Renée Katrin Bechmann

Bioconcentration, biotransformation, and elimination of polycyclic aromatic hydrocarbons in sheepshead minnows (Cyprinodon variegatus) Exposed to Contaminated Seawater

Sheepshead minnows (Cyprinodon variegatus) were continuously exposed to two concentrations of polycyclic aromatic hydrocarbons (PAHs) dissolved in seawater (sigma PAH = 7.57 and 72.31 microg/L) for 36 d, followed by 8 d of depuration. The PAHs studied were naphthalene (NPH or C0-NPH), phenanthrene (PHE or C0-PHE), pyrene (PYR), 2-methylnaphthalene (C1-NPH), 1,3-dimethylnaphthalene (C2-NPH), 2-isopropylnaphthalene (C3-NPH), 9-methylphenanthrene (C1-PHE), and 9-ethylphenanthrene (C2-PHE). Uptake rate constants (k1) for NPHs increased with increasing degree of alkylation and log value of the octanol/water partition coefficient (Kow), whereas k1 values for three- and four-ring PAHs were lower despite their high log Kow values. Elimination rate constants (k2) for the homologue series of NPHs and PHEs generally increased with decreasing degree of alkylation and log Kow values. However, the depuration time did not directly correlate with the molecular size for nonalkylated PAHs. Bioconcentration factors (BCFs) were estimated from the ratio of k1 to k2 and also directly from PAH concentrations in fish tissue and water samples, and the factors generated by the two methods were very similar. A significant positive correlation was determined between log BCFs and log Kow values for the series of C0- through C3-NPH at both low (r2 = 0.985, p = 0.0077) and high (r2 = 0.956, p = 0.022) exposures, although this correlation was not determined for all the PAHs studied. As a result of increased metabolism and/ or reduced bioavailability with increasing lipophilic character, the estimated BCFs for C0- through C2-PHE and PYR were generally lower than those for C0- through C3-NPH. The two exposure levels revealed minor variations in k1 and k2 values for parent PAHs and in the temporal pattern of PAH metabolite concentrations in bile. The present results indicate that the presence and nature of alkyl groups have a significant influence on the kinetics and metabolism of PAHs in fish.

Effects of Ocean Acidification on Early Life Stages of Shrimp (Pandalus borealis) and Mussel (Mytilus edulis)

Ocean acidification (OA) resulting from anthropogenic emissions of carbon dioxide (CO2) has already lowered and is predicted to further lower surface ocean pH. There is a particular need to study effects of OA on organisms living in cold-water environments due to the higher solubility of CO2 at lower temperatures. Mussel larvae (Mytilus edulis) and shrimp larvae (Pandalus borealis) were kept under an ocean acidification scenario predicted for the year 2100 (pH 7.6) and compared against identical batches of organisms held under the current oceanic pH of 8.1, which acted as a control. The temperature was held at a constant 10°C in the mussel experiment and at 5°C in the shrimp experiment. There was no marked effect on fertilization success, development time, or abnormality to the D-shell stage, or on feeding of mussel larvae in the low-pH (pH 7.6) treatment. Mytilus edulis larvae were still able to develop a shell in seawater undersaturated with respect to aragonite (a mineral form of CaCO3), but the size of low-pH larvae was significantly smaller than in the control. After 2 mo of exposure the mussels were 28% smaller in the pH 7.6 treatment than in the control. The experiment with Pandalus borealis larvae ran from 1 through 35 days post hatch. Survival of shrimp larvae was not reduced after 5 wk of exposure to pH 7.6, but a significant delay in zoeal progression (development time) was observed.

Effect of the endocrine disrupter nonylphenol on the marine copepod Tisbe battagliai

Abstract The marine copepod Tisbe battagliai was exposed to the endocrine disrupter nonylphenol (31–500 μg l −1 ) in two life-table experiments. Data on fecundity, longevity, and rate of development were used to calculate the population growth rate ( r m ) for exposed and unexposed cohorts of copepods. The highest concentrations tested (125 and 500 μg l −1 nonylphenol) were acutely lethal to the nauplii. When the copepods were exposed to 62 μg l −1 nonylphenol, only 6% survived to maturity. The surviving copepods, however, produced enough F1 and F2 offspring to increase the size of the population compared to the P-generation. There were no statistically significant effects on any life table parameter for T. battagliai at 31 μg l −1 nonylphenol, although r m was reduced in one of the experiments mainly due to reduced survival to maturity. There was no statistically significant change in the percentage of female in neither the P (parent) nor the F1 (offspring) generation exposed to 31 μg l −1 NP compared to the controls.

