Heavy metal content in perch and rudd tissues and associated health risk assessment.

Fish meat is recommended for consumption as a source of protein, essential unsaturated fatty acids, and fat-soluble vitamins, unfortunately it can also be a source of dangerous contaminants. The aim of the study was to assessment the level of Zn, Cu and Pb in water and bottom sediments collected in summer and autumn from the Koronowo Reservoir and the Wierzchucińskie Duże Lake and in the tissues of perch (Perca fluviatilis L.) and rudd (Scardinius erythrophtalmus L.

Factors influencing accumulation of Zn, Cu, and Ca in the tissues of spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817).

Both physicochemical and biological factors affect the degree of metal accumulation in crayfish tissues. The content of metals and correlations between the metal concentrations in different tissues and the total length of crayfish is suitable indicators of contamination of the aquatic environment. The aim of the study was to analyse the effect of age and sex of crayfish on the degree of accumulation of Ca, Cu, and Zn in the muscle and exoskeleton.

Fertility of Spiny-Cheek Crayfish (Orconectes limosus Raf.) from the Vistula Lagoon.

The aim of this study was to examine fertility of spiny-cheek crayfish harvested in the first half of April from the Vistula Lagoon and to compare it with that of the crayfish from freshwater habitats. The sample consisted of 47 sexually mature females shortly before they were ready to lay eggs. After determining the absolute fertility (number of eggs per ovary), the relative fertility was calculated (number of eggs per 1 g of body weight).