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Historically, 23 freshwater mussel species have been documented from the Buffalo National River (BNR), a 246 km, free-flowing river in northern Arkansas. The potential threats to BNR include land use/land cover changes, eutrophication, recreation, physical habitat changes, and various climate change-related effects. Twelve quantitative mussel bed sites were established and then sampled using a stratified random sampling protocol to evaluate the long-term changes between 2006 and 2020–2021 in population and assemblage characteristics. We compared (1) overall mussel bed persistence, sampling confidence levels and study-wide relative abundances, and compared species' size and size-frequency distributions; (2) 10 overall site assemblage variables using paired t-tests; (3) site-level mean density, richness, and diversity indices using pair-wise Mann–Whitney U statistics; and (4) assemblage composition using Non-Metric Multidimensional Scaling. The major findings included the following: (1) sampling efforts based on a targeted 80% confidence level appears relatively robust, (2) BNR mussel assemblage composition and structure were relatively stable (however, small mussel bed persistence is a concern), (3) 7 of 23 sites were outliers based on freshwater mussel composition and habitat characteristics, and (4) assemblage composition changed with three species declining (Actinonaias ligamentina, Lasmigona costata, and Ptychobranchus occidentalis) and four species increasing (Cambarunio hesperus, Cyclonaias tuberculata, Eurynia dilatata, and Venustaconcha pleasii) between monitoring events. [ABSTRACT FROM AUTHOR]

Over the last 30 years, relocation of freshwater mussels has been used as a conservation strategy for potential impacts from bridge construction and dredging operations. Improved methods have effectively increased relocated mussel survivorship rates of target species from ~ 50% to ~ 90% under ideal circumstances. Success to date is largely based upon survivorship rates without consideration of relocation activity effects upon fitness and behavioral traits of mussels. In 2003, the Federal Highway Administration (FHWA) and Arkansas Highway and Transportation Department (AHTD) funded research to: 1) determine the success of mussel relocation efforts associated with highway construction projects by investigating survivorship, movements, mortality, fitness (as indicated by condition factor), and fecundity of relocated and non-relocated adults and sub-adults, 2) determine success of mussel propagation efforts by investigating survivorship of juveniles returned to identified habitats and used for population enhancement (recruitment), and 3) determine impacts at highway construction sites by comparing pre- and post-construction mussel assemblage abundance and composition, sediment deposition downstream of the construction, and individual mussel fitness. This project seeks, in part, to use the data acquired in the formulation of a programmatic biological assessment/biological opinion streamlining initiative for P. capax that will be proposed to the U. S. Fish and Wildlife Service by the ATHD and FHWA. Biochemical composition (i.e. condition factor) and movement (i.e. displacement) were monitored for two species of freshwater mussels subjected to relocation activity, the federally endangered P. capax and a species with a different life history, Quadrula quadrula and compared with control (i.e. non relocated) populations. Trends were identified in condition factor, through repeated measures ANOVA, associated with short (glycogen), moderate (lipid), and long term energy stores (proteins, RNA:DNA ratios) sampled pre- and post-relocation. Behavioral trends (i.e. displacement) between native and relocated populations of the two species were measured in both short-term (weeks) and long-term (quarterly) intervals. Results pertaining to population enhancement strategies, specifically field methodologies used for in-situ rearing of juvenile P. capax along with growth and survival rates of field reared and lab reared individuals are presented. T

Relocation of freshwater mussel aggregates has been used as a mitigation strategy for nearly 30 years. Methodologies for relocation have been studied showing that identification of appropriate habitat characteristics are among the most important aspects when selecting a viable relocation site. Though relocation methodologies have been studied, little is known about the influence on behavioral patterns following relocation. This project is aimed at addressing information gaps regarding post-relocation monitoring activities which will be incorporated into the biological assessment of a proposed permit streamlining initiative between the US Fish and Wildlife Service, Federal Highway Administration, and Arkansas Transportation and Highway Department. The focus of this initiative is the fat pocketbook, Potamilus capax (Mollusca: Unionidae), which was designated as “Endangered” in June 1976 by the USFWS in the entire range of the species. The present general distribution of P. capax has been reported from the upper Mississippi River on the borders of Minnesota, Wisconsin, Iowa, Illinois, and Missouri, the Ohio River System on the borders of Indiana, Illinois, and Kentucky, especially its tributary the Wabash River in Indiana and Illinois, the White River of Missouri and Arkansas, and the St. Francis River system in Arkansas. These systems typify mid-western Mississippi River drainages with areas of slow moving water and substrate ranging from shifting sand and gravel to sand, silt, and clay substrates, suitable habitat for P. capax. This species is further characterized as being a long-term breeder with fertilization occurring in spring and gravid females present from June to October and uses the freshwater drum (Aplodinotus grunnies) as its host. Though P. capax was at one time present in many of these systems, historical accounts indicate that it was never a predominate species within the assemblage. Though mussels, in general are considered relatively stationary, many species, including P. capax, have adopted a mobility trait which may yield inaccurate monitoring results. The objectives of this study are to 1) analyze seasonal movement patterns of resident and relocated individuals and 2) relate movement to sediment characteristics at the relocation site. We hypothesize that relocated P. capax will show a greater displacement than resident P. capax. We also expect this displacement to be associated with habitat selection and/or reproduction. We have examined movement patterns of resident and relocated P. capax within an agricultural drainage system of the Saint Francis River system of Arkansas and Missouri. Two treatment groups have been monitored with different monitoring intervals. The first group was fitted with radio transmitters and was monitored at a maximum of one month intervals from October, 2005 to January, 2006 and July, 2006 to November, 2006 using radio telemetry. The second treatment group was monitored using mark and recapture (shell etch) techniques and positions recorded once quarterly from May, 2005 through March, 2007. Substrate composition (sand, silt, and clay), water depth, and water velocity were determined using 65 meter bank to bank transects at 10 meter intervals for the length of the 200 meter relocation reach. Substrate, depth and velocity were interpolated using krieging and spatial data analysis in GIS. Initial movement results of the quarterly sampling show native individuals (n = 41) with a displacement range between 0.88 m and 151.92 m while relocated animals (n = 13) have displacement range between 3.44 m and 18.87 m. At the alpha = 0.10, this difference is significant (p = 0.09). Data for the transmitter treatment group are still being collected, but preliminary indications from the October, 2005, to January, 2006, monitoring period contradict this trend. In this time period, resident individuals (n = 11) had a range of total displacement from 0.60 m to 9.12 m while relocated individuals (n = 10) had a range of total displacement from 2.67 m to 14.90 m with a significantly greater average range as well (p

