Chris B. Eads

Environmental occurrence and reproductive effects of the pharmaceutical fluoxetine in native freshwater mussels

The present study measured the occurrence, distribution, and bioaccumulation of fluoxetine in samples of water, polar organic chemical integrative sampler (POCIS), sediment, and caged freshwater mussels at stream sites near a municipal wastewater treatment facility effluent discharge. We assessed the relation of the environmental concentrations to reproductive endpoints in mussels in acute laboratory tests. Concentrations of fluoxetine in water and POCIS samples were similar (<20% difference) within each site and were greatest in the effluent channel (104-119 ng/L), and decreased at 50 m and 100 m downstream. Likewise, concentrations of fluoxetine in sediment and mussel (Elliptio complanata) tissue were greatest in the effluent channel (17.4 ng/g wet wt for sediment and 79.1 ng/g wet wt for mussels). In 96-h lab tests, fluoxetine significantly induced parturition of nonviable larvae from female E. complanata exposed to 300 microg/L (p = 0.0118) and 3,000 microg/L (p < 0.0001) compared to controls. Fluoxetine exposure at 300 microg/L (p = 0.0075) and 3,000 microg/L (p = 0.0001) also resulted in stimulation of lure display behavior in female Lampsilis fasciola and Lampsilis cardium, respectively. In male E. complanata, 3,000 microg fluoxetine/L significantly induced release of spermatozeugmata during a 48-h exposure. These results suggest that fluoxetine accumulates in mussel tissue and has the potential to disrupt several aspects of reproduction in freshwater mussels, a faunal group recognized as one of the most imperiled in the world. Despite the disparity between measured environmental concentrations of fluoxetine and effects concentrations in our short-term tests with these long-lived animals, additional tests are warranted to evaluate the effects of long-term exposure to environmentally relevant concentrations and critical lifestages (e.g., juveniles).

Acute and chronic toxicity of technical-grade pesticides to glochidia and juveniles of freshwater mussels (unionidae)

Chemical contaminants are among many potential factors involved in the decline of freshwater mussel populations in North America, and the effects of pesticides on early life stages of unionid mussels are largely unknown. The objective of this study was to determine the toxicity of technical-grade current-use pesticides to glochidia and juvenile life stages of freshwater mussels. We performed acute toxicity tests with glochidia (five species) and juveniles (two species) exposed to a suite of current-use pesticides including herbicides (atrazine and pendimethalin), insecticides (fipronil and permethrin), and a reference toxicant (NaCl). Because of limited availability of test organisms, not all species were tested with all pesticides. Toxicity tests with fungicides (chlorothalonil, propiconazole, and pyraclostrobin) were performed with one species (Lampsilis siliquoidea). Lampsilis siliquoidea glochidia and juveniles were highly sensitive to the fungicides tested but the technical-grade herbicides and insecticides, at concentrations approaching water solubility, were not acutely toxic to this or the other unionid species. In a 21-d chronic test with four-month-old juvenile L. siliquoidea, the 21-d median effective concentration (EC50) with atrazine was 4.3 mg/L and in atrazine treatments >or=3.8 mg/L mussel growth was significantly less than controls. The relatively high sensitivity of L. siliquoidea to chlorothalonil, propiconazole, and pyraclostrobin is similar to that reported for other aquatic organisms commonly used for toxicity testing. The relative risk associated with acute exposure of early life stages of mussels to technical-grade atrazine, pendimethalin, fipronil, and permethrin is likely low; however, survival and growth results with juvenile L. siliquoidea indicate that chronic exposure to high concentrations (>/=3.8 mg/L) of atrazine may have the potential to impact mussel populations and warrants further investigation.

Status and Life-history Aspects of Villosa constricta (Conrad 1838) (Notched Rainbow), in the Upper Neuse River Basin, North Carolina

Abstract We report the findings of stream-survey data, a length-at-age study, and host-fish determination for Villosa constricta (notched rainbow). Visual surveys were done for freshwater mussels at 44 bridge crossings in the upper Neuse River basin in North Carolina. Three surveyors, each searching a 1-m wide lane, covered a 600-m long stream reach at each site. All mussels found were ide.gified to species and measured, and females were checked for gravidity. Of the 24 sites where V. constricta occurred, the median number found was 3.5 (range = 1–54). We cut thin-sections of 71 individual shells collected from middens at 1 survey site and counted growth lines to determine mussel age. Shell ages ranged from 3 to 14 years. Lab trials determined that Etheostoma flabellare (fantail darter) served as a suitable host for this species.

Brooding Patterns in Three Freshwater Mussels of the Genus Elliptio in the Broad River in South Carolina

Abstract: We investigated brooding patterns and timing of reproduction in three species of freshwater mussels, Elliptio complanata (Lightfoot, 1786), Elliptio roanokensis (Lea, 1839), and Elliptio angustata (Lea, 1831) in the lower Broad River near Columbia, South Carolina. Through repeatedly marking and recapturing individuals from late March through late lune 2008, we determined that E. complanata and E. roanokensis can complete at least two broods during this season, and that E. angustata can complete at least three broods with very little time between broods. The lengths of brooding periods were difficult to estimate and subject to a wide margin of error. However, the brooding period was estimated to be 20 to 36 days in most broods of E. angustata, and could be as short as 18 days in E. roanokensis and 25 days in E. complanata. Mark and recapture of gravid mussels provided a much more detailed picture of brooding strategies than the collection and preservation of different individuals throughout the year.

