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Red Tide

What is red tide

What is red tide, and its causes and species, and monitoring and adaptation approaches. 

Red tide is a natural phenomenon and a global proliferation and  ancient outbreak event, and blooms in single or multiple species, and occurs whenever appropriate factors have combined of water Characteristics, nutrients and light.  The Ministry of Climate Change and the Environment (MOCCAE) prepared a UAE national plan for  red tide  management to cope and adapt to the consequences of climate change impacts associated with such environmental phenomena. its based on coordination and partnership with all local, regional and international bodies, and in which it includes several elements as monitoring program of phytoplankton, modeling and remote sensing and UAE capacity building program.

Red tide is a natural phenomenon that occurs in the marine waters due to rapid reproduction and accumulation of single-celled phytoplankton "Single celled,  free-floating photosynthetic with rapid life cycle growth, and drift in water column .They are capable of autotrophic nutrition and form the base of aquatic food chain", at certain space and time. This phenomena Locally is known as “haith al bahar”

Red tide types:

Red tide takes several colors, including the most common one in our marine water are dark green and dark brown, light green and light brown, red and orange one, and forms patches or filaments shapes along UAE coastal water areas of different types of phytoplankton species that includes Dinoflagellate "are group  of unicellular phytoplankton with two flagella  occurring in large numbers in marine and fresh water with different shapes and colors according to their pigments" or diatoms or blue-green algae.

The number marine phytoplankton species upto 5000 species, 300 species of which have the ability to cause the red tide phenomenon,. Of these 80 species or so are associated with the production of natural toxins and ability to deplete oxygen dissolved in water. The toxic algal blooms generally referred by scientist as harmful algal blooms (HABs)

Reasons for occurrence of Red Tide:

  1. The increasing concentration of the nutrients such as phosphate, silicate, ammonia and nitrite in the sea water
  2. Suitable water temperature.
  3. suitable ocean currents and waves.
  4. Sufficient sun light.
  5. Other environmental factors (acidity of ocean and oxygen level).

Viability of Recurrence

Red Tide phenomenon may be recurred when marine currents carries large quantities of nutrients from the ocean , as in the southern coasts of Arabian Peninsula (Arabian Sea) due to the seasonal changes of the upwelling phenomena resulted from the currents of the Indian Ocean.

  1. In addition to the natural factors related to climate change, global warming, wind currents and wave movement, there are other factors that may contribute blooming of harmful phytoplankton like,
  • Existing of settled or new strains of phytoplankton bloom during favorable conditions.
  • The increasing concentration of nutrients discharge from untreated sewage water, municipality and industrial wastes, fish- farming wastes and the ballast water waste .

Life cycle of phytoplankton species

The life cycle of dinoflagellates involves asexual reproduction by means of binary fission or Sexual reproduction by fusion of two individuals to form a zygote, and that remain mobile in most dinoflagellate and is called a planozygote, this may form a resting stage (cyst) –hypnozygote. These cysts can remain for several years and they reproduce and divide into thousands of cells in the appropriate environmental conditions of temperature, light, oxygen and sufficient nutrient.


The Impacts of Red Tide Phenomena in UAE

A catastrophic event of red tide occurred in the Arabian Gulf/Oman Sea during the 2008-2009 especially in the east coast of UAE. This resulted in,

  • 1. Spread of bad odour as a result of decomposing organic matter of algae and fish
  • 2. Mortality of fish and other marine organisms.
  • 3. Desalination plants halted operation.
  • 4. Coastal tourism affected seriously.
  • 5. Impacts on fishing activities.
  • 6. Large quantities of fish dead in fish cage-nets.