The fat pocketbook, Potamilus capax (Mollusca: Unionidae), was designated as “Endangered” in June 1976 by the USFWS in the entire range of the species. The present general distribution of P. capax has been reported from the upper Mississippi River on the boarders of Minnesota, Wisconsin, Iowa, Illinois, and Missouri, the Ohio River System on the borders of Indiana, Illinois, and Kentucky, especially its tributary the Wabash River in Indiana and Illinois, the White River of Missouri and Arkansas, and the St. Francis River system in Arkansas. Relocation of freshwater mussels prior to large-scale bridge construction, repair, or replacement has been broadly utilized for conventional management of construction impact. The success of that practice related to long-term viability of relocated specimens, however, has not been fully validated. This research was jointly funded by the Federal Highway Administration (FHWA) and the Arkansas State Highway and Transportation Department (AHTD) in 2003 as an Environmental Streamlining Initiative to provide more information regarding the likelihood of specific impacts to mussels attributed to sediment plumes downstream of highway construction activities. The research proposes to support a programmatic Biological Opinion for P. capax, which will provide a protocol for highway projects that may impact the species. Relocation can then be assessed for its ability to minimize loss of endangered freshwater mussel species, and in particular, P. capax. The objectives of this project are: 1) to determine the success of relocation efforts for P. capax associated with highway construction projects by investigating survival, movements, mortality, fitness (as indicated by condition factor), and fecundity of relocated and non-relocated adults and sub-adults, 2) to determine the success of propagation efforts resulting from highway construction projects by investigating the survival of juveniles returned to identified habitats and used for population enhancement (recruitment), and 3) to determine relative impacts at highway construction sites to P. capax and associated mussel assemblage by comparing pre- and post-construction abundance and composition, sediment deposition downstream of the construction, and individual mussel fitness. Data acquired will be submitted to the Fish and Wildlife Service as documentation of the likelihood of impacts for the programmatic Biological Assessment. These data will be utilized by the Fish and Wildlife Service in crafting the programmatic Biological Opinion. Initial observations have indicated relocated P. capax and Quadrula quadrula exhibit very different movement patterns post-relocation. For example, many resident and relocated P. capax are capable of moving 10 miles or more over a 12-hour period, while resident and relocated Q. quadrula have remained stationary up to four months after relocation. A continuation of this pattern may reveal that species-specific life history characteristics potentially influence movement patterns following relocation. Fatalities have occurred in the resident, relocated, and propagation animals of both species, though time to and cause of fatality are not known.

Extrinsic and intrinsic forces combined shape the population structure of every species differently. Freshwater mussels are obligate parasites to a host fish during a juvenile stage (glochidia). Elliptio dilatata ( ED) and Actinonaias ligamentina ( AL) are co-occurring freshwater mussel taxa with similar North American distribution and share some potential host fish. Using mitochondrial DNA, we determined the genotypes of 190 + individuals from collection sites in at least two tributaries in the Lake Erie and Ohio River watersheds, along with the Ouachita and Strawberry rivers in the southeast. Both species had followed a stepping-stone model of dispersal, with greater pairwise genetic structure among collection sites of ED. Also, phylogeographical analysis for ED found significant geographical structuring of haplotype diversity. Overall, within-population variation increased significantly from north to south, with low genetic diversity in the Strawberry River. We calculated significant among-population structure for both species ( ED: ΦST = 0.62, P<0.001; AL: ΦST = 0.16, P<0.001). Genetic analysis identified the Ouachita River as an area of significant reproductive isolation for both species. Results for AL indicated dispersal into northern areas from two genetically distinct glacial refugia, where results for ED indicated dispersal followed by low gene flow in northern areas. The conservation strategies for mussels that co-occur in the same ‘bed’ could be species specific. Species such as ED have management units on the population scale, where AL has a more homogeneous genetic structure across its range. [ABSTRACT FROM AUTHOR]

Freshwater bivalves in the superfamily Unionoidea possess distinct male (M)- and female (F)-transmitted mitochondrial DNA (mtDNA). The former evolves independently of and at a significantly faster rate than the latter. Thus, population genetic and phylogenetic analyses of M sequences facilitate the generation of independent estimates of genetic variation and evolutionary relationships which are often more robust than those provided by analyses of F sequences alone. However, M mtDNA's rapid substitution rate often renders polymerase chain reaction (PCR) amplification difficult with ‘universal’ primers. Herein, we report on three pairs of PCR primers that consistently amplify the hypervariable M COII-COI gene junction region in 25 bivalve genera (Unionoidea: Ambleminae). [ABSTRACT FROM AUTHOR]