Major aspects of foraminiferal variability (standing crop and biomass) on a monthly scale in an intertidal zone

Temporal and spatial variability of intertidal benthic foraminiferal assemblages in the surface (0-1 cm) sediments have been determined by a time series survey (27 months) of the Hamble estuary, southern England. One pair of replicates was collected each month from two stations at different elevations in the intertidal zone. The assemblages were dominated by three species, Haynesina germanica, Ammonia beccarii (forma tepida), and El-phidium excavatum, Patchiness occurred on a scale of a few centimeters and had a major impact on tracking temporal changes in the standing crop. The study clearly shows the need for replicate sampling in order to obtain reliable information especially on absolute abundance data. The absence of juveniles is due to loss through drying the samples prior to picking. The results show that it is not possible to determine the lifespan of continuously reproducing species (i.e., young individuals always present) where it is impossible to follow the growth of cohorts, and for the same reason it is not possible to make production calculations. While there is a cyclicity in standing crop at station 2 (mid intertidal zone), this is not the case at station 1 (lower intertidal zone). Species diversity showed reasonable annual cyclicity at broth stations. At neither station is there any correlation between the size of the standing crop and the chlorophyll a content of the surface sediment. There was some cyclicity in the peaks of biomass (only determined for sta, 1) in all three species and considerable variability from one year to the next. Thus this area is extremely variable, there is no obvious annual pattern in standing crop, and the best measures of seasonality seem to be species diversity and biomass.