Among the risks that involve the Red tide phenomenon is the deterioration of the quality of sea water in affected areas. As a result the intake of the seawater to the desalination plants was severely affected. Accordingly, work was stopped at intervals in several desalination stations in the Eastern Region, they are:

  • 1. Kalba Water Desalination Station
  • 2. Fujairah Port Desalination Station
  • 3. Khorfakkan Water Desalination Station
  • 4. Ghalyla Water Desalination Station – Ras Al Khaimah


Species of phytoplankton behind the occurrence of red tide in the UAE marine coastal water (2008-2009)

The results of identification have shown the existence of 12 species of phytoplankton that cause the red tide during 2008-2009, where 8 species common one as follows:


  • 1. Karenia mikimotoi
  • 2. Prorocentrum micans
  • 3. Dinophysis caudata
  • 4. Pyrodinium bahamense
  • 5. Cochlodinium polykrikoides
  • 6. Gymnodinium catenatum
  • 7. Ceratium furca
  • 8. Ceratium fusus

The fifth species was dominant one in the UAE coastal and marine water during 2008-2009.


Geographical distribution of Cochlodinium polykrikoides worldwide

Studies and reports indicate that the algae Cochlodinium polykrikoides is distributed in East Asian countries, India, the Mediterranean Sea, Spain, USA and Mexico, where the phytoplankton move across water currents from one place to another as shown in the following map between Japan and Korea.

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The photos taken by satellites showed the extension of red tide from Muscat to Musandam reaching to the Arabian Gulf. However, this refers to that red tide found now in the Arabian Gulf was composed by the movement of water currents from Oman Gulf to Arabian Gulf.

National Work Plan to Monitor the Red Tide Phenomenon


  • 1. Protect public health
  • 2. Protect existing and developing fisheries industries (capture and aquaculture)
  • 3. Protect tourists, residents, and the tourism industry from toxic and noxious blooms
  • 4. Protect ecosystem and resources
  • 5. Protect potable water supplies
  • 6. Build national capacity (infrastructure and personnel) for monitoring and management of red tides and other marine environmental issues.

Elements of monitoring programmes:

  • 1. Observation and record of environmental oceanographic parameters, planktons samples and marine organism mortality.
  • 2. Collect samples of water, phytoplankton, finfishes, shellfishes and other marine organisms from the site of the red tide event.
  • 3. Conduct analysis of samples for identification and quantification of phytoplankton species specially harmful algae and HABs toxicity.
  • 4. Assess and interpret the results of the analysis.
  • 5. Establish long term action plans to mitigate the effects of red tide.

Early warning for Red Tide

Utilize satellite images and aerial photos for the detection of any biological activity in the UAE marine and coastal water.


Advantages of the program

  • 1. Develop the ability to identify the harmful plankton and analyze its toxicity.
  • 2. Develop the ability to monitor and predict the harmful planktons at low cost and during a short period of time.
  • 3. Protect coastal waters and public health.
  • 4. Improve the economic and production efficiency of fish farming and ensure safety of marine organisms.
  • 5. Raise the awareness of public towards red tide phenomenon.
  • 6. Take measures to monitor and manage red tide through collecting samples of water from various sites along UAE coasts.
  • 7. Establish action and emergency plan to mitigate the impacts of red tide on marine resources and habitats.
  • 8. Cooperate and coordinate with the competent authorities and desalination plants in monitoring and management of red tide.
  • 9. Establish communicating channels with the experts in red tide


  • 1. Routine monitoring of phytoplankton and toxins in shellfish.
  • 2. Specify the sources and types of nutrients.
  • 3. Conduct studies related to remote sensing and aerial photos.
  • 4. Develop numerical models.
  • 5. Conduct studies and research to mitigate the red tide phenomenon.
  • 6. Regulate water ballast.
  • 7. Adopt modern techniques of early warning systems.
  • 8. Personnel training in the field of marine environment sciences.

Procedures Taken by the Ministry

Formation of technical team work.

The team made extensive efforts to follow up and study this phenomenon, oversee collection and analysis of samples, coordinate the efforts of the relevant bodies and follow up the works of experts who have been recruited to provide technical advice.

