Interactions entre comportement et variations de la croissance des juvéniles de la sole (Solea solea) dans les nourriceries des pertuis Charentais
Laffargue, P. (2004). Interactions entre comportement et variations de la croissance des juvéniles de la sole (Solea solea) dans les nourriceries des pertuis Charentais. PhD Thesis. Université de la Rochelle: La Rochelle. 195 pp.
The objective of this thesis was to identify certain processes related to the operation of the nursery sole Solea solea (L.) in Pertuis Charentais, oyster basin of the first major European ranking and nurseries for sole in the Bay of Biscay. Juveniles sole depend on coastal and estuarine habitats, which involves (i) the ability to adapt to environmental variability of these environments and (ii) access to an entire cycle critical habitat biological species. The nursery carried reports on the adjustments that the fish must be made between the constraints associated with habitat and its ability to manage these constraints, through the selection of feeding areas, rest and refuge. Coupling work courses and mesocosm experiments, methods based on integrative estimators were chosen, growth rate, Fulton condition index and endocrine status of these fish. These results were compared to a behavioral approach to determine how sole use space (acoustic telemetry tracking) and access to food (diet and estimation of carbon ration equivalent) in a sub affect shellfish habitat.Juvenile growth of the Pertuis Breton, sub-maximal during the period of rapid growth, tends to plateau around the autumn equinox. A mesocosm experiment confirmed that in situ temperature can cause the slowdown in growth. But at the same time, these juveniles have poor condition, the lowest levels of circulating thyroid hormones and the lowest feeding activity of the year. This state suggests constraints of the sea Pertuis, system semi-enclosed bays under moderate influence of estuarine plumes. It seems that less favorable marine environment in late summer and / or cascade effects on the trophic web do not allow all of the age group 0 to grow are based on potentials of the species. In the current global context, however, part of them is able to winter in these nurseries where they cover high hormonal levels and restore their feeding activity. Environmental constraints Pertuis Charentais, if order to modulate the growth of soles, do not seem to alter their behavior. We have shown by experience mésoscosme that neither the effect of farm structures, nor that of habitat changes associated with biodeposition not restrict access to areas under oyster-way. Check these results by sea will be needed before concluding that juveniles have access to all the nurseries in the Pertuis Charentais. However, two supply cycles of 30 h in the sluice Antioch demonstrate the ability of very young soles to adjust their rhythms of activity and food intake of intensity according presumably the hydrodynamic context, whether imposed by the cycle of fifteen tidal or wind. This also allowed a first estimate of the daily ration of young soles organic carbon, which will complete the currently developed food web models. Finally, the soles of heavy infestation of sluices by metacercariae a Bucephalidae, encysted in various sensitive organs, reveals unexpected biotic interactions. Cercariae of the parasite being propagated by mussel farms, this parasitosis sheds new light on the interactions between nursery function of coastal habitats and shellfish.
All data in the Integrated Marine Information System (IMIS) is subject to the VLIZ privacy policy
