Preliminary Observations on Responses of Embryonic and Larval Pacific Herring, Clupea pallasi, to Neutral Fraction Biodegradation Products of Weathered Alaska North Slope Oil

Weathered Alaska North Slope crude oil (ANS 521) was subjected to biodegradation in vigorously stirred incubations for 14 days at 15 ± 1°C in 20‰ salinity sterilized seawater, amended with nutrients and inoculated with a hydrocarbon-degrading microorganism (EI2V) isolated from an oil-contaminated beach in Prince William Sound, Alaska. A total of 13.7 mg/L water-soluble neutral fraction (WSF) was recovered from the incubation of weathered ANS 521. Toxicity/teratogenicity tests were conducted with WSF recovered from the biodegradation system using embryonic and larval Pacific herring, Clupea pallasi. Exposures were begun at 4, 48, and 96 h postfertilization of herring eggs. Exposure concentrations were 1, 10, and 100% of the original concentration of WSF recovered from incubations (redissolved in 20‰ salinity sterile seawater at 15 ± 1°C). Sterile 20‰ salinity seawater without the addition of redissolved neutral fraction was used as a control. Significant (p ≤ 0.05) embryo mortality or teratogenic responses were observed at WSF concentrations of 10 and 100%. On days 5 through 8 of embryogenesis, counts of heart contraction rates were significantly lower (p ≤ 0.05) at the 100% WSF concentration for embryos exposed beginning at 4 and 48 h postfertilization. Grow-out of larvae from selected exposures was conducted. High mortality was noted in larvae exposed to the 10% WSF concentration beginning at 4 and 48 h postfertilization. Most of these larvae died 5 to 8 days after hatching when they elicited vertebral displacements at a time concurrent with the onset of feeding behavior. Received: 30 May 1997/Accepted: 9 September 1997     

Effects of Fractions from Biodegraded Alaska North Slope Crude Oil on Embryonic Inland Silversides, <Emphasis Type="Italic">Menidia beryllina</Emphasis>

Embryonic inland silversides, Meinida beryllina, were exposed to neutral, water-soluble fractions (WSFs) resulting from microbial degradation of artificially weathered Alaska North Slope (ANS) crude oil. Three individual microbes obtained from Prince William Sound, Alaska, and designated Phe#6 (enriched on phenanthrene), Hexaco#2 (enriched on the straight-chain alkane, hexacosane), and EI2V (grown by enrichment on Bushnell-Haas medium containing 0.2% pristane, a branched alkane) were used to individually biodegrade weathered ANS crude oil for 14 days in darkness in 20-L glass carboys containing nutrient enriched, sterilized 20‰ salinity sea water at 20 ± 1°C. Neutral WSFs resulting from biodegradation of ANS (lot 521) by each microbe were recovered and weighted. Neutral WSFs recovered were: 1.76 mg/L for Phe#6, 1.85 mg/L for Hexaco#2, and 13.02 mg/L for the EI2V microbe. Embryo toxicity and teratogenicity tests revealed that exposure of embryos to the WSFs from the EI2V incubation (with a total recovered neutral fraction approximately seven times greater than the Phe#6 and Hexaco#2 incubations) resulted in the most severe responses in craniofacial, cardiovascular, and skeletal organ systems. The total neutral WSFs recovered from the EI2V biodegradation of weathered ANS 521 were subfractionated into saturated (eluted with hexane), aromatic (eluted with CH₂Cl₂), polar (eluted with ethyl ether), and recombined (saturated + aromatic + polar) fractions. Developing fish embryos were then exposed to each subfraction and the recombined subfractions. The polar subfraction and recombined subfractions proved to be the most embryo toxic and teratogenic. They resulted in statistically significant (p ≤ 0.05) responses (compared to controls) for craniofacial, cardiovascular, skeletal, and total severity effects in one or both tests with these subfractions. Received: 14 June 2001/Accepted: 26 August 2001     

Responses of embryonic and larval inland silversides, Menidia beryllina, to a water-soluble fraction formed during biodegradation of artificially weathered Alaska North Slope crude oil

