Evaluation of Chronic Effects of Potassium Chloride and Nickel on Survival, Growth, and Reproduction of a Unionid Mussel (Lampsilis siliquoidea).

The ASTM International standard test method for freshwater mussels (E2455-13) recommends 4-week toxicity testing with juveniles to evaluate chronic effects on survival and growth. However, concerns remain that the method may not adequately address the sensitivity of mussels to longer term exposures (>4 weeks), particularly in relation to potential reproductive impairments. No standard method directly evaluates toxicant effects on mussel reproduction. The objectives of the present study were to (1) evaluate toxicity endpoints related to reproduction in fatmucket (Lampsilis siliquoidea) using two common reference toxicants, potassium chloride (KCl) and nickel (Ni); (2) evaluate the survival and growth of juvenile fatmucket in standard 4-week and longer term (12-week) KCl and Ni tests following a method refined from the standard method; and (3) compare the sensitivity of the reproductive endpoints with the endpoints obtained from the juvenile mussel tests. Reproductive toxicity tests were conducted by first exposing female fatmucket brooding mature larvae (glochidia) to five test concentrations of KCl and Ni for 6 weeks. Subsamples of the glochidia were then removed from the adults to determine three reproductive endpoints: (1) the viability of brooded glochidia; (2) the viability of free glochidia in a 24-h exposure to the same toxicant concentrations as their mother; and (3) the success of glochidia parasitism on host fish. Mean viability of brooded glochidia was significantly reduced in the high KCl concentration (26 mg K/L) relative to the control, with a 20% effect concentration (EC20) of 14 mg K/L, but there were no significant differences between the control and any Ni treatment (EC20 > 95 µg Ni/L). The EC20s for viability of free glochidia after the additional 24-h exposure and parasitism success were similar to the EC20s of brooded glochidia. The EC20s based on the most sensitive biomass endpoint in the 4-week juvenile tests were 15 mg K/L and 91 µg Ni/L, similar to or greater than the EC20s from the reproductive KCl and Ni tests, respectively. When exposure duration in the juvenile tests was extended from 4 to 12 weeks, the EC20s decreased by more than 50% in the KCl test but by only 8% in the Ni test. Overall, these results indicate that a standard 4-week test with juvenile mussels can prove effective for estimating effects in chronic exposures with different life stages although a longer term 12-week exposure with juvenile mussels may reveal higher sensitivity of mussels to some toxicants, such as KCl. Environ Toxicol Chem 2024;43:1097-1111. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

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 (ku ) and elimination (ke ) 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. Environ Toxicol Chem 2023;42:1190-1198. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Influence 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 other anthropogenic sources. Previous studies have demonstrated that freshwater mussels are highly sensitive to K in acute and chronic exposures, and that 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 our 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, and 300 mg/L as CaCO3 ) representing most surface waters in the United States. Chronic 28-day K toxicity tests were conducted with 3-week-old juvenile fatmucket in the five hardness waters using an ASTM International 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 wt) and biomass when water hardness was increased from 25 mg/L (soft) to 300 mg/L (very hard). These results provide 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 a 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. Environ Toxicol Chem 2023;42:1085-1093. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

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;42:1183-1189. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Lethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms.

Mercury (Hg), a potent neurotoxic element, can biomagnify through food webs once converted into methylmercury (MeHg). Some studies have found that selenium (Se) exposure may reduce MeHg bioaccumulation and toxicity, though this pattern is not universal. Se itself can also be toxic at elevated levels. We experimentally manipulated the relative concentrations of dietary MeHg and Se (as selenomethionine [SeMet]) for an aquatic grazer (the mayfly, Neocloeon triangulifer) and its food source (diatoms). Under low MeHg treatment (0.2 ng/L), diatoms exhibited a quadratic pattern, with decreasing diatom MeHg concentration up to 2.0 µg Se/L and increasing MeHg accumulation at higher SeMet concentrations. Under high MeHg treatment (2 ng/L), SeMet concentrations had no effect on diatom MeHg concentrations. Mayfly MeHg concentrations and biomagnification factors (concentration of MeHg in mayflies: concentration of MeHg in diatoms) declined with SeMet addition only in the high MeHg treatment. Mayfly MeHg biomagnification factors decreased from 5.3 to 3.3 in the high MeHg treatment, while the biomagnification factor was constant with an average of 4.9 in the low MeHg treatment. The benefit of reduced MeHg biomagnification was offset by non-lethal effects and high mortality associated with 'protective' levels of SeMet exposure. Mayfly larvae escape behavior (i.e., startle response) was greatly reduced at early exposure days. Larvae took nearly twice as long to metamorphose to adults at high Se concentrations. The minimum number of days to mayfly emergence did not differ by SeMet exposure, with an average of 13 days. We measured an LC50SeMet for mayflies of 3.9 µg Se/L, with complete mortality at concentrations ≥6.0 µg Se/L. High reproductive mortality occurred at elevated SeMet exposures, with only 0-18% emergence at ≥4.12 µg Se/L. Collectively, our results suggest that while there is some evidence that Se can reduce MeHg accumulation at the base of the food web at specific exposure levels of SeMet and MeHg, Se is also toxic to mayflies and could lead to negative effects that extend across ecosystem boundaries.

