Responses of Marine Diatom–Dinoflagellate Interspecific Competition to Different Phosphorus Sources

Phosphorus (P) is an essential nutrient element of phytoplankton, as well a limiting factor for phytoplankton growth. It controls the succession blooms from diatoms to dinoflagellates, especially in East China Sea (ECS), where eutrophication serious. Most studies have only considered single aspect dissolved inorganic phosphorus (DIP) or organic (DOP). In contrast, we investigated growth interactions among major bloom-forming marine diatom Skeletonema costatum and dinoflagellates Prorocentrum donghaiense Karenia mikimotoi by using bi-algal cultures combined with DIP DOP. Our results revealed that (1) P. K. survival strategies are superior those S. culture, whether under P-sufficient P-deficient conditions, (2) has slight competitive advantage over when P sufficient, but reverse true deficient. The difference interspecific competition at different concentrations DOP mainly arises variation utilization abilities species regards sources, finding which can also provide strong evidence revealing ECS.