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At least 253 records · Page 14Linked to original sources
USGS2022

Use of riparian spiders as sentinels of persistent and bioavailable chemical contaminants in aquatic ecosystems: A review

Aquatic ecosystems around the world are contaminated with a wide range of anthropogenic chemicals, including metals and organic pollutants, that originate from point and nonpoint sources. Many of these chemical contaminants have complex environmental cycles, are persistent and bioavailable, can be incorporated into aquatic food webs, and pose a threat to the health of wildlife and humans. Identifying appropriate sentinels that reflect bioavailability is critical to assessing and managing aquatic ecosystems impacted by contaminants. The objective of the present study is to review research on riparian spiders as sentinels of persistent and bioavailable chemical contaminants in aquatic ecosystems. Our review of the literature on riparian spiders as sentinels suggests that significant progress has been made during the last two decades of research. We identified 55 published studies conducted around the world in which riparian spiders (primarily of the families Tetragnathidae, Araneidae, Lycosidae, and Pisauridae) were used as sentinels of chemical contamination of lotic, lentic, and estuarine systems. For several contaminants, such as polychlorinated biphenyls (PCBs), Hg, and Se, it is now clear that riparian spiders are appropriate sentinels. However, many contaminants and factors that could impact chemical concentrations in riparian spiders have not been well characterized. Further study of riparian spiders and their potential role as sentinels is critical because it would allow for development of national-scale programs that utilize riparian spiders as sentinels to monitor chemical contaminants in aquatic ecosystems. A riparian spider sentinel program in the United States would be complementary to existing national sentinel programs, including those for fish and immature dragonflies.

Environmental Toxicology and Chemistry↗
USGS2022

Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries

With improved analytical techniques, environmental monitoring studies are increasingly able to report the occurrence of tens or hundreds of chemicals per site, making it difficult to identify the most relevant chemicals from a biological standpoint. For this study, organic chemical occurrence was examined, individually and as mixtures, in the context of potential biological effects. Sediment was collected at 71 Great Lakes tributary sites and analyzed for 87 chemicals. Multiple risk-based lines of evidence were used to prioritize chemicals and locations, including comparing sediment concentrations and estimated porewater concentrations to established whole-organism benchmarks (i.e., sediment and water quality criteria and screening values) and to high-throughput toxicity screening data from the U.S. Environmental Protection Agency's ToxCast database, estimating additive effects of chemical mixtures on common ToxCast endpoints, and estimating toxic equivalencies for mixtures of alkylphenols and polycyclic aromatic hydrocarbons (PAHs). This multiple-lines-of-evidence approach enabled the screening of more chemicals, mitigated the uncertainties of individual approaches, and strengthened common conclusions. Collectively, at least one benchmark/screening value was exceeded for 54 of the 87 chemicals, with exceedances observed at all 71 of the monitoring sites. Chemicals with the greatest potential for biological effects, both individually and as mixture components, were bisphenol A, 4-nonylphenol, indole, carbazole, and several polycyclic aromatic hydrocarbons (PAHs). Potential adverse outcomes based on ToxCast gene targets and putative adverse outcome pathways relevant to individual chemicals and chemical mixtures included tumors, skewed sex ratios, reproductive dysfunction, hepatic steatosis, and early mortality, among others. Results provide a screening level prioritization of chemicals with the greatest potential for adverse biological effects and an indication of sites where they are most likely to occur.

Illinois, Indiana, Michigan, Minnesota, New York, ↗
USGS2022

Site- and individual-level contaminations affect infection prevalence of an emerging infectious disease of amphibians

Emerging infectious disease outbreaks are one of multiple stressors responsible for amphibian declines globally. In the northeastern United States, ranaviral diseases are prevalent in amphibians and other ectothermic species, but there is still uncertainty as to whether their presence is leading to population level effects. Further, there is also uncertainty surrounding the potential interactions among disease infection prevalence in free-ranging animals and habitat degradation (co-occurrence of chemical stressors). The current study was designed to provide field-based estimates of the relationship between amphibian disease and chemical stressors. We visited 40 wetlands across three protected areas, estimated the prevalence of ranavirus among populations of larval wood frogs and spotted salamanders, and assessed chemical and biological stressors in wetland habitats and larval amphibians using a suite of selected bioassays, screening tools and chemical analyses. Estimated ranavirus occupancy varied among the three protected areas and ranged from 0.27 to 0.55 with considerable variation within each protected area. Of the stressors evaluated, ranavirus prevalence was strongly and positively related to concentrations of metalloestrogens (metals with the potential to bind to estrogen receptors) and total metals in wetland sediments and weakly and negatively related to total pesticide concentrations in larval amphibians. These results can be used by land managers to refine habitat assessments to include such environmental factors with the potential to influence disease susceptibility.

