Decadal changes in diversity and occurrence of microalgal blooms in the NW Arabian/Persian Gulf

Kuwait's marine area, located at the far north-western corner of the Arabian/Persian Gulf, is under significant and diverse anthropogenic effects, which are exacerbated by climatic changes. Microalgal blooms occur in Kuwait's waters year round and are caused by proliferation of microalgae, cyanobacteria, and photosynthetic ciliates. The diverse assemblage of potentially toxic diatoms and dinoflagellates known elsewhere to cause syndromes of human poisoning was revealed in Kuwait's marine environment. A wide range of potentially harmful microalgae that can be associated with mortality of marine biota, including known ichthyotoxic dinoflagellates, raphidophycean and haptophyte flagellates, were observed routinely in Kuwait's waters. The chronological overview of recorded algal bloom events indicates that Kuwait's marine environment is increasingly affected by harmful algal blooms (HABs). Both toxic and high biomass blooms were associated with fish mortality in Kuwait's coastal waters. Most of algal blooms occurred during the warm periods in spring and autumn, whereas fish mortality events linked to high biomass blooms mainly during the hot summer season. Long-term variability in occurrence and composition of phytoplankton blooms in Kuwait's waters was largely governed by alteration of dissolved inorganic nitrogen to phosphorus stoichiometric ratio.