Testate amoebae as paleoindicators of surface-moisture changes on Michigan peatlands: modern ecology and hydrological calibration

Peatland testate amoebae are sensitive indicators of local hydrology and have been used as proxies for surface moisture conditions in fossil studies. However, few regional calibration datasets exist in North America, and knowledge of testate amoeba ecology and distribution patterns are limited. The objectives of this study were to (1) investigate the relationship between testate amoebae, environment, and Sphagnum species in Michigan peatlands; (2) generate transfer functions from this dataset that can be applied to fossil data; and (3) describe vertical variation of testate amoebae inhabiting Sphagnum moss. Testate amoeba assemblages from 139 microsites within 11 peatlands in Michigan were compared to assess variability between and within peatlands. Most peatlands contained similar testate amoeba assemblages, although within individual peatlands the amount of assemblage variability is correlated to the amount of environmental heterogeneity. Of the measured environmental variables, depth to water table showed the strongest relationship with testate amoebae. Depth to water table can be reconstructed from fossil data with a mean error of ±7.5 cm, although predictive ability deteriorates in extremely dry environments (>30 cm water table depth). Vertical variation in testate amoeba assemblages was investigated at 89 Sphagnum-dominated microsites by directly comparing amoeba assemblages and the abundance and frequency of common taxa in upper and lower portions of the Sphagnum stem. Except for extremely dry microsites, considerable vertical variation in assemblage composition exists. Many agglutinate taxa are more abundant on lower portions of the Sphagnum stem, and taxa containing symbiotic zoochlorellae are more abundant on upper portions. Refinements in sampling procedures and analysis may improve the predictive ability of transfer functions.     

A rapid response of testate amoebae and vegetation to inundation of a kettle hole mire

Our palaeoecological study covers 73 years of history (1929–2002) of a kettle hole peatland inundated by water from a nearby, dammed lake. Testate amoebae, pollen and non-pollen palynomorphs (NPPs) were used to track the shift to wetter conditions in the peatland. Lead-210 was used to try and construct the chronology. We investigated how peatland testate amoebae communities changed since the damming of a nearby river. Furthermore, we evaluated how rapidly local vegetation responded to the increase in wetness, and how vegetation changes correlated with shifts in testate amoebae and NPPs. The Mukrza kettle hole provided palaeoecological evidence of trophic state and hydrological changes since the lake filled with water in 1929. Three stages of development were revealed. The first two were associated with initial inundation, and the third was related to Sphagnum expansion and acidification. Quantitative reconstruction of groundwater level and pH, inferred using testate amoebae, confirmed our hypotheses about changes in hydrology and trophic state. Subfossil desmid remains lend qualitative support to the reconstruction. The ecology of several testate amoeba taxa is discussed in the context of succession and population establishment. There was complete species replacement since the time of inundation. Our investigation has two important applied aspects: (1) it enables prediction of the response of peatlands to a rise in water table on restored sites; and (2) it provides analogues for palaeoclimatological studies. The history of the Mukrza mire is an example of how palaeoecological studies can be used to assess the degree of change in peatlands transformed by human activities.     

Ecology of testate amoebae in peatlands of central China and development of a transfer function for paleohydrological reconstruction

Testate amoebae are a diverse and abundant group of protozoa that constitute a large proportion of biomass in many ecosystems and probably fill important roles in ecosystem function. These microorganisms have attracted the interest of paleoecologists because the preserved shells of testate amoebae and their known hydrological preferences enable reconstruction of past hydrological change. In ombrotrophic peatlands, surface wetness reflects hydroclimate, so testate amoebae can play an important role in reconstruction of Holocene climate change. Previous studies, however, have been geographically restricted, mostly to North America and Europe. We studied the ecology of testate amoebae in peatlands from central China in relation to hydrology, pH and metal concentrations. We found that testate amoeba community structure was correlated with depth to water table (DWT) and that the hydrological preferences of species generally matched those of previous studies. We developed a weighted average DWT transfer function that enables prediction of water table depth with a cross-validated mean error of <5 cm. Our results demonstrate the potential for using testate amoebae to reconstruct paleohydrology in China. Such studies could contribute to our understanding of Holocene climate changes in China, particularly regarding past Asian monsoon activity.     