Relating biomarkers to whole-organism effects using species sensitivity distributions : A pilot study for marine species exposed to oil

Biomarkers are widely used to measure environmental impacts on marine species. For many biomarkers, it is not clear how the signal levels relate to effects on the whole organism. This paper shows how species sensitivity distributions (SSDs) can be applied to evaluate multiple biomarker responses in species assemblages. To our knowledge, the present study compared for the first time SSDs based on biomarker response levels for marine species to a SSD for whole-organism responses. The comparison indicates that for exposure to dispersed oil in the marine environment, the selected biomarkers were, on average, 35- to 50-fold more sensitive than the whole-organism effect. At the 5% hazardous concentration derived from the SSD for whole-organism effects, which is a conservative threshold level, the potentially affected fraction of species showing biomarker response corresponds to approximately 80%. Variation in species sensitivity, expressed either as biomarker or as whole-organism response levels, were similar. Although uncertainties exist, the link between biomarkers and risk assessment presented here provides a preliminary guideline for deciding when biomarker responses likely are hazardous and, therefore, require further investigation.

Chronic exposure of adults and embryos of Pandalus borealis to oil causes PAH accumulation, initiation of biomarker responses and an increase in larval mortality.

Adult shrimps (Pandalus borealis) and their embryos were exposed to an oil-water dispersion (OWD) at concentrations of 0.015, 0.06 and 0.25 mg/L using a continuous flow system. Lysosomal membrane stability was analysed in haemocytes using the neutral red retention assay and an alkaline unwinding assay was used to measure DNA damage in hepatopancreas tissue. Exposure to oil induced concentration and time dependent biomarker responses in adult shrimps together with the accumulation of PAH in their tissues. Oil exposure of shrimp embryos caused increased mortality in the resultant larvae, even if the larvae were kept in clean water after hatching. There were minor differences observed in larval stage development times in the first part of the experiments. The fatty acid composition of embryos exposed to oil was different to that of non-exposed larvae. PAH tissue concentration and biomarker responses correlated to the reduced survival of the shrimp larvae.

Seasonal variation of histopathological and histochemical markers of PAH exposure in blue mussel (Mytilus edulis L.)

The aim of this work was to study seasonal variation of histopathological and histochemical markers in blue mussels (Mytilus edulis L.) exposed to pyrogenic PAH contaminants. Mussels were collected in January, June, September and October from a sampling site in the vicinity of the discharge from an aluminium smelter and from a clean reference site. Histopathological analysis was carried out on the digestive gland (DG) and the gonads, lipofuscin and neutral lipids were analysed in the DG. Clear responses in lipofuscin and neutral lipids were detected in the DG of mussels collected from the polluted site at some sampling times. Moreover, these mussels presented atrophy in digestive tubules and haemocytic aggregates in the gonad and DG. However, in all parameters studied, the magnitude of the response showed clear seasonal variation.

Exposing Northern shrimp (Pandalus borealis) to fish feed containing the antiparasitic drug diflubenzuron caused high mortality during molting

ABSTRACT Use of the chitin synthesis inhibitor diflubenzuron (DFB) as an antiparasitic drug in salmon aquaculture raises concern over its impact on marine ecosystems. Further, global drivers, such as ocean warming and acidification (OAW), may increase the toxicity of hazardous substances including DFB. The aim of the present study was to examine the combined effects of DFB-medicated salmon feed on ovigerous Northern shrimp (Pandalus borealis) under Control (pHNBS 8.0, 7.0ºC) and OAW conditions (pHNBS 7.6, 9.5ºC). DFB-exposed shrimp consumed on average 0.1–0.3 g medicated feed during the 2-week exposure period, and high mortality (61–73%) was documented at both environmental conditions. There was no significant interaction between OAW and DFB. Only 2–7% of DFB-exposed shrimp molted successfully compared to 65% in Control and 63% in OAW. The shrimp molted earlier (shorter intermolt period) and exhibited higher feeding rate at OAW compared to Control conditions. An additional experiment, where female shrimp were exposed to DFB closer to molting, noted increased mortality after only 4 d exposure, and successful molting for some shrimp after 2 to 3 weeks of depuration. High mortality of shrimp exposed to DFB-medicated feed indicates that the use of this feed in aquaculture could affect local shrimp populations.