The main objective was to investigate the importance of the sediment as a nutrient source for blooms of nuiscance filamentous algae. Nutrient fluxes from the sediment were hypothesised to be of greater importance in maintaining algal biomass than were nutrients originating from the overlying water column. We aimed to assess the relative importance of algal mats on sediment geochemistry and nutrient release under stillwater and controlled flow conditions. Using nutrient fluxes as a surrogate for ecosystem function, we wished to investigate the role of species richness in maintaining the integrity of nutrient diagenesis. In this context, it is not necessarily the number of species that is important in maintaining nutrient supply to algal blooms, but the contribution individual species make to mediate nutrient release.
The sientific aims were successfully achieved and we were able to come to some solid conclusions. The presence of fauna significantly increased the flux of nutrients, but the magnitude of increase depended upon which species were present. Sediments containing several species elicited a lower response than would have been expected from the summation of responses found for the single species treatments. The presence of water flow did not have a significant effect on nutrient flux. We suggest that nutrient fluxes from the sediment are initiating the growth of macroalgal blooms in spring, and such fluxes remain a significant source in maintaining algal mat production during the summer. Currently, two manuscripts are in preparation for submission to peer reviewed journals as follows: I)Bloom or bust? The significance of nuiscance macro-algal blooms on ecosystem function II)The effect of diversity on nutrient release in marine benthic systems and the influence of flow.