Holocene changes in climate and land use drove shifts in the diversity of testate amoebae in a subalpine pond

Testate amoebae that inhabit peat are sensitive indicators of water table position. In this study, we used testate amoebae in sediments from a mire in the western Alps (Lac du Thyl) to: (1) reconstruct the hydrology of the site over the last 7,000 years, (2) determine how hydrological changes affected testate amoebae diversity and (3) infer past trophic state shifts. The study site is located in one of the driest valleys of the Alps and is thus very sensitive to hydrological changes. Our study revealed that the water table depth increased (dry conditions) between 5,800 and 4,000 cal year BP. This triggered establishment of a Sphagnum-type peat and acidic conditions from 5,700 to 4,000 cal year BP. These processes were independent of ongoing transformations of the terrestrial vegetation and soil in the catchment area. After 1,690 cal year BP, the depth to the water table decreased (wetter conditions) and a minerotrophic fen developed. At the same time, the diversity of testate amoebae increased, probably as a result of deforestation that supported the expansion of grassland. Climate and land use were apparently more important factors controlling the lake hydrology than were changes in vegetation and soil in the catchment. Testate amoebae diversity was linked to land cover. Changes in pH were controlled indirectly by external forcing (climate), but more directly by fluctuations in the level of the water table (internal forcing) and autogenous expansion of Sphagnum.     

Testate amoeba analysis of lake sediments: impact of filter size and total count on estimates of density,species richness and assemblage structure

Testate amoebae are informative about palaeoecological conditions, but the methods generally used for their analyses in lake sediments differ from those used for their analyses in peats, making comparisons difficult. This study examines how filter mesh size and total number of individuals counted affect species richness, Shannon diversity, equitability, density and assemblage structure. We analysed the complete testate amoeba contents of six sediment samples from Lake Lautrey, France. The abundance of testate amoebae was high (1,403–10,870 shells cm⁻³), and species smaller than 63 μm in both length and width represented up to 89% of total abundance and 43% of species richness. A simulation showed that using 47- or 63-μm mesh-size filters reduced inter-sample differences and changed the patterns of abundance, species richness and assemblage structure, causing loss of information and leading to potential erroneous palaeoecological interpretation. Rarefaction analyses suggest that although 170 shells are sufficient to assess the general structure of assemblages, such small sample sizes can underestimate species richness by overlooking taxa with relative abundances <4%. Total counts of 400 shells yield better estimates of assemblage structure and recover at least 50% of total species richness, although species with absolute frequencies below 2% may still be missed. Higher counts are required to obtain reliable estimates of species richness and assemblage structure in samples that have high testate amoeba densities but are dominated by a few small taxa. Further studies should determine the bioindicator value and functional roles of small and/or rare species in lakes and thus to what extent overlooking them affects palaeoecological interpretations.     

Holocene fossil Habrotrocha angusticollis (Bdelloidea: Rotifera) in North America

Holocene fossil shells of the rotifer, Habrotrocha angusticollus (Bdelloidea: Rotifera) is reported from two peatlands in northern Ontario, Canada. H. angusticollis is a common component of the microfauna in Sphagnum peatlands and other wet mossy habitats. Our knowledge of the distribution and ecology of H. angusticollis is limited and this paper is the first detailed report of the shells as fossils in North America. Fossil shells of H. angusticollis may prove to be a valuable paleoecological indicator in peat deposits once Quaternary paleoecologists learn to recognize them and neoecologists extend their surveys to peatlands.     

How many is enough? Determining optimal count totals for ecological and palaeoecological studies of testate amoebae

Testate amoebae are increasingly used in ecological and palaeoecological studies of wetlands. To characterise the amoeba community a certain number of individuals need to be counted under the microscope. To date, most studies have aimed for 150 individuals, but that sample size is not based on adequate evidence. When testate amoeba concentrations are low, it can be difficult or impossible to reach this total. The impacts of lower count totals have never been seriously scrutinised. We investigated the impact of count size on number of taxa identified, quantitative inferences of environmental variables and the strength of the links between amoebae and environmental data in the context of predicting depth to water table. Low counts were simulated by random selection of individuals from four existing datasets. Results show progressively diminishing returns by all criteria as count size increases from low numbers to counts of 150. A higher count is required to identify all taxa than to adequately characterise the community for transfer function inference. We suggest that in most cases, it will be a more efficient use of time to count a greater number of samples to a lower count. While a count of 50 individuals may be sufficient for some samples from some sites we recommend that counts of 100 individuals should be sufficient for most samples. Counts need only be increased to 150 or more where the aim is to identify relatively minor, but still potentially ecologically relevant community changes. This approach will help reduce lack of replication and low resolution, which are common limitations in testate amoeba-based palaeoecological and ecological studies.     

