Mechanisms for Detrital Cycling in Nearshore Waters at Bermuda

Welsh, Barbara; Bessette, Diane; Herring, Janet; Read, Luana

The detrital cycle in Whalebone Bay and adjacent coastal waters at Bermuda was investigated to determine how such a relatively open system of exchanges of nutrients and carbon could be maintained in the highly oligotrophic waters which bathe the island. The shore zone and particularly the beach wrack were found to provide a source of materials, and a stranding cycle is described whereby detrital seagrasses and algae are insolated, desiccated, and leached, accelerating the release of dissolved constituents and fine particulates to the water column. Three conservative processes associated with the embayment were noted: tidal recycling of nearshore water, the delaying effects of oscillatory wave motion, and biological uptake by benthic plants which served to reduce exports and retain both nutrients and organic carbon within the Bay, thereby perpetuating the cycle. Little if any particulate material left the Bay. In fact, substantial quantities of C, N, and P were imported from the Sargasso Sea in the form of Sargassum which more than.compensated for any exports. Thus a relatively open detrital system does operate in Bermuda, maintained and perpetuated by a combination of physical, chemical, and biological processes and subsidized from the open ocean, but its influence is confined to a narrow band near shore.

Mechanisms for Detrital Cycling in Nearshore Waters at Bermuda

Series