Characterization of a Levanderina fissa Bloom in Aquaculture Ponds and Its Utilization of Dissolved Organic Phosphorus

Harmful algal blooms (HABs) pose significant threats to ecosystems and human health worldwide, with their frequency and intensity increasing substantially. The present study reports an algal bloom observed in an aquaculture pond near Haizhou Bay in July 2022. The causative species, identified through morphological observation and DNA barcoding analysis, was the dinoflagellate <i>Levanderina fissa</i> (Levander) Moestrup, Hakanen, Gert Hansen, Daugbjerg & M. Ellegaard, 2014, known for causing extensive HAB events in the coastal waters of China. A sharp decline in phytoplankton species diversity was observed during the transition from the pre-bloom to the bloom phase. Furthermore, the uptake of four types of dissolved organic phosphorus (DOP), including glucose-6-phosphate (G6P), adenosine-5-triphosphate (ATP), sodium tripolyphosphate (TPP), and glyphosate, by isolated <i>L. fissa</i> was investigated in the laboratory. The results showed that G6P, ATP, and TPP supported <i>L. fissa</i> growth as effectively as orthophosphate. Additionally, the elevated concentrations of dissolved inorganic phosphorus in the media of the three treatments indicated the involvement of extracellular hydrolysis. However, alkaline phosphatase was not responsible for the hydrolysis of these three forms of DOP. This study demonstrates that the ability of <i>L. fissa</i> to utilize DOP may confer a competitive advantage within phytoplankton communities, potentially leading to algal blooms in aquaculture ponds.