Calculation of annual budget of net benthic production in the Mont Saint-Michel Bay with emphasis on the influence of cloudiness, migration of microphytobenthos and variation of the respiration rate with the alternation of emersion-immersion periods - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Continental Shelf Research Année : 2009

Calculation of annual budget of net benthic production in the Mont Saint-Michel Bay with emphasis on the influence of cloudiness, migration of microphytobenthos and variation of the respiration rate with the alternation of emersion-immersion periods

Résumé

In order to provide an accurate annual rate of net benthic community production, communityphotosynthetic response to incident irradiance and respiration were measured at different times of theyear, at mid-tide level on the muddiest part of the Mont Saint-Michel Bay. As the water turbidityprevented any photosynthesis by the microphytobenthos during immersion periods, primaryproduction was measured only during emersion periods. In contrast respiration was expected to varyaccording to the tidal cycle and was measured during both emersion and immersion periods. Primaryproduction and respiration rates under emersion were assessed using in situ infra-red gas analysis of CO2 exchange measured in a benthic chamber. Respiration rates under immersion were assessedthrough total CO2 concentration variations in incubated cores.When respiration rate was considered constant over a day and equal to the rate measured underemerged conditions, the community respiration was 54.56gCm2yr1. Taking into account thevariations of respiration during the emersion/immersion cycle, community respiration increased to101.76gCm2yr1 (86% increase). Assuming that community primary production varied as a functionof irradiance from the time of exposure until flooding, GCP was 53.22gCm2 yr1 when calculated withtheoretical irradiance and 45.86gCm2yr1 after correction for cloudiness (14% decrease). Then, byintegrating the effect of vertical migration of microphytobenthos, the rate was adjusted to 23.49gCm2yr1 (49% decrease). The net community production budget, calculated as the difference betweenthe GCP and the CR budgets taking into account the corrections described above, was 78.27gCm2yr1. This example of annual budget calculation highlights the need to integrate several processesoccurring over various time scales to accurately reflect the metabolic balance of a system. The resultsalso confirmed the heterotrophic status generally suggested for intertidal muddy sediments.
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Dates et versions

hal-00480702 , version 1 (04-05-2010)

Identifiants

  • HAL Id : hal-00480702 , version 1

Citer

A. Migné, Nicolas Spilmont, G. Boucher, Lionel Denis, C. Hubas, et al.. Calculation of annual budget of net benthic production in the Mont Saint-Michel Bay with emphasis on the influence of cloudiness, migration of microphytobenthos and variation of the respiration rate with the alternation of emersion-immersion periods. Continental Shelf Research, 2009, 29, pp.2280-2285. ⟨hal-00480702⟩
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