Capítulo 14. Bioacumulación de contaminantes orgánicos en moluscos y peces del Mar Menor y sus efectos biológicos

Abstract

Organic pollutants are present in the waters and sediment of coastal systems, as revealed inthe previous chapter of this book, and consequently a certain proportion of these substanceswill be available for uptake by resident organisms. It is therefore essential to evaluate thebioaccumulation of legacy and current-use pollutants and their biological effects on differentspecies in order to identify the best indicators for each pollutant group, a task traditionallyperformed by filtering organisms such as bivalves and fish. This chapter thus describes thebioaccumulation in samples taken from the Mar Menor lagoon of polycyclic aromatic hydrocarbons(PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)in cockles, oysters and noble pen shells; and of pharmaceuticals in clams, sea snails, noblepen shells, cockles, golden grey mullet and flathead mullet. In the case of the former, andconsidering all bivalve samples, PAH concentrations ranged from 8.98 to 370 μg kg-1; thoseof PCBs were between 0.15 and 42.36 μg kg-1; and those of OCPS, such as dichlorodiphenylcompounds (DDXs) went from below the limit of detection to as high as 240.6 μg kg-1, p,p’-DDE being the main fraction. Pharmaceutical concentrations in mollusks and fish, expressedin μg kg-1, were very low, with more compounds being found in flathead mullet than in otherspecies, particularly in muscle tissue. The most relevant compounds were carbamazepine andhydrochlorothiazide, which were detected in all the species analyzed in this study. By and largethere were no significant seasonal variations in concentrations of these pollutants, except ina few cases and in specific areas. p,p’-DDE levels detected in oyster and noble pen shell sampledclose to the El Albujón watercourse were the only ones to exceed the OSPAR/MED POLenvironmental assessment criteria. Large differences in bioaccumulation were found betweenspecies depending on factors such as source proximity, physiology and habits, and thereforethe oyster was proposed as a bioindicator for PAHS and organochlorine pollutants, and theflathead mullet for pharmaceuticals.The biological effects of agricultural and urban pollution on the lagoon were evaluated bymeasuring a variety of biomarkers (neurotoxic effects, xenobiotic biotransformation capacityand oxidative and physiological stress) in clams from a zone that is a priori subject to lowlevels of exposure to pollutants to four points in the lagoon (two reference sites and two sitesaffected by the dispersion of the El Albujón watercourse outflow), during exposure periodslasting 7 and 22 days. The transported clams at the sites close to the watercourse had lowacetilcolinesterase levels and a low growth capacity, contrasting with high glutathione-reductaseand glutathione-S-transferase values, confirming the existence of neurotoxicity andoxidative stress. The metabolomic profiles of these transplanted organisms were also characterized,revealing the modifications to the metabolic pathways relating to cell energy production,protein metabolism and osmotic balance resulting from exposure to agricultural and/or urban pollutants.