Maryland, Massachusetts↗
USGS2011

Teratogenic efects of injected methylmercury on avian embryos

Controlled laboratory studies with game farm mallards ( Anas platyrhynchos ) and chickens ( Gallus gallus ) have demonstrated that methylmercury can cause teratogenic effects in birds, but studies with wild species of birds are lacking. To address this need, doses of methylmercury chloride were injected into the eggs of 25 species of birds, and the dead embryos and hatched chicks were examined for external deformities. When data for controls were summed across all 25 species tested and across all types of deformities, 24 individuals out of a total of 1,533 (a rate of 1.57%) exhibited at least one deformity. In contrast, when data for all of the mercury treatments and all 25 species were summed, 188 deformed individuals out of a total of 2,292 (8.20%) were found. Some deformities, such as lordosis and scoliosis (twisting of the spine), misshapen heads, shortening or twisting of the neck, and deformities of the wings, were seldom observed in controls but occurred in much greater frequency in Hg-treated individuals. Only 0.59% of individual control dead embryos and hatchlings exhibited multiple deformities versus 3.18% for Hg-dosed dead embryos and hatchlings. Methylmercury seems to have a widespread teratogenic potential across many species of birds.

Environmental Toxicology and Chemistry↗
USGS2022

Interlaboratory comparison of three sediment bioaccumulation tests

Standard bioaccumulation tests are commonly conducted using Macoma nasuta (clam), and Alitta virens (polychaete) for marine tests, and Lumbriculus variegatus (an oligochaete) for freshwater tests. Because the interlaboratory variability associated with these tests is unknown, four experienced laboratories conducted standard 28-day bioaccumulation tests with the above species using sediments contaminated with polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Chemical analysis of tissue samples was performed by a single laboratory. The intralaboratory variance among replicates was relatively low for PCB tissue concentrations, with coefficients of variation (CVs) ranging from 9% to 28% for all laboratories and species, with the exception of one laboratory reporting higher variability for L . variegatus (CV = 51%). Intralaboratory variance for PCB tissue concentrations was higher than interlaboratory variance for A. virens and L . variegatus , and the magnitude of difference (MOD) for laboratory means ranged from 1.4 to 2.0 across species. Intralaboratory variability was also low for lipid content, and lipid normalization of PCB and PAH body residues generally had little impact on variability. In addition to variability across bioassay laboratories, analytical variability was evaluated by different laboratories measuring the concentration of PCBs and total lipids in a subsample of tissue homogenate of sediment-exposed test organisms. Variability associated with tissue analysis was higher than bioassay laboratory variability only in tests with L . variegatus . Statistical differences between samples may be observed due to the low intralaboratory variability; however, the biological significance of these differences may be limited because the MOD is low. Considering the MOD when comparing bioaccumulation across treatments accounts for uncertainty related to inherent variability of the test in the interpretation of statistically significant results.

Massachusetts↗
USGS2022

Comparative toxicity of aquatic per- and polyfluoroalkyl substance exposure in three species of amphibians

