Macrobenthic biodiversity and oxygen uptake in estuarine systems: the example of the Seine estuary

作者：Janson Anne Laure^*; Denis Lionel; Rauch Mathieu; Desroy Nicolas

来源：Journal of Soils and Sediments, 2012, 12(10): 1568-1580.

DOI：10.1007/s11368-012-0557-2

• Benthic oxygen fluxes
• Biodiversity
• Bioturbation
• Functional groups
• Macrobenthic communities
• Trophic guilds

Purpose Bioturbation is a major process influencing the functioning of benthic ecosystems. Although controlled experiments with species in monoculture or in artificial combinations have increased the knowledge about the role of biological diversity on geochemical processes, specific interactions have been neglected, making the extrapolation of experimental results to natural systems difficult. In this context, the main objective of this study was to measure the effects of a whole natural macrobenthic community on benthic oxygen uptake.
Materials and methods The relationships between macrofauna and oxygen uptakes were investigated in the estuarine system of the Seine, France, during the winter and fall according to the variability of river discharge. Four undisturbed sediment cores with associated macrofauna and overlying water were sampled at nine subtidal stations in order to perform whole core incubations and measure total oxygen uptake (TOU). Moreover, values of diffusive oxygen uptake (DOU) were obtained using microelectrode profiling and fauna-mediated oxygen uptake (FOU) was calculated as the difference between TOU and DOU. FOUs were thus linked to macrofaunal parameters; both traditional (species richness, abundance and biomass) and functional (trophic guilds and bioturbation modes).
Results and discussion The average FOU (+/- SD) ranged from 170 +/- 36 to 1,324 +/- 701 mu mol m(-2) h(-1), and values represented 33 to 89 % of TOU. Each of the traditional macrofauna parameters had a significant and positive correlation with FOU. In addition, abundance, biomass and species number of some functional groups (e.g. suspension feeders and biodiffusors) were also correlated to FOU, supporting the diversity-stability hypothesis of McArthur (Ecology 36:533-536, 1955). Nevertheless, the relationship between FOU and other functional groups such as conveyors illustrated the idiosyncratic nature of this hypothesis, underlining the difficulty of clearly identifying the role of a macrofaunal community on oxygen exchanges at the sediment-water interface.
Conclusions Our results confirm the importance of functional biodiversity on mineralization processes as well as the need to take into account the whole community. They also suggest that future studies should focus on the functional consequences of species loss and the potential resilience of the communities as a way to maintain ecosystem processes.

• 出版日期2012-12