Weathered Alaska North Slope crude oil (ANS 521) was stirred for 2 and 14 days in 20 salinity sterile seawater or for 14 days in seawater with nutrients and a group of three (GO3) microorganisms from Prince William Sound, Alaska, that were capable of biodegrading hydrocarbons. A total of 0.65 and 0.69 mg/L water soluble fraction (WSF) of neutral fraction hydrocarbons was recovered from the 2- and 14-day stirred sterile systems, respectively. In comparison, a total of 7.5 mg/L WSF neutral fraction hydrocarbons was recovered from systems containing ANS 521 that were stirred and biodegraded by the GO3 microbes for 14 days. Toxicity/teratogenicity tests were conducted with neutral fraction hydrocarbons recovered from the sterile and biodegraded systems using embryonic inland silversides, Menidia beryllina. Hydrocarbons from the sterile systems did not cause statistically significant teratogenic responses at concentrations of 1%, 10%, and 100% (w/v) of recovered fractions (redissolved in 20 salinity sterile seawater). Counts of heart contraction rates were significantly lower (0.05) at the 100% WSF concentration of hydrocarbons on days 5 and 6 of embryogenesis. In contrast, recovered and redissolved neutral fraction hydrocarbons from ANS 521, that were biodegraded for 14 days, caused statistically significant (0.05) teratogenic responses at the 1, 10, and 100% WSF concentrations. Measurement of heart contraction rates showed statistically significant (0.05) reductions at the 100% WSF concentration on days 2 through 6 of embryogenesis, compared to controls.Contribution No. 934 from the Gulf Breeze Environmental Research Laboratory. Mention of trade names does not imply endorsement by the U.S. Environmental Protection Agency.     

Toxicity of Crude Oil to Fresh Water Shrimp, <Emphasis Type="Italic">Macrobrachium macrobrachion</Emphasis> and <Emphasis Type="Italic">Macrobrachium vollenhovenii</Emphasis> From Nigerian Coastal Water

The water soluble fraction (WSF) of crude oil was tested against Macrobrachium macrobrachion and Macrobrachium vollenhovenii, at 2, 4, 6, 8 and 10 mg/L in glass aquaria stocked with ten animals for 96 h under observations for changes. Moribund swimming, restlessness, respiratory difficulties, depigmentation and mortalities were observed in the WSF exposure groups, but not in the controls. LC₅₀ values were estimated at 5 ± 1.76 and 4 ± 1.76 mg/L for M. macrobrachion and M. vollenhovenii respectively. There was no significant difference in mortalities between the two species (p > 0.05), leading to the conclusion that the WSF of crude oil in the Nigerian coastal waters may be equally toxic to M. macrobrachion and M. vollenhovenii.     

Effects of an herbicide and insecticide mixture in aquatic mesocosms

A 1.8 m×2.5 cm reciprocating-plate countercurrent extraction column was evaluated for the preparation of WSF (water-soluble fractions) from Flotta North Sea light crude oil. The energy input from the plate reciprocation speeds was found to be the main factor affecting the characteristics of the extracted WSF, and the throughputs of the stock solution or the ratio of seawater to crude oil had little effect on the concentration and composition of the extracted WSF. A combination of a reciprocation speed of 170 strokes/min, a seawater flow rate of 220 ml/min, and a crude oil flow rate of 2.9 ml/min produced a WSF stock solution with a total hydrocarbon concentration of 13.5±0.30 mg/kg (n=6) which was more reproducible than that made by a previously used large-scale batch extraction method. A settlement time of 5 h or less for the stock solution allowed a full separation of any dispersed droplets of crude oil from the aqueous phase under the above conditions, but further increases in reciprocation speeds caused difficulties in the final separation of this crude oil. The column extraction method was highly reproducible and gave a more concentrated WSF containing a higher proportion of alkanes than a WSF made by the batch extraction method. Low-boiling aromatics were the main components of the total extracted hydrocarbons of the WSF.     