Reconstructing hydrological variability from testate amoebae analysis in Carpathian peatlands

Peatlands offer the potential for high resolution records of water balance over Holocene timescales, yet this potential is under-exploited in many areas of the world. Within Europe, peatlands are mostly confined to areas north of 55° N, but several areas of southern and eastern Europe contain small peatlands which may be suitable for palaeoclimatic reconstruction. In this paper we test the potential of peatlands in the Carpathian region for deriving quantified estimates of water table changes using testate amoebae analysis. A training set for palaeohydrological reconstruction from testate amoebae assemblages was obtained by collecting surface samples from 13 peatlands, including 9 from Hungary and 4 from Transylvania (Romania). Using a simple measure of mean annual water tables estimated from staining of PVC tape, we found that some peatlands were heavily influenced by runoff and groundwater, and were therefore not suitable as modern analogues of ombrotrophic climatically sensitive sites. The relationship between the testate amoebae assemblages in the modern samples and the environmental variables was explored using CCA. The CCA biplot showed that the most important variables are depth to water table and moisture content, confirming that hydrology is a key control on taxon distribution. pH was a secondary gradient. A transfer function for % moisture and depth to water table was established and applied to fossil assemblages from a sequence from Fenyves-tető, Transylvania, Romania. The reconstructed water table shows a number of variations which have parallels with other palaeoclimatic records from Europe and the North Atlantic prominent phases of higher water tables are associated with the periods 8000–8300 cal BP, 3000–2500 cal BP and after 600 cal BP. We suggest that these were periods of particular intensification of westerly airflow which affected eastern Europe as well as western and central Europe.     

Environmental controls on peatland testate amoebae (Protozoa: Rhizopoda) in the North of Ireland: Implications for Holocene palaeoclimate studies

The environmental controls on modern peatland testate amoebae (Protozoa: Rhizopoda) in the North of Ireland were investigated to assess the potential for Holocene palaeoclimate research within this region. Canonical Correspondence Analysis (CCA) revealed that hydrological factors (water table depth and moisture content) are the most important abiotic controls on organism distribution. A series of partial CCAs showed that water table depth explains 15.8% and moisture content explains 5.5% of the total variance. Monte-Carlo permutation tests showed that the results are highly significant (p < 0.002; p < 0.040 respectively). Transfer functions were generated for water table depth using weighted averaging tolerance downweighted (WA-Tol) regression and for moisture content using weighted averaging partial least squares regression (WA-PLS). The performance of the models was assessed using leave-one-out cross-validation (jacknifing). After removal of outlier samples, the improved transfer functions were found to perform well with an r _jack² and root mean square error of prediction_jack of 0.83, 4.99 cm for water table depth and 0.76, 4.60% for moisture content respectively. The water table transfer function was applied to a fossil peat sequence from this region and reconstruction errors were generated by 1,000 bootstrap cycles. The water table reconstruction was also carried out using an established pan-European transfer function and was found to be similar to that based on the North of Ireland dataset. This demonstrates the persistent and comparable control of hydrological variables on the distribution of testate amoebae taxa across Europe and implies that regional training sets can suffice as long as no-analogue situations are not encountered.

Paleolimnological analysis of Ullswater using testate amoebae

Tests of testate amoebae extracted from samples of bottom sediments from 33 tarns in the English Lake District reveal a relationship between their distribution and physical-chemical parameters of the tarn waters.Nebela and several species ofDifflugia appear to prefer more acidic conditions, i.e., pH less than 6.2, while others such asCentropyxis, Lesquereusia and some species ofCyclopyxis andDifflugia are more common in lakes with pH's above that value.Using these data, and inferring rates of sedimentation from the densities of tests found in a 6-m core, a paleolimnological history for the past 11 000 years is presented for Ullswater (English Lake District). The record of testate amoebae, beginning shortly after deglaciation, depicts an uneven increase in acidity and a history of episodes of rapid and slow deposition that correlate reasonably well with paleoclimatological changes and anthropogenic alterations in the catchment.     