Fish Hosts of the Carolina Heelsplitter (Lasmigona decorata), a Federally Endangered Freshwater Mussel (Bivalvia: Unionidae)

Abstract: Two laboratory trials were conducted to determine the required host fish for the Carolina heelsplitter (Lasmigona decorata (Lea, 1852)), an endangered freshwater mussel (Unionidae). The first trial used glochidia from a female collected from the Yadkin-Pee Dee River basin, and the second trial used the glochidia of an adult collected from the Catawba River basin. Two different techniques were utilized for glochidia extraction: flushing and serotonin-induced release. The first female tested (Yadkin-Pee Dee) packaged most of its glochidia attached to unfertilized eggs, and extraction of glochidia by flushing the marsupia with a syringe yielded few glochidia and caused extensive tearing of the gill tissue. In the second trial (Catawba) the female was immersed in 500 mg/L serotonin creatinine sulfate, and the glochidia were readily released without injury to the adult. Several species of minnows (Cyprinidae) from both basins served as hosts. Some sunfish species (Centrarchidae) supported transformation of a few juveniles, but differences in transformation success were observed between the two basins on these species.

Developing a conservation strategy to maximize persistence of an endangered freshwater mussel species while considering management effectiveness and cost

We used a structured decision-making process to develop conservation strategies to increase persistence of Dwarf Wedgemussel (Alasmidonta heterodon) in North Carolina, USA, while accounting for uncertainty in management effectiveness and considering costs. Alternative conservation strategies were portfolios of management actions that differed by location of management actions on the landscape. Objectives of the conservation strategy were to maximize species persistence, maintain genetic diversity, maximize public support, and minimize management costs. We compared 4 conservation strategies: 1) the ‘status quo’ strategy represented current management, 2) the ‘protect the best’ strategy focused on protecting the best populations in the Tar River basin, 3) the ‘expand the distribution’ strategy focused on management of extant populations and establishment of new populations in the Neuse River basin, and 4) the ‘hybrid’ strategy combined elements of each strategy to balance conservation in the Tar and Neuse River basins. A population model informed requirements for population management, and experts projected performance of alternative strategies over a 20-y period. The optimal strategy depended on the relative value placed on competing objectives, which can vary among stakeholders. The protect the best and hybrid strategies were optimal across a wide range of relative values with 2 exceptions: 1) if minimizing management cost was of overriding concern, then status quo was optimal, or 2) if maximizing population persistence in the Neuse River basin was emphasized, then expand the distribution strategy was optimal. The optimal strategy was robust to uncertainty in management effectiveness. Overall, the structured decision process can help identify the most promising strategies for endangered species conservation that maximize conservation benefit given the constraint of limited funding.

Fish Hosts of Four Freshwater Mussel Species in the Broad River, South Carolina

Abstract Freshwater mussel distributions are heavily reliant upon the range and movement of host fishes and are subject to range restrictions when fish migration is blocked. The Columbia Dam on the Broad River in Columbia, SC, has been a barrier to the migration of anadromous species and other fish in the river since 1824. As a result, 5 freshwater mussel species are restricted to reaches of the river downstream of the dam. In 2006, a fish passage was created to facilitate fish movement between stream reaches above and below the dam. Fish hosts that use the passage could facilitate the recolonization of reaches above the dam by freshwater mussels. We conducted laboratory trials to determine the fish hosts of 4 of the species limited to reaches below the dam. The most suitable hosts for Lampsilis cariosa (Yellow Lampmussel) were Morone chrysops (White Bass), Morone saxatilis (Striped Bass), and Pomoxis nigromaculatus (Black Crappie), whereas Micropterus salmoides (Largemouth Bass) and Micropterus dolomieu (Smallmouth Bass) transformed fewer juvenile mussels. Lampsilis siliquoidea (Fatmucket) hosts were Largemouth Bass and Perca flavescens (Yellow Perch). Yellow Perch, Largemouth Bass, Lepomis macrochirus (Bluegill), and Lepomis gibossus (Pumpkinseed) were the best hosts for Ligumia nasuta (Eastern Pondmussel). We suspected that Elliptio roanokensis (Roanoke Slabshell) used anadromous fishes as hosts because its distribution is limited to mainstem rivers below the downstreammost dam. We confirmed that 2 Clupeidae, Dorosoma cepedianum (Gizzard Shad) and Alosa aestivalis (Blueback Herring), and 1 Moronidae, Morone americana (White Perch), are hosts for Roanoke Slabshell. Many of the host-fish species identified in this study are highly mobile, and we expect the range of these mussels to eventually expand upstream of the Columbia Dam as fish make use of the new passage.