threaten an ecosystem (e.g., natural disasters, famine, and dis- eases) (Magurran, 1988). We counted nearly 12,000 gastropod shells across four subsites at HRS, and we note that we did not find any living specimens with organic tissues which needed to be cleaned. We be- lieve that the sampled shells are relatively modern Parameter  Shallow  Deep  Total  Probe Depth (m) mean = 0.54 mean = 0.95 mean = 0.77 TDS (ppt) mean = 3.6, SD = 1.21 mean = 4.8, SD = 0.14 mean = 4.3, SD = 1.01 pH mean = 7.9, SD = 0.07 mean = 7.8, SD = 0.02 mean = 7.8, SD = 0.08 DO (mg/L) mean = 8.4, SD = 0.73 mean = 7.4, SD = 0.23 mean = 7.8, SD = 0.69 Temperature (°C) mean = 18.8, SD = 1.59 mean = 20, SD = 0.08 mean = 19.5, SD = 1.2 Table 1. Water Physical Parameters: Probe Transect Data Summary. 8 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones (i.e., not representing shells last alive thousands or hundreds of years ago) based on their sampling loca- tion at the surface of the spring sediments but recog- nize some might represent older shells that could have been brought to the surface by sediment disturbances, e.g., fish burrows in the spring sediments. We count- ed the number of individuals in each genus to meas- ure the diversity of genera in the ecosystem (Table 2). The Shannon’s Diversity Index at HRS (combining subsites) was 0.432. While the index the- oretically ranges from zero to infinity, this value is low compared to other studies where Shannon’s Di- versity Index often ranges from 1.5-3.5 (Magurran and McGill, 2011; Ifo and others, 2016). We measured gastropod population diversity dif- ferences between the subsites (Figure 1E), which we further grouped into the shallow and deep sections following the distinctions shown in Figure 3A. Sub- sites HRS-2 and HRS-3 are considered shallow, and subsites HRS-0, HRS-1, and HRS-4 are considered deep (although HRS-0 was not sampled to character- ize gastropod diversity). The shallow sediment sam- ples yielded a higher density of shells, where 76% (n = 9087) of individual shells counted were from the shallow samples and both shallow and deep samples had the same volume of sediment collected. Pyr- gulopsis and Tyronia were the most common genera found, with a few Physella (n = 18) found in both shallow and deep subsites. While different genera, Pyrgulopsis and Tyronia are both members of the same gastropod family, and their joint presence may be due to shared preference for similar environmental conditions. A chi-squared (χ2) analysis of the ob- Figure 4. Trace element con- centrations of springwaters. Marsh waters have relatively higher elemental concentra- tions due to evaporation and relatedly less water input. Genera HRS‐1  (Deep) HRS‐2  (Shallow) HRS‐3  (Shallow) HRS‐4  (Deep) Pyrgulopsis 2404 2149 5253 334 Tyronia 112 72 1596 47 Physella 1 0 17 0 Table 2. Gastropod Population: Count of Individuals in Sampled Community. 9 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 served number of Pyrgulopsis, Tyronia, and Physella genera counted from the shallow versus deep subsites resulted in a χ2 of 219 (p < 0.05), thus indicating a statistically significant difference (albeit small) be- tween populations in the small and deep parts of the HRS pond. δ13C and δ18O Shells were analyzed for δ13C and δ18O and com- pared to Total Dissolved Inorganic Carbon (TDIC) δ13C and water δ18O to understand the potential ef- fects of environmentally related and biomediated car- bon isotope fractionation (Appendix 3). δ13C and δ18O metrics can be representative of environmental condi- tions during the time of snail activity and can be used as an indicator of source carbon and source water, useful for evaluating environmental changes in the past (recorded in sedimentary records), and in future collections. Shell samples were aggregated by subsite at BL and HRS (Figure 5A, Table 3). At BL, the subsite av- Figure 5. Stable isotope measurements of gastropod shells. A) δ13C and δ18O measurements of bulk, homogenized shells by site and subsite. B) εC and εo of bulk, homogenized shells by genera. C) δ13C and δ18O variation within in- trashell transects on Melanoides shells. D) Modelled shell formation (ambient water) temperatures based on δ18O composition by site and genera. 10 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones erage δ13C values of shells ranged from -2.1 to -3.5‰ (a range of by 1.4‰), whereas the δ13CTDIC values in water samples at BL averaged -4.2‰ (SD = 0.43, n=4) (Lerback and others, 2023). An ANOVA shows that there are no significant differences between sub- site δ13Cshell values (F = 0.765, p = 0.519). At BL, the subsite shell averages of δ18O values ranged from - 11.9 to -17.3‰ (a range of by 5.4‰). Subsites had statistically different values (ANOVA F= 36.18, p < 0.01), where a Tukey’s HSD test showed that pair- wise, the BL-Marsh was different than every other site at p < 0.01 with a difference of more than 4‰). This is likely because the marsh had shallow standing water which may have had significant evaporative ef- fects. Water samples (converted to VPBD from VSMOW) of BL discharge averaged -45.5‰ (SD = 0.1, n=12). Data for water stable isotopes at these sites is provided in Appendix 4. At HRS, the subsite averages of δ13C ranged from -4.5 to -5.2‰ (a range of 0.8‰), whereas δ13CTDIC values from water at HRS yielded a value of 7.2‰ (n = 1) (Lerback and others, 2019). The δ13CTDIC values were not statistically different across sites (ANOVA F = 0.479, p = 0.75). At HRS, the shell subsite aver- ages of δ18O (VPDB) values ranged from -14.7 to - 15.9‰ (a range of 2.6‰). The δ18O of shells at HRS was statistically different between sites (ANOVA F = 32.28, p < 0.01), where a Tukey’s HSD test showed that pairwise, the HRS-0 was different than the other sites at p < 0.01, with a difference of 1‰).Water at HRS had a measured value (converted to VPBD from VSMOW) of -45.5‰ (SD=0.1, n=8). δ13C values of bulk sediment were -26.6 and - 20.7‰ at BL-pond and HRS-0, respectively (Lerback and others, 2023), which are within the range of val- ues expected of plant material in the region (Hart and others, 2010). Shell δ13C values are more reflective of water δ13C (TDIC) than sediment, similar to findings by Fritz and Poplowski (1974). Stable isotope data of shells were also aggregated by genera (Figure 5B, Table 4) δ13C (VPDB) values in shells ranged from -1.7‰ of a Tryonia at BL to - 9.0‰ from a Planorbella at HRS. Significant differ- ences existed in δ13C between genera (ANOVA F = 7.172, p < 0.01), where the Tukey HSD found a dif- ference of greater than 1‰ between Melanoides and all other genera (p < 0.1) but no significant differ- ences between the four other genera (p > 0.1). δ18O (VPDB) values in shells range from -10.0‰ of a Suc- cineidae at BL-Marsh at BL to -17.5‰ of a Mela- noides at BL-Spring. We found differences between the genera δ18O (ANOVA F = 45.41, p < 0.01), where the Tukey HSD showed a pairwise difference be- tween Melanoides and Tyronia (difference of 1.3‰, p < 0.01), and between Melanoides and Pyrgulopsis (difference of 1.9‰, p < 0.01). There was a differ- ence of at least 4‰ between Succineidae and all other genera including Melanoides (p < 0.01). Lastly, there was also a difference of 1.3‰ between Planorbella and Pyrgulopsis (p < 0.1). The fractionation between the measured shell and the spring waters is represented by epsilon (ε) for shell-TDIC in carbon and for shell-H2O in oxygen stable isotope values (element denoted with a sub- script). Water δ18O for BL and HRS was reported rel- ative to a VSMOW standard, which we convert to the VPDB standard before calculating the fractionation values for oxygen (εO). Planorbella and Succineidae have εC near 0, while the other shells (Melanoides, Physella, and Tyronia) show εC of greater than 1.5‰. All genera but Succineidae, had an average εO of 29.6 (SD = 1.2, n = 57). The elevated εO of +34‰ (SD = 0.44, n = 6) found in Succineidae is unsurprising be- cause Succineidae is a genus only found at BL- Site Average of δ13C SD of δ13C Count of δ13C Average of δ18O SD of δ18O Count of δ18O BL‐Lake ‐3.01 0.41 8 ‐17.13 0.16 8 BL‐Marsh ‐3.48 1.44 10 ‐11.91 1.85 10 BL‐Pond ‐2.85 1.10 21 ‐16.41 1.12 21 BL‐Spring ‐2.13 0.33 14 ‐17.31 0.46 14 HRS‐Subsite‐00 ‐5.22 1.06 15 ‐15.89 0.20 15 HRS‐Subsite‐01 ‐5.06 0.23 4 ‐14.82 0.41 4 HRS‐Subsite‐02 ‐4.72 0.25 4 ‐14.77 0.14 4 HRS‐Subsite‐03 ‐4.46 0.45 4 ‐14.68 0.35 4 HRS‐Subsite‐04 ‐4.77 0.38 4 ‐14.79 0.17 4 Table 3. Gastropod Shell δ13C and δ18O Data by Site. 11 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 Marsh, where evaporation is occurring in shallow standing water (Morgan, 1970). Shanahan and others (2005) posit that Succineidae and Physella are pulmo- nates (lung-breathing), enabling them to live in these shallow areas where more evaporation is occurring and seasonally changing the water δ18O. Following the methodologies provided by Sha- nahan and others (2005), we also evaluated the varia- tion within the whorls of a single shell. The within- shell (intrashell) isotopic variation here may be due to biomediated fractionation or due to seasonal variation in waters during stages of growth. We examined the isotopes in intrashell transects along the long axis of growth from shell aperture to tip (Figure 5C, Appen- dix 5). These variations are otherwise averaged by ho- mogenizing bulk shells. Variation of δ13C was less than 1‰ through the shell, where three out of four shells increased by almost 1‰ overall. For δ18O (VSMOW) values, the maximum variation observed was a linear decrease in one shell from -16.5‰ to - 17.5‰ along the transect, whereas the other three shells did not vary more than 0.3‰. The variation within shells indicates that intrashell variation is mini- mal compared to the variation between bulk shells. This likely reflects the stable conditions provided by the mesothermal, seasonally stable discharge at BL. We used the measured shell δ18O values and measured average water δ18O (which are assumed in paleoclimate studies) to calculate the expected shell formation temperatures (Figure 5D, Appendix 6). Like Shanahan and others (2005), we compare these estimated temperatures to measured temperatures of the springs reported by Lerback and others (2023). The fractionation equation from Kim and O'Neil (1997) estimates temperatures for synthetic calcite, where Kim and others (2007) estimate the formation temperature for synthetic aragonite, and finally, the equation by White and others (1999) estimates the formation temperature for aragonitic molluscs. Each of these equations predicts a temperature lower than the measured discharge temperatures of 28℃ at BL and 21℃ at HRS, but predicted temperatures for the genera Melanoides, Physella, Planorbella, and Tyro- nia by White and others (1997) are within the range found at BL between the Spring subsite discharge and the Lake subsite, and this equation also is closer to the mesothermal temperatures at HRS as well. Because Physella, Planorbella and Succinidae are all pulmo- nates, we might expect these to have more similar pre- dicted temperatures, and different as compared to the gil-breathing genera. However, Physella and Planor- bella predicted temperatures are more closely aligned with the gil-breathing genera, so the δ18O may be more dependent on the microclimate associated with the location than the genera-specific vital effects that Shanahan and others (2005) discussed. Trace Elements We measured alkali metals (Li, Na, K, Rb, and Cs), alkaline earth metals (Be, Mg, Ca, Sr, and Ba), and select metals and metalloids (Al, Mn, Fe, Zn) in gastropod shells from HRS and BL to understand how shell chemistry may represent water or environmental chemistry (Figure 6, Appendix 7). On average, higher concentrations of Li, K, Rb, Be, Sr, Mn, Zn, and As were found in shells from BL than HRS. We provide these data to develop some baseline values as shells can be used as bioindicators of environmental change but note these associations need to be studied in more detail for genera-specific biases. Notably, the single Tyronia shell from HRS had concentrations of Na, Rb, Cs, Mg, Ba, Al, and Mn distinctly higher than shells from the same location, although the data are too sparse to draw statistical significance. However, the difference in trace element concentration may in- dicate there may be phyla- and genera-specific differ- ences in how elements will bioaccumulate in body materials (including shells) (Langston and others, 1998; Rainbow, 2007). Bolotov and others, (2015) showed that freshwater bivalve trace element concen- trations are significantly impacted by biological shell- building processes and geography (water elemental concentrations as related to the proximity of chemical sources). Land snail shell incorporation of environ- mental trace elements have also been discussed as bi- Genera Average of δ13C SD of δ13C Count of δ13C Average of δ18O SD of δ18O Count of δ18O Melanoides 1.71 0.46 26 ‐0.95 1.19 15 Physella ‐0.70 NA 2 ‐0.64 NA 2 Pyrgulopsis 2.13 0.31 27 1.03 0.81 19 Planorbella ‐0.10 1.10 6 ‐0.31 0.75 5 Succineidae ‐0.06 1.33 6 5.41 0.44 6 Tryonia 2.30 0.26 16 0.41 0.89 16 Table 4. Gastropod Shell δ13C and δ18O Data by Genera. 