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At least 235 records · Page 13Linked to original sources

USGS2024

Length in assessing status of freshwater fish populations: A review

Objective Effective policy formulation regarding the conservation of freshwater fish necessitates an understanding of water‐specific prevailing conditions and trends. Assessing fish populations in inland waters is difficult and expensive because there are many independent systems that need to be evaluated. Therefore, numerous freshwater systems are beset by insufficient data and the lack of systematic assessments of their status. To alleviate this deficiency, the objective of this study was to review length‐based metrics that may have utility in evaluating the well‐being of freshwater fish populations. Methods Length measurements can serve as proxies for a range of ecological and population dynamics attributes that are essential for the effective management of fish and associated fisheries. A review of the historical development of length measurements in fish conservation is provided, along with an examination of the potential biases that may arise from the use of lengths in practical contexts. In addition, we examine techniques that enable the spatial and temporal visualization of length data sets, as well as a range of indices and metrics that can be computed using length measurements. Result Building populations assessments around length may be a cost‐effective strategy that allows a first cut at managing a large number of waters. Length‐based assessments can signal if management intervention is necessary, if management policies are yielding the intended outcome, or if surveys beyond mere length are necessary. Conclusion Our review indicates that length offers a straightforward and efficient approach to evaluate the status of fish populations in inland systems. We encourage pursuing additional study and to this end propose specific areas for investigation.

North American Journal of Fisheries Management↗

USGS2008

Reproductive ecology of Actinonaias ligamentina (Bivalvia:Unionidae) in a regulated river

Factors affecting the reproductive success of freshwater mussels in lotic systems are poorly understood. Gravidity, fecundity, and fertilization success of Actinonaias ligamentina were examined at 4 sites along a 63-km reach of the Green River immediately below the Green River Dam, Kentucky. No gravid females were collected at the site closest to the dam, and the percentage of gravid females at downstream sites ranged from 20 to 36%. Not all females became gravid, despite the presence of early stages of ova in the gonadal fluid. This observation suggests that female A. ligamentina undergo a resting stage and, therefore, might not become gravid every year. Fecundity differed among sites and increased with distance from the dam. Fertilization rates ranged from 32 to 97% among sites and increased with distance from the dam. Fertilization rate was independent of local mussel density and position in the mussel bed. The high fertilization rates observed in the upstream portions of mussel beds indicate that freshwater mussel sperm have the ability to travel to distant females in lotic systems. Therefore, females are not necessarily dependent upon nearby males for fertilization. Successful fertilization of A. ligamentina at low mussel densities in the Green River suggests that natural recovery of rare endangered species might be possible if host fish and suitable conditions for juvenile survival and growth are present. ?? 2008 by The North American Benthological Society.

Journal of the North American Benthological Societ↗

USGS2017

Bioenergetics models to estimate numbers of larval lampreys consumed by smallmouth bass in Elk Creek, Oregon

Nonnative fishes have been increasingly implicated in the decline of native fishes in the Pacific Northwest. Smallmouth Bass Micropterus dolomieu were introduced into the Umpqua River in southwest Oregon in the early 1960s. The spread of Smallmouth Bass throughout the basin coincided with a decline in counts of upstream-migrating Pacific Lampreys Entosphenus tridentatus . This suggested the potential for ecological interactions between Smallmouth Bass and Pacific Lampreys, as well as freshwater-resident Western Brook Lampreys Lampetra richardsoni . To evaluate the potential effects of Smallmouth Bass on lampreys, we sampled diets of Smallmouth Bass and used bioenergetics models to estimate consumption of larval lampreys in a segment of Elk Creek, a tributary to the lower Umpqua River. We captured 303 unique Smallmouth Bass (mean: 197 mm and 136 g) via angling in July and September. We combined information on Smallmouth Bass diet and energy density with other variables (temperature, body size, growth, prey energy density) in a bioenergetics model to estimate consumption of larval lampreys. Larval lampreys were found in 6.2% of diet samples, and model estimates indicated that the Smallmouth Bass we captured consumed 925 larval lampreys in this 2-month study period. When extrapolated to a population estimate of Smallmouth Bass in this segment, we estimated 1,911 larval lampreys were consumed between July and September. Although the precision of these estimates was low, this magnitude of consumption suggests that Smallmouth Bass may negatively affect larval lamprey populations.