Per- and polyfluoroalkyl substances (PFAS) are contaminants of concern due to their widespread occurrence in the environment, persistence, and potential to elicit a range of negative health effects. Per- and polyfluoroalkyl substances are regularly detected in surface waters, but their effects on many aquatic organisms are still poorly understood. Species with thyroid-dependent development, like amphibians, can be especially susceptible to PFAS effects on thyroid hormone regulation. We examined sublethal effects of aquatic exposure to four commonly detected PFAS on larval northern leopard frogs ( Rana [Lithobates] pipiens ), American toads ( Anaxyrus americanus ), and eastern tiger salamanders ( Ambystoma tigrinum ). Animals were exposed for 30 days (frogs and salamanders) or until metamorphosis (toads) to 10, 100, or 1000 μg/L of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), or 6:2 fluorotelomer sulfonate (6:2 FTS). We determined that chronic exposure to common PFAS can negatively affect amphibian body condition and development at concentrations as low as 10 µg/L. These effects were highly species dependent, with species having prolonged larval development (frogs and salamanders) being more sensitive to PFAS than more rapidly developing species (toads). Our results demonstrate that some species could experience sublethal effects at sites with surface waters highly affected by PFAS. Our results also indicate that evaluating PFAS toxicity using a single species may not be sufficient for accurate amphibian risk assessment. Future studies are needed to determine whether these differences in susceptibility can be predicted from species' life histories and whether more commonly occurring environmental levels of PFAS could affect amphibians.

Environmental Toxicology and Chemistry↗
USGS2022

Increased mercury and reduced insect diversity in linked stream-riparian food webs downstream of a historical mercury mine

Historical mining left a legacy of abandoned mines and waste rock in remote headwaters of major river systems in the western United States. Understanding the influence of these legacy mines on culturally and ecological important downstream ecosystems is not always straight-forward because of elevated natural levels of mineralization in mining-impacted watersheds. To test the ecological effects of historic mining in the headwaters of the upper Salmon River watershed (USA), we measured multiple community and chemical endpoints in downstream linked aquatic-terrestrial food webs. Mining inputs impacted downstream food webs through increased mercury accumulation and decreased insect biodiversity. Total mercury (THg) in seston, aquatic insect larvae, adult aquatic insects, riparian spiders, and fish at sites up to 7.6 km downstream of mining was in much higher concentrations (1.3 to 11.3-fold) and isotopically distinct compared with sites immediately upstream of mining inputs. Methylmercury (MeHg) concentrations in bull trout and riparian spiders were sufficiently high (732 – 918 and 347 – 1,140 ng MeHg g -1 dw) to affect humans, birds, and piscivorous fish. Furthermore, the alpha-diversity of benthic insects was locally depressed by 12-20% within 4.3 to 5.7 km downstream of from the mine. However, because total insect biomass was not affected by mine inputs, the mass of mercury in benthic insects at a site (i.e., ng Hg m -2 ) was extremely elevated downstream (10 – 1,778-fold) compared with directly upstream of mining inputs. Downstream adult aquatic insect-mediated fluxes of total mercury were also high (~16 ng THg m -2 d -1 ). Abandoned mines can have ecologically important effects on downstream communities, including reduced biodiversity and increased mercury flux to higher order consumers, including fish, birds, and humans.

Idaho↗
USGS2022

Toxicity of wildland fire-fighting chemicals in pulsed exposures to rainbow trout and fathead minnows

Intrusions of fire-fighting chemicals in streams can result from containment and suppression of wildfires and may be harmful to native biota. We investigated the toxicity of seven current-use fire-fighting chemicals to juvenile rainbow trout ( Oncorhynchus mykiss ) and fathead minnows ( Pimephales promelas ) by simulating chemical intrusions under variable field conditions to provide insight on the potential damage these chemicals may cause in waterways. We manipulated water flow rate, water hardness, and concentration of the chemicals in three separate attenuated exposure assays where chemical concentrations decreased throughout the 96-hour exposure period. Concentration of retardant, temperature, duration of chemical exposure, and the number of exposures were manipulated in four pulsed assays where up to one-hour exposures were followed by an observation period in control water to determine delayed toxicity or recovery. Mortality of rainbow trout was higher across treatments at a warmer temperature and also increased with increasing concentration rate, increasing exposure duration, and with sequential exposures across assays. For fathead minnows, mortality increased with increasing concentration of fire retardant and longer exposure durations. Chemical exposure can exert additional stress during wildfire events that may impact stream fishes. Since the ratio of toxic unionized ammonia to ionized ammonia is greater with increasing temperature and pH, future studies could investigate the effects of water temperature and pH on native fishes under environmentally relevant concentrations of fire-fighting chemicals.

