Polychlorinated biphenyls (PCBs) are ubiquitous, persistent, organic nvironmental
pollutants. They are extremely stable, lipophillic compounds that do not break down easily in the environment and bioaccumulate readily in biota and fine sediments, increasing in concentration up the food chain. Research has shown the various effects and implications this bioaccumulation can have in numerous animal species around the globe. Pollutants may be accumulated in eggs before spawning occurs, reducing the female body burden but with potential risks for the next generation. This study aimed to elucidate the potential impacts of these compounds on marine fish by investigating the effects of exposure on reproduction and larval growth, survival, behaviour and physiology using the European plaice, Pleuronectes platessa (Linnaeus) as a model species.
Adult plaice and egg samples were sampled from the Irish Sea and juvenile fish from nursery grounds in both the Irish and North Seas in order to collect data on
environmental PCB concentrations and supplement data already in the literature.
Samples were analysed using gas chromatography-mass spectrometry (GC-MS) and nursery grounds contaminated with PCBs were identified.
Two large scale broodstock experiments involving the oral dosing of female fish over subsequent spawning seasons aimed to determine the potential effects of maternal pollutant transfer on fe1iilised eggs and larvae. PCB exposure was found to reduce the size at hatch of larvae and resulted in a delay in development compared to larvae from non-dosed females that lasted until metamorphosis. Routine swimming activity of exposed larvae was significantly less than that of fish from control females though the differences had disappeared by metamorphosis. Response to vibratory stimuli did not differ between fish from the different treatments.
A relatively new biochemical assay for assessing the impacts of pollution on aquatic organisms called the cellular energy allocation (CEA) method was used to determine the impact of PCB exposure on the physiology of both larvae exposed through maternal transfer and juvenile O+ plaice exposed through the diet. Both experiments showed a significant reduction in the activity of the electron transpo1i system in exposed fish at the times most likely associated with PCB metabolism. The electron transport system is involved in the production of ATP that provides energy for growth and physical activity.
All experiments were complemented by subsequent analysis of tissue samples by GC-MS to determine PCB body burdens and compare them to environmental
concentrations. Significant correlations of PCB concentration were found with many of the parameters that showed significant differences between treatments in the experimental work.
Implications of exposure to PCBs for species in the environment are discussed as well as the future and importance of integrated ecotoxicological studies and the continued release of new and discontinued chemicals to the environment.