The Mediterranean Sea, a crossroads of civilisations and a privileged holiday destination, is unfortunately also a gigantic dumping ground where marine life is affected by a wide range of pollutants. A very comprehensive study (1) conducted between 2006 and 2013 by the University of Liege and the WWF(2), whose results have just been published, has revealed the existence of alarming levels of contamination by certain lipophilic pollutants in three species of whales permanently inhabiting the Mediterranean Sea. The species in question are the pilot whale, the sperm whale and the fin whale. This study is remarkable and innovative both in terms of its scale and the method used for sample-taking. A total of 70 organic pollutants were researched (and detected) in no less than 180 blubber and skin samples taken from 61 sperm whales (Physeter Macrocephalus, 14 females and 47 males), 49 pilot whales (Globicephala Melas, 23 females and 26 males), and 70 fin whales (Balaenoptera Physalus, 35 females and 35 males). A screening programme on this scale involving such a broad range of pollutants is very unusual. This study is also remarkable due to the fact that samples were taken from live whales as opposed to relying on samples from the carcasses of stranded animals. The results obtained underline the necessity of continuing the fight to have these persistent pollutants banned and the need to press for enforcement of the relevant legislation.

Before examining the subject of whales in the Mediterranean Sea and their intoxication by persistent lipophilic pollutants (non-soluble in water) or POPs (persistent organic pollutants) it would first be necessary to take a look at their particular environment: the Mediterranean Sea. The University of Liege and its Oceanographic Laboratory has a long history of research in this area thanks in particular to its oceanographic station STARESO which is located in Corsica. “The Mediterranean has always been of interest to researchers because it is not only a sea but is also a small ocean with very particular water circulations. From an oceanographic point of view, it is a very important site which raises a lot of scientific questions”, explains Krishna Das, a Senior Lecturer at the University of Liege and research associate at the FRS – FNRS and a member of ULg’s Oceanology Laboratory. The Mediterranean is distinguished by its particular geographical location because, although it is not exactly an inland sea, it is surrounded by several national territories. In fact, it is surrounded by no less than “twenty-one countries that are engaged in economic activities resulting in various degrees of pollution. The fact of being surrounded by so many countries makes the study of this sea very relevant both from the point of view of ecosystems and the fight against pollution”, states Marianna Pinzone, first author of the study and a researcher in marine ecotoxicology at the University of Liege. Also the legislation with regard to the use of the pollutants examined in the study is sometimes radically different in these 21 countries. In fact, the use of PCB, in particular, has been banned in Europe for over forty years. More generally, most countries of the world have signed up to this prohibition with the ratification and implementation of the Stockholm Convention on Persistent Organic Pollutants. However, some countries are not in agreement with the terms of the convention. This is the case with Italy which is the only country in the EU and Europe that objects to the terms of the convention. “On a global level, many other countries have not signed up to the agreement either. For example, in Cambodia in Asia, DDT, which is a pesticide that has been banned in Europe for decades, is still used because it is an efficient treatment for malaria. So there are some exceptions”. The same phenomenon can be observed around the Mediterranean where long-since industrialised countries to the North have a history of using industrial chemical substances while so-called developing countries to the South are only just beginning to develop environmental awareness. In addition, Mediterranean coastlines are extremely urbanised. It is estimated that there will be around 530 million inhabitants in these urban areas by 2025. In the light of these facts, it is easy to see why the Mediterranean is such a melting pot of cultures that is very unsavoury for its occupants which include pilot whales, sperm whales and fin whales.

(1) POPs in free-ranging pilot whales, sperm whales and fin whales from the Mediterranean Sea: Influence of biological and ecological factors, M. Pinzone et al. Environmental Research, 2015.
(2) The study was jointly conducted by three Liege-based laboratories, the Oceanology Laboratory, The Mass Spectrometry Laboratory (Pr. Gauthier Eppe), the Animal Ecology and Ecotoxicology Laboratory (Pr. Jean-Pierre Thomé), and by three French organisations: the University of Bordeaux (Institute of Molecular Sciences and the Physico- and Toxico-Chemistry Laboratory of the environment) and the CNRS EPOC (Oceanic and Continental Environments and Paleoenvironments).