Oregon↗

USGS2010

BRIDGES: Evolution of basic and applied linkages in benthic science

Growing awareness of environmental degradation resulted in stricter environmental regulations and laws for aquatic ecosystems. These regulations were followed by an increase in applied research and monitoring beginning in the early 1970s. The number of applied scientists who were members of the North American Benthological Society grew at a commensurate rate. The editors of J-NABS recognized that, despite these increases, submitted manuscripts mostly addressed basic science. In response, the BRIDGES section of J-NABS was created in 1994 to provide a forum for linking basic ecological principles to applied science problems and issues. We examined the emergence of applied science topics in J-NABS and its predecessor, Freshwater Invertebrate Biology , from their beginning in 1982 to 2009. We classified papers among 11 categories that included a basic/applied science linkage. In the 1980s, applied papers were predominantly on effects of eutrophication/pollution and landuse changes. When BRIDGES was established in 1994, papers were solicited by editors and BRIDGES sections usually included >1 paper on a common theme to express complementary or alternate viewpoints. Forty-two papers appeared in BRIDGES between 1994 and 2009, but the number per issue declined after 2001. The total number of applied science papers in J-NABS has increased since ∼1994. Citation analysis of BRIDGES papers illustrates how information is being cited, but applied papers often are used in ways that might not lead to citations. BRIDGES transitioned to a new format in September 2009 to address new types of complex, multifaceted linkages. All new BRIDGES articles will be open access, and authors will be encouraged to produce lay-language fact sheets and to post them on the web.

Journal of the North American Benthological Societ↗

USGS2018

Differing modes of biotic connectivity within freshwater ecosystem mosaics

We describe a collection of aquatic and wetland habitats in an inland landscape, and their occurrence within a terrestrial matrix, as a “freshwater ecosystem mosaic” (FEM). Aquatic and wetland habitats in any FEM can vary widely, from permanently ponded lakes, to ephemerally ponded wetlands, to groundwater‐fed springs, to flowing rivers and streams. The terrestrial matrix can also vary, including in its influence on flows of energy, materials, and organisms among ecosystems. Biota occurring in a specific region are adapted to the unique opportunities and challenges presented by spatial and temporal patterns of habitat types inherent to each FEM. To persist in any given landscape, most species move to recolonize habitats and maintain mixtures of genetic materials. Species also connect habitats through time if they possess needed morphological, physiological, or behavioral traits to persist in a habitat through periods of unfavorable environmental conditions. By examining key spatial and temporal patterns underlying FEMs, and species‐specific adaptations to these patterns, a better understanding of the structural and functional connectivity of a landscape can be obtained. Fully including aquatic, wetland, and terrestrial habitats in FEMs facilitates adoption of the next generation of individual‐based models that integrate the principles of population, community, and ecosystem ecology.

Journal of the American Water Resources Associatio↗

USGS2014

Associations between water physicochemistry and Prymnesium parvum presence, abundance, and toxicity in west Texas reservoirs

Toxic blooms of golden alga ( Prymnesium parvum ) have caused substantial ecological and economic harm in freshwater and marine systems throughout the world. In North America, toxic blooms have impacted freshwater systems including large reservoirs. Management of water chemistry is one proposed option for golden alga control in these systems. The main objective of this study was to assess physicochemical characteristics of water that influence golden alga presence, abundance, and toxicity in the Upper Colorado River basin (UCR) in Texas. The UCR contains reservoirs that have experienced repeated blooms and other reservoirs where golden alga is present but has not been toxic. We quantified golden alga abundance (hemocytometer counts), ichthyotoxicity (bioassay), and water chemistry (surface grab samples) at three impacted reservoirs on the Colorado River; two reference reservoirs on the Concho River; and three sites at the confluence of these rivers. Sampling occurred monthly from January 2010 to July 2011. Impacted sites were characterized by higher specific conductance, calcium and magnesium hardness, and fluoride than reference and confluence sites. At impacted sites, golden alga abundance and toxicity were positively associated with salinity-related variables and blooms peaked at ~10°C and generally did not occur above 20°C. Overall, these findings suggest management of land and water use to reduce hardness or salinity could produce unfavorable conditions for golden alga.

