[1] Univ Vet Med Hannover, Inst Terr & Aquat Wildlife Res, Weiftstr 6, D-25761 Busum, Germany
[2] German Oceanog Museum, Katharinenberg 14-20, D-18439 Stralsund, Germany
[3] Univ Basel, Programme Man Soc Environm, Dept Environm Sci, Vesalgasse 1, CH-4051 Basel, Switzerland
[4] Univ Vet Med Hannover, Dept Pathol, Bunteweg 17, D-30559 Hannover, Germany