International partnership:

The Ministry of Climate Change and Environment recruited group of specialized experts from:

  • Kuwait
  • Malaysia
  • France
  • USA (Woods Hole Oceanographic Institution
  • UAE University
  • UN University (UAE)

The recruited experts conducted field visits to red tide areas for:

  • Collecting samples of sea water from various depths to categorize the species that cause red tide.
  • Analyzing the physical, chemical and biological characteristics of sea water.
  • Evaluate the HABs toxicity.

The ministry also has been in regular contact with the Regional Organization for the Protection of Marine Environment(ROPME) to coordinate the common efforts with the member countries through monitoring and exchange of information and satellite images.

Laboratory Analysis

Chemical, physical and biological laboratory analysis was done for samples collected from the areas of red tide by:

  • The Central Laboratories of the Ministry of Climate Change and Environment.
  • UAE University
  • Abu Dhabi Environment Agency
  • General Environment Authority – Kuwait
  • Aero fence Laboratories – France
  • Woods Hole Oceanographic Institution USA

Results of the initial physical analysis

  • Oceanographic physical results showed that temperature between 220C- 310 C suitable for the proliferation of phytoplankton which lead to red tide phenomenon.
  • Reduced concentration of dissolved oxygen within depths as a result of decomposition of the dead algae and consumption of dissolved oxygen.
  • Results of chemical analysis: It revealed high concentration of phosphate (PO4) and nitrate (NO3) which are considered the most stipulated nutrients for the propagation of phytoplankton that cause this phenomenon.

Training Courses:

The main aim of a training program is to train personnel in phytoplankton identification and monitoring, to design and implement a phytoplankton and environmental monitoring program and to conduct an assessment of the program.

Number of trainings was conducted including:

  • Training course on Phytoplankton Taxonomy and Identification ,from 14th -18th March 2010, which had the participation of 31 trainees from various Federal and Local bodies.
  • Training course on Phytoplankton and Environmental Monitoring, from 3-4 May 2010. The number of participating trainees was 36 from various Federal, Regional and Local bodies.
  • A Workshop on Red tide and Desalination: Impacts and Solutions ,from 12-13 July 2010. The number of participating trainees was 25 from Federal, Local authorities and Private Sector..


Causes of fish kills in UAE sea water

Most technical reports, made by international, regional and local authorities, explained that the most common cause of fish kills is oxygen depletion, i.e. dissolved oxygen in water due to a die-off of the phytoplankton and decomposition. These reports ( Table below) also showed that the main cause of this phenomenon is the algae Cochlodinium polykrikoides.

No. Title Executing Authority Causative Phytoplankton identified Harmful effect
1 A report of red tide phenomenon (Phytoplankton Bloom) in Fujairah Beach. October 29 – 31, 2008. Environment Public Authority, Kuwait Pyrodinium bahamense var.compressum Cochlodinium polykrikoides Dissolved oxygen depletion in deep water
2 Microscopic test of samples collected from Fujairah sea. October 30, 2008 UAEU, Faculty of Science, Life Sciences Department Gymnodinium sp. --
3 A field report about fish perishing in Fujairah fishing port. October 28,2008 Environment Agency, Abu Dhabi Gymnodinium sp. Dissolved oxygen depletion in deep water
4 Preliminary notes about red tide in Dibba Al Hissin Asmak Gymnodinium sp. Dissolved oxygen depletion in cages
5 A draft report of harmful red tide and marine life die off in the country. Regional Organization for the Protection of the Marine Environment according to the report of Environment Public Authority, Kuwait Pyrodinium bahamense var.compressum Cochlodinium polykrikoides ---
6 Algae existing in Fujairah. November 17, 2008 United Nations University, Dubai Heterosigma sp 1.Dissolved oxygen depletion.
2. Toxins released from algae
7 C.P. Phytoplankton blooming in the Gulf of Oman Ministry of Fisheries Wealth, Marine Science and Fisheries Centre October – November, 2008. Cochlodinium polykrikoides Dissolved oxygen depletion
8 A report of red tide phenomenon in the Eastern region of UAE Kuwait Institute for Scientific Research November, 2008 Cochlodinium polykrikoides Dissolved oxygen depletion
9 A report of red tide phenomenon on the Iranian costs. Environmental Protection Agency December, 2008 Cochlodinium polykrikoides Dissolved oxygen depletion
10 A report of red tide phenomenon Woods Hole Oceanographic Institution, MA, USA Cochlodinium polykrikoides --