Journal of the American Water Resources Associatio↗

USGS1996

The Westphalian D fossil lepidodendrid forest at Table Head, Sydney Basin, Nova Scotia: Sedimentology, paleoecology and floral response to changing edaphic conditions

Strata of Westphalian D age on the western coast of the Sydney Basin expose a fossil forest of approximately 30 lepidodendrid trees within one of several clastic splits of the Harbour Seam. A multidisciplinary approach was employed to interpret the origins of the coat bed, the depositional history of the site and the response of the fossil forest to changing edaphic conditions. The megaspore and miospore records indicate that the mire vegetation was dominated by arboreous lycopsids, especially Paralycopodites , with subdominant tree ferns. Petrographic, palynological and geochemical evidence suggest that the Harbour coal bed at Table Head originated as a rheotrophic (cf. planar) mire (eutric histosol). The mire forest is interpreted to have been engulfed by prograding distributary-channel sediments; sparse protist assemblages are suggestive of a freshwater delta-plain lake environment occasionally in contact with brackish waters. Lepidodendrids persisted as site colonizers of clastic substrates even after burial of the rheotrophic peatland and influenced the morphology of deposited sediment, but apparently were unable to colonize distributary channels. Equivocal taxonomic data (compression fossils) show the fossil forest to have been composed of both monocarpic ( Lepidodendron ) and polycarpic ( Diaphorodendron, Paralycopodites, ?Sigillaria ) lycopsids, genera recorded in the palynology of the uppermost ply of the underlying coal bed. Comparatively rare within the clastic beds of the fossil forest, however, is the stem compression of Paralycopodites , whose dispersed megapores and miospores dominate the underlying coal bed. Tree diameter data recorded equivalent to breast height indicate a forest of mixed age. These data would appear to suggest that some lepidodendrids employing a polycarpic reproductive strategy were better able to cross the ecological barrier imposed between peat and clastic substrates. Foliar compressions indicate that an understory or stand of Psaronius type tree ferns co-existed with the lepidodendrids on clastic substrates, which developed as incipient gleysol soils. The entombment of the forest can be ascribed to its distributary coastal setting, local subsidence and a seasonal climate that fostered wildfire and increased sedimentation.

International Journal of Coal Geology↗

USGS2014

Spatiotemporal associations of reservoir nutrient characteristics and the invasive, harmful alga Prymnesium parvum in West Texas

Golden alga ( Prymnesium parvum ) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga.

Journal of the American Water Resources Associatio↗

USGS2026

Documentation of giant floater (Pyganodon grandis) glochidia attached to larval lake whitefish (Coregonus clupeaformis) in the Laurentian Great Lakes

Native freshwater mussels (family Unionidae) are in decline globally, including in the Laurentian Great Lakes. Glochidia, the parasitic larvae of unionid mussels, typically attach to sub-adult and adult fishes. Attachment of glochidia to larval fishes is more rare, and a lack of documentation exists on glochidial attachment on fish in the Great Lakes in general. We document the attachment of four glochidia to three larval lake whitefish ( Coregonus clupeaformis ) in shallow waters of Lake Superior, and we genetically identified the glochidia as giant floater ( Pyganodon grandis ). We only observed glochidia at 3% of all sites sampled on ∼0.02% of all fish (∼15,000) collected across lakes Superior, Michigan, and Huron. Although glochidial encystment on larval lake whitefish may be rare, it may also be difficult to detect with conventional sampling methods. Regardless, the association could have important implications for the ecology and conservation of both unionids and coregonines in the ever-changing Great Lakes.

Michigan, Ontario, Wisconsin↗

USGS2020

Effects of latitude, season, and temperature on Lake Sturgeon movement

Ecologists have a limited understanding of the rangewide variation in movement behavior in freshwater fishes, but recent expansion of biotelemetry allows biologists to investigate how fish movement can help to predict behavioral shifts in response to changing environments. The Lake Sturgeon Acipenser fulvescens is a wide-ranging, migratory, coolwater species, making it a candidate species for studying patterns in movement ecology. We conducted a literature review and meta-analysis of seasonal movement data compiled from 38 Lake Sturgeon telemetry studies in North America to build an understanding of spatiotemporal variation in movement behavior. Lake Sturgeon movement studies were underrepresented for low-latitude populations in the Mississippi, Missouri, and Ohio/Tennessee River basins. Highest movement usually occurred during spring spawning migrations, whereas other populations exhibited their highest movement in the fall, potentially in order to overwinter near spawning grounds. Our meta-regression analysis indicated that latitude or summer maximum temperature best predicted standardized mean difference between spring and summer movement in Lake Sturgeon populations across the species’ range. Our results suggest that Lake Sturgeon populations at lower latitudes and those that experience warmer summer temperatures have lower summer movement relative to spring movement. Managers may use this information to prioritize actions promoting the conservation of seasonally important habitats for the continued recovery of migratory coolwater fish (e.g., Lake Sturgeon) that potentially experience stressful thermal conditions.