Acute and Chronic Toxicity of Sodium Nitrate and Sodium Sulfate to Several Freshwater Organisms in Water-Only Exposures.

Elevated nitrate (NO3 ) and sulfate (SO4 ) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO3 and SO4 . The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO3 (tested as NaNO3 ) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO4 (tested as Na2 SO4 ) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO3 median effect concentrations (EC50s) ranged from 189 to >883 mg NO3 -N/L, and chronic NO3 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO3 -N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO3 exposures. Acute SO4 EC50s for the 2 mussel species (2071 and 2064 mg SO4 /L) were similar to the EC50 for the amphipod (2689 mg SO4 /L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO4 /L) were >2-fold lower than the EC20 of the amphipod (1111 mg SO4 /L), indicating the high sensitivity of mussels in chronic SO4 exposures. However, the fathead minnow, with an EC20 of 374 mg SO4 /L, was the most sensitive species in chronic SO4 exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO4 /L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na2 SO4 study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2-fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na2 SO4 toxicity to the minnow. Environ Toxicol Chem 2020;39:1071-1085. © 2020 SETAC.

Influence of remediation on sediment toxicity within the Grand Calumet River, Indiana, USA.

The Grand Calumet River (GCR), located in northern Indiana, is contaminated due to a wide range of historical industrial activities. This study was conducted to determine the influence of sediment remediation within the GCR on concentrations of chemical contaminants and toxicity to sediment-dwelling organisms. Between 2005 and 2016, sediments with high concentrations of metals and toxic organic compounds were remediated through a combination of removal, addition of activated carbon and organoclay amendments, and capping with sand or relatively uncontaminated sediment. Short-term and long-term sediment toxicity tests with the amphipod Hyalella azteca, the midge Chironomus dilutus, and the mussel Lampsilis siliquoidea were conducted with samples collected in 2013, 2015, and 2017, from 29 sites, including both remediated and non-remediated sites. Sediment chemistry and toxicity data for three groups of remediated sites (US Steel, West Branch, and East Branch) were compared to samples from contaminated but unremediated sites and to relatively uncontaminated reference sites. In general, remediated sediments had lower levels of PAHs, PCBs and metals, although sediments from the US Steel area still had elevated levels of PAH, PCB and chromium. Sediments from the three remediated sites and from reference sites showed significantly reduced toxic effects in short-term sediment bioassays, compared to unremediated sites. Variation in the long-term success of remediation may reflect site-specific factors such as the type of remediation and the potential for recontamination from uncontrolled sources.

Sensitivity of Warm-Water Fishes and Rainbow Trout to Selected Contaminants.

Guidelines for developing water quality standards allow U.S. states to exclude toxicity data for the family Salmonidae (trout and salmon) when deriving guidelines for warm-water habitats. This practice reflects the belief that standards based on salmonid data may be overprotective of toxic effects on other fish taxa. In acute tests with six chemicals and eight fish species, the salmonid, Rainbow Trout (Oncorhynchus mykiss), was the most sensitive species tested with copper, zinc, and sulfate, but warm-water species were most sensitive to nickel, chloride, and ammonia. Overall, warm-water fishes, including sculpins (Cottidae) and sturgeons (Acipenseridae), were about as sensitive as salmonids in acute tests and in limited chronic testing with Lake Sturgeon (Acipenser fulvescens) and Mottled Sculpin (Cottus bairdi). In rankings of published acute values, invertebrate taxa were most sensitive for all six chemicals tested and there was no trend for greater sensitivity of salmonids compared to warm-water fish.

Evaluation of chronic toxicity of sodium chloride or potassium chloride to a unionid mussel (Lampsilis siliquoidea) in water exposures using standard and refined toxicity testing methods.

