|Use of skin and blubber biopsies to assess the eco-toxicological status of cetaceans in the Mediterranean Sea|
Pinzone, M. (2014). Use of skin and blubber biopsies to assess the eco-toxicological status of cetaceans in the Mediterranean Sea. MSc Thesis. Universiteit Gent/VUB/Universiteit Antwerpen: Gent, Brussel, Antwerpen. 15, 50 pp.
chemical tracer, biopsy, blubber, trophic level, toxicity, Northwestern Mediterranean Sea
d13C, d15N values and blubber lipids concentrations of 31 PCBs, 15 organgochlorine compounds, 9 PBDEs and 17 PCDD/Fs were measured in Northwestern Mediterannean Sea long-finned pilot whales (Globicephala melas), sperm whales (Physeter macrocephalus) and fin whales (Balaenoptera physalus). The isotopic analysis was performed using an EA-IRMS coupled in continuous flow to an elemental analyzer; while pollutans levels were measured by gas chromatography with electroncapture detection. To assess the toxic potency of the dioxin-like compounds the TEQ approach recommended by the World Health Organization for human and wildlife health was applied. In total 75 fin whales, 61 sperm whales and 49 long-finned pilot whales were collected between 2006 and 2013. A clear distinction in d15N values was observed among the three species, with sperm whales at the higher trophic level, followed by long-finned pilot whales and fin whales; in accordance with their dietary regimes. d13C values resulted significantly different between the toothed-whales and the baleen whale. Long-finned pilot whales displayed the highest concentrations of SPCBs, SDDTs and SPBDEs, followed by sperm whales and fin whales. In general, pollutant concentrations found in our species were significantly higher than both their Southern Hemisphere and North Atlantic counterparts. Sex differences were observed only in sperm whales and fin whales with males presenting higher contaminant burden than females. The congeners profiles did not differ among species; however the congeners concentrations were substantial in their differentiation. Finally, in the two odontocetes dioxin-like PCBs accounted for over 80% of the total TEQ. This study demonstrated the serious threat that the release of pollutants in the Mediterranean Sea is excercising on the local cetacean populations, especially on toothed-whales, of which most of the analysed individuals showed pollutants concentrations higher than the estimated threshold toxicity value of 17000 ng.g-1 for blubber in marine mammals. It also showed limitations and potential problems of experimental procedures such as the use of biopsies for blubber sampling in species such as the sperm whale, and the use of d15N as only surrogate for trophic position.