New Insights on Harmful Algal Blooms in Sohar Industrial Area

19 Nov, 2019 |

Arid countries around the world, particularly in the Middle East, rely on seawater desalination process to produce fresh water. The rabid increase in the construction of the sea water reverse osmosis desalination plants has been accompanied with the expansion of Harmful Algal Blooms (HABs).

Harmful Algal Blooms (HABs) is a common phenomenon in Oman waters usually detectable by the presence of green or red color of sea water. This is due to high density of microscopic photosynthetic organisms, such as diatoms and dinoflagellates. In the Sultanate, HABs lead to economic losses due to high fish mortality and disruption of desalination plant’s work because of membrane clogging. HABs are a concern for desalination plants due to the high algal biomass present in sea water and toxin production by some HABs species. In severe cases, desalination plants have to be taken off-line. During HABs accident of 2008-2009, the desalination plant in the Barka site ceased operations for 55 days. It is estimated that in the US only, HABs result in economic loss of US82 million each year. Some of these harmful species can have resting stages called cysts that propagate when the environmental conditions are favorable. There has been only limited information about of the composition and abundances of HABs species and their cysts in Oman waters in particular in the areas near desalination plants.

Marine Science and Fisheries (MSF) Department of the College of Agricultural and Marine Sciences (CAMS) at Sultan Qaboos University (SQU) is a leader in the marine science research and teaching dealing with the marine environment and fisheries in the Sultanate of Oman and among GCC countries. The MSF focuses research mainly on fisheries, aquaculture, oceanography, ecology of marine species and marine biotechnology. The Department offers a B.Sc. in Marine Science and Fisheries and a M.Sc. in Marine Science and Fisheries. In 2008, the Department has started a Ph.D. program in Marine Science and Fisheries.

The MSF Master of Science student Ms. Ahlam Al-Kharusi recently successfully defended her thesis entitled “The effect of environmental factors on harmful algal blooms at Majis desalination plant, Sohar industrial area, Sea of Oman”. Her work was supervised by Dr. Sergey Dobretsov, Director of Centre of Excellence in Marine Biotechnology and co-supervised by Dr. Khalid Al-Khashmi and Dr. Gerd Bruss. This study was partially supported by Majis Industrial Services Company. This is the first study that investigated the presence of HABs forming algae and their cysts near a desalination plant located in an industrial area. During the study conducted from April 2018 to March 2019, water samples were taken every week and the presence of HABs species was evaluated. Ms. Ahlam’s work resulted in identification of 64 species of microscopic dinoflagellates and diatoms present in Sohar industrial area. Compare to HABs in the open sea waters, which are dominated by the dinoflagellate Noctiluca scintillans, HABs in the industrial area are caused by diatom species. Some of the recorded HABs microalgae are potential toxin producing species. There has been a variation of densities of HABs species during Northeast and Southwest Monsoons. Localized nutrient enrichment and the changes in sea water temperature were the most important factors controlling the seasonal fluctuations of HABs during the study period.

For the first time, the presence of cysts was studied in sediments of Sohar industrial area and the port. No cysts were found near the desalination plant. In opposite, cysts of seven HABs forming species were observed in sediments of Sohar industrial port. Most of these species belonged to potentially toxin producing dinoflagellate species. This finding revealed that this area provides suitable environmental conditions for HABs-forming algae. Presence of cysts also can be one of the reasons for HABs in the studied area. Finally, the study of Ms. Ahlam provided important recommendations for the desalination plant to mitigate and prevent HABs. He study facilitates our understanding and prediction of harmful algal blooms and the distribution and abundance of potential HABs species.


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