Embryotoxicity of weathered crude oil from the Gulf of Mexico in mallard ducks (Anas platyrhynchos)

Weathered crude oil in the Gulf of Mexico can result from oil spills such as the Deepwater Horizon incident that occurred on April 20, 2010 or from natural seeps. Adult waterbirds of the Gulf Coast region may become exposed to weathered crude oil while foraging, wading, or resting, and residues can then be transferred to nests, eggs, and hatchlings. Although the toxicity of many types of crude oil to avian embryos has been thoroughly studied, the effects of weathered crude oil on developing avian embryos are not well characterized. The objective of the present study was to examine embryotoxicity of weathered crude oil collected from the Gulf of Mexico in June 2010 using mallard ducks (Anas platyrhynchos) as a model species. Weathered crude oil was applied to fertilized mallard duck eggs by paintbrush in masses ranging from 0.1 to 99.9?mg on day 3 of incubation. Mortality occurred as early as day 7 and the conservatively derived median lethal application of weathered crude oil was 30.8?mg/egg (0.5?mg/g egg) or 30.7?μl/egg (0.5?μl/g egg). Body mass, liver and spleen mass, crown-rump and bill lengths, and frequency of deformities were not significantly different among hatchlings from oiled and control eggs. In comparison to published reports of fresh crude oil embryotoxicity, weathered crude oil was considerably less toxic. We conclude that avian toxicity varies according to the degree of crude oil weathering and the stage of embryonic development at the time of exposure. Results indicate bird eggs exposed to weathered crude oil from the Gulf of Mexico during summer 2010 may have had reduced hatching success.     

Changes in the physical condition of Meretrix casta exposed to water-soluble fractions of refined and crude oil

Meretrix casta were exposed to water-soluble fractions (WSF) of diesel, engine oil (Servo 30), and Kuwait crude, for a period of 30 days and changes in their wet weight, percentage dry weight and condition index were observed. No significant alteration in shell growth was noted during the experimental period but clams treated with 1.22 mg/L (0.5 Sublethal Toxic Unit) and 2.34 mg/L (1.0 S.T.U.) WSF of diesel; 1.93 mg/L (1.0 S.T.U.) WSF of engine oil and 3.18 mg/L (1.0 S.T.U.) WSF of crude, were noted to lose dry weight faster than wet weight when compared to control animals. Changes in the condition index of both controls and experimental forms were directly proportional to dry weight. Mortalities of 30% and 5% were noticed among diesel and engine oil-treated animals, respectively, indicating a definite stress experienced by these animals when compared to crude treated forms.     

Morphological and Neurotoxicological Findings in Tropical Freshwater Fish (<Emphasis Type="Italic">Astyanax</Emphasis> sp.) After Waterborne and Acute Exposure to Water Soluble Fraction (WSF) of Crude Oil

The water-soluble fraction (WSF) of crude oil is a complex highly volatile and toxic mixture of hydrocarbon chains (polyaromatics, heterocyclics), phenols, and heterocyclic compounds containing nitrogen and sulfur. To evaluate the toxic effects of WSF in tropical freshwater teleosts and to develop methodologies that could investigate the toxic mechanisms of WSF in tropical organisms, an acute toxicity experiment was conducted with Astyanax sp. Three dilutions (15%, 33%, and 50%) of WSF obtained from Campos Bays crude oil (Brazil) were used to study morphological and biochemical responses of the fish. Prior to exposure, the distribution and rate of volatilization of the WSF into each aquarium for the same exposure period was quantified by spectrofluorimetry. Five individuals of Astyanax sp. were exposed to duplicate WSF of 0, 15, 33, and 50% for each of 12-, 24-, and 96-h exposures for a total of 120 individuals. Liver and gills were sampled from five fish from each treatment and were analyzed by histology, scanning and transmission electron microscopy. A fragment of muscle was also collected from each fish to measure acetylcholinesterase activity. Water analysis showed that only 4 h after dilution, an important loss of hydrocarbons in 33% and 50% of WSF was observed. In addition, 50% of hydrocarbon mass was lost in all tested dilutions after 24 h with significant difference for the 50% WSF at all measured times, demonstrating the high volatility of WSF in freshwater. Damage in the liver and the gills included the presence of necrosis, loss of hepatocytes limit, inflammation areas, cellular proliferation, aneurysms, and disorganization of the second lamellae. The 33% WSF significantly reduced acetylcholinesterase activity in fish. Our study demonstrated that the WSF of crude oil caused damage in organs and tissues of tropical freshwater Astyanax sp. and provided also the basis for a better understanding of the toxic mechanisms of WSF in freshwater fishes.     

