Biology Reference
In-Depth Information
play a major role in the transfer of these elements to microphagous, suspension-feeding,
deposit-feeding (including sediment-ingesting) animals, and consequently to all aquatic
food webs. However, when integrating in a temporal dimension (rate of renewal of the var-
ious organisms), the fluxes are much higher than the stored quantities (200 kg year -1 , 4 tons
year -1 , 4 tons year -1 , and 12 tons year -1 for Cd, Pb, Cu, and Zn, respectively). Furthermore,
because of their very high productivity, this mobilization is essentially attributable to the
primary producers, in particular, the microphytobenthos (Figure 7.4e-h).
Dwarf
eelgrass
Sea-
purslane
Dwarf
eelgrass
Sea-
purslane
(a)
(e)
Other
species
1.0%
7.2%
2.1%
0.0%
8.9%
Other
species
µPB
0.5%
31.6%
µPB
Oysters
Oysters
97.9%
50.2%
0.6%
Dwarf
eelgrass
Dwarf
eelgrass
Sea-
purslane
(b)
(f )
Sea-
purslane
0.0%
13.7%
0.8%
1.2%
Other
species
Other
species
0.1%
3.2%
Oysters
µPB
µPB
Oysters
0.0%
99.1%
75.4%
6.4%
Dwarf
eelgrass
Other
species
Sea-
purslane
Sea-
purslane
(c)
(g)
Dwarf
eelgrass
0.5%
7.6%
0.9%
0.1%
1.4%
Other
species
µPB
1.3%
10.9%
Oysters
µPB
2.9%
Oysters
95.3%
79.3%
Dwarf
eelgrass
Sea-
purslane
Sea-
purslane
(d)
Other
species
(h)
1.0%
0.8%
0.8%
1.6%
Dwarf
eelgrass
Other
species
1.0%
1.6%
µPB
Oysters
Oysters
2.0%
94.5%
µPB
94.5%
2.0%
FIGURE 7.4
Quantities (%) of (a) Cd, (b) Pb, (c) Cu, and (d) Zn fixed by the major benthic organisms and fluxes (%) of (e) Cd,
(f) Pb, (g) Cu, and (h) Zn associated with these organisms in the Marennes-Oléron basin (according to Pigeot
20 01). μPB, microphytobenthos.
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