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Rezumat articol ediţie STUDIA UNIVERSITATIS BABEŞ-BOLYAI
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Rezumat: In ecotoxicological studies, stable isotopes (15N and 13C) are more and more used as a
complementary method of dietary analysis, to describe trophic links and to assess
food-web structure. Stable isotopes are regarded as indicators of organic matter
sources able to describe trophic links and matter transfer along a food chain. These
studies allow an accurate determination of the trophic level, based on the calculation
of the diet-tissue fractionation factor. However the latter, determined for the whole
organism or for particular tissues, may vary substantially in natura. Vanderklift and
Ponsard’s (2003) analyses point to several important sources of variation in δ15N
enrichment such as tissues, diet, taxon, main biochemical form of nitrogen excretion
or nutritional status. The potential effect of pollutants on the diet-tissue fractionation
factor is seldom taken into account. Therefore we raised perch, Perca fluviatilis in
controlled conditions, and fed them for 6 weeks with commercial pellets contaminated
with DDT, an ubiquist contaminant. DDT exhibite estrogenic activity stimulates
production of liver microsomal enzymes that lead to hydroxylation of steroids in
experimental animals which may have adversely affected reproductive success and
development. In the present study, δ13C and δ15N were analysed in lipid-free tissues
(liver, gills, white muscle), showing various metabolic activities. |
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