Abstract
An experiment was performed in a seagrass bed to examine fertilizer efficiency in enhancing porewater nutrient concentration by analysing nutrient concentration at two levels of a slow-release fertilizer addition (3.6 g and 8.4 g) to the sediment in situ. Nutrient concentrations were analysed in porewater samples taken at different times after fertilization. Ammonium porewater concentration was significantly higher in all experimental treatments than in controls even 20 days after fertilization, while phosphate porewater concentration was enhanced only 2 days after fertilization.
The nutrient status of Cymodocea nodosa suggested nutrient limitation at the site for the content either in the below ground and above ground tissues compared with the critical ones reported in the literature. Conversely, the results did not indicate nutrient limitation of Caulerpa taxifolia at the site. Phosphate content in the below ground portion of C. taxifolia grown in medium and high fertilization areas was 88% and 11% higher than in control areas, while P content in blades at the highest nutrient addition decreased by 65 %. Below ground biomass of C. taxifolia was related to the enrichment gradient, while above ground biomass was independent of enrichment.
Copyright (c)1999 by Walter de Gruyter GmbH & Co. KG
