Granulometric parameters, benthic biomasses of living organic matter, and oxygen and nitrogen fluxes at the water-sediment interface were investigated on triplicate samples, or in dark experiments, at 12 stations in the lagoon in SW New Caledonia. Analysis of functional characteristics of 3 bottom types revealed significant differences in the benthic food-webs. Onshore muddy bottoms had the lowest respiraiion, related to the lowest ATP pool and meiofauna density, in spite of high organic and pigment content. Near-reef white-sand bottoms were a sink for DON (dissolved organic nitrogen). exported no significant DIN (dissolved inorganic nitrogen), and supported the highest living biomass (ATP) via meiofauna and active microphytes. Intermediate grey-sand bottoms had the highest respiration, related to macrophyte cover and to a lesser extent to larger macrobenthos biomass, and were a source of nutrients for the water-column (DIN and DON). Partitioning of benthic biomass was investigated using non-linear multiple regression. Oxygen consumption was mainly related to ATP content, considered a s representative of micro-and meiofauna biomass, then to macrophyte bio~nass and to a lesser extent to macrofauna biomass. Pigment content did not implove the relationship. Depletion of inorganic nitrogen efflux, when compared to high respiration rates, increased from muddy bottoms to white-sand bottoms. Organic nitrogen (DON) exchanges were an order of magnitude greater than DIN exchanges ~ndicating a considerable nitrogen demand In the sediment.
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Boucher et al. (1990) studied this question.