Trace-element and stable-isotope geochemistry of non-marine ostracod shells in Quaternary palaeoenvironmental reconstruction

Ostracods are small bivalved aquatic crustancean. They secrete shells of low-Mg calcite that are often preserved in lake sediments. Recent work has shown that the uptake of trace elements (especially Mg and Sr) into the shell may be a function of the salinity and temperature of the host water. Furthermore, ostracod shells are a source of carbonate for stable-isotope analysis. This paper reviews the application of ostracod shell chemistry to Quaternary palaeolimnology. Although such work has revealed the excellent potential of these techniques to provide quantitative palaeolimnological reconstructions, a number of problems have also emerged. These problems relate to (1) methods used for extraction of ostracod shells from sediment and their subsequent cleaning (2) post-mortem diagenesis and alteration of the shell (3) complications with the calcification mechanism (4) spatial and temporal variability in shell composition (5) the ecological tolerances of individual species and (6) the relationships between shell chemistry and palaeohydrology. To some extent, these problems are an inevitable outcome of the diversity of lacustrine systems: they may be overcome by developing a thorough understanding of the physiology, life-cycle and ecology of the species concerned, together with the modern limnology of the study site. Overall, these techniques have excellent potential in Quaternary palaeolimnology, especially when used with other palaeoenvironmental indicators.     

Multi-proxy paleoenvironmental record of colonial land-use change in the lower Rideau Canal system (Colonel By Lake), Ontario,Canada

The construction of the Rideau Canal was one of the greatest engineering accomplishments of the nineteenth century, creating a navigable waterway linking the Ottawa River with Lake Ontario. Colonel By Lake, located at the southern end of the canal near Kingston Mills, was created by the damming of the lower Cataraqui River. The canal flooding in 1831 raised water levels by almost 8 m, inundating former wetlands and lowland areas. European settlement in the pre-canal-era (ca. 1780s) was associated with widespread deforestation and limited flooding of wetlands by construction of mill dams. A detailed sediment coring program was conducted in Colonel By Lake to reconstruct the pre-canal environment and to document water level and land-use changes associated with European settlement and canal construction. The paleoenvironmental record was obtained through analysis of multiple environmental indicators including sediment facies, particle size, magnetic susceptibility and downcore changes in testate amoebae (thecamoebian) diversity. The core lithostratigraphy consists of organic-rich muds overlying peaty gyttja and a lowermost unit of fine to coarse silts. The canal flooding surface (ca. 1831) is clearly defined by a shift to finer grain sizes and increased magnetic susceptibility within the upper 40–60 cm. The shift is associated with an overall increase in thecamoebian abundance and diversity, and high numbers of Difflugia oblonga and Cucurbitella tricuspis that indicate a shift to a deeper and more eutrophic environment. In contrast, the pre-canal environment has lower thecamoebian abundance with assemblages characteristic of marsh environments (Centropyxis constricta, Centropyxis aculeata). The onset of canal flooding (ca. 1790s) is identified by an increase in Pontigulasia compressa (~50 cm), recording a higher water flow rate. The study shows that a multi-proxy paleoenvironmental approach can clearly define different environmental changes due to land-use changes during colonisation and canal-era construction activities.     

Evaluation of ostracod-based palaeoenvironmental reconstruction with instrumental data from the arid Faiyum Depression,Egypt

The utility of ostracod-based palaeoenvironmental reconstruction was evaluated using instrumental data for Lake Qarun, Egypt. The euryhaline ostracod Cyprideis torosa was the only species found in the lake’s recent sediment record. This species is known to tolerate salinity levels and water solute compositions that may prevent colonisation by other species. Oxygen and carbon isotope ratios of ostracod carbonate from lake sediments covary with changes in instrumental values for lake level and salinity for the period 1890–1974. δ¹³C-values correlate negatively with lake water salinity (r ² = 0.87) and δ¹⁸O-values correlate negatively with measured lake level changes (r ² = 0.41). Other ostracod proxy data provide qualitative information on lake level trends. Fossil assemblage data (juvenile/adult and valve/carapace ratios and valve preservation) provide information on wave energy. Ecophenotypic variation of C. torosa valves provided some useful palaeolimnological information. Sr/Ca and Mg/Ca ratios in ostracods were not found to reflect water composition, due to the uncoupling of these ratios with salinity in Lake Qarun. Overall, our results highlight the need to calibrate ostracod proxy data in modern systems prior to their use for palaeoenvironmental reconstruction.     

