Temporal variability of foraminiferal densities in the northern Adriatic Sea

Over a period of two years (August 1996 to July 1998) foraminiferal abundances have been monitored at two stations in the northern Adriatic Sea. Environmental variables such as oxygen concentrations, salinity and temperature were measured and the trophic state of the seawater at both localities was calculated. Foraminiferal numbers fluctuated considerably during the two years, but not in a straightforward yearly cycle. Most taxa, however, showed abundance patterns very similar to many of the others. Despite the lack of clear annual cyclicity in foraminiferal numbers, there appears to be a strong correlation between densities of several important taxa and high bottom-water oxygenation or a less extreme trophic state of water column. There is some time-lag, however, before the biotic response to environmental changes is reflected in the faunal patterns of foraminifera >63 μm.