Environmental Toxicology and Chemistry↗
USGS2022

Prioritizing pharmaceutical contaminants in Great Lakes tributaries using risk-based screening techniques

In a study of 44 diverse sampling sites across 16 Great Lakes tributaries, 110 pharmaceuticals were detected of 257 monitored. The present study evaluated the ecological relevance of detected chemicals and identified heavily impacted areas to help inform resource managers and guide future investigations. Ten pharmaceuticals (caffeine, nicotine, albuterol, sulfamethoxazole, venlafaxine, acetaminophen, carbamazepine, gemfibrozil, metoprolol, and thiabendazole) were distinguished as having the greatest potential for biological effects based on comparison to screening-level benchmarks derived using information from two biological effects databases, the ECOTOX Knowledgebase and the ToxCast database. Available evidence did not suggest substantial concern for 75% of the monitored pharmaceuticals, including 147 undetected pharmaceuticals and 49 pharmaceuticals with screening-level alternative benchmarks. However, because of a lack of biological effects information, screening values were not available for 51 detected pharmaceuticals. Samples containing the greatest pharmaceutical concentrations and having the highest detection frequencies were from Lake Erie, southern Lake Michigan, and Lake Huron tributaries. Samples collected during low-flow periods had higher pharmaceutical concentrations than those collected during increased-flow periods. The wastewater-treatment plant effluent content in streams correlated positively with pharmaceutical concentrations. However, deviation from this correlation demonstrated that secondary factors, such as multiple pharmaceutical sources, were likely present at some sites. Further research could investigate high-priority pharmaceuticals as well as those for which alternative benchmarks could not be developed.

Indiana, Michigan, Minnesota, New York, Ohio, Wisc↗
USGS2022

Elevated mercury concentrations and isotope signatures (N, C, Hg) in yellowfin tuna (Thunnus albacares) from the Galápagos Marine Reserve and waters off Ecuador

We examined how dietary factors recorded by C and N influence Hg uptake in 347 individuals of yellowfin tuna ( Thunnus albacares ), an important subsistence resource from the Galápagos Marine Reserve (GMR) and the Ecuadorian mainland coast (EMC) in 2015-2016. We found no differences in total Hg (THg) measured in red muscle between the two regions and no seasonal differences, likely due to the age of the fish and slow elimination rates of Hg. Our THg concentrations are comparable to other studies in the Pacific (0.06–2.88 mg/kg wet weight), but a subset of individuals exhibited the highest mercury concentrations yet reported in yellowfin tuna. Mercury isotope values differed between Δ199Hg and δ202Hg in both regions (Δ199Hg = 2.86±0.04‰ vs. Δ199Hg = 2.33 ± 0.07‰), likely related to shifting food webs and differing photochemical processing of Hg prior to entry into the food web. There were significantly lower values of both δ15N and δ13C in tuna from GMR (δ15N: 8.5–14.2‰, δ13C: -18.5–-16.1‰) compared to those from the EMC (δ15N: 8.3–14.4‰, δ13C: -19.4–-11.9‰), of which δ13C values suggest spatially-constrained movements of tunas. Results from the pooled analysis, without considering region, indicated that variations in δ13C and δ15N values tracked changes of Hg stable isotopes. Our data indicate that the individual tuna from this study were resident fish of each region and heavily influenced by upwellings related to the Eastern Pacific Oxygen Minimum Zone and the Humboldt Current System. C, N, and Hg isotopes reflect foraging behavior mainly on epipelagic prey in shallow waters and that food web shifts drive Hg variations between these populations of tuna.

