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Carcasses collection
The national stranding network in France (RNE; Réseau National d’échouage) established in 1972 consists of local correspondents available to intervene when a stranding of marine mammal occurs along the French coast. The network is coordinated by the « Centre de Recherche sur les Mammiferes Marins » (CRMM) under the supervision of the Ministry of the Environment. Once a stranding of marine mammal is reported, the CRMM prevent the corresponding of the area to intervene and examine the animal. In our study area, the « Observatoire pour la Conservation et l’Etude des Animaux et Milieux Marins » (OCEAMM) and the « Ligue Protectrice des Animaux du Nord » (LPA) Calais were the correspondents in case of a stranding along northern France coast. For the strandings along the Bay of Biscay coast, different correspondents may intervene (such as CRMM, Ligue pour la Protection des Oiseaux (LPO) marais Breton, LPO marais de Mullembourg, etc). Whereas for the marine mammals stranded along the Belgian coast, the Belgian Marine Mammals Network intervenes in case of stranding. On the coast where the stranding occurred, basic information such as the species in question, sex, size, status, date and place were systematically recorded. Other parameters as well as tissues and organs collection were obtained after dissection.
Protocol of dissection, collection and preservation of samples
Freshly dead or slightly decomposed carcasses of porpoises stranded along the southern North Sea (Figure 2.1) were transported to the Veterinary Medicine, University of Liege as soon as possible to be preserved in freezing rooms for further necropsies and investigations (Figure 2.2). All individuals provided for necropsies were labeled. Animals were measured, weighed and the sex and the overall length were determined. For the harbour porpoises stranded along the Bay of Biscay, necropsies were held at the CRMM, La Rochelle – France. Stranding locations are presented in figure 2.3
Analysis on ICP-AES
After excitation by high temperature argon plasma, the relaxation of the excited electrons is accompanied by the emission of energy at a given wavelength as they return to the ground state. The energy emitted is characteristic of the element present in the sample and the intensity of that energy at a given wavelength is proportional to the concentration of the element in the sample analyzed. The ICP-AES used is available with radial and axial view configurations (Figure 2.5). We used the axial view since it improves on the sensitivity and quantification limits of the radial view by about a factor of 10 or more depending on the element. These improvements are not without inconveniences. Axially viewed plasma is much more susceptible to interferences for some elements. ICP-AES is a fast, multi-elemental technique and has the advantage of minimizing the matrices effects compared to other spectroscopic methods. Elements such as Cu, Mn, Se and Zn were analyzed using ICP-AES in both livers and kidneys of harbour porpoises. Whereas As and Cd which were relatively concentrated in some samples of kidneys, these elements were analyzed using both ICP-AES and ICP-MS depending on their concentrations in samples. Limits of quantification are presented in table 2.3.
Analysis on ICP-MS
Via the interface cone, the elements in the sample converted into ions are bought into the mass spectrometer. An intermediate vacuum region created by two intermediate cones: the sampler and the skimmer (~1mm) transmit the ions coming from the ICP torch with an atmospheric pressure into a low pressure region of the mass spectrometer. The mass spectrometer used is a quadrupole mass filter. It consists on the fact that electrostatic lenses with a positive charge serve to collimate the ion beam (also positively charged) and focus it into the entrance slit of the mass spectrometer. The ions are therefore separated by their mass-to-charge ratio (m/e). This mass filter only transmits the ions with an m/e ratio according to the frequency previously applied to the quadrupole. For a given isotope, the signal is the number of pulses which is converted into concentration after calibration. ICP-MS is a fast, multi-elemental technique and has much lower detection capabilities compared to ICP-AES. Elements such as As, Cr, Cd, Pb and V were determined in livers and kidneys (depending on concentration levels in the sample) using ICP-MS. Limits of quantification are presented in table 2.3.