North American Journal of Fisheries Management↗

USGS2021

What can commercial fishery data in the Great Lakes reveal about juvenile sea lamprey (Petromyzon marinus) ecology and management?

The Laurentian Great Lakes of North America support a large and profitable freshwater fishery, but one continuously beset by parasitism from the invasive sea lamprey ( Petromyzon marinus ). Despite being the life stage that inflicts damage to the fishery, therefore necessitating a bi-national control program, our knowledge of juvenile sea lamprey ecology is poor and their response to control efforts are not assessed. Incidental capture of juvenile sea lamprey by commercial fishers is one means to collect data on this enigmatic life stage, and in Lake Huron such data have been collated since 1967. Here, we explore incidental captures of juvenile sea lamprey and their hosts from northern Lake Huron between 1987 and 2017 ( n = 33,246 observations) to address four objectives. Firstly, we document collection efforts by fishers to provide historical context to the dataset. Secondly, we pose and test a series of questions related to fishery encounter, host selection, growth, distribution, and sex ratio to highlight how these types of data can be informative regarding juvenile sea lamprey ecology. Results presented here could be used to develop biological hypotheses to be addressed in future work. Thirdly, we directly assessed whether juvenile sea lamprey capture data could be useful in corroborating trends observed in adult sea lamprey abundance and wounding, as well as in identifying abundance and wounding hotspots. Lastly, we summarize research and outreach efforts that have benefited from the capture of juvenile sea lamprey in recent years.

Great Lakes↗

USGS2015

Decision support system for optimally managing water resources to meet multiple objectives in the Savannah River Basin

Managers of large river basins face conflicting demands for water resources such as wildlife habitat, water supply, wastewater assimilative capacity, flood control, hydroelectricity, and recreation. The Savannah River Basin, for example, has experienced three major droughts since 2000 that resulted in record low water levels in its reservoirs, impacting dependent economies for years. The Savannah River estuary contains two municipal water intakes and the ecologically sensitive freshwater tidal marshes of the Savannah National Wildlife Refuge. The Port of Savannah is the fourth busiest in the United States, and modifications to the harbor to expand ship traffic since the 1970s have caused saltwater to migrate upstream, reducing the freshwater marsh’s acreage more than 50 percent. A planned deepening of the harbor includes flow-alteration features to minimize further migration of salinity, whose effectiveness will only be known after all construction is completed. One of the challenges of large basin management is the optimization of water use through ongoing regional economic development, droughts, and climate change. This paper describes a model of the Savannah River Basin designed to continuously optimize regulated flow to meet prioritized objectives set by resource managers and stakeholders. The model was developed from historical data using machine learning, making it more accurate and adaptable to changing conditions than traditional models. The model is coupled to an optimization routine that computes the daily flow needed to most efficiently meet the water-resource management objectives. The model and optimization routine are packaged in a decision support system that makes it easy for managers and stakeholders to use. Simulation results show that flow can be regulated to substantially reduce salinity intrusions in the Savannah National Wildlife Refuge, while conserving more water in the reservoirs. A method for using the model to assess the effectiveness of the flow-alteration features after the deepening also is demonstrated.

Georgia, North Carolina, South Carolina↗

USGS2018

Selenium, mercury, and their molar ratios in sportfishes from drinking water reservoirs

Mercury (Hg) bioaccumulates in aquatic ecosystems and may pose a risk to humans who consume fish. Selenium (Se) has the ability to reduce Hg toxicity, but the current guidance for human consumption of fish is based on Hg concentration alone. The purpose of the present study was to examine the relationship between Se and Hg in freshwater sportfish, for which there is a paucity of existing data. We collected three species of fish from different trophic positions from two drinking water reservoirs in central North Carolina, USA, to assess Hg and Se concentrations in relation to fish total length and to compare two measures of the protective ability of Se, the Se:Hg molar ratio and Se health benefit value (HBV Se ), to current guidance for Hg. According to the Se:Hg molar ratio, all of the low trophic position fish sampled and the middle trophic position fish sampled from one of the reservoirs were safe for consumption. The same number of fish were considered safe using the HBV Se . More fish were deemed unsafe when using the Se:Hg molar ratio and HBV Se than were considered unsafe when using the U.S. Environmental Protection Agency (USEPA) Hg threshold. These findings suggest that the measures of Se protection may be unnecessarily conservative or that the USEPA Hg threshold may not be sufficiently protective of human health, especially the health of sensitive populations like pregnant or nursing mothers and young children. Future examination of the Se:Hg molar ratio and HBV Se from a variety of fish tissue samples would help refine the accuracy of these measures so that they may be appropriately utilized in ecological and human health risk assessment.

