The spatial distribution of the muddy fine sand community from the Bay of Veys (western English Channel) were investigated during spring and autumn 1997. A grid of 55 and 54 sites was sampled in ...March and October, respectively, using two replicates per site of a Hamon grab (0.25 m
2) for macrofauna collection and an additional one for sediment analysis. A total of 172 species were sampled with a dominance of polychaetes, followed by crustaceans and bivalves. The species richness and abundance show low temporal changes despite higher values in October than in March. In March, the mean abundance was 165 ind. 0.5 m
−2; in October, the mean abundance was 212 ind. 0.5 m
−2. Four assemblages from the
Abra alba–
Pectinaria koreni community were identified corresponding to a bathymetric and sedimentary gradient from muddy fine sands with high levels of fine particles in shallow water to fine sands in deeper water. The discussion focuses on factors prevailing on the spatial structure of sandy communities in the English Channel.
La répartition du macrozoobenthos intertidale de la baie des Veys (Manche occidentale, France) a été étudiée en 2000. Les résultats ont été comparés avec les acquisitions de 1985, qui font partie ...d'un suivi à long terme depuis 1973. Ces assemblages d'espèces s'organisent toujours suivant un gradient estuarien-marin, avec une singularisation du flanc est, séparé du reste de la baie par le chenal d'une rivière. La baie est soumise à une intrusion marine accompagnée d'une homogénéisation des assemblages d'espèces au centre et à l'ouest. Les installations conchylicoles du flanc est provoquent une très forte diminution locale du peuplement à
Scoloplos armiger et
Urothoe poseidonis, précédemment considéré comme typique de cette zone.
Pour citer cet article : O. Timsit et al., C. R. Biologies 327 (2004).
The distribution of intertidal macrozoobenthos in the ‘Baie des Veys’ (French coast of the eastern English Channel) has been studied in 2000. Results were compared with those of 1985, which are included in a long-term monitoring program established since 1973. The populations remained distributed along an estuarine-marine gradient, with a particularity on the eastern side, which is isolated from the rest of the bay by a river channel. The western and central tidal flats became more subjected by marine influence, which led to a homogenisation of the benthic communities. Oyster farming locally caused a fast decrease of the typical eastern community, which was characterized by
Scoloplos armiger and
Urothoe poseidonis.
To cite this article: O. Timsit et al., C. R. Biologies 327 (2004).
Intertidal macrozoobenthos evolution of the 'Baie des Veys' between 1985 and 2000. The distribution of intertidal macrozoobenthos in the 'Baie des Veys' (French coast of the eastern English Channel) ...has been studied in 2000. Results were compared with those of 1985, which are included in a long-term monitoring program established since 1973. The populations remained distributed along an estuarine-marine gradient, with a particularity on the eastern side, which is isolated from the rest of the bay by a river channel. The western and central tidal flats became more subjected by marine influence, which led to a homogenisation of the benthic communities. Oyster farming locally caused a fast decrease of the typical eastern community, which was characterized by Scoloplos armiger and Urothoe poseidonis.
The distribution of intertidal macrozoobenthos in the `Baie des Veys' (French coast of the eastern English Channel) has been studied in 2000. Results were compared with those of 1985, which are ...included in a long-term monitoring program established since 1973. The populations remained distributed along an estuarine-marine gradient, with a particularity on the eastern side, which is isolated from the rest of the bay by a river channel. The western and central tidal flats became more subjected by marine influence, which led to a homogenisation of the benthic communities. Oyster farming locally caused a fast decrease of the typical eastern community, which was characterized by Scoloplos armiger and Urothoe poseidonis.Original Abstract: La repartition du macrozoobenthos intertidale de la baie des Veys (Manche occidentale, France) a ete etudiee en 2000. Les resultats ont ete compares avec les acquisitions de 1985, qui font partie d'un suivi a long terme depuis 1973. Ces assemblages d'especes s'organisent toujours suivant un gradient estuarien-marin, avec une singularisation du flanc est, separe du reste de la baie par le chenal d'une riviere. La baie est soumise a une intrusion marine accompagnee d'une homogeneisation des assemblages d'especes au centre et a l'ouest. Les installations conchylicoles du flanc est provoquent une tres forte diminution locale du peuplement a Scoloplos armiger et Urothoe poseidonis, precedemment considere comme typique de cette zone.
The relation between condition and copper concentration was assessed in three bivalve species (the Baltic clam
Macoma balthica, the cockle
Cerastoderma edule and the mussel
Mytilus edulis) from ...several Dutch and French estuaries. In general, the copper concentration in the bivalves was negatively related to condition. The slope of this relation was strongest in the Baltic clam
M. balthica, with an almost inversely proportional change of Cu concentration at a change of condition, indicating an almost constant Cu content (body burden) per individual, i.e. no elimination or accumulation of Cu. In the mussel
M. edulis, the slope of this relation was absent or the weakest, with an almost uniform Cu concentration at a change of condition, indicating an almost proportional elimination (or accumulation) of Cu at a decrease (or increase) of the condition. Thus in Baltic clams the copper body burden is kept at an almost constant level, whereas in mussels the copper concentration is almost constant. In Baltic clams, but not in mussels and cockles, spatial differences were related to copper concentrations in the sediment. It is discussed that mussels maintain a homeostatic Cu concentration within a short time-period (days; copper highly exchangeable by complexation to metallothioneins), whereas the Cu concentration in Baltic clams is more slowly regulated (several weeks; fossilization of copper in mineral granules) and remains on an average in (partitioning) equilibrium with the Cu concentration in the sediment. Therefore, the Baltic clam is a better indicator of sediment copper pollution than the commonly used mussel. In addition, the observed differences between species were compared with differences in their life-strategies. The Cu concentration in the sediment is strongly related to the silt fraction (< 16 μm) of the sediment.
Consistent patterns of genetic variation in the marine bivalve
Macoma balthica (L.) were found after exposure to low levels of copper, starvation, and along geographic clines. The geographic clines ...were related to temperature and salinity. Genetic differences were primarily found in the LAP (Leucine aminopeptidase) locus; under stress the frequency of one specific allele, and thereby the heterozygosity, decreased strongly. The degree of changes depended on age and condition of the animals; adult animals showing stronger changes than juveniles. Low concentrations of copper yielded stronger genetic changes than high concentrations. It is concluded that genetic diversity and stress-sensitivity of species change predictably along a gradient in response to environmental harshness. Animals near the southern limit of their range were more sensitive to additional stress.
Sediments and the associated biota constitute an important compartment in the biogeochemical cycle of trace metals in soft substrate megatidal estuaries. The relationship between physicochemical, ...ecological properties, metal concentrations determined in megatidal estuary sediments from the French coast of the English Channel, the Baie des Veys and the macrobenthic organisms, are analysed, interpreted and reported. Total concentrations of zinc, cadmium, lead and copper were measured in mudflats and saltmarsh sediments using Differential Pulse Voltammetry. Sediment characteristics were obtained by measurement of particle size, water content, total organic carbon and carbonate content, using AFNOR standards. A semi-quantitative scale was used for assessing the density of the macrobenthic flora and fauna at each sampling site. Analysis of data obtained from this study showed a correlation between the concentrations of monitored trace metals and species of the macrobenthic fauna. The results of this study show that the physico-chemical characteristics of the sediments affect the retention of metals in the sediment and this in turn affects the biota.