Galápagos Marine Reserve, Pacific Ocean↗
USGS2022

Influence of test method variables on sensitivity of Neocloeon triangulifer to a reference toxicant in short-term, effluent style evaluations

Recent literature has demonstrated the sensitivity of mayflies to environmental contaminants. However, to date, there are no methods approved by the US Environmental Protection Agency for using sensitive insects like mayflies in whole-effluent toxicity or receiving water toxicity tests. The parthenogenetic mayfly Neocloeon triangulifer has been shown to be amenable to continuous culture in the laboratory, and methods have been described for its use in both acute and chronic toxicity studies. The goal of the present study was to investigate aspects of N. triangulifer testing and culturing methods that might require adjustment so that they are applicable for testing effluents and receiving waters in a short-term exposure. To this end, the influence of organism age, test duration, and test temperature on sensitivity to NaCl as a reference toxicant were tested (concentrations ranging from 182 to 2489 mg/L). Further studies were conducted to assess the utility of commercially available diets and the influence of nutrient amendment of water on organism growth and sensitivity. Seven-day NaCl tests started with less than 24-h-old larvae were similar in sensitivity to 14-day and full life chronic tests, and were much more sensitive than those started with 7-day-old organisms. Reducing test temperature from 25 °C to 22 °C had a minor influence on culture timing, and little impact on sensitivity to NaCl. In other experiments, reconstituted test water supplemented with nutrients to potentially improve in-test food quality had minimal effect on growth at 7 days and did not significantly alter acute sensitivity to NaCl relative to unamended reconstituted water. A suitable commercially available, ready-to-feed diet substitute for cultured diatoms was not found. Testing N. triangulifer in effluents or receiving waters with the methods recommended will complement similar methods for Ceriodaphnia dubia .

Environmental Toxicology and Chemistry↗
USGS2022

The capacity of freshwater ecosystems to recover from exceedances of aquatic life criteria

In the United States, national chemical water quality criteria for the protection of aquatic life assume that aquatic ecosystems have sufficient resiliency to recover from criteria exceedences occurring up to once every 3 years. This resiliency assumption was critically reviewed through two approaches: 1) synthesis of case studies and 2) population modeling. The population modeling examined differences in recovery of species with widely different life histories. One invertebrate ( Hyalella azteca ) and four fish species were modeled (fathead minnow, brook trout, lake trout, and shortnose sturgeon) with various disturbance magnitudes and intervals. The synthesis of ecosystem case studies showed generally faster recoveries for insect communities rather than fish, and recoveries from pulse (acute) disturbances were often faster than recoveries from press (chronic) disturbances. When the recovery dataset excluded severe disturbances that seemed unrepresentative of common facility discharge upsets that might cause criteria exceedences, the median recovery time was 1 year, 81% of the cases were considered recovered within 3 years, and 95% were considered recovered within 10 years. The modeling projected that short-lived fish species with high recovery times could thrive despite enduring 50% mortality disturbances every other year. However, long-lived fish species had longer recovery times and declined under the 1 disturbance every 3 years scenario. Overall, the analyses did not refute the long-standing judgements that 3 years is generally sufficient for recovery from non-repetitive, moderate intensity disturbances of a magnitude up to 2X the chronic criteria in waters without other pollution sources or stresses. However, these constraints may not always be met and if long-lived fish species are a concern, longer return intervals such as 5 to 10 years could be indicated.

Environmental Toxicology and Chemistry↗
USGS2022

Do pharmaceuticals in the environment pose a risk to wildlife?

The vast majority of knowledge related to the question of, “To what extent do pharmaceuticals in the environment pose a risk to wildlife?”, stems from the Asian vulture crisis (>99% decline of some species of old-world vultures on the Indian subcontinent related to the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac). The hazard of diclofenac and other NSAIDs (carprofen, flunixin, ketoprofen, nimesulide, phenylbutazone) to vultures and other avian species has since been demonstrated; indeed only meloxicam and tolfenamic acid have been found to be vulture-safe. Since diclofenac was approved for veterinary use in Spain and Italy in 2013 (home to ~95% of vultures in Europe), the risk of NSAIDs to vultures in these countries has become one of the principal concerns related to pharmaceuticals and wildlife. Many of the other bodies of work on pharmaceutical exposure, hazard and risk to wildlife also relate to adverse effects in birds, (e.g., poisoning of scavenging birds in North America and Europe from animal carcasses containing pentobarbital; secondary and even tertiary poisoning of birds exposed to pesticides used in veterinary medicine as cattle dips; migratory birds as a vector for the transfer of antimicrobial and antifungal resistance). While there is some research related to endocrine disruption in reptiles and potential exposure of aerial insectivores, there remain numerous knowledge gaps for risk posed by pharmaceuticals to amphibians, reptiles and mammals. Developing non-invasive sampling techniques and new approach methodologies (e.g., genomic, in vitro , in silico , in ovo ) are important if we are to bridge the current knowledge gaps without extensive vertebrate testing.