Toxicity evaluation of a commercial bioremediation agent mixed with crude oil

The toxicity and efficacy of a bacteria-based commercial bioremediation agent (CBA) was assessed through bioassays with juvenile inland silverside minnows, Menidia beryllina, and flask studies of oil degradation. Addition of the CBA to weathered Alaska, USA North Slope crude oil (ANS-521) prior to testing increased toxicity of the water-soluble fraction (WSF) of the oil in both chronic (growth) and acute (mortality) toxicity tests. Time-course toxicity assessment of the water-soluble fraction of the CBA/oil combination indicated increases in effect after 7 to 14 d of mixing that coincided with elevated concentrations of both alkanes and aromatics in the WSF. Under controlled laboratory conditions, the CBA significantly enhanced degradation of the oil compared with a treatment with nutrients alone. The alkane fraction was degraded by nearly 100% over a 42-d period while the aromatic fraction was decreased by 70%. While toxicity testing is not currently required to list bioremediation agents on the product schedule of the National Oil and Hazardous Substances Pollution Contingency Plan, the potential interaction between bioremediation agents and oil should be further investigated and listing requirements reassessed as necessary. Recommendations for future investigations of this issue include characterization of temporal trends in toxicity of CBA and oil mixtures, use of multiple test methods (battery testing) when evaluating toxicity, comparative evaluations of indigenous versus product-derived microorganisms in efficacy studies, and the use of a comparable oil between studies to facilitate comparison of efficacy and toxicity data for different products.     

Toxicity,Uptake, and Release of the Water-Soluble Fraction of Crude Oil in Different Developing Stages of the Prawn <Emphasis Type="Italic">Macrobrachium borellii</Emphasis>

The effects of a water-soluble fraction of light crude oil dissolved in freshwater (WSF) on Macrobrachium borellii exposed at three life stages was evaluated. Adults, larvae (PL), and embryos were exposed to five levels of WSF for 96 h. At 48 and 72 h PL were significantly more sensitive to WSF than adults, though values for 96-h LC50 were not significantly different (1.56 and 1.41 mg/L, respectively). Mortality was never high enough to allow LC50 calculation in embryos, but chronic exposure to WSF increased the mortality near hatching and significantly decreased PL survival compared to the control group. The uptake, accumulation, and depuration of WSF were evaluated in adult prawns (lipid content 1.5% wet wt) exposed to a sublethal concentration for 96 h followed by a 10-d depuration period. Hydrocarbons were rapidly taken up, and after 24 h most of them reached an equilibrium concentration. Increases in the number and alkylation of the aromatic rings enhanced both their accumulation and their retention. When returned to clean freshwater, levels of lighter aromatics dropped rapidly over 12 h. From these studies we conclude that early life stages of M. borellii are not very vulnerable to WSF toxicity, while adults have a rapid uptake and release of most of the contaminating hydrocarbons, probably due to their low lipid levels.     

Ecotoxicity Assessment of Contaminated Dredged Material with the Marine Amphipod Corophium volutator

