Parasitism is a common phenomenon in nature, where one species benefits at the expense of another. In marine environments, fungal parasites are known to infect phytoplankton, causing disease and death, and contributing to the loss of phytoplankton populations. The impact of fungal parasites on phytoplankton communities can be significant, as selective parasitism on one species of phytoplankton can encourage the development of other species and may be one of the factors influencing communities' seasonal succession. Fungi parasites play a crucial role in sinking by inducing cell death and promoting cell aggregation, which can lead to the export of phytoplankton to the deep sea. Although fungal parasites are well studied in freshwater phytoplankton, there is still little information on marine phytoplankton parasites. Recent studies have shown that large diatoms are the preferred hosts for fungal parasites in cold waters, while the infection of dinoflagellates is reported in the oligotrophic Mediterranean Sea. However, the occurrence and impact of fungal parasites on phytoplankton communities in the Red Sea remain largely unknown. Therefore, the proposed project aims to investigate the occurrence of fungal parasites that infect phytoplankton and analyze their role in the export of phytoplankton to the deep sea in the Red Sea. By understanding the ecological impacts, life cycle, host range, and infection strategies of fungal parasites on populations of Red Sea phytoplankton, this study can provide critical information on the dynamics of marine ecosystems and carbon cycling.