Regional scale estimation of carbon fluxes from long-term monitoring of intertidal exposed rocky shore communities

Abstract

The observed increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. Recent studies highlight the importance of identifying the role of marine coastal communities in carbon exchanges. Our objective was to couple macrozoobenthos abundance data from long-term monitoring with species metabolism rates to contribute to the estimation of CO2 fluxes from an intertidal exposed rocky shore community at a regional scale. The carbon fluxes due to respiration and calcification were calculated both during emersion and immersion, and the effect of temperature variation on carbon emissions was then predicted. Spatial and temporal natural variations of carbon fluxes were investigated and the contribution of exposed intertidal rocky shore communities to regional carbon emissions was calculated. The method was used to calculate the carbon budget allowed to account for the natural spatial variability of the community composition and carbon emissions. Mean annual calculated CO2 emission was 14.3molCm−2yr−2, and the annual regional CO2 flux was estimated at 2978tCyr−1. Simulations showed that the potential feedback of a rise in temperature of 1°C would lead to an increase of 4–7% in carbon emissions for this type of community. The results give a first quantification of intertidal exposed rocky shore carbon emissions that could be considered in evaluating further the global CO2 budget.