The sensitivity of the deepsea species northern shrimp (Pandalus borealis) and the cold-water coral (Lophelia pertusa) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil.

This study investigated the sensitivity of two deepsea species using mortality of northern shrimp (Pandalus borealis) and polyp activity of stony coral (Lophelia pertusa) to dispersant, Corexit 9500 and aromatic hydrocarbons (toluene, 2-methylnaphthalene, phenanthrene) in 96-h tests. Resulting hydrocarbon toxicity data were fit to the Target Lipid Model to generate predictive models and determine species sensitivity. Toxicity of chemically enhanced water accommodated fractions of Alaskan North Slope crude oil (ANS-oil) was also investigated with shrimp using nominal loading, total petroleum hydrocarbons and biomimetic extraction (BE) as oil exposure metrics. Coral were more sensitive to dispersant than shrimp while similar sensitivity was observed for hydrocarbons. Study and literature findings indicate deepsea species exhibit acute sensitivities to dispersant, hydrocarbons and oil that are comparable to pelagic species. Results support use of passive sampling methods to quantify dissolved oil for interpreting oil toxicity tests and suggest models for predicting time-dependence of toxicity warrant re-evaluation.

The sensitivity of a deep-sea fish species (Anoplopoma fimbria) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil.

A predominant concern following oil spills is toxicity to aquatic organisms. However, few data are available on effects in deep-sea cold water fishes. The present study had 3 major objectives. The first was to investigate the relative sensitivity of the deep-sea species Anoplopoma fimbria (sablefish) to acute effects of 3 aromatic compounds (toluene, 2-methylnaphthalene, and phenanthrene), dispersant alone, and chemically enhanced water accommodated fractions (CEWAFs) of Alaskan North Slope crude oil. The second was to determine the critical target lipid body burden (CTLBB) for sablefish by fitting aromatic hydrocarbon toxicity data to the target lipid model (TLM), which then allowed expression of CEWAF exposures in terms of dissolved oil toxic units. The final aim was to apply a passive sampling method that targets bioavailable, dissolved hydrocarbons as an alternative analytical technique for improved CEWAF exposure assessment. The results indicate that sablefish exhibit sensitivity to Corexit 9500 (96-h median lethal concentration [LC50] = 72.2 mg/L) within the range reported for other fish species. However, the acute CTLBB of 39.4 ± 2.1 µmol/goctanol lies at the lower end of the sensitivity range established for aquatic species. The utility of both toxic units and passive sampling measurements for describing observed toxicity of dispersed oil is discussed. The present study is novel in that a new test species is investigated to address the uncertainty regarding the sensitivity of deep-sea fishes, while also employing modeling and measurements to improve exposure characterization in oil toxicity tests. Environ Toxicol Chem 2018;37:2210-2221. © 2018 SETAC.

Effects of roof and rainwater characteristics on copper concentrations in roof runoff.

Copper sheeting is a common roofing material used in many parts of the world. However, copper dissolved from roof sheeting represents a source of copper ions to watersheds. Researchers have studied and recently developed a simple and efficient model to predict copper runoff rates. Important input parameters include precipitation amount, rain pH, and roof angle. We hypothesized that the length of a roof also positively correlates with copper concentration (thus, runoff rates) on the basis that runoff concentrations should positively correlate with contact time between acidic rain and the copper sheet. In this study, a novel system was designed to test and model the effects of roof length (length of roof from crown to the drip edge) on runoff copper concentrations relative to rain pH and roof angle. The system consisted of a flat-bottom copper trough mounted on an apparatus that allowed run length and slope to be varied. Water of known chemistry was trickled down the trough at a constant rate and sampled at the bottom. Consistent with other studies, as pH of the synthetic rainwater decreased, runoff copper concentrations increased. At all pH values tested, these results indicated that run length was more important in explaining variability in copper concentrations than was the roof slope. The regression equation with log-transformed data (R(2) = 0.873) accounted for slightly more variability than the equation with untransformed data (R(2) = 0.834). In log-transformed data, roof angle was not significant in predicting copper concentrations.

Influence of dissolved organic carbon on toxicity of copper to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) in acute and chronic water exposures.

