Efficacy of the application of organic fertilizer to oyster growth

Hiroshima Bay is the top oyster-producing bay in Japan. However, the bay ecosystem has suffered from oligotrophication due to a 40-year nutrient reduction measure. Poor growth of cultured oysters caused by oligotrophication is a serious problem. The aim of the present study was to evaluate the efficacy of a newly developed organic solid fertilizer on oyster growth. In the field experiments, it was demonstrated that oyster meat weight increased by 34 % with the application of the fertilizer than without. A simulation model revealed that the nutrients eluted from the fertilizer enhanced the growth of oysters through the growth of phytoplankton. The observations implied that the decomposition of dissolved organic matter excreted from phytoplankton and the decomposition of detrital matter accelerated nutrient cycling and the oyster growth. The developed organic solid fertilizer is effective in enhancing oyster growth in an oligotrophic area.