12 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones omonitors for changing environmental conditions (de Vaufleury and Pihan, 1999; Madejon and others, 2013; Pauget and others, 2013), but need to be more carefully studied because of high soil variability and complexity of ecosystems. We show that spring snails throughout HRS ponds live in relatively chemically homogeneous environments, and thus we believe aquatic snail shells may be represent more consistent environmental proxies (within same-genera groups) than land snails. We calculated the elemental ratios (mol/mol) of shells and water that have been evaluated in gastropod shells for paleoclimate reconstructions (Figure 7). These include Mg/Ca which have been used for tem- perature reconstruction in marine and lake foraminif- era collections (Nurenberg and others, 1996; Lea and others, 1999; Elderfield and Ganssen, 2000; Dekens and others, 2002; Anand and others, 2003; Tripati and others, 2003Khider and others, 2015; Gray and Evans, 2019; Saenger and Evans, 2019). The study of Mg/Ca ratios in bivalves and gastropods have been limited and focus primarily on marine systems (Wanamaker and others, 2008; García-Escárzaga and others, 2015). Ulrich and others (2021) found that there was strong association between biomineral elemental chemistry and shell-building genera relatedness and that amongst the marine gastropods that were studied, ele- ment incorporation patterns arose at the class level. Our data test whether the Mg/Ca relationship works in the select freshwater gastropod taxa. At BL, waters had higher Mg/Ca ratios than were observed in Suc- cineidae shells (approximately 0.8 mmol/mol in wa- ter, and 0.0 mmol/mol in shells), whereas in HRS shell the Mg/Ca values were all very low, less than 2.0 mmol/mol. Dellinger and others (2018) show data for marine mollusks that confirm lower Mg/Ca ratios (0.3-8 mmol/mol) than can be expected for more arag- onitic materials. Using the calibration equation from Anand and others (2003) (which was derived for ma- rine foraminifera which incorporates source water Figure 6. Trace element con- centrations measured in gastro- pod shells. 13 M.D. Vanden Berg, R. Ford, C. Frantz, H. Hurlow, K. Gunderson, G. Atwood, editors 2024 Utah Geological Association Publication 51 Mg/Ca geochemistry), the expected Mg/Ca ratio for these shells is 3.011 and 2.515 mmol/mol, respective- ly (using the water temperatures of 23°C at BL and 21°C at HRS reported by Lerback and others, 2023). Given the measured ratios of 3.1 and 4.3 mmol/mol for BL and HRS, these spring water gastropod genera record very different Mg/Ca ratios that may reflect the gastropod shell-building processes partitioning of ele- mental species, especially in comparison to the marine foraminiferal calibrations that have been previously reported. Therefore, freshwater gastropods are likely unsuitable for temperature reconstruction with the Mg/Ca paleothermometer without further study. Gastropod elemental ratios of Fe/Mn and Mn/Sr have been used as a proxy for a variety of processes, such as changes in water chemistry including sedi- ment input, redox conditions, and water balance fluc- tuations (Rosenthal and Katz, 1989; Wanamaker Jr and others, 2008; Korponai and others, 2010). More specifically, Fe/Mn and Mn/Sr have been used in sedi- mentary records as indicators of redox conditions at the time of deposition and may also indicate potential alteration via diagenesis (Templeton and others, 2000). Examples of such factors affecting Fe/Mn and Mn/Sr ratios are changing mixing regimes, erosional input of sediment, aquatic productivity, soil leaching, and eutrophication. Water Fe/Mn ratios were not re- ported because concentrations were below the instru- ment detection limit. The Fe/Mn values of Succine- idae shells found at BL range from 0.21 to 0.85 mol/ mol, whereas the Fe/Mn values of Pyrgulopsis and single Tryonia collected at HRS range from 2.08 to 31.56 mol/mol (Figure 7, Table 8). We observed with- in-genera variability even within the same site; one Pyrgulopsis shell from HRS has Fe/Mn and Mn/Sr values that show an elevated signal compared to the two other Pyrgulopsis samples, falling nearer that Tryonia sample from the same site. We also observed some subsite variation; the Succineidae samples from BL show a depleted Fe/Mn signal relative to sampled marsh surface water, and an elevated Mn/Sr signal when compared to both marsh surface and pond sur- face water. This elevated Mn/Sr may reflect preferen- tial uptake or more bioavailability of the trace element Mn as compared to the more abundant elements. Figure 7. Trace element ratios in waters and shells. 14 J.C. Lerback, B.B. Bowen, S. Bagge, M. Heberer, R. Cocke, H.L. Bricker Bonneville Basin Critcal Zones CONCLUSIONS Wetland critical zones are important sites to moni- tor for changes to water resources and biodiversity and are sites for sedimentological preservation of wet- land critical zone processes. The water chemistry shapes wetland critical zones over long time periods, and the chemistry provides solutes that contribute to the saline ecosystems of the Bonneville basin. Aspects of the water chemistry are preserved in gastropod shells, which can (1) provide an ongoing observation- al metric as “sentinel” organisms, rapidly capturing chemical changes to the system, and (2) also which are preserved in sediments, providing historical rec- ords of the magnitude of change in spring chemistries which contextualize modern environmental changes. We provide chemical characteristics of modern water from two mesothermal, playa-margin springs in the western Bonneville basin, and evaluate gastropod chemistry as providing potential records of spring chemistry