Freshwater mussels are generally underrepresented in toxicity databases used to derive water quality criteria, especially for long-term exposures. Multiple tests were conducted to determine the chronic toxicity of sodium chloride (NaCl) or potassium chloride (KCl) to a unionid mussel (fatmucket, Lampsilis siliquoidea). Initially, a 4-wk NaCl test and a 4-wk KCl test were conducted starting with 2-mo-old mussels in water exposures with and without a thin layer of sand substrate. A feeding study was conducted later to refine test conditions for longer-term 12-wk exposures, and 3 chronic NaCl tests were then conducted following the refined method to assess the influence of test duration (4-12 wk) and age of organisms (starting age ∼1 wk to 2 mo) on mussel sensitivity. Biomass (total dry wt of surviving mussels in a replicate) was generally a more sensitive endpoint compared to survival and growth (length and dry wt). In the 4-wk NaCl or KCl test started with 2-mo-old juveniles, a 20% effect concentration (EC20) based on biomass (264 mg Cl/L from the NaCl test or 8.7 mg K/L from the KCl test) in the exposure with sand was 2-fold lower than the EC20 in the exposure without sand. The longer-term 12-wk NaCl tests started with the 1-wk-old and 2-mo-old juveniles were successfully completed under refined test conditions based on the feeding study, and younger juveniles were more sensitive to NaCl than older juveniles. The NaCl toxicity did not substantially change with extended exposure periods from 4 to 12 wk, although the 4-wk EC20s for biomass were slightly greater (up to 37%) than the 12-wk EC20s in the 2 longer-term exposures. Including the toxicity data from the present study into existing databases would rank fatmucket the most sensitive species to KCl and the second most sensitive species to NaCl for all freshwater organisms. Environ Toxicol Chem 2018;37:3050-3062. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Acute toxicity of sodium chloride and potassium chloride to a unionid mussel (Lampsilis siliquoidea) in water exposures.

Freshwater mussels (order Unionoida) are one of the most imperiled groups of animals in the world. However, many ambient water quality criteria and other environmental guideline values do not include data for freshwater mussels, in part because mussel toxicity test methods are comparatively new and data may not have been available when criteria and guidelines were derived. The objectives of the present study were to evaluate the acute toxicity of sodium chloride (NaCl) and potassium chloride (KCl) to larvae (glochidia) and/or juveniles of a unionid mussel (fatmucket, Lampsilis siliquoidea) and to determine the potential influences of water hardness (50, 100, 200, and 300 mg/L as CaCO3 ) and other major ions (Ca, K, SO4 , or HCO3 ) on the acute toxicity of NaCl to the mussels. From the KCl test, the 50% effect concentration (EC50) for fatmucket glochidia was 30 mg K/L, similar to or slightly lower than the EC50s for juvenile fatmucket (37-46 mg K/L) tested previously in our laboratory. From the NaCl tests, the EC50s for glochidia increased from 441 to 1597 mg Cl/L and the EC50s for juvenile mussels increased from 911 to 3092 mg Cl/L with increasing water hardness from 50 to 300 mg/L. Increasing K from 0.4 to 1.9 mg/L, SO4 from 13 to 40 mg/L, or HCO3 from 44 to 200 mg/L in the 50 mg/L hardness water did not substantially change the NaCl EC50s for juvenile mussels, whereas increasing Ca from 9.9 to 42 mg/L increased the EC50s by a factor of 2. The overall results indicate that glochidia were equally or more sensitive to NaCl and KCl compared with juvenile mussels and that the increased water hardness ameliorated the acute toxicity of NaCl to glochidia and juveniles. These responses rank fatmucket among the most acutely sensitive freshwater organisms to NaCl and KCl. Environ Toxicol Chem 2018;37:3041-3049. © 2018 SETAC. This article is a US government work and, as such, is in thepublic domain in the United States of America.

Primary sources and toxicity of PAHs in Milwaukee-area streambed sediment.

High concentrations of polycyclic aromatic hydrocarbons (PAHs) in streams can be a significant stressor to aquatic organisms. To understand the likely sources and toxicity of PAHs in Milwaukee-area streams, streambed sediment samples from 40 sites and parking lot dust samples from 6 sites were analyzed for 38 parent PAHs and 25 alkylated PAHs. Diagnostic ratios, profile correlations, principal components analysis, source-receptor modeling, and mass fractions analysis were used to identify potential PAH sources to streambed sediment samples, and land-use analysis was used to relate streambed sediment PAH concentrations to different urban-related land uses. On the basis of this multiple lines-of-evidence approach, coal-tar pavement sealant was indicated as the primary source of PAHs in a majority of streambed sediment samples, contributing an estimated 77% of total PAHs to samples, on average. Comparison with the probable effect concentrations and (or) the equilibrium partitioning sediment benchmark indicates that 78% of stream sediment samples are likely to cause adverse effects to benthic organisms. Laboratory toxicity tests on a 16-sample subset of the streambed sites using the amphipod Hyalella azteca (28-d) and the midge Chironomus dilutus (10-d) measured significant reductions in 1 or more biological endpoints, including survival, in 75% of samples, with H. azteca more responsive than C. dilutus. Environ Toxicol Chem 2017;36:1622-1635. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Survival and Growth of Freshwater Pulmonate and Nonpulmonate Snails in 28-Day Exposures to Copper, Ammonia, and Pentachlorophenol.

