Abundance of harmful algal blooms in the coastal waters of Oman: 2006–2011

Over the last decade, the ecosystem of the Sea of Oman and Arabian Sea has been showing signs of rapid and profound changes in terms of phytoplankton diversity and harmful algal bloom outbreaks. Frequent blooms have been on the rise in the coastal waters of Oman causing adverse impacts on marine life. The population dynamics of potentially harmful phytoplankton in relation to environmental parameters was investigated from June 2006 to April 2011. Our studies recorded 24 potentially harmful species. Dinoflagellates Prorocentrum minimum, Scrippsiella trochoidea, Cochlodinium polykrikoides and Noctiluca scintillans were the most abundant species. Diatoms Pseudo-nitzschia seriata, Climacodium frauenfeldianum and Guinardia flaccida were the most abundant, but occurred at low concentrations. Scrippsiella trochoidea and Noctiluca scintillans were reported previously as common phytoplankton in Oman coastal waters; however, Prorocentrum minimum and Cochlodinium polykrikoides are reported for the first time. Here we report their occurrence and persistence in relation to changes in environmental parameters. In addition, the potential long-term implications of changes in phytoplankton species and harmful algal blooms outbreaks on ecological, economic, social and human health impacts will be discussed.