changes through time. The Shannon’s Diversity Index at four HRS sub- sites indicates that the ecological diversity is low, with one snail genera, Pyrgulopsis (an imperiled genera) being the dominant shell found (Magurran, 1988; Ma- gurran and McGill, 2011). While more research (particularly into paleoenvironmental conditions and past population distributions) can clarify a baseline di- versity in these springs, the low diversity index report- ed here may reflect that the ecosystem’s overall stabil- ity may be sensitive to environmental changes, includ- ing land use change that impacts the geochemical pro- file of the water. The modern chemistry of the shells can also be used as a baseline to compare with sedi- mentary shell records or future shell collections as bi- oindicators of environmental change. We present iso- topic and trace element data among subsites and gene- ra to constrain the variables relevant to scientists in- terested in using shells as proxies for spring water changes through time. We found genera and subsite differences in δ13C and δ18O variations and trace ele- ment chemistry of modern water and shells, which will need to be better constrained in order to effective- ly use these chemical relationships to interpret past environments. Our data did not find evidence for sig- nificant physiological differences based on pulmonate versus gil-breathing genera in the stable isotope data. Overall, this paper describes wetland critical zone chemistry and metrics of biodiversity in a system of ecological importance in the Great Salt Lake water- shed. As gastropods deposited in spring sediments can be used as recorders of environmental change, we evaluate the factors that may impact geochemical preservation and thus environmental reconstructions. ACKNOWLEDGMENTS Thanks to Kate Holcomb, Lisbeth Louderback, Don Sada, and Saxon Sharp for assistance with gas- tropod identification. Thank you to reviewers Jay Quade and Jesse Bateman for their helpful comments, which greatly improved this paper. This work is par- tially supported by the Global Changes and Sustaina- bility Center at the University of Utah, the NSF/GSA Graduate Student Geoscience Grant #12745-20, which is funded by NSF Award #1949901, and by the UC Presidential Postdoctoral Fellowship Program. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Liver- more National Laboratory under Contract DE-AC52- 07NA27344, release number LLNL-JRNL-855225. 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Time Group Depth (m) Temperature (°C) Total Dissolved Solids (ppt) pH RDO Concentration (mg/L) Specific Conductivity (µS/cm) 1 Shallow 0.373 11.27 2.5 8.1 11.68 3852.72 2 Shallow 0.383 11.27 2.64 8.13 11.78 4067.68 3 Shallow 0.393 11.28 2.78 8.15 11.88 4282.65 4 Shallow 0.403 11.28 2.92 8.17 11.99 4497.62 5 Shallow 0.362 15.12 2.52 8.15 10.2 3869.74 6 Shallow 0.363 15.32 2.55 8.16 10.14 3916.6 7 Shallow 0.365 15.53 2.58 8.17 10.08 3963.46 8 Shallow 0.461 16.38 2.79 8.03 9.7 4286.13 9 Shallow 0.465 16.5 2.78 8.02 9.64 4282.09 10 Shallow 0.469 16.62 2.78 8.01 9.58 4278.05 11 Shallow 0.5 17.22 2.73 7.98 9.21 4197.18 12 Shallow 0.504 17.26 2.73 7.97 9.19 4199.55 13 Shallow 0.508 17.3 2.73 7.97 9.17 4201.92 14 Shallow 0.526 17.5 2.5 7.95 9.03 3849.93 15 Shallow 0.527 17.52 2.49 7.95 9.01 3828.27 16 Shallow 0.528 17.54 2.47 7.95 9 3806.61 17 Shallow 0.53 17.55 2.46 7.95 8.99 3784.95 18 Shallow 0.546 17.76 2.41 7.93 8.83 3700.48 19 Shallow 0.547 17.77 2.4 7.93 8.82 3688.59 20 Shallow 0.548 17.78 2.39 7.93 8.81 3676.71 21 Shallow 0.53 17.95 2.39 7.93 8.69 3684.06 22 Shallow 0.529 17.97 2.39 7.93 8.68 3683.68 23 Shallow 0.528 17.98 2.39 7.93 8.67 3683.31 24 Shallow 0.554 18.06 2.44 7.93 8.61 3746.17 25 Shallow 0.555 18.07 2.44 7.93 8.6 3750.11 26 Shallow 0.555 18.07 2.44 7.93 8.6 3754.06 27 Shallow 0.497 18.2 2.37 7.93 8.51 3643.82 28 Shallow 0.494 18.21 2.37 7.93 8.51 3638.84 29 Shallow 0.491 18.22 2.36 7.93 8.5 3633.87 30 Shallow 0.488 18.23 2.36 7.93 8.5 3628.89 31 Shallow 0.532 18.3 2.44 7.93 8.48 3758.54 32 Shallow 0.533 18.31 2.45 7.93 8.48 3763 33 Shallow 0.534 18.32 2.45 7.93 8.47 3767.47 34 Shallow 0.511 18.44 2.46 7.93 8.4 3780 35 Shallow 0.511 18.45 2.46 7.93 8.39 3783.48 36 Shallow 0.511 18.46 2.46 7.93 8.39 3786.96 37 Shallow 0.524 18.53 2.37 7.93 8.37 3649.47 38 Shallow 0.524 18.54 2.37 7.93 8.37 3641.83 39 Shallow 0.524 18.54 2.36 7.93 8.37 3634.18 40 Shallow 0.531 18.63 2.38 7.92 8.35 3661.48 41 Shallow 0.531 18.63 2.38 7.92 8.34 3660.27 42 Shallow 0.532 18.64 2.38 7.92 8.34 3659.06 43 Shallow 0.533 18.65 2.38 7.92 8.34 3657.85 44 Shallow 0.49 18.69 2.68 7.92 8.31 4119 45 Shallow 0.488 18.7 2.69 7.92 8.31 4144.63 46 Shallow 0.486 18.7 2.71 7.92 8.31 4170.27 47 Shallow 0.516 18.74 2.43 7.91 8.27 3738.22 48 Shallow 0.516 18.74 2.42 7.91 8.27 3723.76 49 Shallow 0.517 18.75 2.41 7.91 8.27 3709.3 50 Shallow 0.563 18.78 2.8 7.91 8.24 4312.73 51 Shallow 0.566 18.79 2.82 7.91 8.24 4336.27 52 Shallow 0.569 18.79 2.83 7.91 8.24 4359.8 53 Shallow 0.522 18.86 2.86 7.93 8.21 4407.27 54 Shallow 0.52 18.87 2.87 7.93 8.21 4422.75 55 Shallow 0.518 18.87 2.88 7.93 8.21 4438.23 56 Shallow 0.516 18.87 2.89 7.93 8.21 4453.71 57 Shallow 0.535 18.82 2.96 7.92 8.24 4550.99 58 Shallow 0.535 18.82 2.96 7.92 8.24 4555.91 59 Shallow 0.534 18.82 2.96 7.92 8.24 4560.83 60 Shallow 0.572 18.96 2.32 7.92 8.22 3570.09 61 Shallow 0.574 18.97 2.29 7.92 8.22 3517.96 62 Shallow 0.577 18.97 2.25 7.92 8.22 3465.82 63 Shallow 0.554 19.02 2.28 7.92 8.26 3510.2 64 Shallow 0.553 19.03 2.27 7.92 8.26 3493.2 65 Shallow 0.553 19.03 2.26 7.92 8.26 3476.19 66 Shallow 0.577 19.06 1.8 7.9 8.29 2773.32 67 Shallow 0.578 19.06 1.78 7.9 8.3 2738.19 68 Shallow 0.579 19.07 1.76 7.9 8.3 2703.05 69 Shallow 0.579 19.07 1.73 7.9 8.3 2667.92 70 Shallow 0.538 19.13 2.38 7.88 8.29 3666.19 71 Shallow 0.536 19.13 2.41 7.88 8.29 3705.42 72 Shallow 0.535 19.13 2.43 7.88 8.29 3744.64 73 Shallow 0.586 19.19 2.63 7.88 8.25 4041.07 74 Shallow 0.588 19.19 2.65 7.88 8.25 4078.32 75 Shallow 0.59 19.19 2.68 7.88 8.25 4115.56 76 Shallow 0.565 19.23 2.48 7.87 8.22 3819.99 77 Shallow 0.565 19.23 2.47 7.87 8.21 3806.91 78 Shallow 0.565 19.23 2.47 7.87 8.21 3793.82 79 Shallow 0.577 19.25 2.74 7.88 8.2 4218.14 80 Shallow 0.577 19.25 2.75 7.88 8.2 4234.77 81 Shallow 0.577 19.25 2.76 7.88 8.2 4251.4 82 Shallow 0.577 19.25 2.77 7.88 