The incorporation of toxicological data from bioassays can improve the present system of sediment quality criteria in the Netherlands. The use of acute lethality toxicity tests alone does not however provide sufficient discrimination and sensitivity for predicting ecological effects of slightly and moderately contaminated dredged material. Sublethal endpoints are needed for the assessment of environmental hazards of such dredged material. In this study, two approaches were used to identify toxicity of marine sediments collected from 16 locations classified as “slightly and moderately contaminated” on the basis of chemical data: (1) a comparison of growth vs. mortality as different endpoints in the marine amphipod Corophium volutator (Pallas); (2) an investigation on the use of sediment dilutions to characterize the degree of toxicity. The influence of sediment storage time on toxicity was also evaluated. In four out of 16 locations, mortality over 10 days of exposure ranged 80–100%; in two out of 16 locations mortality ranged 40–60%. In the other 10 locations, mortality was below 15%. Results on growth showed that in all locations final dry weight values were significantly lower (a factor of 1.5 to 3) than in controls. Results of dilution experiments showed that if sediments were diluted with a reference sediment of similar physicochemical characteristics, total concentrations of metals, mineral oil, and PAHs decreased as expected and so did the effects on C. volutator. In the 100% contaminated sediments growth was reduced by 32–60% compared to controls. The dilution rate necessary to reduce toxicity to the EC₁₀ value for growth of C. volutator was considered an appropriate endpoint for the evaluation. When sediments were stored for a period of 3–5 months at 4°C and retested, effects on mortality and growth decreased, although some effects on growth were still measured after 5 months of storage. The experiments illustrate the usefulness of ecotoxicity assessment to evaluate contaminted dredged material. Received: 10 March 1997/Accepted: 6 November 1997     

Toxicity of Herbal Pharmaceutical Wastewater to a Freshwater Crustacean <Emphasis Type="Italic">Ceriodaphnia dubia</Emphasis>

The main objective of this study was to evaluate the acute toxicity of raw, neutralized and physico-chemically treated and biologically treated effluent of herbal pharmaceutical industry. The acute toxicity test was determined using freshwater crustacean Ceriodaphnia dubia under laboratory conditions. LC₅₀ values for raw, neutralized and physico-chemically treated effluent for 12, 24, 36 and 48 h ranged between 3.0–4.5%, 3.9–10.8% and 22–28% respectively. It is evident from the results that physicochemical treatment reduced the toxicity by around 25% while biological treatment reduced the toxicity completely. Results subjected to statistical evaluation depicted regression coefficient of more than 0.9 indicating good correlation between the mortality rate and effluent concentrations.     

Comparative toxicity of oil, dispersant, and oil plus dispersant to several marine species

Dispersants are a preapproved chemical response agent for oil spills off portions of the U.S. coastline, including the Texas-Louisiana coast. However, questions persist regarding potential environmental risks of dispersant applications in nearshore regions (within three nautical miles of the shoreline) that support dense populations of marine organisms and are prone to spills resulting from human activities. To address these questions, a study was conducted to evaluate the relative toxicity of test media prepared with dispersant, weathered crude oil, and weathered crude oil plus dispersant. Two fish species, Cyprinodon variegatus and Menidia beryllina, and one shrimp species, Americamysis bahia (formerly Mysidopsis bahia), were used to evaluate the relative toxicity of the different media under declining and continuous exposure regimes. Microbial toxicity was evaluated using the luminescent bacteria Vibrio fisheri. The data suggested that oil media prepared with a chemical dispersant was equal to or less toxic than the oil-only test medium. Data also indicated that continuous exposures to the test media were generally more toxic than declining exposures. The toxicity of unweathered crude oil with and without dispersant was also evaluated using Menidia beryllina under declining exposure conditions. Unweathered oil-only media were dominated by soluble hydrocarbon fractions and found to be more toxic than weathered oil-only media in which colloidal oil fractions dominated. Total concentrations of petroleum hydrocarbons in oil-plus-dispersant media prepared with weathered and unweathered crude oil were both dominated by colloidal oil and showed no significant difference in toxicity. Analysis of the toxicity data suggests that the observed toxicity was a function of the soluble crude oil components and not the colloidal oil.     

Embryotoxicity and Biotransformation Responses in Zebrafish Exposed to Water-Soluble Fraction of Crude Oil

The toxic effects of water-soluble fraction (WSF) of crude oil (API27, Petrobras Campos Basin, Brazil) were evaluated during the early life stages of zebrafish, as well as its biotransformation in juvenile fish. Embryonic development was studied during 96 h. Reduced heartbeat rate, weak pigmentation, tail defects, and embryo mortality were observed for all of the tested concentrations of the WSF. Activities of the biotransformation enzymes were induced at the highest concentrations, showing that these enzymes played a role in its elimination. As shown in this study the crude oil WSF altered the normal embryonic development of fish.     