Table of contents :
PREFACE
RESUME DETAILLE DE LA THESE
LIST OF FIGURES
LIST OF TABLES
CHAPTER 1 INTRODUCTION
The harbour porpoise (Phocoena phocoena)
Distribution and description
Distribution on a local scale
Protection status of harbour porpoises in the European waters
Diet of harbour porpoises
Threats
Assessment of chemical contamination
Studying the feeding ecology of harbour porpoises
Objectives of the study
Outline of the study
CHAPTER 2 STRATEGIES, PROTOCOLS AND METHODOLOGIES
1. Sample collection and necropsies
1.1. Carcasses collection
1.2. Protocol of dissection, collection and preservation of samples
2. Chemical analyses
2.1. Metallic analyses
2.1.1. Analysis on ICP-AES
2.1.2. Analysis on ICP-MS
2.1.3. Analysis on AMA-254
2.1.4. Quality control procedures
2.2. Persistent Organic Pollutants analyses
2.3. Data treatment
3. Feeding ecology
3.1. Stomach content analysis
3.1.1. Otoliths
3.1.2. Diet composition
3.1.3. Feeding strategy
3.2. Stable isotopes analysis
3.3. Fatty acids analysis
3.4. Compound-Specific Stable Isotope Analysis (CSIA)
3.5. Data treatment
3.5.1. Mixing model: Stable isotope analysis in R (SIAR)
3.5.2. Fatty acids data treatment
3.6. Environmental data
CHAPTER 3 HARBOUR PORPOISES (PHOCOENA PHOCOENA) STRANDED ALONG THE SOUTHERN NORTH SEA: AN ASSESSEMENT THROUGH METALLIC CONTAMINATION
Abstract
Introduction
1. Materials and methods
1.1. Sampling and data collection
1.2. Metal analysis
1.3. Data treatment
2. Results
2.1. Metal contaminants and maturity status
2.2. Metal contaminants and causes of death
3. Discussion
3.1. Non essential elements
3.2. Essential elements
3.3. Temporal trends
Conclusion
Acknowledgements
CHAPTER 4 ORGANOCHLORINES IN HARBOUR PORPOISES (PHOCOENA PHOCOENA) STRANDED ALONG THE SOUTHERN NORTH SEA BETWEEN 2010-2013
Abstract
Introduction
1. Materials and methods
1.1. Sampling and data collection
1.2. POP analysis
1.3. Data treatment
2. POP results
2.1. POPs and maturity status
2.2. POPs and causes of death
3. Discussion
3.1. PCB levels
3.2. DDX levels
Conclusion
Acknowledgements
CHAPTER 5 THE DIET OF HARBOUR PORPOISES (PHOCOENA PHOCOENA) IN THE SOUTHERN NORTH SEA: A RELATIONSHIP WITH PREY AVAILABILITY
Abstract
Introduction
1. Materials and methods
1.1. Sampling and data collection
1.2. Stomach content analyses
1.3. Stable isotopes analyses
1.4. Fatty acids composition
1.5. Compound-Specific Stable Isotope Analysis (CSIA)
1.5. Data treatment
2. Results
2.1. Stomach contents
2.2. Stable isotopes and SIAR
2.3. Fatty acids composition and CSIA
3. Discussion
3.1. Diet of harbour porpoises stranded along the southern North Sea
3.2. General diet composition
Conclusion
Acknowledgements
CHAPTER 6 FEEDING HABITS OF HARBOUR PORPOISES (PHOCOENA PHOCOENA) FROM THE SOUTHERN NORTH SEA AND THE BAY OF BISCAY INFERRED FROM A MULTI APPROACH DIETARY ANALYSES
Abstract
Introduction
1. Materials and methods
1.1. Sampling and data collection
1.2. Stomach content analysis
1.3. Stable isotopes analysis
1.4. Fatty acids analysis
1.5. Data treatment
2. Results
2.1. Stomach contents
2.2. Stable isotope analyses of δ13C and δ15N
2.3. Lipid composition
3. Discussion
3.1. Diet composition
3.2. Comparison with previous studies
Conclusion
Acknowledgements
CHAPTER 7 GENERAL DISCUSSION
Contamination status of harbour porpoises in the southern North Sea
Changes in the distribution of harbour porpoises in the North Sea
Value of a multi-approach dietary analysis
Conclusions and perspectives
REFERENCES
