Trophic relationships within intertidal communities of the Brittany Coasts: A stable carbon isotope analysis

More than 100 species belonging to plant and animal tars that are commonly observed in the intertidal zone were collected on both rocky and soft bottom shores of Brittany, France, to be analysed for their C-13/C-12 ratio. Plant material displayed a wide range of delta(13)C values (from -12 to -34 parts per thousand), with relatively distinct values among producer groups (Chlorophyce ae, Fucales, Laminariales, Rhodophyce ae seagrasses, plankton), and among strata of intertidal zonation. Animal delta(13)C range was narrower (-15 to -22 parts per thousand), and in general, values differed more between than within phyla or classes, according to the staple diet of organisms. A good correlation between the delta(13)C values of food and consumers was noted, together with a slight C-13- enrichment (approximate to 1 parts per thousand) with increasing trophic levels from suspension-feeders to predators

Zn, Cu, Cd and Hg binding to metallothioneins in harbour porpoises <i>Phocoena phocoena</i> from the southern North Sea

Background: Harbour porpoises Phocoena phocoena from the southern North Sea are known to display high levels of Zn and Hg in their tissues linked to their nutritional status (emaciation). The question arises regarding a potential role of metallothioneins (MTs) with regard to these high metal levels. In the present study, metallothionein detection and associated Zn, Cd, Cu and Hg concentrations were investigated in the liver and kidney of 14 harbour porpoises collected along the Belgian coast. Results: Metallothioneins seemed to play a key role in essential metal homeostasis, as they were shown to bind 50% of the total hepatic Zn and 36% of the total hepatic Cu concentrations. Renal MTs also participated in Cd detoxification, as they were shown to bind 56% of the total renal Cd. Hg was mainly found in the insoluble fraction of both liver and kidney. Concomitant increases in total Zn concentration and Zn bound to MTs were observed in the liver, whereas Zn concentration bound to high molecular weight proteins remained constant. Cu, Zn and Cd were accumulated preferentially in the MT fraction and their content in this fraction increased with the amount in the hepatocytosol. Conclusion: MTs have a key role in Zn and Cu homeostasis in harbour porpoises. We demonstrated that increasing hepatic Zn concentration led to an increase in Zn linked to MTs, suggesting that these small proteins take over the Zn overload linked to the poor body condition of debilitated harbour porpoises

Long-term feeding ecology and habitat use in harbour porpoises Phocoena phocoena from Scandinavian waters inferred from trace elements and stable isotopes

BACKGROUND: We investigated the feeding ecology and habitat use of 32 harbour porpoises by-caught in 4 localities along the Scandinavian coast from the North Sea to the Barents Sea using time-integrative markers: stable isotopes (δ(13)C, δ(15)N) and trace elements (Zn, Cu, Fe, Se, total Hg and Cd), in relation to habitat characteristics (bathymetry) and geographic position (latitude). RESULTS: Among the trace elements analysed, only Cd, with an oceanic specific food origin, was found to be useful as an ecological tracer. All other trace elements studied were not useful, most likely because of physiological regulation and/or few specific sources in the food web. The δ(13)C, δ(15)N signatures and Cd levels were highly correlated with each other, as well as with local bathymetry and geographic position (latitude). Variation in the isotopic ratios indicated a shift in harbour porpoise's feeding habits from pelagic prey species in deep northern waters to more coastal and/or demersal prey in the relatively shallow North Sea and Skagerrak waters. This result is consistent with stomach content analyses found in the literature. This shift was associated with a northward Cd-enrichment which provides further support to the Cd 'anomaly' previously reported in polar waters and suggests that porpoises in deep northern waters include Cd-contaminated prey in their diet, such as oceanic cephalopods. CONCLUSION: As stable isotopes and Cd provide information in the medium and the long term respectively, the spatial variation found, shows that harbour porpoises experience different ecological regimes during the year along the Scandinavian coasts, adapting their feeding habits to local oceanographic conditions, without performing extensive migration

Genetic and historic evidence for climate-driven population fragmentation in a top cetacean predator: the harbour porpoises in European water

Recent climate change has triggered profound reorganization in northeast Atlantic ecosystems, with substantial impact on the distribution of marine assemblages from plankton to fishes. However, assessing the repercussions on apex marine predators remains a challenging issue, especially for pelagic species. In this study, we use Bayesian coalescent modelling of microsatellite variation to track the population demographic history of one of the smallest temperate cetaceans, the harbour porpoise (Phocoena phocoena) in European waters. Combining genetic inferences with palaeo-oceanographic and historical records provides strong evidence that populations of harbour porpoises have responded markedly to the recent climate-driven reorganization in the eastern North Atlantic food web. This response includes the isolation of porpoises in Iberian waters from those further north only approximately 300 years ago with a predominant northward migration, contemporaneous with the warming trend underway since the ‘Little Ice Age’ period and with the ongoing retreat of cold-water fishes from the Bay of Biscay. The extinction or exodus of harbour porpoises from the Mediterranean Sea (leaving an isolated relict population in the Black Sea) has lacked a coherent explanation. The present results suggest that the fragmentation of harbour distribution range in the Mediterranean Sea was triggered during the warm ‘Mid-Holocene Optimum’ period (approx. 5000 years ago), by the end of the post-glacial nutrient-rich ‘Sapropel’ conditions that prevailed before that time

Phylogeography of harbour porpoise (Phocoena phocoena) in the Southeastern North Atlantic and in the Black sea explored by the analyses of nuclear and mitochondrial DNA

19th Annual Conference of the European Cetacean Society and associated workshop, April 2-7, 2005, La Rochelle, FranceIn recent years, a decline in harbour porpoise (Phocoena phocoena) populations in the North Atlantic has been reported and this has raised concern over population sustainabilityN

Determination of organohalogenated contaminants in liver of harbour porpoises (Phocoena phocoena) stranded on the Belgian North Sea coast

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