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Structure, fonctionnement, évolution des communautés benthiques ...

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tel-00009359, version 1 - 1 Jun 2005<br />

Mean gross particle fluxes<br />

Chapitre 3 - Fonctionnement du réseau trophique benthique de la Grande Vasière<br />

Mean values of the 12-h sediment trap deployments are summarised in Table 4. These results<br />

correspond to the gross sedimentation (net sedimentation + sedimentation of re-suspended matter).<br />

Parameter ranges<br />

As for bottom-water suspended particulate matter, the null hypothesis of mean global<br />

homogeneity must be rejected in all cases (ANOVA, p 90%) in the station under the river plumes influence (F), intermediate<br />

values in G (66 to 80%) and lowest values in the central ‘Grande Vasière’ stations (26 to 43-68%).<br />

The PON fluxes were in the ranges 5-18 mg N.m -2 .h -1 in spring, vs. 1-18 mg N.m -2 .h -1 in late<br />

summer. Mean PON fluxes on the central ‘Grande Vasière’ stations were 7.77 ± 2.24 mg N.m -2 .h -1 in<br />

spring, vs. 2.18 ± 0.76 mg N.m -2 .h -1 in late summer. As for POC fluxes, higher values were found in<br />

the coastal zone (Stn F: 17.77 and 4.75 mg N.m -2 .h -1 in spring and late summer, respectively), but the<br />

seasonal trend was similar that is a 3.5-fold decrease in PON flux between spring and late summer.<br />

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