Determination of structure and functioning of the benthic community, pools and fluxes of N-compounds across sediment-water interface on the Concepcion shelf.

Determination of the structure and functioning of the benthic
community, and pools and fluxes of N-compounds (ammonia, nitrate,
nitrite) across the sediment-water interface in relation to local
physical forcing, oxygen minimum, biological production cycles and
sediment characteristics on the Concepcion shelf.

10 one-day oceanographic cruises were undertaken. These provided an
adequate temporal resolution at the seasonal scale during the three
years of the programme, as well as an adequate spatial scale that
includes the bay of Concepcion and the adjacent shelf. The study
period coincided witht he onset and end of the 1997-98 El Nino.

Several important chemical parameters and processes were measured and
studied in order to estabish their contribution to organic
mineralization and the potential effect on meiobenthic and
macrobenthic communites. Chemical parameters in the water column
(temperature, salinity, nutrient, oxygen) and in sediments (i.e. total
organic carbon, total nitrogen, Chl-a redox, H2S, Fe2O, Mn4+, NO3-,
NO2-, NH4+ pool sizes) were studied. Also measurement of nitrogen
fluxes across the water-sediment interface, mineralization processes
were performed.