Algae Types in UAE

Below are the microscopic images of species responsible for red tide bloom events in UAE between 2011-2015. No harmful effects or marine organism mortality was reported.

No harmful effects or marine organism mortality was reported.


Does Red tide change the color of sea water?

Yes, however, red tides are not always red. They can appear greenish, brownish, and even purple in color. The water can also remain its normal color during a bloom. The color of the red tide depends on the phytoplankton species and its pigment.


Does Red tide have impact on fish farms?

Yes, however, red tides are not always red. They can appear greenish, brownish, and even purple in color. The water can also remain its normal color during a bloom. The color of the red tide depends on the phytoplankton species and its pigment.

Does Red tide change the color of sea water?

Yes, it has an impact on fishes which are cultured in floating cage nets due to depletion of dissolved oxygen in water that leads to suffocation and death. Fishes cultured in land based ponds that intakes seawater will not be affected by depleted dissolved oxygen levels due to the presence of air pumps .

What are the efforts by the Ministry of Climate Change and Environment to monitor toxicities in marine organisms?

A dedicated team of technicians and specialists in Marine Environment Research Department conduct regular monitoring program for collecting samples of sea water, dead fishes and other marine organisms along the UAE coasts. Collecting of samples include the East Coast (Kalba , Khor Fakhan and Dibba Al Hussin )and the West Coast including (Ras AlKhaimah, Umm Al Quwain, Al Hamriah,Ajman, Sharjah and Dubai). The survey aims at monitoring, observation and identification of phytoplankton species that cause the red tide. Laboratory analysis shows the presence of dinoflagellate Cochlodinium ploykrikoides but less in abundance.

Does Red tide have the ability for poisoning all marine organisms?

No, only some species of marine organisms have probability to be poisoned by red tide especially shellfishes.

Does cooking destroy the toxins in shellfish meat (muscles)?

No, cooking does not destroy red tide toxins because some toxins are not affected with high temperature.

Is it possible to eat live fishes that caught in near to affected areas by Red tide?

Yes, in general it is possible to have the meat (muscles) of fish, mollusk and crustaceans without head and the inner gills, taking into consideration not to eat dead, distressed or unhealthy organisms from the affected areas of red tide.

Is fishing allowed during the incidence of red tide?

In general it shall not be allowed to catch fishes and other marine organisms in the affected areas of red tide, while fishing is allowed in areas that not show the red tide.

Is it possible to practice swimming on the affected areas by red tide?

It is preferable not to swim in the affected areas with red tide especially for persons who are suffering from allergies. According to the instructions of the international organizations specialized in red tide, which reports not to practice swimming in the sea water when you cannot see your feet in the water or when the sea water is at the knee level.

What are the symptoms associated with having toxic shellfish?

Consuming toxic shellfish will cause symptoms like tingling of the lips, fingers, and toes, skin irritation, stomach cramps, vomiting, nausea, diarrhoea, fever, sore throat, headache, muscle and joint pain, blisters of the mouth and liver damage. The affected person has to visit the nearest health center immediately.


The catastrophic 2008–2009 red tide in the Arabian Gulf region, with observations on the identification and phylogeny of the fish-killing dinoflagellate Cochlodinium polykrikoides, Harmful Algae 9 (2010) 163–172


Laboratory desalination experiments with some algal toxins, Desalination 293 (2012) 1–6