Environmental Toxicology and Chemistry↗
USGS2022

Riparian spiders: Sentinels of polychlorinated dibenzo-p-dioxin and dibenzofuran-contaminated sediment

Polychlorinated dibenzo- p -dioxin and polychlorinated dibenzofuran (PCDD/F) are persistent, toxic, and bioaccumulative. Currently, PCDD/F monitoring programs primarily use fish and birds with potentially large home ranges to monitor temporal trends over broad spatial scales; sentinel organisms that provide targeted sediment contaminant information across small geographic areas have yet to be developed. Riparian orb-weaving spiders, which typically have small home ranges and consume primarily adult aquatic insects, are potential PCDD/F sentinels. Recent studies have demonstrated that spider tissue concentrations indicate the source and magnitude of dioxin-like chlorinated compounds in contaminated sediments, including polychlorinated biphenyls (PCBs). Our aim in the present study was to assess the utility of riparian spiders as sentinels for PCDD/F-contaminated sediments. We measured PCDD/F (total [Σ] and homologs) in surface sediments and spiders collected from three sites within the St. Louis River basin (Minnesota and Wisconsin, USA). We then compared (1) patterns in ΣPCDD/F concentrations between sediment and spiders, (2) the distribution of homologs within sediments and spiders when pooled across sites, and (3) the relationship between sediment and spider concentrations of PCDD/F homologs across 13 stations sampled across the three sites. The ΣPCDD/F concentrations in sediment (mean ± standard error 286 591 ± 97 614 pg/g) were significantly higher than those in riparian spiders (2463 ± 977 pg/g, p < 0.001), but the relative abundance of homologs in sediment and spiders were not significantly different. Spider homolog concentrations were significantly and positively correlated with sediment concentrations across a gradient of sediment PCDD/F contamination ( R 2 = 0.47, p < 0.001). Our results indicate that, as has been shown for other legacy organic chemicals like PCBs, riparian spiders are suitable sentinels of PCDD/F in contaminated sediment.

Minnesota, Wisconsin↗
USGS2023

Ecotoxicological studies indicate that sublethal and lethal processes limit insect-mediated contaminant flux

Merolimnic insects can accumulate and transport considerable amounts of aquatic contaminants to terrestrial systems. The rate of contaminant biotransport, termed insect-mediated contaminant flux (IMCF), depends on emergent insect biomass and contaminant accumulation, both functions of environmental concentration. Here we develop a mathematical model of IMCF and apply it to three ecotoxicological studies obtained through the U.S. Environmental Protection Agency's ECOTOX database to determine at which concentration maximum IMCF occurs. Model results demonstrate that the maximum IMCF depends on competing rates of biomass loss and contaminant accumulation and does not necessarily occur at the highest insect or environmental contaminant concentration. Additionally, modeling results suggest that sublethal contaminant effects (e.g., decreased growth) on insect biomass can be an important and potentially underappreciated control on IMCF.

Environmental Toxicology and Chemistry↗
USGS2023

Bioaccumulation kinetics of model pharmaceuticals in the freshwater unionid pondmussel, Sagittunio subrostratus

