Structure, fonctionnement, évolution des communautés benthiques ...

tel-00009359, version 1 - 1 Jun 2005
Chapitre 3 - Fonctionnement du réseau trophique benthique de la Grande Vasière
September) and few deposit feeders (5.4% of total biomass), (ii) carnivores dominant on the northern
part of the muddy bank (59.5% of total biomass in late summer) and also well represented on the
offshore margin of the bank (30.8% of total biomass in late summer and higher biomass value than the
one in Stn. G), and (iii) deposit feeders leading the benthic macrofauna biomass on the central ‘Grande
Vasière’ in spring. In late summer, the trophic group dominance patterns appeared more variable on
the muddy bank, with deposit feeders being dominant in stations B and C (45.5 and 57.3% of total
biomass, respectively), but suspension feeders leading the macrofauna biomass in stations A and D
(39.9 and 50.8% of total biomass, respectively; Fig. 11). By contrast, suspension feeders exhibited
very low if any biomass on the most silty station of the ‘Grande Vasière’ (G).
Biomass (mg. m -2 )
3500
3000
2500
2000
1500
1000
500
100%
80%
60%
40%
20%
0%
0
Surface deposit feeders
Sub-surface deposit feeders
Suspension feeders
Carnivorous
G spring
G spring
G summer
A spring
A summer
B spring
201
B summer
C spring
C summer
Carnivorous Suspension feeders
Sub-surface deposit feeders Surface deposit feeders
G summer
A spring
A summer
B spring
B summer
C spring
C summer
D summer
D summer
E summer
E summer
Figure 11. Benthic macrofaunal biomass (mg AFDW.m -2 ) displayed in three major trophic groups (deposit
feeders, suspension feeders and carnivores). Samples were collected with a 0.25 m 2 Hamon grab during
the trap experiments. No data in Stn F.