More analysis needed to confirm ‘algal bloom’ species |05 December 2020

Dr Ibrahim, flanked by Ms Dias and Mr Goviden, speaking during the interview (Photo: Anel Robert)

 For the time being, the Seychelles Fishing Authority (SFA) is not prepared to comment on the exact species of the ongoing algal bloom since further analysis is needed to confirm whether it is the same species as the 2015 bloom, Dr Ameer Ibrahim, principal fisheries scientist has revealed.

Dr Ibrahim was giving an update on the phenomenon which was first reported to local authorities on Friday November 27, and is still ongoing, with turbid water and slicks with colours ranging from yellow to dark brown.

He explained that the research section of the SFA has been collaborating with the Ministry of Environment, stakeholders and members of the public to collect samples from Denis Island and several areas around Praslin.

Dr Ibrahim added that results of analysis conducted on the samples from Denis Island was clear and it is being presumed that the bloom has been moving away from the island, despite having reports of fish deaths on the island.

He however noted that samples from Praslin, specifically from the Anse Lazio and Pointe Chevalier areas, revealed concentrations of algae.

Dr Ibrahim also explained that they have been in close contact with the meteorological services which provided them with some sea surface current maps which indicated the alga bloom is moving into the north-easterly direction of Praslin.

This, he said, might prevent the bloom from hitting Mahé, but it will all depend on the weather which he added is unpredictable.

“If there is any change in the weather conditions, the bloom might hit other islands,” explained Dr Ibrahim, who further added that the phenomenon is around Praslin as they have been getting reports from Curieuse and Felicite, while the latest report from yesterday indicated that it had reached La Digue.

He added they are hopeful that if the current keeps pushing in the north-easterly direction, the bloom will move out to the outer sea.

Comparing the 2015 bloom to the ongoing one, Dr Ibrahim said they both happened during the same time of the year and when comparing what the two periods have in common they both are transition period from the south-east trade winds to the north-west monsoon.

The former, he said, brings along cooler water, while the later brings warmer water and when both waters merge, it brings an upwelling, providing a lot of nutrients which makes the perfect condition for the algae to flourish.

“Calm period is also a perfect habitat for the algae,” added Dr Ibrahim.

He also advised people not to eat the fish that are washed up the beaches, even if there is no scientific evidence to show that such phenomenon has ill-effect on human.

He however advised members of the public to avoid shellfish which are considered as filter feeders –a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialised filtering structure – since it accumulates in the body much faster it carries a higher risk of having effects on the human body.

On his part, chief fisheries scientist at the SFA, Rodney Govinden, advised fishermen who notice any algae concentration to inform the authority for sample collection and analysis.

He also advised fishermen not to collect the dead fishes and to avoid the contaminated water which he said can cause skin irritation.

On behalf of the department of environment, Ashley Dias said the situation is causing an imbalance in the ecosystem.

She added that since there are several natural patterns that come into play in relation to the activity, there is nothing much they can do.

For now, Ms Dias said they are collaborating with other partners in data collection which she said will help them to be better prepared in the future.

She added that despite the fact that it is not easy to predict such phenomenon, the data can still help them in improving their capacity on how to identify the different species of algae and to put up necessary protocol in terms of disseminating information to the public.

Ms Dias further noted that the situation is not only an environmental problem but rather a general and economic one since the livelihood of many people depends on the sea.

An algal bloom is a natural phenomenon involving the rapid growth and population explosion of algae in the sea whenever there are sufficient nutrients, calm conditions, hot temperatures and other specific conditions. These blooms may cause death of fish and other marine animals.

The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic, multicellular organisms like seaweed and microscopic, unicellular organisms like cyanobacteria.

Consequences range from the benign feeding of higher trophic levels, to more harmful effects like blocking sunlight from reaching other organisms, causing a depletion of oxygen levels in the water, and, depending on the organism, secreting toxins into the water.

Roland Duval