Toxic algae threat may increase in Norfolk Broads, UEA research finds

Blue Green algae now hits Whitlingham Broad on the southern edge of Norwich - Sept 2011. Picture: Mike Page.

The threat of toxic blue-green algae could grow if the planet's temperature continues to rise, new research from the University of East Anglia has found.

Blue Green Algae at Ranworth Broad. Picture: Mike Page.

The UEA research shows that rising ocean temperatures could upset natural cycles of carbon dioxide (CO2), nitrogen and phosphorous: but the increasing algae could also affect the Norfolk Broads.

A blue-green algae alert closes Whitlingham Little Broad to people hoping to enjoy the bank holiday weather in August 2001.

The UEA findings, which have been published in the Nature Climate Change journal, reveal that water temperature has a direct impact on maintaining the delicate plankton ecosystem of our oceans.

Plankton plays an important role in the ocean's carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis and storing it deep under the sea – isolated from the atmosphere for centuries.

Researchers from UEA's School of Environmental Sciences and School of Computing Sciences investigated phytoplankton, microscopic plant-like organisms which rely on photosynthesis to reproduce and grow.

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Lead researcher Dr Thomas Mock, said: 'We are talking about a global phenomenon here and I'm afraid almost all ecosystems will be affected by this, especially marine ones.

'Marine algae, fresh water algae, algae which live in streams, all will be affected by temperature in very similar ways.

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'If warming continues at the current rate then it will affect the Broads as well, but it is very complex, it is not just a simple mechanism, it is a multi-layer change of ecosystem, so we can't be sure what will happen in the next decade or several decades.

'But when the Broads warm up, all the algae in the Broads will be affected.'

Dr Mock said if the necessary nutrients were depleted enough in the varied waterways of the Broads, then blue-green algae could have a 'terrible' effect.

The blue-green algae is capable of producing toxins which have been known to kill wild animals, farm livestock and fish, and previously broads at the likes of Ranworth and Whitlingham have had signs put up to warn visitors of the potential health hazard.

Collaborators from the University of Exeter, co-authors of the study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.

'We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before,' said Dr Mock.

'Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorous and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorous, increasing the demand for nitrogen in the oceans.

'This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen.'

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