Ecological significance of benthic foraminifera: 13C Labelling experiments

Abstract

We examined the ability of foraminifera in taking up freshly deposited algal carbon in intertidal estuarine sediments. Lyophylized 13C-labelled axenic Chlorella was added to intact sediment cores containing natural benthic biota. The response of the system as a whole was rapid; ~5% of the added carbon was respired to CO2 within 6 h. Bacteria assimilated ~2 to 4% of the added carbon within 12 h. Among the foraminifera, the dominant foraminifer Ammonia exhibited rapid uptake and it is estimated that ~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 foraminifera to meiobenthic abundance and biomass (37 and 47% respectively) suggest that foraminifera play an important role in the carbon cycle in these sediments.