Positive linear relationship between phytoplankton diversity and productivity in an artificial reef ecosystem

The relationship between biodiversity and ecosystem functioning (BEF) is one of the central themes of ecological research. Phytoplankton play important ecological functions in aquatic ecosystems. Although the BEF in phytoplankton communities was found in various types of natural aquatic ecosystems, it has not been examined in artificial ecosystems at small scale. Artificial reef, a submerged device built by human, can pump nutrient-rich bottom water to the surface, mimicking natural upwelling to feed phytoplankton. Here we quarterly investigated the phytoplankton communities in the artificial reef zone and its adjacent water in a subtropical bay. Our results showed positive linear relationship of phytoplankton richness to productivity in the artificial reef zone. The slope of richness-productivity relationship increased with water temperature and was relatively higher in the summer. Phytoplankton resource use efficiency (RUE) was positively correlated with richness but negatively correlated with evenness in the artificial reef zone. Compared to the adjacent natural zone, the artificial reef zone had more diverse phytoplankton communities and higher productivity during the growing season. The phytoplankton BEF pattern we found provides evidence for the role of artificial reef in the functioning of subtropical bay ecosystem.