8.2 4268.03 83 Shallow 0.58 19.27 3.44 7.88 8.19 5288.08 84 Shallow 0.58 19.27 3.48 7.88 8.19 5352.31 85 Shallow 0.581 19.27 3.52 7.88 8.19 5416.53 86 Shallow 0.581 19.22 4.24 7.87 8.19 6517.24 87 Shallow 0.581 19.22 4.29 7.87 8.19 6596.06 88 Shallow 0.581 19.21 4.34 7.87 8.19 6674.87 89 Shallow 0.54 19.26 4.82 7.88 8.17 7421.89 90 Shallow 0.538 19.26 4.86 7.88 8.16 7481.36 91 Shallow 0.535 19.26 4.9 7.88 8.16 7540.84 92 Shallow 0.519 19.54 4.95 7.87 8.07 7613.5 93 Shallow 0.517 19.56 4.96 7.87 8.07 7627.92 94 Shallow 0.515 19.57 4.97 7.87 8.06 7642.34 95 Shallow 0.514 19.59 4.98 7.87 8.06 7656.77 96 Shallow 0.554 19.7 4.98 7.86 8.02 7661.11 97 Shallow 0.556 19.71 4.98 7.86 8.01 7660.43 98 Shallow 0.558 19.72 4.98 7.86 8.01 7659.74 99 Shallow 0.571 19.77 4.99 7.88 7.97 7680.29 100 Shallow 0.573 19.77 4.99 7.88 7.97 7681.31 101 Shallow 0.574 19.78 4.99 7.88 7.96 7682.32 102 Shallow 0.578 19.8 4.97 7.86 7.94 7650.34 103 Shallow 0.579 19.81 4.97 7.86 7.94 7649.01 104 Shallow 0.579 19.81 4.97 7.86 7.94 7647.67 105 Shallow 0.585 19.84 4.98 7.86 7.86 7658.82 106 Shallow 0.586 19.84 4.98 7.86 7.86 7658.77 107 Shallow 0.586 19.84 4.98 7.86 7.85 7658.71 108 Shallow 0.587 19.84 4.98 7.86 7.85 7658.65 109 Shallow 0.571 19.83 4.98 7.88 7.87 7657.5 110 Shallow 0.57 19.83 4.98 7.88 7.87 7657.75 111 Shallow 0.57 19.83 4.98 7.88 7.87 7657.99 112 Shallow 0.589 19.81 4.97 7.88 7.93 7648.08 113 Shallow 0.59 19.81 4.97 7.88 7.93 7647.5 114 Shallow 0.59 19.8 4.97 7.88 7.94 7646.92 115 Shallow 0.55 19.84 4.97 7.86 7.94 7647.9 116 Shallow 0.548 19.85 4.97 7.86 7.94 7647.75 117 Shallow 0.547 19.85 4.97 7.86 7.95 7647.61 118 Shallow 0.58 19.89 4.97 7.87 7.89 7643.28 119 Shallow 0.581 19.89 4.97 7.87 7.89 7643.09 120 Shallow 0.582 19.89 4.97 7.87 7.89 7642.9 121 Shallow 0.583 19.9 4.97 7.87 7.89 7642.71 122 Shallow 0.594 19.87 4.97 7.87 7.89 7642.89 123 Shallow 0.595 19.87 4.97 7.87 7.89 7642.82 124 Shallow 0.596 19.87 4.97 7.87 7.89 7642.74 125 Shallow 0.517 19.92 4.97 7.87 7.95 7639.41 126 Shallow 0.513 19.93 4.97 7.87 7.96 7639.25 127 Shallow 0.509 19.93 4.97 7.87 7.96 7639.08 128 Shallow 0.502 19.85 4.96 7.85 8.08 7632.75 129 Shallow 0.5 19.85 4.96 7.85 8.09 7632.33 130 Shallow 0.498 19.85 4.96 7.85 8.1 7631.92 131 Shallow 0.502 19.94 4.96 7.85 8.09 7636.98 132 Shallow 0.502 19.95 4.96 7.85 8.09 7637.16 133 Shallow 0.503 19.95 4.96 7.85 8.09 7637.33 134 Shallow 0.503 19.96 4.96 7.85 8.09 7637.5 135 Shallow 0.559 19.94 4.95 7.83 8.1 7608.89 136 Shallow 0.562 19.95 4.94 7.82 8.1 7607.48 137 Shallow 0.565 19.95 4.94 7.82 8.1 7606.07 138 Shallow 0.587 20.04 4.94 7.8 8 7601.13 139 Shallow 0.59 20.04 4.94 7.8 8 7600.29 140 Shallow 0.592 20.04 4.94 7.8 7.99 7599.45 141 Shallow 0.576 20.03 4.94 7.79 7.93 7592.73 142 Shallow 0.575 20.03 4.94 7.79 7.92 7592.35 143 Shallow 0.574 20.03 4.93 7.79 7.91 7591.96 144 Shallow 0.588 20.02 4.93 7.78 7.86 7586.62 145 Shallow 0.588 20.02 4.93 7.78 7.86 7586.22 146 Shallow 0.588 20.01 4.93 7.78 7.86 7585.82 147 Shallow 0.589 20.01 4.93 7.78 7.85 7585.42 148 Shallow 0.629 20.01 4.93 7.77 7.77 7578.26 149 Shallow 0.631 20.01 4.93 7.77 7.77 7577.78 150 Deep 0.634 20.01 4.93 7.77 7.76 7577.3 151 Deep 0.704 20.02 4.93 7.77 7.69 7576.95 152 Deep 0.708 20.02 4.92 7.77 7.68 7576.81 153 Deep 0.713 20.02 4.92 7.77 7.67 7576.66 154 Deep 0.774 20 4.92 7.77 7.62 7576.71 155 Deep 0.779 19.99 4.92 7.77 7.62 7576.73 156 Deep 0.784 19.99 4.92 7.77 7.62 7576.75 157 Deep 0.856 19.99 4.92 7.77 7.57 7572.97 158 Deep 0.861 19.99 4.92 7.77 7.57 7572.77 159 Deep 0.866 19.99 4.92 7.77 7.56 7572.56 160 Deep 0.871 19.98 4.92 7.77 7.56 7572.35 161 Deep 0.977 19.98 4.92 7.77 7.52 7569.69 162 Deep 0.984 19.98 4.92 7.77 7.52 7569.47 163 Deep 0.991 19.98 4.92 7.77 7.52 7569.25 164 Deep 1.028 19.99 4.92 7.77 7.5 7567.25 165 Deep 1.032 19.99 4.92 7.77 7.5 7567.09 166 Deep 1.035 19.99 4.92 7.77 7.5 7566.94 167 Deep 1.154 19.98 4.92 7.78 7.49 7572.95 168 Deep 1.161 19.98 4.92 7.78 7.49 7573.25 169 Deep 1.167 19.98 4.92 7.78 7.49 7573.55 170 Deep 1.123 19.98 4.92 7.77 7.49 7572.76 171 Deep 1.123 19.98 4.92 7.77 7.49 7572.84 172 Deep 1.123 19.98 4.92 7.77 7.48 7572.92 173 Deep 1.122 19.98 4.92 7.77 7.48 7572.99 174 Deep 1.268 19.98 4.93 7.77 7.46 7583.29 175 Deep 1.275 19.98 4.93 7.77 7.46 7583.81 176 Deep 1.281 19.98 4.93 7.77 7.45 7584.33 177 Deep 1.225 19.97 4.93 7.77 7.46 7581.18 178 Deep 0.745 20.23 4.91 7.72 7.04 7546.57 179 Deep 0.773 20.24 4.9 7.72 7.03 7545.79 180 Deep 0.802 20.24 4.9 7.72 7.02 7545.01 181 Deep 0.784 20.14 4.91 7.76 7.03 7551.84 182 Deep 0.793 20.13 4.91 7.76 7.03 7552.02 183 Deep 0.802 20.12 4.91 7.76 7.03 7552.19 184 Deep 0.959 20.08 4.92 7.75 7.06 7570.66 185 Deep 0.966 20.08 4.92 7.75 7.06 7571.86 186 Deep 0.973 20.07 4.92 7.75 7.06 7573.06 187 Deep 0.979 20.07 4.92 7.75 7.07 7574.27 188 Deep 0.908 20.07 4.93 7.75 7.07 7578.24 189 Deep 0.907 20.07 4.93 7.75 7.07 7578.83 190 Deep 0.906 20.07 4.93 7.75 7.07 7579.42 191 Deep 0.954 20.05 4.92 7.74 7.09 7576.65 192 Deep 0.955 20.05 4.92 7.74 7.09 7576.53 193 Deep 0.956 20.05 4.92 7.74 7.09 7576.41 194 Deep 1.06 20.08 4.94 7.75 7.1 7594.5 195 Deep 1.067 20.08 4.94 7.75 7.1 7595.42 196 Deep 1.074 20.08 4.94 7.75 7.1 7596.35 197 Deep 1.112 20.1 4.93 7.75 7.1 7590.61 198 Deep 1.116 20.1 4.93 7.75 7.1 7590.65 199 Deep 1.12 20.1 4.93 7.74 7.1 7590.69 200 Deep 1.124 20.1 4.93 7.74 7.1 7590.72 201 Deep 1.135 20.11 4.92 7.75 7.11 7572.66 202 Deep 1.136 20.11 4.92 7.76 7.11 7571.53 203 Deep 1.138 20.11 4.92 7.76 7.11 7570.39 204 Deep 1.121 20.08 4.93 7.77 7.17 7583.62 205 Deep 1.121 20.08 4.93 7.77 7.17 7584 206 Deep 1.12 20.08 4.93 7.77 7.17 7584.38 207 Deep 1.143 20.07 4.93 7.78 7.25 7584.39 208 Deep 1.144 20.06 4.93 7.78 7.26 7584.7 209 Deep 1.145 20.06 4.93 7.78 7.26 7585.02 210 Deep 1.146 20.06 4.93 7.78 7.27 7585.33 211 Deep 1.088 20.04 4.93 7.79 7.32 7583.78 212 Deep 1.086 20.04 4.93 7.8 7.32 7583.68 213 Deep 1.083 20.04 4.93 7.8 7.33 7583.58 214 Deep 1.108 20.03 4.93 7.79 7.38 7588.5 215 Deep 1.108 20.03 4.93 7.79 7.38 7588.74 216 Deep 1.109 20.03 4.93 7.79 7.38 7588.97 217 Deep 1.075 20.04 4.93 7.77 7.37 7590.77 218 Deep 1.074 20.04 4.93 7.77 7.38 7590.97 219 Deep 1.073 20.04 4.93 7.77 7.38 7591.17 220 Deep 1.095 20.06 4.93 7.77 7.36 7590.4 221 Deep 1.095 20.06 4.93 7.77 7.36 7590.37 222 Deep 1.096 20.06 4.93 7.76 7.36 7590.35 223 Deep 1.096 20.07 4.93 7.76 7.36 7590.33 224 Deep 