International Journal of Environmental Research an↗

USGS2022

Atmospheric river storm flooding influences tidal marsh elevation building processes

Disturbances are a key component of ecological processes in coastal ecosystems. Investigating factors that affect tidal marsh accretion and elevation change is important, largely due to accelerating sea-level rise and the ecological and economic value of wetlands. Sediment accumulation rates, elevation change, and flooding were examined at five marshes along a riverine-tidal gradient in the northern San Francisco Bay-Delta, California, USA during an Atmospheric River storm event in 2017 using Surface Elevation Tables (SETs), feldspar marker horizons (MH), and continuous water-level sensors. Our results showed that localized marsh flooding increased during the storm event, but not evenly across sites. Marsh surface elevation increased the most at the tidal freshwater marsh site in response to the storms, with an average surface elevation gain of 45.6 ± 13.1 mm, and the least at a tidal saline marsh with an average surface elevation gain of 4.0 ± 1.2 mm. A marsh located on the large embayment did not exhibit an immediate response to the storm but had a surface elevation gain of 21.5 ± 13.7 mm 6 months after the storm. During the storm period, marsh distance to the bay was the strongest predictor of elevation change, followed by SET-MH elevations. Conversely, during non-storm periods, SET-MH elevation was a relatively strong predictor of elevation change. Atmospheric Rivers appear to be a major factor affecting short-term spatial and temporal variability in flooding and sedimentation rates in tidal marsh systems. Incorporating information about storms into monitoring could increase our understanding of how episodic storms can impact marshes.

Journal of Geophysical Research: Biogeosciences↗

USGS2010

Persistent organic pollutants in the blood of free-ranging sea otters (Enhydra lutris ssp.) in Alaska and California

As part of tagging and ecologic research efforts in 1997 and 1998, apparently healthy sea otters of four age-sex classes in six locations in Alaska and three in California were sampled for persistent organic pollutants (POPs) and other chemicals of ecologic or environmental concern (COECs). Published techniques for the detection of POPs (specifically Σpolychlorinated biphenyls [PCBs], ΣDDTs, Σhexachlorocyclohexanes [HCHs], Σpolycyclic aromatic hydrocarbons [PAHs], Σchlordanes [CHLs], hexachlorobenzene [HCB], dieldrin, and mirex) in the tissue of dead otters were modified for use with serum from live sea otters. Toxic equivalencies (TEQs) were calculated for POPs with proven bioactivity. Strong location effects were seen for most POPs and COECs; sea otters in California generally showed higher mean concentrations than those in Alaska. Differences in contaminant concentrations were detected among age and sex classes, with high levels frequently observed in subadults. Very high levels of ΣDDT were detected in male sea otters in Elkhorn Slough, California, where strong freshwater outflow from agricultural areas occurs seasonally. All contaminants except mirex differed among Alaskan locations; only ΣDDT, HCB, and chlorpyrifos differed within California. High levels of ΣPCB (particularly larger, more persistent congeners) were detected at two locations in Alaska where associations between elevated PCBs and military activity have been established, while higher PCB levels were found at all three locations in California where no point source of PCBs has been identified. Although POP and COEC concentrations in blood may be less likely to reflect total body burden, concentrations in blood of healthy animals may be more biologically relevant and less influenced by state of nutrition or perimortem factors than other tissues routinely sampled.