We performed toxicity tests with two species of pulmonate snails (Lymnaea stagnalis and Physa gyrina) and four taxa of nonpulmonate snails in the family Hydrobiidae (Pyrgulopsis robusta, Taylorconcha serpenticola, Fluminicola sp., and Fontigens aldrichi). Snails were maintained in static-renewal or recirculating culture systems with adults removed periodically to isolate cohorts of offspring for toxicity testing. This method successfully produced offspring for both species of pulmonate snails and for two hydrobiid species, P. robusta and Fluminicola sp. Toxicity tests were performed for 28 days with copper, ammonia, and pentachlorophenol in hard reconstituted water with endpoints of survival and growth. Tests were started with 1-week-old L. stagnalis, 2-week-old P. gyrina, 5- to 13-week-old P. robusta and Fluminicola sp., and older juveniles and adults of several hydrobiid species. For all three chemicals, chronic toxicity values for pulmonate snails were consistently greater than those for hydrobiid snails, and hydrobiids were among the most sensitive taxa in species sensitivity distributions for all three chemicals. These results suggest that the toxicant sensitivity of nonpulmonate snails in the family Hydrobiidae would not be adequately represented by results of toxicity testing with pulmonate snails.

Acute and chronic toxicity of sodium sulfate to four freshwater organisms in water-only exposures.

The acute and chronic toxicity of sulfate (tested as sodium sulfate) was determined in diluted well water (hardness of 100 mg/L and pH 8.2) with a cladoceran (Ceriodaphnia dubia; 2-d and 7-d exposures), a midge (Chironomus dilutus; 4-d and 41-d exposures), a unionid mussel (pink mucket, Lampsilis abrupta; 4-d and 28-d exposures), and a fish (fathead minnow, Pimephales promelas; 4-d and 34-d exposures). Among the 4 species, the cladoceran and mussel were acutely more sensitive to sulfate than the midge and fathead minnow, whereas the fathead minnow was chronically more sensitive than the other 3 species. Acute-to-chronic ratios ranged from 2.34 to 5.68 for the 3 invertebrates but were as high as 12.69 for the fish. The fathead minnow was highly sensitive to sulfate during the transitional period from embryo development to hatching in the diluted well water, and thus, additional short-term (7- to 14-d) sulfate toxicity tests were conducted starting with embryonic fathead minnow in test waters with different ionic compositions at a water hardness of 100 mg/L. Increasing chloride in test water from 10 mg Cl/L to 25 mg Cl/L did not influence sulfate toxicity to the fish, whereas increasing potassium in test water from 1 mg K/L to 3 mg K/L substantially reduced the toxicity of sulfate. The results indicate that both acute and chronic sulfate toxicity data, and the influence of potassium on sulfate toxicity to fish embryos, need to be considered when environmental guidance values for sulfate are developed or refined.

Chronic sensitivity of white sturgeon (Acipenser transmontanus) and rainbow trout (Oncorhynchus mykiss) to cadmium, copper, lead, or zinc in laboratory water-only exposures.

Chronic toxicity of cadmium, copper, lead, or zinc to white sturgeon (Acipenser transmontanus) and rainbow trout (Oncorhynchus mykiss) was evaluated in water-only exposures started with newly hatched larvae or approximately 1-mo-old juveniles. The 20% effect concentration (EC20) for cadmium from the sturgeon tests was higher than the EC20 from the trout tests, whereas the EC20 for copper, lead, or zinc for the sturgeon were lower than those EC20s for the trout. When the EC20s from the present study were included in compiled toxicity databases for all freshwater species, species mean chronic value for white sturgeon was in a relatively low percentile of the species sensitivity distribution for copper (9th percentile) and in the middle percentile for cadmium (55th percentile), zinc (40th percentile), or lead (50th percentile). However, the species mean chronic value for rainbow trout was in a high percentile for copper, lead, and zinc (∼68th-82nd percentile), but in a low percentile for cadmium (23rd percentile). The trout EC20s for each of the 4 metals and the sturgeon EC20s for cadmium or lead were above US Environmental Protection Agency chronic ambient water quality criteria (AWQC) or Washington State chronic water quality standards (WQS), whereas the sturgeon EC20s for copper or zinc were approximately equal to or below the chronic AWQC and WQS. In addition, acute 50% effect concentrations (EC50s) for copper obtained in the first 4 d of the chronic sturgeon test were below the final acute value used to derive acute AWQC and below acute WQS for copper.