Cytochrome P450 1A1 and 2B protein expression as biomarker for the first assessment of the ecotoxicological status of Cuvier's beaked (Ziphius cavirostris) in the NW Mediterranean sea

Cuvier's beaked whale is one of the least known cetaceans in the world. The Mediterranean subpopulation is now ranked as data deficient (DD) in the “Red List of Threatened Species” by IUCN because data on distribution, population structure and abundance in the Mediterranean basin are lacking except for very limited areas. The few studies carried out on threats posed to this species highlight that one of the main threat is the underwater noise but the ecotoxicological risk it is unknown. The xenobiotics compounds (OCs, PBDEs, etc.) in the environment can accumulate along marine food chains, having noxious effects on marine predators especially on long-living species. The objective of this study is to investigate for the first time the ecotoxicological status of Cuvier's beaked whale in the NW Mediterranean Sea (Pelagos Sanctuary). Among the diverse investigations that can be performed to obtain information about the health status of a species, a useful tool is represented by biomarkers. In this study the expression and induction of cytochrome's P450 (CYP1A1 and CYP2B isoforms) was evaluate as a molecular biomarker of exposure to OCs in 22 skin biopsies of free-ranging specimens belongings of both sexes and different age classes. This sample represent about the 20% of the resident population in the area which has been monitored during the last fifteen years. In the same samples the OCs levels (HCB, DDTs and PCBs) were analysed. This study represents an important step forward in our understanding of the effects of toxic compounds on Cuvier's beaked whale, considering also the information gathered on the gender differences, age and the life history of the animals. Further investigations need to be performed in this and other areas to better understand the ecotoxicological status of this data deficient species.