A major role in terms of danger to the aquatic ecosystem is played by heavy metals, which stand out by their persistence and accumulability. In this study an overview on recent monitoring (2003-2005) of some heavy metals (Cu, Zn, Cd, Pb) analyzed in fish species, plants and benthic macro invertebrates from Danube Delta Biosphere Reserve. In the system of contamination classes elaborated by (Wachs B. 2Q00), for the grading of the situation of ecosystems in term of heavy metal content, of all the various compartments, fish constitute the only critical part.
The fish organs – in particular the muscles – show a very wide spread of concentration. Fish are very sensitive to cadmium and lead poisoning, but certain species, for example roach, perch and gibbel carp in aquatic ecosystem from Danube Delta was found with high concentration of cadmium and lead. The accumulation of contaminants in aquatic organisms can prove harmful to a number of fish species during sensitive stages within the lifecycle.
The contamination of fresh waters with a wide range of pollutants has become a matter of concern over the last few decades. The natural aquatic systems may extensively be contaminated with heavy metals released from domestic, industrial and other man-made activities. Heavy metal contamination may have devastating effects on the ecological balance of the recipient environment and a diversity of aquatic organisms.
Among animal species, fishes are the inhabitants that cannot escape from the detrimental effects of these pollutants. Fish are widely used to evaluate the health of aquatic ecosystems because pollutants build up in the food chain and are responsible for adverse effects and death in the aquatic systems.
The studies carried out on various fishes have shown that heavy metals may alter the physiological activities and biochemical parameters both in tissues and in blood. The toxic effects of heavy metals have been reviewed, including bioaccumulation.
The organisms developed a protective defense against the deleterious effects of essential and inessential heavy metals and other xenobiotics that produce degenerative changes like oxidative stress in the body. Cichlidae species are the most popular and highly economic fish.
In the present research, Cyprinus carpio (Common carp) was selected due to its adoption in polluted aquatic environment. The purpose of this research is to quantify the accumulation of heavy metals in various organs in Cyprinus carpio (Common carp).