Acute and chronic toxicity of copper (Cu) to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) were determined in water exposures at four concentrations of dissolved organic carbon (DOC; nominally 0.5, 2.5, 5, and 10 mg/L as carbon [C]). Test waters with DOC concentrations of 2.5 to 10 mg C/L were prepared by mixing a concentrate of natural organic matter (Suwannee River, GA, USA) in diluted well water (hardness 100 mg/L as CaCO(3) , pH 8.3, DOC 0.5 mg C/L). Acute median effect concentrations (EC50s) for dissolved Cu increased approximately fivefold (15-72 µg Cu/L) for mussel survival in 4-d exposures and increased about 11-fold (25-267 µg Cu/L) for cladoceran survival in 2-d exposures across DOC concentrations from 0.5 to 10 mg C/L. Similarly, chronic 20% effect concentrations (EC20s) for the mussel in 28-d exposures increased about fivefold (13-61 µg Cu/L for survival; 8.8-38 µg Cu/L for biomass), and the EC20s for the cladoceran in 7-d exposures increased approximately 17-fold (13-215 µg Cu/L) for survival or approximately fourfold (12-42 µg Cu/L) for reproduction across DOC concentrations from 0.5 to 10 mg C/L. The acute and chronic values for the mussel were less than or approximately equal to the values for the cladoceran. Predictions from the biotic ligand model (BLM) used to derive the U.S. Environmental Protection Agency's ambient water quality criteria (AWQC) for Cu explained more than 90% of the variation in the acute and chronic endpoints for the two species, with the exception of the EC20 for cladoceran reproduction (only 46% of variation explained). The BLM-normalized acute EC50s and chronic EC20s for the mussel and BLM-normalized chronic EC20s for the cladoceran in waters with DOC concentrations of 2.5 to 10 mg C/L were equal to or less than the final acute value and final chronic value in the BLM-based AWQC for Cu, respectively, indicating that the Cu AWQC might not adequately protect the mussel from acute and chronic exposure, and the cladoceran from chronic exposure.

Effects of dissolved organic matter and reduced sulphur on copper bioavailability in coastal marine environments.

Copper-induced toxicity in aqueous systems depends on its speciation and bioavailability. Natural organic matter (NOM) and reduced sulphur species can complex copper, influencing speciation and decreasing bioavailability. NOM composition in estuaries can vary, depending on inputs of terrigenous, autochthonous, or wastewater source material. At a molecular level, variability in NOM quality potentially results in different extents of copper binding. The aims of this study were to measure acute copper EC(50) values in coastal marine and estuarine waters, and identify the relationships between total dissolved copper EC(50) values and measured water chemistry parameters proportional to NOM and reduced sulphur composition. This has implications on the development of marine-specific toxicity prediction models. NOM was characterised using dissolved organic carbon (DOC) concentration and fluorescence measurements, combined with spectral resolution techniques, to quantify humic-, fulvic-, tryptophan-, and tyrosine-like fractions. Reduced sulphur was measured by the chromium-reducible sulphide (CRS) technique. Acute copper toxicity tests were performed on samples expressing extreme DOC, fluorescent terrigenous, autochthonous, and CRS concentrations. The results show significant differences in NOM quality, independent of DOC concentration. CRS is variable among the samples; concentrations ranging from 4 to 40 nM. The toxicity results suggest DOC as a very good predictive measure of copper EC(50) in estuaries (r(2)=0.87) independent of NOM quality. Furthermore, for filtered samples, CRS exists at concentrations that would be saturated with copper at measured EC(50), suggesting that while CRS might bind Cu and decrease bioavailability, it does not control copper speciation at toxicologically relevant concentrations and therefore is not a good predictive measure of copper toxicity in filtered samples.

A comparison of the copper sensitivity of six invertebrate species in ambient salt water of varying dissolved organic matter concentrations.

The copper sensitivity of four saltwater invertebrates (the mussel Mytilus galloprovincialis, the oyster Crassostrea virginica, the sand dollar Dendraster excentricus, and the sea urchin Strongylocentrotus purpuratus) was determined experimentally using chronic-estimator embryo-larval test procedures. The effect of sample dissolved organic matter (DOM) content on Cu bioavailability was determined for these species using commonly prescribed test procedures. Comparisons were made among these test results and test results reported previously for two other invertebrate species: the mussel Mytilus edulis and the copepod Eurytemora affinis. All six species exhibited a direct and significant relationship between the sample dissolved organic carbon (DOC; a surrogate measure of DOM) and either the dissolved Cu median lethal concentration (LC50) values or median effect concentration (EC50) values. This relationship is significant even when the DOM has different quality as evidenced by molecular fluorescence spectroscopy. Once normalized for the effects of DOM, the Cu sensitivity of these species from least to most sensitive were E. affinis < D. excitricus < C. virginica approximately S. purpuratus approximately M. edulis approximately M. galloprovincialis. This ranking of species sensitivity differs from the saltwater species sensitivity distribution proposed in 2003 by the U.S. Environmental Protection Agency. These results support the need to account for factors that modify Cu bioavailability in future saltwater Cu criteria development efforts. More specifically, Cu saltwater species sensitivity distribution data will need to be normalized by factors affecting Cu bioavailability to assure that accurate and protective criteria are subsequently developed for saltwater species and their uses.

