Distribution of Ulva macroalgae before and after the outbreak of the Yellow Sea green tide in aquaculture ponds and rivers nearshore Jiangsu, China

Abstract

Green tide caused by the extensive proliferation of Ulva macroalgae in the Yellow Sea has been continuously occurring for 17 years. Previous studies indicate the Neopyropia aquaculture area in Jiangsu to be the main source of green tides in the Southern Yellow Sea. However, whether there are additional supplementary sources for the green tide in the Yellow Sea remains to be studied. This study conducted sampling of Ulva macroalgae in 14 aquaculture ponds and rivers nearshore Jiangsu in February and November in 2022. The molecular biology identification of samples through ITS and 5S indicates that the Ulva macroalgae in aquaculture ponds and rivers are composed of Ulva prolifera, Ulva linza, Ulva simplex, Ulva torta, Ulva flexuosa, and Ulva meridionalis. The results of micropropagules indicate that the abundance of micropropagules in aquaculture ponds is significantly higher than in rivers. In both February and November, the points with the highest abundance of micropropagules were located in aquaculture ponds, reaching 2090 inds L−1 and891 inds L−1, respectively. This study found that before and after the outbreak of green tide, the dominant species of green tide outbreak,5S-II U. prolifera,existed in aquaculture ponds and rivers nearshore Jiangsu. 5S-II U. prolifera in aquaculture ponds and rivers may have a potential impact on the outbreak of green tide in the Yellow Sea.