Algal bloom in South West is so big it can be spotted from space

[UK] A huge algal bloom off the South West coast has been visible from space.

The tiny chains of phytoplankton cells – typically no more than 0.05mm long – put on such a show they were spotted by a satellite more than 500 miles above the Earth.

Scientists from the Plymouth Marine Laboratory (PML) were able to collect samples to study under the microscope while also examining infrared-red images captured by the Suomi-NPP satellite, operated by the US National Oceanographic and Atmospheric Administration.

The bloom by the species, Guinardia delicatula, was unusually large because of the fine spring weather, said PML ecologist Claire Widdicombe.

“This year, the spring period has been particularly dry (restricting inputs of freshwater and nutrients from the land), sunny and relatively calm,” she said.

“This promoted the formation of near-surface stratification in the sea, which in turn provided a plentiful supply of nutrients and light allowing phytoplankton such as Guinardia delicatula to thrive in concentrations higher than we’ve seen in recent years.”

As the plankton uses nitrates in the water as food to proliferate, the nutrients are rapidly used up and the bloom fades.

Guinardia are a key link in coastal food chains at this time of year as tiny animals, zooplankton, consume the plant bounty and in turn are eaten by larger creatures such as fish.

Simultaneous measurements taken at the Western Channel Observatory L4 data buoy, stationed eight miles off Plymouth, allowed PML scientists to track the decline in nitrate as it was consumed by the expanding bloom.

The combination of satellite, microscope and buoy information allows the scientists to piece together how the seas and the life they contain function.

As the tiny algae arrived earlier than in recent years a much larger ocean dweller has also put in an appearance ahead of schedule. Basking sharks – which feast on plankton – have been spotted in Falmouth Bay a month earlier than they were last year. The gentle giants typically reach six to eight metres (about 20-26 feet) in length.



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