Evaluation of acute copper toxicity to juvenile freshwater mussels (fatmucket, Lampsilis siliquoidea) in natural and reconstituted waters.

The influence of dissolved organic carbon (DOC) and water composition on the toxicity of copper to juvenile freshwater mussels (fatmucket, Lampsilis siliquoidea) were evaluated in natural and reconstituted waters. Acute 96-h copper toxicity tests werec onducted at four nominal DOC concentrations (0, 2.5, 5, and 10 mg/L as carbon [C]) in dilutions of natural waters and in American Society for Testing and Materials (ASTM) reconstituted hard water. Toxicity tests also were conducted in ASTM soft, moderately hard, hard, and very hard reconstituted waters (nominal hardness 45-300 mg/L as CaCO3). Three natural surface waters (9.5-11 mg/L DOC) were diluted to obtain a series of DOC concentrations with diluted well water, and an extract of natural organic matter and commercial humic acid was mixed with ASTM hard water to prepare a series of DOC concentrations for toxicity testing. Median effective concentrations (EC50s) for dissolved copper varied >40-fold (9.9 to >396 gg Cu/L) over all 21 treatments in various DOC waters. Within a particular type of DOC water, EC50s increased 5- to 12-fold across DOC concentrations of 0.3 to up to 11 mg C/L. However, EC50s increased by only a factor of 1.4 (21-30 gg Cu/L) in the four ASTM waters with wide range of water hardness (52-300 mg CaCO3/L). Predictions from the biotic ligand model (BLM) for copper explained nearly 90% of the variability in EC50s. Nearly 70% of BLM-normalized EC50s for fatmucket tested in natural waters were below the final acute value used to derive the U.S. Environmental Protection Agency acute water quality criterion for copper, indicating that the criterion might not be protective of fatmucket and perhaps other mussel species.

A comparison of the copper sensitivity of two economically important saltwater mussel species and a review of previously reported copper toxicity data for mussels: important implications for determining future ambient copper saltwater criteria in the USA.

Saltwater bivalves of the genus Mytilus are among the most copper sensitive taxa listed in both the current and recently proposed U.S. EPA ambient saltwater copper criteria documents. The copper saltwater quality criteria are somewhat unique in that the criteria were set specifically to protect Mytilus. However, there is considerable uncertainty in the reported taxonomy of Mytilus species in the criteria database and it has recently been demonstrated the copper toxicity to M. galloprovincialis is dependent on the organic matter content of the test water. A review of the toxicity and biogeography literature was conducted to rationalize the existing criteria database. Elimination of some data is suggested due to the uncertainty of test organism genotype. Moreover, due to the lack of reported dissolved organic matter content of the test waters in tests included in the criteria database, it is impossible to determine if the difference in species mean acute values reported in the criteria documents for Mytilus was due to differences in water chemistry or differences in species sensitivity. Experiments were designed and conducted with M. galloprovincialis and M. edulis (genetically confirmed) to determine if copper toxicity is a function of organic matter content for these two species and if there is a significant difference in species copper sensitivity. Results showed that copper toxicity is a function of organic matter concentration for both species and copper sensitivity of each species was statistically similar. Results support the normalization of the saltwater copper criteria database with respect to dissolved organic matter when developing ambient saltwater copper criteria. The USEPA toxicity database would benefit from future testing of M. trossulus and M. californianus.

An assessment of the application factor used to derive the saltwater acute ambient water quality copper criterion.

