Endocrine modulation in Atlantic cod (Gadus morhua L.) exposed to alkylphenols, polyaromatic hydrocarbons, produced water, and dispersed oil.

Effluent from oil production activities contains chemicals that are suspected of inducing endocrine disruption in fish. In this study, Atlantic cod (Gadus morhua L.) were exposed to mixtures of low- and medium-molecular-weight alkylphenols (AP) (methyl- to heptylphenol), polycyclic aromatic hydrocarbons (PAH), diluted produced water, and dispersed oil for 15 d in a flow-through exposure system. Condition index (CI), hepatosomatic index (HSI), gonadosomatic index (GSI), concentration of the estrogenic biomarker vitellogenin (Vtg), and modulation of the total sex steroid-binding capacity in plasma were determined to assess whether these mixtures were capable of interfering with endocrine-regulated physiological processes in Atlantic cod. No marked differences in plasma Vtg levels were found between control and exposed groups of either males or females, possibly due to high intergroup variances and low sample numbers. An apparent numerical increase in the number of male and female fish with high plasma Vtg levels was, however, observed in some exposure groups compared to control. This purported weak estrogenic effect was several orders of magnitude lower than that observed for potent estrogens and suggested that the levels of estrogen receptor (ER) agonists were low. Exposure of female fish to a mixture of dispersed oil and a mixture of AP, PAH, and dispersed oil led to upregulation of the plasma total sex steroid-binding capacity, indicating interference with the normal blood steroid transport. No significant effects were seen for CI, HSI, and GSI, suggesting that the endocrine-disrupting potential was not sufficient to elicit effects on general physiological conditions and gonad development during this short exposure period.

Immune modulation in the blue mussel Mytilus edulis exposed to North Sea produced water.

The discharge of oil well produced water (PW) provides a constant source of contaminants to the marine environment including polycyclic aromatic hydrocarbons, alkylated phenols, metals and production chemicals. High concentrations of PW cause adverse effects to exposed biota, including reduced survival, growth and reproduction. Here we explore the effects of PW on immune function in the blue mussel, Mytilus edulis. Mussels were exposed for 21 days to sublethal PW concentrations (0.125-0.5%) and cellular parameters were measured. Cell viability, phagocytosis and cytotoxicity were inhibited after exposure to 0.25% and 0.5% PW, whilst the 0.125% PW treatment produced significant increases in these biomarker responses. This biphasic response was only observed after 7 days exposure; longer exposure periods led to a reduction in immune parameters. Results indicate that PW concentrations close to the discharge point cause modulation to cellular immunity. The implications for longer-term disease resistance are discussed.

Genetic variation in the hooded seal, Cystophora cristata, based on enzyme polymorphism and multi-locus DNA fingerprinting.

The genetic population structure of hooded seal, Cystophora cristata, was examined by electrophoretic analysis of allozymes and with multilocus DNA fingerprinting. Samples were collected in the Jan Mayen area and off Newfoundland. Allele products were resolved by isoelectric focusing. Only five of 32 protein-coding loci investigated were polymorphic at the 95% level. The proportion of polymorphic loci was estimated to P = 0.233, and average heterozygosity to H = 0.047. Tissue distribution, genotype distribution, and approximate pI (4 degrees C) of the proteins are reported. The allele frequencies of the AAT-2, GPD-2, and GPI-1 loci, were used in genetic comparisons of samples from the two stocks. Chi-square and G-tests showed no significant difference among the samples from the two groups. Highly variable profiles of HaeIII, HinfI and MboI digested genomic DNA were revealed using the human minisatellites 33.15 and 33.6 (HinfI digests only) as hybridization probes. Comparisons of band-sharing coefficients from HinfI and MboI digest were carried out. We were unable to detect significant differences in band-sharing between Newfoundland and the Jan Mayen area. The hypothesis that there is a considerable degree of intermixing between the stocks cannot be rejected.