DNA adducts and polycyclic aromatic hydrocarbon (PAH) tissue levels in blue mussels (Mytilus spp.) from Nordic coastal sites.

DNA adducts in gills and digestive gland, as well as polycyclic aromatic hydrocarbon (PAH) tissue levels were analysed in blue mussels (Mytilus spp.) from Nordic coastal areas (Iceland, Norway and Sweden) with diffuse or point sources of PAHs of various origins. Both DNA adduct and PAH tissue levels were generally low, indicating low PAH exposure to the mussels in the areas studied. DNA adducts were found to be higher in gills than in digestive gland of the mussels at all sites studied. Elevated DNA adduct levels in gills were found at 6 sites out of 18 compared to reference sites in respective coastal zones. Adduct levels ranged from 0.5 to 10 nmol adducts/mol normal nucleotides, being highest in mussels from Reykjavík harbour, Iceland (intertidal mussels), and from Fiskaatangen, Norway (subtidal mussels). Total PAH tissue levels in the mussels ranged between 40 and 11,670 ng/g dry wt., and were significantly correlated with DNA adduct levels (r(2)=0.73, p<0.001). PAH ratio values indicated that the PAHs were in most cases of pyrolytic origin, but with petrogenic input near harbours and an oil refinery.

Seasonal and intertidal impact on DNA adduct levels in gills of blue mussels (Mytilus edulis L.).

The aim of this study was to elucidate possible seasonal variation in DNA adduct levels in blue mussels (Mytilus edulis), and to investigate the impact of intertidal exposure on the DNA adduct levels, i.e. to explore if DNA adduct levels in mussels in the intertidal zone differ from those in the subtidal zone. Blue mussels were deployed separately in the intertidal and subtidal zone at a contaminated and a reference site in Iceland, and sampled regularly during one year. Gill DNA adduct levels were found to be higher in mussels in the intertidal zone compared to the subtidal zone at the contaminated site, the difference being largest in winter. Total PAH tissue levels were also higher in mussels in the intertidal zone. Seasonal variation was observed in both DNA adduct and PAH tissue levels in mussels at the contaminated site, with lower levels from the time of transplantation in summer to autumn, maximum levels in winter, which decreased to lower levels again in spring and summer the following year. DNA adducts and PAH levels were low or below the detection limits in mussels at the reference site at all times, both in the intertidal and subtidal zone.

DNA strand breakage in mussels (Mytilus edulis L.) deployed in intertidal and subtidal zone in Reykjavík harbour.

DNA single-strand breaks were analysed in the blue mussel (Mytilus edulis L.) deployed in intertidal and subtidal zones in the PAH contaminated Reykjavík harbour and at a reference site, Hvalfjörethur, Iceland. DNA strand breaks were analysed by Comet assay in isolated gill and haemocyte cells from six mussels from each site and depth. Increased DNA damage in both gill cells and haemocytes were observed in mussels deployed in Reykjavík harbour compared to the reference site. Intertidal mussels from Reykjavík harbour had higher DNA damage in haemocytes compared to subtidal mussels. The Comet assay seems to be useful for measuring genotoxic exposure in mussels from the field, and that DNA damage might be higher in the intertidal zone either due to higher exposure to contaminants or because of physiological and biochemical responses to variations in oxygen availability.

Biomarker responses and resin acids in fish chronically exposed to effluents from a total chlorine-free pulp mill during regular production.

This study used rainbow trout (Oncorhynchus mykiss) to investigate the biological effects of long-term exposure to a total chlorine-free (TCF) pulp mill effluent. Fish tanks were set up on the premises of the pulp mill, and fresh effluent water was led through a pipe directly from the pulp mill to the tanks. The fish were exposed to effluent for up to 50 days and kept for up to 70 days afterward to study the recovery process. Two independent experiments were carried out. Ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), and glutathione reductase (GR) activity were elevated in fish exposed to a 2% concentration of pulp mill effluent, as were levels of DNA adducts. These effects could be detected during exposure and also after a period of recovery. The results demonstrate that the pulp mill effluent contains substances that affect the detoxification process and also have genotoxic potential. The continued occurrence of effects after a 70-day recovery period was demonstrated in both experiments, and may indicate that the effluent contained compounds with persistent properties. The content of free and conjugated resin acids in the bile of the fish was found to be a useful indicator of exposure to pulp mill effluent.

Accumulation and effects of aluminum smelter-generated polycyclic aromatic hydrocarbons on soft-bottom invertebrates and fish.

An integrated study involving measurements of polycyclic aromatic hydrocarbon (PAH) levels in bottom sediments, assessments of resident soft-bottom communities, the accumulation of PAHs in soft-bottom invertebrates, and biomarker responses in invertebrates and fish was conducted to assess the impact of an aluminum reduction plant in a Norwegian fjord. The fjord sediments were heavily contaminated by PAHs in the inner reaches near the aluminum smelter, where concentrations were well above levels elsewhere reported to induce biological effects. Nevertheless, the PAH contamination in the fjord did not seem to have severe effects on the benthic biota. This conclusion can be drawn from the soft-bottom communities as well as from biomarker analyses. Presumably, contaminant speciation is important for explaining the restricted biological effects. The results support the assumption that PAHs associated with soot-like structures have limited bioavailability. They also point to the need to link various single-species approaches to measurements of effects on higher levels of organization and with an understanding of the speciation of the chemical contaminant.