Toxicity and Pathogenicity Testing of the Insect Pest Control Fungus Metarhizium anisopliae

Renewed interest in the use of Metarhizium anisopliae and its toxins for insect control prompted the following safety assessment. A neutral extract (methylene chloride, pH 7.2), derived from M. anisopliae cultures, was evaluated for toxicity and mutagenicity using aquatic animal bioassays and the Ames test. The average LC₅₀ of the neutral extract obtained in static, acute 96-h tests conducted with ≤24-h-old Mysidopsis bahia was 2.41 mg L⁻¹. By partially purifying destruxins from the neutral extract, it was shown that destruxins alone were not responsible for the observed toxicity in mysids. The neutral extract was fetotoxic to developing grass shrimp, Palaemonetes pugio, and frog, Xenopus laevis, embryos; the LC₅₀ values were 52 and 32 mg L⁻¹, respectively. Eye spot abnormalities were observed in shrimp and frog embryos exposed to the neutral extract. In extract-exposed frog embryos, moderate to severe cranial, facial, and gut malformations were also observed. The neutral extract was toxic to juvenile mosquito fish, Gambusia affinis, at an LC₅₀ value of 141 mg L⁻¹. Adult female G. affinis surviving a 24-h exposure to 200 μg ml⁻¹ of the neutral extract produced healthy broods. After 3 months, no mortalities or adverse effects were observed in adult G. affinis fed a diet partially composed of a freeze-dried M. anisopliae culture. The neutral extract did not show mutagenicity in the Ames test using strains TA98 and TA100 with and without metabolic activation by rat liver S9. Significant (p  ≤ 0.05) mortalities were obtained when embryos of grass shrimp and inland silverside fish, Menidia beryllina, were exposed to the same lot of M. anisopliae conidiospores. Exposure of frog embryos to M. anisopliae conidiospores did not cause significant (p > 0.05) mortalities or malformations. Received: 31 October 1997/Accepted: 5 February 1998     

Bioaccumulation of Phenol,Guaiacol and Some Chlorophenols by Selected Freshwater Species of Leeches

In the recent study, the bioaccumulation ability of phenolic substances was determined with field-collected specimens of three leech species, i.e., Erpobdella octoculata (Linnaeus), Theromyzon tessulatum (O. F. Műller) and Glossiphonia complanata (Linneaus). It was found that the examined leeches bioaccumulated phenol (0.03–27.10 mg/kg), 4-methylphenol (0.09–1.83 mg/kg), chlorophenols (0.03–14.90 mg/kg), guaiacol (0.22–2,941 mg/kg), tetrachloroguaiacol (0.06–1.98 mg/kg), 3-chlorosyringol (0.04–15.28 mg/kg) and chlorocatechols (0.33–23.24 mg/kg) present in the water (0.03–25.23 μg/L) and in the bottom sediments (0.75–760.5 μg/kg) of three ecosystems that were characterized by different contamination levels. Analysis of both the external mucous coat of the leeches and the tissue of the dermato-muscular sac showed that substantial quantities of the phenolic compounds may be accumulated in both the mucous (0.03–2,941 mg/kg) and the tissue (0.03–1,189.8 mg/kg).     

Bioaccumulation and Hepatic Speciation of Copper in Rainbow Trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) During Chronic Waterborne Copper Exposure

To protect cells from toxicity, metal-sensitive cellular compartments must be insulated against essential but toxic metals [such as copper (Cu)] accumulated in excess of metabolic requirements. We measured Cu concentrations at the organ and hepatic subcellular levels in juvenile rainbow trout (Oncorhynchus mykiss) during exposure to sublethal waterborne Cu (40 μg/L) for 21 days. There was a time-dependent accumulation of Cu in the gill, liver, plasma, and carcass, with significant difference in Cu-exposed fish relative to the controls being evident by day 7. This significant accumulation of Cu was not associated with impaired growth. Copper concentrations in purity-tested liver subcellular fractions normalized to the liver protein concentration were in decreasing order: organelles > heat-stable proteins > nuclei-debris > NaOH-resistant granules > heat-labile proteins. As a proportion of the total, the majority of the hepatocellular Cu burden (60–68%) was associated with a metabolically active pool (organelles, nuclei-debris, and heat-stable proteins) and the remainder (32–40%) was associated with a metabolically detoxified pool (heat-stable proteins and NaOH-resistant granules) irrespective of the Cu-exposure regime. Because Cu concurrently accumulated in metabolically active and detoxified pools, we conclude that the spillover hypothesis of metal toxicity did not hold under the exposure conditions employed in this study. Moreover, these data suggest that rainbow trout can withstand significant above-background Cu accumulation in hepatic putative metal-sensitive compartments without chronic toxic effects at the organism level.     

