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Publication de trois articles pour Nicolas Toupoint

Au cours de l’année 2016, Nicolas Toupoint a publié trois articles. Voici les résumés et les références des trois articles en question :

- Gilmore-Solomon, L., Toupoint, N., Myrand, B., Tremblay, R. 2016. Influence of Seston Quality on Physiological Condition of Mytilus edulis in Oligotrophic Lagoon. Journal of Aquaculture & Marine Biology, MedCrave Group, USA, 1-21.

Mytilus edulis culture depends on natural plankton with seasonal variations in dietary nutritional value. The microbial communities assimilated by M. edulis in Magdalen Islands lagoons (St. Lawrence Gulf, Canada), are mainly dominated by small heterotrophic eukaryotes, which vary taxonomically and in terms of lipid composition over the growing season. Particular lipids classes and fatty acids found in the mussels’ food source may have an effect on their physiological condition. From May to October, four physiological measurement series (oxygen consumption and clearance rates), were performed on 1- and 2- years-old mussels under two nutritional conditions. The fist group of mussels was fed with their natural diet and the second group was fed microalgae rich in essential fatty acids. Both diets were characterized according to their composition in lipid classes and fatty acids. The relationship between metabolic rates and diets quality, in terms of lipids class and fatty acids components was compared. No signifiant differences in mussels’ metabolic rates were found between two different diets. Indeed, only signifiant changes over time and between mussel’s ages were noted for clearance rate. These diets were different in their fatty composition and associated with signifiant differences in the mussel’s gills fatty acids composition, particularly in polyunsaturated fatty acids.

 

- Toupoint N., Barbier P., Tremblay R., Archambault P.,
McKindsey C.W., Winkler G., Meziane T, Olivier F. 2016. Influence of intertidal recreational fisheries and ‘ bouchot’ mussel culture on bivalve recruitment. Marine Environmental Research 117 : 1-12.

In coastal environments, fishing and aquaculture may be important sources of disturbance to ecosystem functioning, the quantification of which must be assessed to make them more sustainable. In the Chausey Archipelago, France, recreational fishing and commercial shellfish farming are the only two evident anthropogenic activities, dominated by bivalve hand-raking and ‘bouchot’ mussel culture, respectively. This study evaluates the impact of both activities on bivalve recruitment dynamics by comparing primary recruitment intensity (short-term effect) and recruitment efficiency (medium-term effect) by sampling bivalves in reference (undisturbed) and disturbed (i.e. subjected to hand-raking or in ‘bouchot’ mussel culture areas) parcels throughout and at the end of the recruitment season, respectively. Specific hypotheses evaluated were that (H1) bivalve hand-raking negatively affects bivalve recruitment and that (H2) ‘bouchot’ mussel culture promotes bivalve recruitment. Patterns in bivalve community structure in reference parcels (i.e. natural pattern) differed between initial and final recruitment, underlining the great importance of early post-settlement processes,
particularly secondary dispersal. Primary recruitment intensity was inhibited in hand-raking parcels whereas it was promoted in ‘bouchot’ mussel culture parcels, but the effect on recruitment efficiency was muted for both activities due to post-settlement processes. Nevertheless, the importance of effects that occur during the first step of recruitment should not be ignored as they may affect bivalve communities and induce immediate consequences on the trophic web through a cascade effect. Finally, it is highlighted that hand-raking damages all life stages of the common cockle Cerastoderma edule, one of the
major target species, suggesting that this activity should be managed with greater caution than is currently done.


- Moynihan M.A., Barbier P., Olivier F.,  Toupoint N., Meziane T. 2016. Spatial and temporal dynamics of nano- and pico-size particulate organic matter (POM) in a coastal megatidal marine system. Limnology and Oceanograph, 61(3) : 1087-1100.

 

Surface water samples of size-selected seston (0.7–20 lm) were collected from April 2013 to September 2013 at three similar coarse-sand benthic habitats. Additionally, seston sampling was performed at a fixed location throughout a complete tidal cycle (2014). A combination of fatty acid (FA), isotope, and flow cytometry analyses were used to determine the quality and quantity of nano- and pico-sized particulate organic matter (POM). High variability was found between fatty acid replicate samples. Similar temporal patterns were observed at two sheltered sites, while the exposed site displayed less pronounced seasonal changes. Lower concentrations of 16C and 18C polyunsaturated fatty acids were found during low tide sampling. Globally, POM was dominated by picoeukaryotes, with concentrations exceeding 50,000 cells mL 21, and (16:4 x3 1 18:3 x3)/ R x3 is proposed as novel biomarker of picoeukaryotes in this region.