An assessment of the chemical contamination and the diet changes of the harbour porpoise (Phocoena phocoena) stranded along the southern North Sea

• Main Author: Mahfouz, Celine
• Other Authors: Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), National Center for Marine Sciences Lebanon, National Council for Scientific Research = Conseil national de la recherche scientifique du Liban Lebanon (CNRS-L), Université du Littoral Côte d'Opale, Rachid Amara, Gaby Khalaf
• Format: Thesis
• Language: English
• Published: HAL CCSD 2014
• Subjects: stable isotopes; fatty acids; stomach contents; diet; chemical contamination; southern North Sea; harbour porpoise; isotopes stable; contenus stomacaux; acides gras; marsouin commun; sud mer du Nord; contamination chimique; régime alimentaire; envir; geo; Harbour porpoise; Phocoena phocoena
• Online Access: https://tel.archives-ouvertes.fr/tel-01128126/file/Mahfouz%20Celine%20thesis%20final.pdf; https://tel.archives-ouvertes.fr/tel-01128126

The North Sea is heavily impacted by human activities such as overfishing and pollution. Due to their position as top predators in the ocean, marine mammals are becoming increasingly affected by anthropogenic activities. The large-scale surveys SCANS in 1994 and SCANS II in 2005 that were held in the North Sea to estimate the abundance of small cetaceans highlighted a major shift in the distribution of harbour porpoises (Phocoena phocoena) from the northern parts of the North Sea to its eastern parts. Alongside, over the past few decades harbour porpoises stranding has increased in the southern North Sea particularly along the French and Belgian coastal waters. Since the contaminant exposure presents, among others, a potential threat to harbour porpoises inhabiting the North Sea, the first objective of the present study was to assess the contamination status of this species in the southern North Sea. On the other hand, the distribution and abundance of marine mammals is expected to follow the distribution of their main prey species. Hence, the second objective of this study was to investigate whether the changes in the distribution of porpoises in the southern North Sea may be a result of the changes in prey availability. Moreover, the third objective was to evaluate the interest of combining three methods to investigate the diet of harbour porpoises: stomach contents, stable isotopes (carbon and nitrogen) and fatty acids analyses.First, the contamination status was evaluated through the determination of two components of chemical contaminants (metals and persistent organic pollutants) in tissues of harbour porpoises stranded along the southern North Sea between 2006 and 2013. Several chemical contaminants presented higher concentrations in diseased animals compared to healthy animals. In addition, some metallic contaminants showed bioaccumulation with age. Comparison with previous study suggests that the population status of harbour porpoises in term of chemical concentration has been stable from 1994 to 2013. ...