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Navon M.,Normandie University | Navon M.,Laboratoire Morphodynamique Continentale et COtiere | Navon M.,French National Center for Scientific Research | Navon M.,Station Marine Of Luniversite Of Caen Basse Normandie | And 4 more authors.
Cahiers de Biologie Marine | Year: 2013

Recreational clam digging is a traditional activity on the large intertidal zone of the western coasts of the Cotentin (western English Channel). A variety of fishing gears are used to harvest the target species the warty venus Venus verrucosa (Linnaeus, 1758). In this note, the immediate effect (i.e., four days) of fork harvesting was studied during the March 2012 spring tide, following a control-impact design with a control station and three impacted stations using pebble forks. An immediate significant decreases of coarse sand and gravel benthic macrofauna is observed in fishing area. In the future, it is recommended that pebble fork fishing should be prohibited to harvest this target species. Source


Dauvin J.-C.,Normandie University | Dauvin J.-C.,Laboratoire Morphodynamique Continentale et COtiere | Dauvin J.-C.,French National Center for Scientific Research | Dauvin J.-C.,Station Marine Of Luniversite Of Caen Basse Normandie | And 14 more authors.
Cahiers de Biologie Marine | Year: 2014

On the western coast of the Cotentin peninsula (English Channel, France), small estuaries, called havres, were transitional systems between terrestrial and aquatic habitats. This study concerns the macrobenthos and the evolution of the habitat areas of two estuaries: Blainville and Regnéville. In 2002, 2007 and 2010, aerial photographs showed that the total areas for both estuaries were stable for the last 10 years. Macrofauna characteristics (e.g., species richness, abundance, and biomass) and habitat areas were used to estimate the carrying capacity of both Blainville and Regnéville estuaries in 2010 as an indicator of their trophic value. The estimated carrying capacities showed the importance of salt marshes in both estuaries. However, the carrying capacity was higher in Regnéville (0.408 tAFDW.ha-1) than in Blainville (0.147 tAFDW.ha-1), which was due to the high degree of anthropogenic changes in the Blainville estuary. Salt marsh data revealed the dominance of typical north-eastern Atlantic estuarine species, (i.e., Carcinus maenas, Orchestia gammarellus and Talitrus saltator), with 135 to 1,000 ind.m-2 and a biomass between 23 to 80 g AFDW.m-2 The abundances and biomasses per m2 of the macrofauna observed in those small estuaries were similar to those observed in other larger north-western Atlantic estuaries and provide similar services such as feeding zones for fishes and birds. In the future, the Regnéville habitat areas must be preserved to maintain high benthic biomasses. Source


Beck F.,University of Caen Lower Normandy | Beck F.,French National Center for Scientific Research | Beck F.,Station Marine Of Luniversite Of Caen Basse Normandie | Pezy J.-P.,University of Caen Lower Normandy | And 8 more authors.
ICES Journal of Marine Science | Year: 2015

Recreational and professional clam fishing was an important activity on the extensive intertidal zone of thewesternCotentin coast (western English Channel). A variety of fishing gear was used to harvest the target species: the European clam Ruditapes decussatus (Linnaeus, 1758) and the introduced Manila clam R. philippinarum (Adams and Reeve, 1850). In this study, we studied the effect of rake harvesting during the spring tides of February-March 2014, following an experimental design with a control station and three stations impacted by rake harvesting in three sediment types: sandy, gravelly, and mixed gravelly rocky habitats. No significant sediment and macrofauna changes occurred at the three sites after rake harvesting. Nevertheless, the number of clams decreased significantly after raking on the gravelly habitat, whereas in the other two habitats, sediment transport in this high-energy hydrodynamic environment was able to transfer clams and other macrofauna species across the fishing sites, thus minimizing the effects of rake harvesting. Therefore, although the effect of rake harvesting appeared limited during winter, the regional impact (high fishing pressure along 60 km of coast) and increase of recreational fishers during summer needed to be studied in the future. © 2015 International Council for the Exploration of the Sea. All rights reserved. Source

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