1.11 20.05 4.94 7.76 7.34 7592.75 225 Deep 1.111 20.05 4.94 7.76 7.34 7592.85 226 Deep 1.113 20.05 4.94 7.76 7.34 7592.96 227 Deep 1.008 20.05 4.94 7.76 7.31 7595.79 228 Deep 1.002 20.05 4.94 7.76 7.3 7595.99 229 Deep 0.997 20.05 4.94 7.76 7.3 7596.19 230 Deep 0.919 20.05 4.68 7.76 7.27 7197.13 231 Deep 0.912 20.05 4.66 7.76 7.27 7175.5 232 Deep 0.906 20.05 4.65 7.76 7.27 7153.87 233 Deep 0.928 20.05 4.62 7.76 7.27 7114.05 234 Deep 0.928 20.05 4.62 7.76 7.27 7104.11 235 Deep 0.928 20.05 4.61 7.76 7.27 7094.18 236 Deep 0.928 20.05 4.6 7.76 7.27 7084.24 237 Deep 0.99 20.05 4.61 7.83 7.47 7099.62 238 Deep 0.994 20.05 4.62 7.84 7.48 7100.44 239 Deep 0.998 20.05 4.62 7.84 7.49 7101.27 240 Deep 0.833 20.04 4.63 7.84 7.64 7130.42 241 Deep 0.825 20.04 4.64 7.84 7.65 7132.41 242 Deep 0.817 20.04 4.64 7.84 7.66 7134.39 243 Deep 0.909 20.03 4.62 7.78 7.76 7105.67 244 Deep 0.911 20.03 4.62 7.77 7.77 7104.64 245 Deep 0.912 20.03 4.62 7.77 7.78 7103.6 246 Deep 0.987 20.03 4.63 7.79 7.77 7116.45 247 Deep 0.993 20.03 4.63 7.79 7.77 7116.51 248 Deep 0.999 20.03 4.63 7.79 7.77 7116.57 249 Deep 1.006 20.03 4.63 7.79 7.77 7116.64 250 Deep 1.04 20.03 4.64 7.78 7.82 7131.62 251 Deep 1.043 20.02 4.64 7.78 7.82 7132.73 252 Deep 1.046 20.02 4.64 7.78 7.82 7133.84 253 Deep 1.044 20.02 4.64 7.78 7.82 7136.56 254 Deep 1.044 20.01 4.64 7.78 7.82 7136.98 255 Deep 1.044 20.01 4.64 7.78 7.82 7137.4 256 Deep 0.87 20.01 4.63 7.77 7.84 7121.68 257 Deep 0.86 20.01 4.63 7.77 7.84 7120.84 258 Deep 0.85 20.01 4.63 7.77 7.84 7120 259 Deep 0.792 20 4.61 7.76 7.82 7094.36 260 Deep 0.786 20 4.61 7.76 7.82 7092.63 261 Deep 0.779 20 4.61 7.76 7.82 7090.9 262 Deep 0.773 20 4.61 7.76 7.82 7089.17 263 Deep 0.85 20.01 4.6 7.76 7.77 7078.52 264 Deep 0.853 20.01 4.6 7.76 7.77 7077.45 265 Deep 0.856 20.01 4.6 7.76 7.77 7076.38 266 Deep 0.979 20.01 4.61 7.76 7.76 7099.24 267 Deep 0.988 20.01 4.62 7.76 7.76 7100.3 268 Deep 0.996 20.01 4.62 7.76 7.75 7101.37 269 Deep 0.981 20.01 4.6 7.76 7.73 7081.11 270 Deep 0.982 20.01 4.6 7.76 7.73 7080.49 271 Deep 0.984 20.01 4.6 7.76 7.73 7079.86 272 Deep 0.963 20 4.6 7.76 7.69 7077.37 273 Deep 0.961 20 4.6 7.76 7.69 7076.78 274 Deep 0.959 20 4.6 7.76 7.69 7076.19 275 Deep 0.957 20 4.6 7.76 7.68 7075.59 276 Deep 1.056 19.98 4.62 7.75 7.67 7104.38 277 Deep 1.061 19.98 4.62 7.75 7.66 7105.89 278 Deep 1.066 19.97 4.62 7.75 7.66 7107.39 279 Deep 1.029 19.96 4.65 7.76 7.66 7147.6 280 Deep 1.029 19.96 4.65 7.76 7.66 7150.33 281 Deep 1.029 19.96 4.65 7.76 7.65 7153.06 282 Deep 1.057 19.95 4.61 7.76 7.65 7098.87 283 Deep 1.057 19.95 4.61 7.76 7.65 7096.65 284 Deep 1.058 19.95 4.61 7.76 7.65 7094.42 285 Deep 0.932 19.95 4.62 7.75 7.63 7101.76 286 Deep 0.926 19.95 4.62 7.75 7.62 7100.99 287 Deep 0.92 19.95 4.62 7.75 7.62 7100.22 288 Deep 0.913 19.95 4.61 7.75 7.62 7099.45 289 Deep 0.83 19.95 4.83 7.75 7.59 7426.1 290 Deep 0.823 19.95 4.84 7.75 7.59 7443.64 291 Deep 0.816 19.95 4.85 7.75 7.58 7461.18 292 Deep 0.431 19.95 4.85 7.76 7.54 7465.86 293 Deep 0.409 19.95 4.86 7.76 7.53 7472.57 294 Deep 0.387 19.95 4.86 7.76 7.53 7479.27 295 Deep 0.519 19.95 4.88 7.75 7.46 7502.56 296 Deep 0.519 19.95 4.88 7.75 7.45 7503.16 297 Deep 0.871 19.95 4.89 7.76 7.29 7522.43 298 Deep 0.879 19.95 4.89 7.76 7.29 7522.81 299 Deep 0.879 19.94 4.89 7.76 7.28 7524.61 300 Deep 0.879 19.94 4.89 7.76 7.28 7524.72 301 Deep 0.879 19.94 4.89 7.76 7.28 7524.82 302 Deep 0.776 19.94 4.89 7.77 7.29 7520.93 303 Deep 0.768 19.94 4.89 7.77 7.29 7520.66 304 Deep 0.761 19.94 4.89 7.77 7.29 7520.39 305 Deep 0.754 19.94 4.89 7.77 7.29 7520.13 306 Deep 0.907 19.91 4.89 7.77 7.3 7527.86 307 Deep 0.913 19.91 4.89 7.77 7.3 7528.18 308 Deep 0.919 19.91 4.89 7.76 7.3 7528.49 309 Deep 0.791 19.91 4.89 7.77 7.32 7528.08 310 Deep 0.787 19.9 4.89 7.77 7.32 7528.22 311 Deep 0.783 19.9 4.89 7.77 7.32 7528.36 312 Deep 0.805 19.9 4.89 7.76 7.32 7523.26 313 Deep 0.803 19.9 4.89 7.76 7.32 7522.95 314 Deep 0.802 19.9 4.89 7.76 7.32 7522.63 315 Deep 0.829 19.89 4.92 7.76 7.31 7563.5 316 Deep 0.831 19.89 4.92 7.76 7.3 7565.7 317 Deep 0.834 19.88 4.92 7.76 7.3 7567.89 318 Deep 0.836 19.88 4.92 7.76 7.3 7570.08 319 Deep 0.85 19.86 4.92 7.76 7.29 7569.92 320 Deep 0.851 19.86 4.92 7.76 7.29 7570.78 321 Deep 0.853 19.86 4.92 7.76 7.29 7571.64 322 Deep 0.859 19.84 4.92 7.77 7.29 7573.14 323 Deep 0.86 19.84 4.92 7.77 7.29 7573.11 324 Deep 0.861 19.84 4.92 7.77 7.29 7573.08 325 Deep 0.726 19.82 4.91 7.77 7.29 7558.29 326 Deep 0.718 19.82 4.91 7.77 7.29 7557.48 327 Deep 0.711 19.82 4.91 7.77 7.29 7556.68 328 Deep 0.858 19.84 4.91 7.76 7.28 7558.94 329 Deep 0.863 19.84 4.91 7.76 7.28 7558.79 330 Deep 0.869 19.85 4.91 7.76 7.28 7558.63 331 Deep 0.874 19.85 4.91 7.76 7.28 7558.48 332 Deep 1.114 19.86 4.91 7.75 7.26 7556.52 333 Deep 1.13 19.86 4.91 7.75 7.26 7556.5 334 Deep 1.146 19.86 4.91 7.75 7.26 7556.49 335 Deep 1.182 19.87 4.92 7.76 7.25 7563.37 336 Deep 1.188 19.88 4.92 7.76 7.25 7563.71 337 Deep 1.194 19.88 4.92 7.76 7.25 7564.04 338 Deep 1.184 19.87 4.91 7.76 7.27 7561.04 339 Deep 1.183 19.87 4.91 7.76 7.27 7561.01 340 Deep 1.182 19.87 4.91 7.76 7.27 7560.98 341 Deep 0.987 19.87 4.91 7.76 7.26 7559.3 342 Deep 0.976 19.87 4.91 7.76 7.26 7559.13 343 Deep 0.964 19.87 4.91 7.76 7.26 7558.95 344 Deep 0.953 19.87 4.91 7.76 7.26 7558.78 345 Deep 0.988 19.86 4.91 7.76 7.27 7557.15 Appendix 2. Water Trace Element Data (mg/L). Site subsite Li Na K Rb Cs Be Mg Ca Sr Ba Al Sc Mn Fe Cu Ni Zn As BL Marsh 3.81 3897 274 1.25 0.102 0.0002 122.1 278 5.5 0.11 0.02 <0.0002 0 0.042 <0.5 0 0.02 <0.04 BL Pond 1.71 1501 114 0.56 0.046 <0.000006 52.1 109 2.5 0.06 0.02 0.0002 0 <0.008 <0.5 0 0.01 <0.04 HRS Deep 0.59 1496 57 0.05 0.004 <0.00005 53.9 118 1.1 0.07 <0.005 <0.0004 <0.003 <0.04 <0.0007 <0.0002 0.01 <0.04 HRS Surface 0.59 1498 58 0.05 0.004 <0.00005 53.8 117 1 0.07 0.01 <0.0004 <0.003 <0.04 0 <0.0002 0.02 <0.04 Appendix 3. Bulk shell stable isotope data. Sample Name Site Sample Type Genera Sub-site δ 13 C (‰-VPDB) δ 18 O (‰-VSMOW) Data Source Lab BL-M-T6-1 BL Shell Succineidae BL-Marsh -3.4 -10.017 this study SIRFER BL-M-T6-2 BL Shell Succineidae BL-Marsh -3.33 -10.017 this study SIRFER BL-M-T6-6 BL Shell Succineidae BL-Marsh -4.23 -10.546 this study SIRFER BL-M-T6-3 BL Shell Succineidae BL-Marsh -3.07 -10.703 this study SIRFER BL-M-T6-4 BL Shell Succineidae BL-Marsh -5.18 -10.812 this study SIRFER BL-M-T6-5 BL Shell