The basis for all US Environmental Protection Agency (USEPA) acute ambient water quality criteria is the chemical specific final acute value (FAV; an estimate of the concentration of the chemical corresponding to a cumulative probability of 0.05 of acute toxicity values for all genera with which acceptable acute tests have been conducted). The acute criterion for all chemicals is equal to the chemical's FAV divided by an application factor of 2. The intention of dividing the FAV by a factor of 2 is to convert the acute toxicity value to an incipient acute toxicity value, resulting in an acute criterion concentration that will protect against toxic effects to aquatic organisms. In the case of copper (Cu) in saltwater, the FAV is reduced from the normal 0.05 probability to equal to the genus mean acute value (GMAV; the geometric mean of copper effect concentration 50% [EC50] values) of the economically important marine bivalves of the genus Mytilus. Analyses to determine an application factor specific to Mytilus and copper were performed to assess the adequacy of the application factor of 2. An estimate of a dissolved copper application factor that is specific to and protective of Mytilus was determined using the results of sixty-four 48-h embryo survival and shell development copper toxicity tests of natural water samples collected from sites around the United States. A variety of point-estimate effects concentrations (EC1, EC5, EC10, EC20, and chronic values [ChV]) and statistical toxic-effect endpoints (no observed effect concentration [NOEC] and lowest observed effect concentration [LOEC]) were derived from the test results and compared. The most similar toxic effect endpoint estimates were EC1 approximately equal to NOEC, EC10 approximately equal to ChV, and EC20 approximately equal to LOEC. Probabilistic methods were used to determine a specific application factor with a high probability of providing protection. This analysis suggests that an application factor of 1.5 (rather than 2) is adequate to provide a high degree of protection against acute effects of dissolved copper to Mytilus. In context, this translates to an acute saltwater dissolved copper criterion of 6.4 microg Cu/L compared to the current acute criterion of 4.8 microg Cu/L.

Effects of using synthetic sea salts when measuring and modeling copper toxicity in saltwater toxicity tests.

Synthetic sea salts are often used to adjust the salinity of effluent, ambient, and laboratory water samples to perform toxicity tests with marine and estuarine species. The U.S. Environmental Protection Agency (U.S. EPA) provides guidance on salinity adjustment in its saltwater test guidelines. The U.S. EPA suggests using commercial sea salt brands, such as Forty Fathoms (now named Crystal Sea Marinemix, Bioassay Grade), HW Marinemix, or equivalent salts to adjust sample salinity. Toxicity testing laboratories in Canada and the United States were surveyed to determine synthetic sea salt brand preference. The laboratories (n = 27) reported using four brands: Crystal Sea Marinemix (56%), HW Marinemix (22%), Instant Ocean (11%), and Tropic Marin (11%). Saline solutions (30 g/L) of seven synthetic sea salts were analyzed for dissolved copper and dissolved organic carbon (DOC) content. Brands included those listed above plus modified general-purpose salt (modified GP2), Kent Marine, and Red Sea Salt. The synthetic sea salts added from < 0.1 to 1.2 microg Cu/L to the solution. Solutions of Crystal Sea Marinemix had significantly elevated concentrations of DOC (range = 5.4-6.4 mg C/L, analysis of variance, Tukey, alpha = 0.05, p < 0.001) while other brands generally contained < 1.0 mg C/L. The elevated DOC in Crystal Sea Marinemix was expected to reduce copper toxicity. However, the measured dissolved copper effective concentration 50% (EC50) for Crystal Sea Marinemix was 9.7 microg Cu/L, similar to other tested sea salts. Analysis indicates that the organic matter in Crystal Sea Marinemix differs considerably from that of natural organic matter. On the basis of consistently adding little DOC and little dissolved copper, GP2 and Kent Marine are the best salts to use.

Assessment of aquatic ecological risk and site-specific criteria of copper in San Francisco Bay, California, USA.

A new regression-based copper toxicity model was applied in a case study of San Francisco Bay, California, USA, to demonstrate its utility in estimating risk and site-specific water quality criteria. This was accomplished using probabilistic techniques and a simple model relating dissolved organic carbon (DOC) concentrations with the toxicity of dissolved copper to embryos of the most copper sensitive taxon (Mytilus) in the US Environmental Protection Agency's (USEPA) water quality criteria database. Similar probabilistic techniques were applied to data developed for San Francisco Bay using the USEPA's water-effect ratio (WER) methods for comparison with the DOC-based method. Based on 595 site- and date-specific DOC model observations at 26 sites in San Francisco Bay, none suggested risk of chronic toxicity. Safety factors (1/risk quotient) on average across all sites ranged from 2.4 to 9.1. Comparisons were made between 1) estimates of site-specific criteria made using the DOC method, 2) estimates of site-specific criteria made using the WER method, 3) USEPA national and California Toxics Rule criteria, and 4) region-specific criteria recommended for regulatory implementation by the Clean Estuary Partnership. The DOC- and WER-based methods indicated that copper criteria for San Francisco Bay could be increased above USEPA and California Toxics Rule criteria and will retain the level of protection (> or =97%) embodied in the USEPA copper saltwater water quality criteria. The DOC method overall was more conservative (i.e., implies the need for lower criteria in the Bay) than the WER method. The DOC method suggests that the region-specific criteria being recommended for regulatory implementation would be underprotective in some areas and yet could be increased and remain protective in other areas of San Francisco Bay.

