Determination o f the role of the meiobenthos in Antarctic ecosystems on the basis of: - estimates of secondary production (calculated on the basis of detailed temporal series of biomass data) and metabolic activity (measurements of respiration and perhaps also production of direct heat); - relations between the meiobenthos and its abiotic environment (e.g. what role is played by the meiobenthos in the biogeochemistry of the bottom sediments (in remineralization processes) and what is the influence of organic C (POC and DOC), coming from the water column or regenerated on the sea bed, on the distribution and activity of sea floor fauna); - determination of the POC/DOC biomass balance at the water column-sediment interface and determination of the importance of meiofauna in this balance; - food experiments (nematodes-bacteria grazing and importance of diatoms as a food for meiofauna in the littoral regions). OBJECTIVES Study of the biomass balance (POC/DOC) at the sediment-water interface in Antarctic sea floor ecosystems and study of energy fluxes through meiobenthic communities (numerically, the meiobenthos is the main group of metazoons in the sea floor ecosystem which occupies several trophic levels and has a very intensive bioturbation activity), with a view to assessing the role of the meiobenthos in, inter alia, remineralization processes. The following problems will be examined within the framework of this research: - What is the influence of primary production in the water column on benthic activity (in the bioturbation zone)? - What quantity of organic C is stored in the bottom layer below the bioturbation zone? - What quantity of organic material is reintroduced into the water column as a result of benthic activity? Within the framework of this research, the accent will be placed above all, in so far as flux aspects are concerned, on the activities of nematodes, which represent 90-95% of meiobenthos densities. The total biomass of the benthos will be calculated partly from specific measurements (meiobenthos) and partly in conjunction with data from other research teams (macrobenthos: BAS; microbenthos : NIOZ). It has been clearly demonstrated in temperate regions that there is a direct and positive relationship between the quantity of organic matter in the water column and the sea bed biomass. The role played by the benthos in remineralization processes is deduced in particular from the fact that it has been demonstrated that meiobenthic organisms (and nematodes especially) can have a strong positive influence on the production of bacteria in the sediments, thus having a direct influence on the biogeochemistry of the sea floor. Determining the order of magnitude of the interactions mentioned is one of the primary objectives of this research.