Succineidae BL-Marsh -6.49 -11.096 this study SIRFER BL-P-T5-8 BL Shell Melanoides BL-Pond -1.84 -12.646 this study SIRFER BL-M-T2-1 BL Shell Pyrgulopsis BL-Marsh -2.34 -13.182 this study SIRFER BL-M-T2-3 BL Shell Pyrgulopsis BL-Marsh -2.52 -13.894 this study SIRFER BL-M-T2-4 BL Shell Pyrgulopsis BL-Marsh -2.14 -14.243 this study SIRFER HRS-01-PP-O1 HRS Shell Pyrgulopsis HRS-Subsite-01 -5.24 -14.343 this study SIRFER HRS-03-PP-O1 HRS Shell Pyrgulopsis HRS-Subsite-03 -4.85 -14.361 this study SIRFER HRS-03-PP-O2 HRS Shell Pyrgulopsis HRS-Subsite-03 -3.95 -14.406 this study SIRFER HRS-02-TP-O2 HRS Shell Tryonia HRS-Subsite-02 -4.39 -14.568 this study SIRFER HRS-04-TP-O1 HRS Shell Tryonia HRS-Subsite-04 -4.42 -14.578 this study SIRFER BL-M-T2-2 BL Shell Pyrgulopsis BL-Marsh -2.09 -14.634 this study SIRFER HRS-04-TP-O2 HRS Shell Tryonia HRS-Subsite-04 -4.48 -14.733 this study SIRFER HRS-01-TP-O2 HRS Shell Tryonia HRS-Subsite-01 -4.76 -14.776 this study SIRFER HRS-02-PP-O1 HRS Shell Pyrgulopsis HRS-Subsite-02 -4.67 -14.795 this study SIRFER HRS-01-PP-O2 HRS Shell Pyrgulopsis HRS-Subsite-01 -5.23 -14.83 this study SIRFER HRS-02-PP-O2 HRS Shell Pyrgulopsis HRS-Subsite-02 -4.86 -14.851 this study SIRFER HRS-02-TP-O1 HRS Shell Tryonia HRS-Subsite-02 -4.97 -14.858 this study SIRFER HRS-04-PP-O1 HRS Shell Pyrgulopsis HRS-Subsite-04 -5 -14.879 this study SIRFER HRS-03-TP-O1 HRS Shell Tryonia HRS-Subsite-03 -4.82 -14.88 this study SIRFER HRS-04-PP-O2 HRS Shell Pyrgulopsis HRS-Subsite-04 -5.18 -14.959 this study SIRFER HRS-03-TP-O2 HRS Shell Tryonia HRS-Subsite-03 -4.2 -15.059 this study SIRFER BL-P-T4-2 BL Shell Planorbella BL-Pond -4.82 -15.295 this study SIRFER HRS-01-TP-O1 HRS Shell Tryonia HRS-Subsite-01 -5.01 -15.349 this study SIRFER HRS-T2-4 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.14 -15.565 this study SIRFER HRS-T4-1 HRS Shell Planorbella HRS-Subsite-00 -8.96 -15.67 this study SIRFER HRS-T2-1 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.19 -15.718 this study SIRFER HRS-T2-5 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.19 -15.778 this study SIRFER HRS-T2-2 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.08 -15.788 this study SIRFER HRS-T2-3 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.03 -15.883 this study SIRFER HRS-T1-3 HRS Shell Tryonia HRS-Subsite-00 -4.95 -15.98 this study SIRFER BL-P-T2-2 BL Shell Pyrgulopsis BL-Pond -1.92 -16.045 this study SIRFER HRS-T1-4 HRS Shell Tryonia HRS-Subsite-00 -4.98 -16.068 this study SIRFER HRS-T1-1 HRS Shell Tryonia HRS-Subsite-00 -4.57 -16.085 this study SIRFER HRS-T1-5 HRS Shell Tryonia HRS-Subsite-00 -5.02 -16.131 this study SIRFER HRS-T1-2 HRS Shell Tryonia HRS-Subsite-00 -4.96 -16.158 this study SIRFER BL-P-T2-1 BL Shell Pyrgulopsis BL-Pond -1.72 -16.282 this study SIRFER BL-P-T3-2 BL Shell Physella BL-Pond -5.02 -16.341 this study SIRFER BL-S-T1-1 BL Shell Tryonia BL-Spring -1.92 -16.374 this study SIRFER BL-P-T1-1 BL Shell Tryonia BL-Pond -1.71 -16.524 this study SIRFER BL-P-T4-5 BL Shell Planorbella BL-Pond -4.5 -16.641 this study SIRFER BL-P-T3-1 BL Shell Physella BL-Pond -4.82 -16.819 this study SIRFER BL-P-T4-1 BL Shell Planorbella BL-Pond -3.65 -16.823 this study SIRFER BL-P-T5-6 BL Shell Melanoides BL-Pond -2.24 -16.858 this study SIRFER BL-L-T5-4 BL Shell Melanoides BL-Lake -2.93 -16.893 this study SIRFER BL-P-T4-4 BL Shell Planorbella BL-Pond -3.71 -16.916 this study SIRFER BL-P-T5-3 BL Shell Melanoides BL-Pond -2.48 -17.015 this study SIRFER BL-P-T5-4 BL Shell Melanoides BL-Pond -2.15 -17.058 this study SIRFER BL-P-T5-1 BL Shell Melanoides BL-Pond -2.44 -17.084 this study SIRFER BL-P-T5-7 BL Shell Melanoides BL-Pond -2.49 -17.125 this study SIRFER BL-P-T5-2 BL Shell Melanoides BL-Pond -2.46 -17.135 this study SIRFER BL-L-T5-3 BL Shell Melanoides BL-Lake -2.99 -17.162 this study SIRFER BL-L-T5-1 BL Shell Melanoides BL-Lake -3.02 -17.238 this study SIRFER BL-L-T5-2 BL Shell Melanoides BL-Lake -2.38 -17.238 this study SIRFER BL-S-T5-4 BL Shell Melanoides BL-Spring -2.23 -17.343 this study SIRFER BL-S-T5-1 BL Shell Melanoides BL-Spring -2.1 -17.516 this study SIRFER BL-S-T5-5 BL Shell Melanoides BL-Spring -2.29 -17.519 this study SIRFER BL-S-T1-2 BL Shell Tryonia BL-Spring -1.91 -17.541 this study SIRFER BL-S-T5-2 BL Shell Melanoides BL-Spring -2.13 -17.549 this study SIRFER BL-P-T4-3 BL Shell Planorbella BL-Pond -3.08 - this study SIRFER BL-Spring-Shell-2019-1 BL Shell Melanoides BL-Spring -2.21 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2019-2 BL Shell Melanoides BL-Spring -2.26 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2019-3 BL Shell Melanoides BL-Spring - - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2019-4 BL Shell Melanoides BL-Spring -3.08 - Lerback and others, 2023 NOSAMS BL-Pond-Shell-2019-1 BL Shell Melanoides BL-Pond -2.17 - Lerback and others, 2023 NOSAMS BL-Pond-Shell-2019-2 BL Shell Melanoides BL-Pond -2.09 - Lerback and others, 2023 NOSAMS BL-Pond-Shell-2019-3 BL Shell Melanoides BL-Pond -2.37 - Lerback and others, 2023 NOSAMS BL-Pond-Shell-2019-4 BL Shell Melanoides BL-Pond -2.14 - Lerback and others, 2023 NOSAMS BL-Lake-Shell-2018-1 BL Shell Melanoides BL-Lake -3.06 - Lerback and others, 2023 NOSAMS BL-Lake-Shell-2018-2 BL Shell Melanoides BL-Lake -2.85 - Lerback and others, 2023 NOSAMS BL-Lake-Shell-2018-3 BL Shell Melanoides BL-Lake -2.98 - Lerback and others, 2023 NOSAMS BL-Lake-Shell-2018-4 BL Shell Melanoides BL-Lake -3.89 - Lerback and others, 2023 NOSAMS HRS-Pond-Shell-2020-1 HRS Shell Pyrgulopsis HRS-Subsite-00 -5.18 - Lerback and others, 2023 NOSAMS HRS-Pond-Shell-2020-2 HRS Shell Pyrgulopsis HRS-Subsite-00 -4.43 - Lerback and others, 2023 NOSAMS HRS-Pond-Shell-2020-3 HRS Shell Pyrgulopsis HRS-Subsite-00 -4.77 - Lerback and others, 2023 NOSAMS HRS-Pond-Shell-2020-4 HRS Shell Pyrgulopsis HRS-Subsite-00 -4.79 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2020-5 BL Shell Pyrgulopsis BL-Spring -1.82 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2020-6 BL Shell Pyrgulopsis BL-Spring -1.97 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2020-7 BL Shell Pyrgulopsis BL-Spring -1.94 - Lerback and others, 2023 NOSAMS BL-Spring-Shell-2020-8 BL Shell Pyrgulopsis BL-Spring -1.83 - Lerback and others, 2023 NOSAMS BL-Pond-Sediment-2020-1 BL Sediment - BL-Pond -26.61 - Lerback