Aryl hydrocarbon receptor-independent toxicity of weathered crude oil during fish development

Polycyclic aromatic hydrocarbons (PAHs), derived largely from fossil fuels and their combustion, are pervasive contaminants in rivers, lakes, and nearshore marine habitats. Studies after the Exxon Valdez oil spill demonstrated that fish embryos exposed to low levels of PAHs in weathered crude oil develop a syndrome of edema and craniofacial and body axis defects. Although mechanisms leading to these defects are poorly understood, it is widely held that PAH toxicity is linked to aryl hydrocarbon receptor (AhR) binding and cytochrome P450 1A (CYP1A) induction. Using zebrafish embryos, we show that the weathered crude oil syndrome is distinct from the well-characterized AhR-dependent effects of dioxin toxicity. Blockade of AhR pathway components with antisense morpholino oligonucleotides demonstrated that the key developmental defects induced by weathered crude oil exposure are mediated by low-molecular-weight tricyclic PAHs through AhR-independent disruption of cardiovascular function and morphogenesis. These findings have multiple implications for the assessment of PAH impacts on coastal habitats.     

Toxicity of Metals to the Bivalve Tellina deltoidalis and Relationships Between Metal Bioaccumulation and Metal Partitioning Between Seawater and Marine Sediments

The Australian benthic bivalve Tellina deltoidalis tolerates a wide range of sediment and water conditions, is easy to handle in the laboratory, and is a useful species for undertaking whole-sediment toxicity tests. The sensitivity of T. deltoidalis to metals was investigated in 10-day metal-spiked sediment exposures for Cd, Cu, Ni, Pb, and Zn and in water-only exposures for Cu and Zn. The survival of T. deltoidalis in 10-day exposures to metal-spiked sediments was 88–100% for Cd, Ni, Pb, and Zn concentrations of 75, 420, 1,000, and 4,000 mg/kg, respectively. The 4-day LC₅₀s for dissolved Cu and Zn were 0.18 and 13 mg/L, respectively. The 8-day LC₅₀ for Cu was 31 (24–34) μg/L. Cu and Zn concentrations in the tissues of T. deltoidalis increase linearly with increasing dissolved exposure concentration. In the Cu-spiked sediment and water exposures, the survival was negatively correlated with the Cu concentration in both the overlying water and in the tissues of T. deltoidalis. In contrast, particulate Cu concentrations were found to be a poor predictor of Cu bioaccumulation and toxicity for Cu-spiked sediments.     

Weathered crude oil effects on chicks of Fork-Tailed Storm-Petrels (Oceanodroma furcata)

Adult Storm-Petrels had between 0.004 and 0.0008 ml of fossil fuel hydrocarbons present in their food samples when they were considered contaminated. Chicks of Fork-Tailed Storm-Petrels (Oceanodroma furcata) were fed 0.1 ml of weathered Prudhoe Bay crude oil, which should be close to the maximum dose they might receive at a feeding. Chicks dosed orally once, twice, or weekly with 0.1 ml weathered Prudhoe Bay crude oil did not differ significantly in gross morphology, bill, tarsus, or wing growth from control chicks. Chicks dosed one time gained weight between the ages of 0–21 days at significantly slower rates. Chicks aged 22–51 days grew similarly regardless of treatment.Dosed chicks fledged on average two days later than control chicks. Ingesting small amounts of weathered oil had little effect perhaps because Storm-Petrels may be able to ingest long-chained hydrocarbons (like petroleum) with relative impunity, because these compounds are relatively nontoxic and are part of their normal diet.