Structure, fonctionnement, évolution des communautés benthiques ...

tel-00009359, version 1 - 1 Jun 2005
Chapitre 3 - Fonctionnement du réseau trophique benthique de la Grande Vasière
Figure 1. Geographical location of the study sites sampled on the continental shelf of the Bay of Biscay in
April-May and September 2002 (R.V. Thalassa).
Sampling sites and strategy
Seven stations were sampled, in order to characterise water column and to estimate particulate
matter sedimentation on the northern part of the Bay of Biscay continental shelf (Fig. 1). A stratified
sampling scheme was applied to select these stations along an inshore/offshore gradient (including the
river plumes influence) representing (i) the sediment type and faunal assemblage successions as
described by Glémarec (1969), and (ii) the bottom-trawling fishing effort (Table 1). Four study sites
(A, B, C, D) were selected on the central part of the ‘Grande Vasière’ (thus taking small scale spatial
heterogeneity into account), plus one in the river plumes (F; Vilaine, Loire and sometimes Gironde
influences), one on the shelf slope (E), and one in the pure mud area located north of the ‘Grande
Vasière’ (G). Station depth ranged from 45 to 143 m from coast to large.
Spring sampling occurred from 26 April to 3 May 2002 (GASPROD cruise), while late summer
samples were collected between 13 and 19 September 2002 (TROPHAL cruise; R.V. Thalassa).
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