SEDIMENT-WATER COLUMN COUPLING AND THE FATE OF THE SPRING PHYTOPLANKTON BLOOM IN LOCH LINNHE, A SCOTTISH FJORDIC SEA-LOCH - SEDIMENT PROCESSES AND SEDIMENT-WATER FLUXES

Sediment-water fluxes of oxygen and nutrients before and after the imp act of the spring phytoplankton bloom were measured by core incubation experiments. Less than 10 days after the bloom had settled, chlorophy ll was found down to a depth of 2 cm in the sediment. This rapid buria l was probably due to mixing during resuspension events. There was som e increase in oxygen uptake by the sediment after settlement of the bl oom and a concomitant increase in the apparent oxygen diffusion coeffi cient; this latter increase may indicate a stimulation of bio-irrigati on. There was a nitrate influx after settlement of the bloom, but no m easurable efflux of ammonium or phosphate from the sediment. There was no increase of sulphate reduction activity after the impact of the bl oom nor was solid-phase extractable manganese used as an alternative t erminal electron acceptor for oxidation of carbon. We conclude that mu ch of the readily biodegradable organic components of the bloom was mi neralized in the water column during sediment resuspension events. (C) 1995 Academic Press Limited