Structure, fonctionnement, évolution des communautés benthiques ...

tel-00009359, version 1 - 1 Jun 2005
TPM flux (g.m -2 .h -1 )
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Chapitre 3 - Fonctionnement du réseau trophique benthique de la Grande Vasière
spring
summer
F G A B C D E
Stations
Figure 5. Total Particulate Matter flux (TPM, g.m -2 .h -1 ) and Particulate Organic Carbon:Total Particulate
Matter ratios in particulate matter collected in the bottom-moored sediment traps during spring (April
26 th to May3 rd ) and late summer (September 13 th -19 th ) sampling on the Bay of Biscay continental shelf.
Stations are ranked according to an inshore-offshore gradient.
The δ 13 C values in particles sedimented in the traps ranged from –22.74 (Stn D) to –20.00‰
(Stn A) in spring vs. –24.62 (Stn B) to –20.35‰ (Stn G) in late summer. Stations A and G showed
carbon stable isotopic ratios similar to those of the inshore station (F) overall (Table 4), while the
central ‘Grande Vasière’ stations B, C and D exhibited higher δ 13 C values (-22.71 ± 0.02‰ in spring
and -24.60 ± 0.04‰ in late summer). The δ 13 C value of the offshore station (E) in September was
close to the values recorded on the central ‘Grande Vasière’. The δ 15 N values ranged from 2.59 (Stn
C) to 4.40‰ (Stn F) in spring vs. 2.07 (Stn A) to 4.63‰ (Stn F) in late summer. The central ‘Grande
Vasière’ (3.46 ± 0.60‰) exhibited a 1‰ difference with the coastal zone in spring and a 1.5‰
difference in late summer (3.15 ± 0.99‰).
POC flux (mg C.m -2 .h -1 )
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0
191
spring
summer
F G A B C D E
Stations
Figure 6. Particulate Organic Carbon flux (POC, mg C.m -2 .h -1 ) and Particulate Organic Carbon:Total
Particulate Carbon ratios in particulate matter collected in the bottom-moored sediment traps during
spring (April 26 th to May 3 rd ) and late summer (September 13 th -19 th ) sampling on the Bay of Biscay
continental shelf. Stations are ranked according to an inshore-offshore gradient.
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POC:TPM (%)
POC:PTC (%)