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Zooarchaeology is the study of animal remains (bone, shell, antler, and other organic tissues) from archaeological sites, which can provide conservation biologists with data on human–environmental interactions with greater time depth than historical records. Such data are of interest because they can be used to study whether or not contemporary animal communities (in this case of freshwater mussels) have changed in terms of species composition or range as a result of human-induced changes to habitat, which is essential for determining a species’ conservation status and formulating actions to protect remaining populations. This study considers whether or not the taxonomic composition of the freshwater mussel community from the Leon River in central Texas differs between the late Holocene and today. Specifically, we analyzed two zooarchaeological assemblages and compared those results with recent surveys conducted within the Leon River. Three species proposed for listing under the Endangered Species Act are found in the zooarchaeological record, of which two are now extirpated from the river basin (Truncilla macrodon and Fusconaia mitchelli). The results of this study provide an example of how zooarchaeological data can be used to evaluate mussel community change through time and provide evidence of range curtailment for threatened mussel species. [ABSTRACT FROM AUTHOR]

Zooarchaeological freshwater mussel remains provide information about past environments, faunal communities, and human behaviors. However, one challenge of using archaeological assemblages of animal remains is differential preservation such that bones and shells of some taxa are more vulnerable to processes that destroy or remove them from the record over time. Thus, remains of some species of freshwater mussels may be underrepresented in terms of presence/absence data as well as abundance compared to the life or death assemblages. Evaluating the representativeness of assemblages before using such data to answer zooarchaeological and paleozoological research questions is common practice in archaeology, particularly for vertebrate remains. However, little research has focused on evaluating representativeness for molluscan assemblages. In this paper, three processes that potentially influence archaeomalacological data are addressed: mussel life history strategies, shell identifiability, and shell robusticity. Expectations about taxonomic abundances in unionid zooarchaeological assemblages are framed and assessed using two datasets from sites from the Leon River in central Texas. As expected, shell robusticity and identifiability influence zooarchaeological abundance data; differences in life history strategy can be used to interpret past stream environments. The expectations derived in this paper can be used as interpretive tools for understanding factors that influence archaeomalacological taxonomic abundance data. [ABSTRACT FROM AUTHOR]

Abstract: Expectations for survival of vertebrate remains have been well developed and intensely studied in the zooarchaeological taphonomic literature. Taphonomic studies of shellfish remains focus on marine species and on variables relevant to remains from paleontological contexts (e.g., fossil marine beds). In this paper we develop a conceptual framework from which to derive expectations concerning the preservation of freshwater mussel remains focusing on two parameters, shell microstructure and shell shape. Shell size does not influence survivorship. Our model is validated through application to late Holocene zooarchaeological mussel assemblages from north Texas. Taphonomically robust species are important regarding zooarchaeological and biogeographic interpretations based on mussel paleofaunas, and fragile species are important indicators of whether or not an assemblage is well preserved. [Copyright &y& Elsevier]

Abstract: Biometry is useful for a suite of analyses relevant to zooarchaeology, which include analysis of mortality profiles, taphonomy, paleoecology, among other purposes. Here, size-age prediction models are developed for 10 freshwater mussel species found in north Texas to develop a method for studying paleoenvironmental conditions. Shell length is often used to evaluate the structures of modern mussel populations, but its use on paleozoological specimens is not feasible because complete shells rarely preserve. Instead, pallial line-to-lateral teeth length (PLL) and pseudocardinal teeth-to-pallial line length (PSP) are evaluated as proxy measures for shell length. Linear regression models based on PLL and PSP using modern mussels demonstrate that they are accurate proxies of shell length for multiple species from a variety of habitats. In addition, ontogenetic-age structures for a modern sample and for two late Holocene assemblages from north Texas are developed using PLL and PSP. These techniques are useful tools for evaluating past ecological conditions of freshwater mussel populations when large samples are available for study, which expands analytical potential of zooarchaeological studies of prehistoric unionid remains. [Copyright &y& Elsevier]

The impoundment of running waters is a threat to freshwater mussels and has only been cursorily examined in Texas. To address this, we evaluate mussel assemblage structure in the Sabine River downstream of a flood control and hydropower reservoir. We use the serial discontinuity concept (SDC) and the Life History Continuum model (LHCM) to explain relationships between stream position (i.e., downstream distance from either dam) and mussel species richness, catch-per-unit effort (CPUE), and life history strategy. Using 90th, 85th, and 80th quantile regression models, we observed that mussel species richness and abundance were reduced for stream segments located near Lake Tawakoni and Toledo Bend Reservoir and that these reductions decreased with distance from either reservoir. We also observed significant shifts in life history composition of mussel assemblages depending on stream position from either dam. Opportunistic strategists were more abundant in reaches located immediately downstream of Lake Tawakoni and Toledo Bend Reservoir whereas periodic and equilibrium strategists were most abundant in reaches located at intermediate distances from either reservoir. Findings from this study confirm the negative impact large impoundments have on downstream mussel populations and demonstrate the value of using the SDC and LHCM for evaluating mussel response to river impoundment. [ABSTRACT FROM AUTHOR]