Alaska, California↗

USGS2022

Effects of warming winter embryo incubation temperatures on larval cisco (Coregonus artedi) survival, growth, and critical thermal maximum

Freshwater whitefishes, Salmonidae Coregoninae, are cold stenothermic fishes of ecological and socio-economic importance in northern hemisphere lakes that are warming in response to climate change. To address the effect of warming waters on coregonine reproduction we experimentally evaluated different embryo incubation temperatures on post-hatching survival, growth, and critical thermal maximum of larval cisco ( Coregonus artedi ) sampled from lakes Superior and Ontario. Embryos were incubated at water temperatures of 2.0, 4.4, 6.9, and 8.9 °C to simulate present and increased winter temperatures, and hatched larvae were reared in a common environment. For the populations from both lakes, larval survival and critical thermal maximum were negatively related to incubation temperature, and larval growth was positively related to incubation temperature. The magnitude of change across incubation temperatures was greater in the population sampled from Lake Superior than Lake Ontario for all traits examined. The more rapid decrease in survival and critical thermal maximum across incubation temperatures for larval cisco in Lake Superior, compared to those from Lake Ontario, suggests that Lake Superior larvae may possess a more limited ability to acclimate to and cope with increasing winter water temperatures. However, the rapid increase in growth rates across incubation temperatures in Lake Superior larvae suggests they could recover better from hatching at a small length induced by warm winters, as compared to Lake Ontario larvae. Our results suggest propagation and restoration programs may want to consider integrating natural habitat preferences and maximizing phenotypic variability to ensure offspring are set up for success upon stocking.

Lake Ontario, Lake Superior↗

USGS2009

Experimental removal of wetland emergent vegetation leads to decreased methylmercury production in surface sediment

We performed plant removal (devegetation) experiments across a suite of ecologically diverse wetland settings (tidal salt marshes, river floodplain, rotational rice fields, and freshwater wetlands with permanent or seasonal flooding) to determine the extent to which the presence (or absence) of actively growing plants influences the activity of the Hg(II)-methylating microbial community and the availability of Hg(II) to those microbes. Vegetated control plots were paired with neighboring devegetated plots in which photosynthetic input was terminated 4–8 months prior to measurements, through clipping aboveground biomass, severing belowground connections, and shading the sediment surface to prevent regrowth. Across all wetlands, devegetation decreased the activity of the Hg(II)-methylating microbial community (k meth ) by 38%, calculated MeHg production potential (MP) rates by 36%, and pore water acetate concentration by 78%. Decreases in MP were associated with decreases in microbial sulfate reduction in salt marsh settings. In freshwater agricultural wetlands, decreases in MP were related to indices of microbial iron reduction. Sediment MeHg concentrations were also significantly lower in devegetated than in vegetated plots in most wetland settings studied. Devegetation effects were correlated with live root density (percent volume) and were most profound in vegetated sites with higher initial pore water acetate concentrations. Densely rooted wetlands had the highest rates of microbial Hg(II)-methylation activity but often the lowest concentrations of bioavailable reactive Hg(II). We conclude that the exudation of labile organic carbon (e.g., acetate) by plants leads to enhanced microbial sulfate and iron reduction activity in the rhizosphere, which results in high rates of microbial Hg(II)-methyation and high MeHg concentrations in wetland sediment.

Journal of Geophysical Research: Biogeosciences↗

USGS2013

Newly documented host fishes for the eastern elliptio mussel (Elliptio complanata)

The eastern elliptio Elliptio complanata is a common, abundant, and ecologically important freshwater mussel that occurs throughout the Atlantic Slope drainage in the United States and Canada. Previous research has shown E. complanata glochidia to be host fish generalists, parasitizing yellow perch Perca flavescens , banded killifish Fundulus diaphanus , banded sculpin Cottus carolinae , and seven centrarchid species. Past laboratory studies have been conducted in the Midwest; however, glochidia used in these studies were obtained from adult mussels in the Great Lakes or St. Lawrence River basins, or glochidia sources were not reported. The objective of this study was to identify host fishes for E. complanata from streams in the Mid-Atlantic region. We used artificial laboratory infections to test host suitability of 38 fish and 2 amphibian species with E. complanata glochidia from the Chesapeake Bay drainage. Glochidia successfully metamorphosed into juvenile mussels on five fish species: American eel Anguilla rostrata , brook trout Salvelinus fontinalis , lake trout Salvelinus namaycush , mottled sculpin Cottus bairdii , and slimy sculpin Cottus cognatus . American eel was the most effective host, yielding the highest overall metamorphosis success (percentage of attached glochidia that transformed into juvenile mussels; ≥0.90) and producing 13.2 juveniles per fish overall. No juvenile E. complanata metamorphosed on other fish or amphibian species tested, including many previously identified host fishes that appear in the literature. Reasons for discrepancies in published host fish could include geographic variation in host use across the species' range, differences in host use between lentic and lotic populations, or poorly resolved taxonomy within the genus Elliptio .

Journal of Fish and Wildlife Management↗