Bias of ostracod stable isotope data caused by drying of sieve residues from water

Stable isotope analysis of ostracod shells is used routinely for palaeoenvironmental studies of ostracod-bearing records. Sample treatment usually involves the disaggregation of sediments and sieving; before the sieving residues were washed with water onto petri dishes and oven-dried. In our study, we compared δ¹⁸O and δ¹³C values of shells that were oven-dried from water and from ethanol alternatively. Large isotopic differences of up to 3‰ were determined for δ¹⁸O values, whereas differences in δ¹³C values were less pronounced with differences of up to 1.6‰. Stable isotope values of shells dried from water were lower for both oxygen and carbon as a result of calcite crystals precipitated on the shell surfaces during the drying process. Therefore, ostracod shells for stable isotope analysis should not be prepared by drying from water. Instead, shells should be dried from ethanol to obtain reliable stable isotope data; likewise freeze-drying is expected to provide trustworthy results.     

Molecular fingerprinting of wetland organic matter using pyrolysis-GC/MS: an example from the southern Cape coastline of South Africa

Pyrolysis–gas chromatography mass spectrometry (py-GC/MS) allows the characterisation of complex macromolecular organic matter. In lakes and wetlands this can potentially be used to assess the preservation/diagenesis and provenance of sediment organic matter. It can complement palaeoenvironmental investigations utilising ‘bulk’ sediment variables such as total organic carbon (TOC) and TOC/total nitrogen ratios. We applied py-GC/MS analyses to a ~32,000-year sediment record from the southern Cape coastline of South Africa. We used the results to evaluate the sources and extent of degradation of organic matter in this semi-arid environment. Marked down-core changes in the relative abundance of multiple pyrolysis products were observed. Correspondence analysis revealed that the major driver of this down-core variability in OM composition was selective preservation/degradation. Samples comprising highly degraded OM are primarily confined to the lower half of the core, older than ~12,000 years, and are characterised by suites of low-molecular-weight aromatic pyrolysis products. Samples rich in organic matter, e.g. surface sediments, are characterised by products derived from fresh emergent or terrestrial vegetation, which include lignin monomers, plant-derived fatty acids and long-chain n-alkanes. Pyrolysates from the late glacial-early Holocene period, approximately mid-way down the core are characterised by distinct suites of long-chain n-alkene/n-alkane doublets, which may reflect the selective preservation of recalcitrant aliphatic macromolecules and/or enhanced inputs of the algal macromolecule algaenan/polymerised algal lipids. Increased TOC, lower δ¹³C and increased abundance of more labile lignin and fatty acid products at the same depths suggest this period was associated with increased lake primary productivity and enhanced inputs of terrestrial OM. TOC is the only ‘bulk’ parameter correlated with the correspondence analysis axes extracted from the py-GC/MS data. Distinct fluctuations in TOC/total nitrogen ratio are not explained by variation in organo-nitrogen pyrolysis products. Notwithstanding, the study suggests that py-GC/MS has potential to complement palaeolimnological investigations, particularly in regions such as southern Africa, where other paleoenvironmental proxy variables in sediments may be lacking or equivocal.     

Rates of peat accumulation over the past 200 years in fiveSphagnum-dominated peatlands in the United States

Using²¹⁰Pb-dating of peat cores, corroborated by pollen and acid-insoluble ash approaches, rates of vertical height growth, dry mass accumulation, and organic matter accumulation were determined for fiveSphagnum-dominated peatland sites (one in Minnesota, one in Pennsylvania, one on the Maryland/West Virginia border, two in West Virginia), spanning a mean annual temperature range of 4.5 °C and differing in total annual precipitation by a factor of almost 2. Site differences in rates of vertical height growth and dry mass accumulation were documented, but both within-core and between-site differences in bulk density and ash concentrations of peat confound efforts to relate vertical height growth and dry mass accumulation to net organic matter accumulation. Taking bulk densities and ash concentrations into account, rates of net organic matter accumulation over the past 150–200 years were strikingly similar at four of the five sites, an unexpected result given the general trend that with decreasing latitude, peat deposits become older, thinner, and more highly decomposed. More comprehensive studies are needed in which net organic matter accumulation is determined at several locations within a single peatland, at several peatlands within a particular geographic/climatic region, and at peatland sites in different geographic/climatic regions. If additional studies confirm that recent (past 200 years) net organic matter accumulation is relatively insensitive to broad-scale regional climatic differences, boreal and subarctic peatlands may continue to function as a net sink for atmospheric CO₂ and a net source of atmospheric CH₄ with no change in rates of net organic matter accumulation, even under predicted scenarios of global climate change.This publication is the third paper in a series of papers presented at the session on Past Climatic Change and the Development of Peatlands at the ASLO and SWS Meetings in Edmonton, Canada, May 30–June 3, 1993. Dr P. Kuhry and Dr S. C. Zoltai are serving as Guest Editors.     

