Ecological significance of benthic foraminifera: C-13 labelling experiments

We examined the ability of foraminifera in taking up freshly deposited alga l carbon in intertidal estuarine sediments. Lyophylized C-13-labelled axeni c Chlorella was added to intact sediment cores containing natural benthic b iota. The response of the system as a whole was rapid; similar to 5% of the added carbon was respired to CO2 within 6 h. Bacteria assimilated similar to 2 to 4 % of the added carbon within 12 h. Among the foraminifera, the do minant foraminifer Ammonia exhibited rapid uptake and it is estimated that similar to 1 to 7% of the added carbon was ingested within 3 to 53 h. This rapid, substantial uptake by Ammonia and the significant contribution of fo raminifera to meiobenthic abundance and biomass (37 and 47% respectively) s uggest that foraminifera play an important role in the carbon cycle in thes e sediments.