The Canary Islands Government Ministry of Territorial Policy, Sustainability and Security have released a statement saying that the blooms of Trichodesmium erythraeum cyanobacteria (microalgae), also known as Sea Sawdust, being widely reported, often erroneously, in the British press, are due to a series “natural conditions” that have facilitated “a massive proliferation” of algae approaching the coasts of the archipelago. They cite surface warming of the ocean due to the arrival of summer, after a long period of calm and repeated episodes of Calima asl causes of the abundant sightings of algae discolouring the waters around some parts of the islands. Critics, however, say that it is just not that simple.
According to the official statement, technicians and scientists say a massive influx of nutrient-rich waters to the south of La Gomera and Tenerife, resulting from a long period of calm seas during the month of June, have been accompanied by repeated calimas, bringing hot dusty winds from the Sahara Air Layer (SAL), along with surface warming of the ocean just as summer has arrived, have all contributed to triggering cyanobacteria proliferation, added to which environmental conditions favourable to the organisms, such as iron and nutrient rich Saharan dust (calima) settling on the sea, encouraging the microorganisms ascend toward the surface, reproducing at high speed, clustering and forming visible chains, spots, stains or blooms that spread across the surface of the water discolouring it to a murky green or brown.
Environmental conditions and ocean circulation have all contributed to this episode lasting longer than on other occasions, says the Autonomous Government of The Canary Islands statement, which has especially been affecting the western and eastern coasts of the islands of El Hierro, La Gomera, La Palma, Tenerife, and to a lesser extent, the south west of Gran Canaria.
In addition, the press release continues, strong seas over recent days have agitated the organic matter, generating an accumulation of foam on some beaches, as has been observed.
The Vice-Ministry of the Environment and the Observatory of Climate Change are currently studying this natural process, whose manifestations are increasingly evident due to the global warming of the planet.
From the scientific and technical information collected, say the Regional Government, this process will disappear, just as it arrived, due to the effect of the waves and ocean currents, which which are expected to disperse the worrisome critters.
The Government statement finishes by once again reminding us that this is a natural process, that happens in other similar regions of the planet, and that has already occurred before in the Canary Islands both in 2004 and 2011.
The US Government’s NOAA National Ocean Service says:
Phytoplankton, also known as microalgae, are similar to terrestrial plants. They contain chlorophyll and so require sunlight in order to live and grow.
Most are buoyant and float in the upper part of the ocean, where sunlight penetrates the water.
Phytoplankton also require inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.
In a balanced ecosystem, phytoplankton provide food for a wide range of sea creatures including whales, shrimp, snails, and jellyfish.
It’s one of the reasons we get more than a third of the worlds whale and dolphin species visiting us here, as they feed from the favourable conditions presented by The Canary Current, from which they shelter in the lee of the islands, feeding from the abundant flow of microalgae.
When too many nutrients are available, phytoplankton may grow out of control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds that have harmful effects on fish, shellfish, mammals, birds, and even people.
Official advice is to avoid swimming in areas where the microalgae can be seen. It can irritate the skin if you come into contact with it.