First subfossil records of Daphnia headshields and shells (Anomopoda,Daphniidae) about 10 000 years old from northernmost Greenland,plus Alona guttata (Chydoridae)

Silty pond sediments from Wulff Land in northernmost Greenland, radiocarbon dated 10480 BP, yielded many headshields, shells, and ephippia of Daphnia pulex, and headshields, shells, ephippia, and one postabdomen of Alona guttata. This is the first documentation of recognizable headshields and shells of Daphnia in the fossil record.     

The use of egg shells to infer the historical presence of copepods in alpine lakes

Copepods (Class Crustacea, Order Copepoda) are rarely included in paleoecological studies of lakes because they lack long-lasting exoskeletal remains. We describe the remains of eggs (egg shells) from Hesperodiaptomus copepods that are well preserved and abundant in alpine lake sediments. We demonstrate that the egg shells are the remains of Hesperodiaptomus eggs based on (i) the similar size and morphology of egg shells collected from sediments and those produced from the hatching of eggs obtained from laboratory-maintained Hesperodiaptomus, and (ii) the finding that diapausing eggs collected from lake sediments and hatched in the laboratory produced copepod nauplii that were morphologically indistinguishable from those hatched from eggs produced by laboratory-maintained Hesperodiaptomus. Egg shells were approximately two orders of magnitude more abundant in sediment cores than were viable diapausing eggs, making egg shells superior to viable diapausing eggs for quantifying the historical presence and abundance of Hesperodiaptomus. These results have important implications for alpine lake restoration as egg shells can be used to identify lakes in which Hesperodiaptomus was eliminated by fish introductions but has failed to return after fish eradication, lakes in which the pre-disturbance conditions are likely to be restored only by reintroductions of this important taxon.     

Quaternary and extant euryhaline Lamprothamnium Groves (Charales) from Australia: Gyrogonite morphology and paleolimnological significance

Charophytes are very common in Australian modern and Quaternary waterbodies, and are quite commonly incorrectly reported as “Chara” sp. or Lamprothamnium papulosum (Wallroth) Groves. This paper is the first attempt at the identification of the widespread euryhaline genus Lamprothamnium in Australia, and its use as a paleoenvironmental indicator. Lamprothamnium is distributed worldwide in all continents, except north and central America. The Australian environment, characterized by increasing aridity during the last 500 ka, has an abundance of saline lakes. We sampled 30 modern lakes and identified extant Lamprothamnium macropogon (A. Braun) Ophel and Lamprothamnium succinctum (A. Braun in Ascherson) Wood. Fossil gyrogonites, from lacustrine sediments ∼65 ka old from Madigan Gulf, Lake Eyre, were identified as Lamprothamnium williamsii sp. nov. We applied statistical analysis (analysis of variance, ANOVA) to the morphometry of the gyrogonites from one fossil and three living Lamprothamnium populations. The ANOVA test suggests all the populations are different, including two separate populations of extant L. macropogon, interpreted in this case as the expression of ecophenotypic variability. Lamprothamnium is a useful paleoenvironmental indicator because it indicates a non-marine environment with varying salinity ranging from fresh (usually 2–3 g l⁻¹) to 70 g l⁻¹, and water bodies holding water for at least 70 consecutive days. Collectively, these parameters provide important information in the study of ephemeral habitats.     

高原湖泊中萝卜螺属壳体研究现状及展望

湖泊的古水文及古水化学重建是湖泊研究领域最具挑战性的工作之一。在湖泊、河湖相及高湖面沉积物中,萝卜螺属壳体化石广泛分布;而且现生萝卜螺属亦广泛地分布于全球的湖泊及河流。这些生物碳酸盐(文石)壳体成为一种潜在的和高分辨率的环境信息记录载体。近年来,萝卜螺属的生境及其壳体的稳定碳氧同位素和元素已经逐步被用于了解青藏高原及其他地区的古水文、古水化学和古气候的信息。然而,在萝卜螺属壳体如何记录其宿生水体的古水文、古水化学等信息,以及如何基于萝卜螺属壳体化石重建古环境等方面,仍有许多科学问题有待探索。本文在前人研究的基础上,侧重在作为环境信息载体的萝卜螺属的分类体系、生境研究及其应用和壳体指标(δ¹³C_shell,δ¹⁸O_shell,⁸⁷Sr/⁸⁶Sr,Sr/Ca和Mg/Ca)特征及其在环境重建中的应用等方面进行总结和展望。