Probability-based estimates of site-specific copper water quality criteria for the Chesapeake Bay, USA.

The object of this study was to estimate site- and region-specific dissolved copper criteria for a large embayment, the Chesapeake Bay, USA. The intent is to show the utility of 2 copper saltwater quality site-specific criteria estimation models and associated region-specific criteria selection methods. The criteria estimation models and selection methods are simple, efficient, and cost-effective tools for resource managers. The methods are proposed as potential substitutes for the US Environmental Protection Agency's water effect ratio methods. Dissolved organic carbon data and the copper criteria models were used to produce probability-based estimates of site-specific copper saltwater quality criteria. Site- and date-specific criteria estimations were made for 88 sites (n = 5,296) in the Chesapeake Bay. The average and range of estimated site-specific chronic dissolved copper criteria for the Chesapeake Bay were 7.5 and 5.3 to 16.9 microg Cu/L. The average and range of estimated site-specific acute dissolved copper criteria for the Chesapeake Bay were 11.7 and 8.3 to 26.4 microg Cu/L. The results suggest that applicable national and state copper criteria can increase in much of the Chesapeake Bay and remain protective. Virginia Department of Environmental Quality copper criteria near the mouth of the Chesapeake Bay, however, need to decrease to protect species of equal or greater sensitivity to that of the marine mussel, Mytilus sp.

Acute toxicity of copper to the threespine stickleback, Gasterosteus aculeatus.

This study focuses on characterizing the acute toxicity of copper in freshwater to the threespine stickleback, Gasterosteus aculeatus, a small and widely distributed euryhaline fish. The threespine stickleback is used as an effluent monitoring species in both Canada and the United States, yet in some locations natural populations are listed as threatened or endangered. Four 96-h static renewal acute toxicity tests were performed in moderately hard water using U.S. EPA methods with adult fish (mean wet weight = 0.41 g/fish). The geometric mean of the 24-, 48-, 72- and 96-h LC(50)s based on measured concentrations of total copper (estimated dissolved copper in parentheses) in the test solutions were 382.2 (366.9), 278.7 (267.6), 256.6 (246.3), and 227.2 (218.1) microg Cu/L, respectively. Conservative estimates of acute toxicity thresholds, made using LC1 values, for adult threespine sticklebacks over 24-, 48-, 72- or 96-h exposure periods in moderately hard water are approximately 114.3 (109.7), 78.3 (75.2), 67.0 (64.3), and 52.4 (50.3) microg Cu/L, respectively. Test results were normalized to a range of water hardness from very soft to very hard using two U.S. EPA methods, the water hardness and the Biotic Ligand Model normalization procedures. Subsequently, interspecies sensitivity comparisons were made with aquatic animal species used in both the current and proposed U.S. EPA copper water quality criteria documents. Information reported in this study may be useful in effluent toxicity identification evaluations, ecological risk assessments and criteria development where copper is a concern.

Effects of dissolved organic carbon on copper toxicity: implications for saltwater copper criteria.

During the past three decades, significant advances have been made in understanding how environmental factors modify the bioavailability and the toxicity of metals such as copper in aquatic environments. Several of these advances have led to the development of guidelines to indirectly account for modifying factors, adjustment of criteria on a site-specific basis, and direct changes to the U.S. Environmental Protection Agency (U.S. EPA) freshwater quality criteria. To date, most of this effort has focused on freshwater systems, although similar modifying factors exist in marine environments as well. This paper focuses on one such modifying factor, dissolved organic carbon (DOC), and describes a method to aid in risk assessments or to refine the saltwater copper criteria on a site-specific basis. The relationship between DOC and toxicity of copper to the most sensitive saltwater genus in the U.S. EPA criteria database, Mytilus, is extensively analyzed. Dissolved copper 50% effective concentrations (EC50s) are highly correlated (r2 = 0.71, n=54, p < 0.001) across a wide range of sample DOC concentrations (0.3-10 mg carbon [C]/L) and are explained by the equation EC50 = 11.53DOC(0.54). Two equations based on DOC are proposed for consideration as a means for deriving site-specific final chronic criteria (FCC) and final acute criteria (FAC) for copper in marine and estuarine environments (Copper FCC(DOC) = 3.71DOC(0.54) and Copper FAC(DOC) = 5.843DOC(0.54).