Bioaccumulation of ionizable pharmaceuticals has been increasingly studied, with most reported aquatic tissue concentrations in field or laboratory experiments being from fish. However, higher levels of antidepressants have been observed in bivalves compared with fish from effluent-dominated and dependent surface waters. Such observations may be important for biodiversity because approximately 70% of freshwater bivalves in North America are considered to be vulnerable to extinction. Because experimental bioaccumulation information for freshwater bivalves is lacking, we examined accumulation dynamics in the freshwater pondmussel, Sagittunio subrostratus , following exposure to a model weak acid, acetaminophen (mean (±SD) = 4.9 ± 1 µg L –1 ), and a model weak base, sertraline (mean (±SD) = 1.1 ± 1.1 µg L –1 ) during 14-day uptake and 7-day depuration experiments. Pharmaceutical concentrations were analyzed in water and tissue using isotope dilution liquid chromatography–tandem mass spectrometry. Mussels accumulated two orders of magnitude higher concentrations of sertraline (31.7 ± 9.4 µg g –1 ) compared to acetaminophen (0.3 ± 0.1 µg g –1 ). Ratio and kinetic-based bioaccumulation factors of 28,836.4 (L kg –1 ) and 34.9 (L kg –1 ) were calculated for sertraline and for acetaminophen at 65.3 (L kg –1 ) and 0.13 (L kg –1 ), respectively. However, after 14 days sertraline did not reach steady-state concentrations, although it was readily eliminated by S. subrostratus . Acetaminophen rapidly reached steady-state conditions but was not depurated over a 7-day period. Future bioaccumulation studies of ionizable pharmaceuticals in freshwater bivalves appear warranted. Environ Toxicol Chem 2023;00:1–7. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Missouri↗
USGS2023

Influences of water hardness on chronic toxicity of potassium chloride to a unionid mussel (Lampsilis siliquoidea)

Elevated concentrations of potassium (K) often occur in effluents from wastewater treatment plants, oil and gas production operations, mineral extraction processes, and from other anthropogenic sources. Previous studies have demonstrated that freshwater mussels are highly sensitive to K in acute and chronic exposures, and acute toxicity of K decreases with increasing water hardness. However, little is known about the influence of hardness on the chronic toxicity of K. The objective of this study was to evaluate the chronic toxicity of K (tested as KCl) to a commonly tested unionid mussel (fatmucket , Lampsilis siliquoidea ) at five hardness levels (25, 50, 100, 200, 300 mg/L as CaCO 3 ) representing most surface waters in the United States. Chronic 28-d K toxicity tests were conducted with 3-week-old juvenile fatmucket in the five hardness waters using an ASTM standard method. The maximum acceptable toxicant concentrations (geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration) increased from 15.1 to 69.3 mg K/L for survival and from 15.1 to 35.8 mg K/L for growth (length and dry weight) and biomass when water hardness was increased from 25 mg/L (soft) to 300 mg/L (very hard). These results provided evidence to support water hardness influence on chronic K toxicity to juvenile fatmucket. However, the chronic effect concentrations based on the more sensitive endpoint (growth or biomass) increased only 2.4-fold from the soft water to the very hard water, indicating that water hardness had limited influence on the chronic toxicity of K to the mussels. These results can be used to establish chronic toxicity thresholds for K across a broad range of water hardness and to derive environmental guideline values for K to protect freshwater mussels and other organisms.

Environmental Toxicology and Chemistry↗
USGS2023

Laboratory-derived bioaccumulation kinetic parameters for four per- and polyfluoroalkyl substances in freshwater mussels

Although freshwater mussels are imperiled and identified as key conservation priorities, limited bioaccumulation information is available on these organisms for contaminants of emerging concern. In the present study we investigated the bioaccumulation of per- and polyfluoroalkyl substances (PFAS) in the model freshwater pond mussel Sagittunio subrostratus because mussels provide important ecosystem services and are important components of aquatic systems where PFAS occur. In the present study we selected four representative perfluorinated carboxylic acids and sulfonic acids, then determined the bioaccumulation kinetics of freshwater mussels in a controlled laboratory study. Because uptake ( k u ) and elimination ( k e ) rate constants and time to steady state are important parameters for food web bioaccumulation models, we derived bioaccumulation kinetic parameters following exposure to perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), and perfluorodecanoic acid (PFDA) at 10 µg/L and perfluoroundecanoic acid (PFUnDA) at 1 µg/L during a 14-day uptake period followed by a 7-day elimination period. Kinetic and ratio-based bioaccumulation factors (BAFs) were subsequently calculated, for example ratio-based BAFs for mussel at day 7 were determined for PFHxS (0.24 ± 0.08 L/kg), PFOS (7.73 ± 1.23 L/kg), PFDA (4.80 ± 1.21 L/kg), and PFUnDA (84.0 ± 14.4 L/kg). We generally observed that, for these four model PFAS, freshwater mussels have relatively low BAF values compared with other aquatic invertebrates and fish.

Environmental Toxicology and Chemistry↗