and others, 2023 NOSAMS HRS-Pond-Sediment-2020-1 HRS Sediment - HRS-Subsite-00 -20.65 - Lerback and others, 2023 NOSAMS Appendix 4 . Water stable isotope data. Site Type δ18O (‰-VSMOW) δ18O (‰-VPDB converted) δ13C (‰-VPDB) δ13C Source Lab Source Subsite BL Water - - -3.73 Measured NOSAMS Lerback and others, 2023 BL-Lake BL Water - - -4 Measured NOSAMS Lerback and others, 2023 BL-Pond BL Water - - -4.5 Measured NOSAMS Lerback and others, 2019 Supplementary Data. "Lookout Point, 6/2/2017" BL-Spring BL Water - - -4.65 Measured NOSAMS Lerback and others, 2023 BL-Spring HRS Water - - -7.02 Measured NOSAMS Lerback and others, 2023 HRS-Subsite-00 BL Water -15.9 -45.42 - SIRFER Lerback and others, 2019 BL-Spring BL Water -16.05 -45.56 - SIRFER Lerback and others, 2019 BL-Spring BL Water -15.92 -45.43 - SIRFER Lerback and others, 2019 BL-Spring BL Water -15.99 -45.5 - SIRFER Lerback and others, 2019 BL-Spring BL Water -16 -45.51 - SIRFER Lerback and others, 2019 BL-Spring BL Water -16.1 -45.61 - SIRFER Lerback and others, 2019 BL-Spring BL Water -15.86 -45.37 - SIRFER Lerback and others, 2019 BL-Lake BL Water -15.74 -45.26 - SIRFER Lerback and others, 2019 BL-Lake HRS Water -16.23 -45.73 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -16.06 -45.57 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -15.98 -45.49 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -16.04 -45.55 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -16 -45.51 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -15.89 -45.41 - SIRFER Lerback and others, 2023 HRS-Subsite-00 HRS Water -16.01 -45.52 - SIRFER Lerback and others, 2023 HRS-Subsite-00 Appendix 5. Gastropod Intrashell δ 13 C and δ 18 O Transect Data. Sample Name Drill site Number δ 13 C δ 18 O BL-S-T5-9-4 4 -2.91 -17.46 BL-S-T5-9-3 3 -2.41 -17.48 BL-S-T5-9-2 2 -2.21 -17.32 BL-S-T5-9-1 1 -2.24 -17.49 BL-S-T5-8-4 4 -2.64 -17.25 BL-S-T5-8-3 3 -2.54 -17.33 BL-S-T5-8-2 2 -2.13 -17.37 BL-S-T5-8-1 1 -1.91 -17.51 BL-S-T5-7-4 4 -2.54 -17.67 BL-S-T5-7-3 3 -2.08 -17.33 BL-S-T5-7-2 2 -2.24 -17.65 BL-S-T5-7-1 1 -2.25 -17.26 BL-S-T5-6-4 4 -2.97 -16.57 BL-S-T5-6-3 3 -2.84 -16.96 BL-S-T5-6-2 2 -2.41 -17.18 BL-S-T5-6-1 1 -2.2 -17.36 Appendix 6. Calculated formation temperatures of gastropod shells Sample Name Genera Sub-site T (℃; Kim and O'Neill, 1997) T (℃; Kim and others, 2007) T (℃; White and others, 1999) BL-M-T6-1 Succineidae BL-Marsh -11.4 -8.6 -6.8 BL-M-T6-2 Succineidae BL-Marsh -11.4 -8.6 -6.8 BL-M-T6-6 Succineidae BL-Marsh -9.3 -6.5 -4.5 BL-M-T6-3 Succineidae BL-Marsh -8.7 -5.9 -3.8 BL-M-T6-4 Succineidae BL-Marsh -8.3 -5.4 -3.3 BL-M-T6-5 Succineidae BL-Marsh -7.2 -4.3 -2.1 BL-P-T5-8 Melanoides BL-Pond -0.8 2.2 5 BL-M-T2-1 Pyrgulopsis BL-Marsh 1.4 4.5 7.5 BL-M-T2-3 Pyrgulopsis BL-Marsh 4.5 7.7 11 BL-M-T2-4 Pyrgulopsis BL-Marsh 6 9.2 12.7 BL-M-T2-2 Pyrgulopsis BL-Marsh 7.7 11 14.6 BL-P-T4-2 Planorbella BL-Pond 10.7 14.1 18 BL-P-T2-2 Pyrgulopsis BL-Pond 14.1 17.7 21.9 BL-P-T2-1 Pyrgulopsis BL-Pond 15.2 18.8 23.2 BL-P-T3-2 Physella BL-Pond 15.5 19.1 23.5 BL-S-T1-1 Tryonia BL-Spring 15.7 19.2 23.7 BL-P-T1-1 Tryonia BL-Pond 16.4 20 24.5 BL-P-T4-5 Planorbella BL-Pond 16.9 20.5 25.1 BL-P-T3-1 Physella BL-Pond 17.8 21.4 26.1 BL-P-T4-1 Planorbella BL-Pond 17.8 21.4 26.1 BL-P-T5-6 Melanoides BL-Pond 17.9 21.6 26.3 BL-L-T5-4 Melanoides BL-Lake 18.1 21.8 26.5 BL-P-T4-4 Planorbella BL-Pond 18.2 21.9 26.6 BL-P-T5-3 Melanoides BL-Pond 18.7 22.4 27.1 BL-P-T5-4 Melanoides BL-Pond 18.9 22.6 27.4 BL-P-T5-1 Melanoides BL-Pond 19 22.7 27.5 BL-P-T5-7 Melanoides BL-Pond 19.2 22.9 27.7 BL-P-T5-2 Melanoides BL-Pond 19.3 23 27.8 BL-L-T5-3 Melanoides BL-Lake 19.4 23.1 27.9 BL-L-T5-1 Melanoides BL-Lake 19.8 23.5 28.4 BL-L-T5-2 Melanoides BL-Lake 19.8 23.5 28.4 BL-S-T5-4 Melanoides BL-Spring 20.3 24 28.9 BL-S-T5-1 Melanoides BL-Spring 21.1 24.9 29.9 BL-S-T5-5 Melanoides BL-Spring 21.1 24.9 29.9 BL-S-T1-2 Tryonia BL-Spring 21.2 25 30 BL-S-T5-2 Melanoides BL-Spring 21.3 25.1 30.1 HRS-01-PP-O1 Pyrgulopsis HRS-Subsite-01 6.3 9.5 13 HRS-03-PP-O1 Pyrgulopsis HRS-Subsite-03 6.3 9.6 13.1 HRS-03-PP-O2 Pyrgulopsis HRS-Subsite-03 6.5 9.8 13.3 HRS-02-TP-O2 Tryonia HRS-Subsite-02 7.3 10.6 14.1 HRS-04-TP-O1 Tryonia HRS-Subsite-04 7.3 10.6 14.2 HRS-04-TP-O2 Tryonia HRS-Subsite-04 8 11.3 15 HRS-01-TP-O2 Tryonia HRS-Subsite-01 8.2 11.5 15.2 HRS-02-PP-O1 Pyrgulopsis HRS-Subsite-02 8.3 11.6 15.3 HRS-01-PP-O2 Pyrgulopsis HRS-Subsite-01 8.4 11.8 15.4 HRS-02-PP-O2 Pyrgulopsis HRS-Subsite-02 8.5 11.9 15.6 HRS-02-TP-O1 Tryonia HRS-Subsite-02 8.5 11.9 15.6 HRS-04-PP-O1 Pyrgulopsis HRS-Subsite-04 8.6 12 15.7 HRS-03-TP-O1 Tryonia HRS-Subsite-03 8.6 12 15.7 HRS-04-PP-O2 Pyrgulopsis HRS-Subsite-04 9 12.4 16.1 HRS-03-TP-O2 Tryonia HRS-Subsite-03 9.4 12.8 16.6 HRS-01-TP-O1 Tryonia HRS-Subsite-01 10.8 14.2 18.1 HRS-T2-4 Pyrgulopsis HRS-Subsite-00 11.7 15.2 19.2 HRS-T4-1 Planorbella HRS-Subsite-00 12.2 15.7 19.8 HRS-T2-1 Pyrgulopsis HRS-Subsite-00 12.4 15.9 20 HRS-T2-5 Pyrgulopsis HRS-Subsite-00 12.7 16.2 20.3 HRS-T2-2 Pyrgulopsis HRS-Subsite-00 12.8 16.3 20.4 HRS-T2-3 Pyrgulopsis HRS-Subsite-00 13.2 16.7 20.9 HRS-T1-3 Tryonia HRS-Subsite-00 13.6 17.2 21.4 HRS-T1-4 Tryonia HRS-Subsite-00 14.1 17.6 21.8 HRS-T1-1 Tryonia HRS-Subsite-00 14.1 17.7 21.9 HRS-T1-5 Tryonia HRS-Subsite-00 14.4 17.9 22.2 HRS-T1-2 Tryonia HRS-Subsite-00 14.5 18 22.3 Appendix 7. Gastropod Shell Trace Element Data (mg/kg) Site Taxa Li Na K Rb Cs Be Mg Ca Sr Ba Al Sc Mn Fe Cu Ni Zn As BL Succineidae 3.3 2573 370 0.12 0.008 0.0392 56.7 407754 2486.8 40.07 4.86 0.0268 12.19 2.611 5.4 0.21 2.44 0.11 BL Succineidae 5.93 2268 456 0.19 0.037 0.195 130.5 425888 2666.1 55.38 13.16 0.032 9.67 8.333 3.7 0.22 3.91 0.36 BL Succineidae 2.86 2464 561 0.2 0.021 0.0516 82.2 430344 2473.6 42.62 11.31 0.0398 12.02 10.424 3.4 0.15 2.11 0.42 BL Succineidae 4.14 2340 427 0.13 0.007 0.064 40.6 401159 2463.8 36.12 3.7 0.0271 12.63 5.667 11.2 0.35 3.55 0.26 HRS Pyrgulopsis 1.6 2170 21 0.03 0.017 0.007 80.6 398182 1263.9 99.39 5.95 0.09 3.12 100.026 <11 1.9 2.09 0.26 HRS Pyrgulopsis 2 2667 22 <0.03 0.007 0.0105 51.1 415211 1200.8 106.43 7.12 0.0949 6.75 14.235 <11 2.2 1.05 0.11 HRS Pyrgulopsis 1.47 1960 18 0.03 0.015 0.0077 63.9 347402 1131.3 83.02 12.29 0.0812 2.51 67.234 <9 1.67 0.74 0.26 HRS Tryonia 1.44 2879 45 0.25 0.093 0.0134 230.9 425229 1317.5 129.36 81.88 0.1146 8.45 64.693 <20 2.25 2.11 0.14