New York, April 4 (IANS) It has been described as the “cockroach of lakes”, and it is spreading so fast that it is adversely affecting not only marine life, but humans as well. According to a new study, algae - the green scum seen creeping across the surface of water bodies across the globe - has been linked with digestive, neurological, skin and liver disease in humans.

The irony is that algae, or cyanobacteria, are the reason we are all here - the oxygen required for life to flourish on earth was first produced by it.

Now, however, it threatens the health and livelihood of people who depend on infested waters for drinking water or income from fishing and recreational use, said the study, published in the latest issue of the journal Science.

According to Hans Paerl of the University of North Carolina and co-author of the study, the problem is only likely to get worse: global warming has created longer growing seasons, enabling algae to grow in northern waters once too cold for their survival.

“It’s everywhere and it’s hard to exterminate - and when the sun comes up it doesn’t scurry to a corner, it’s still there, and it’s growing, as thick as three feet in some areas,” he said.

“It’s long been known that nutrient runoff contributes to cyanobacterial growth. Now scientists can factor in temperature and global warming,” said Paerl.

Algae also thrive in wet, soggy ground in areas experiencing periodic floods. Fish and other aquatic animals and plants stand little chance against it.

It crowds the surface water, shading out plants - fish food - below. The fish generally avoid cyanobacteria, so they’re left without food.

And when the algae die they sink to the bottom where their decomposition can lead to extensive depletion of oxygen.

These algae were first on the scene, said Paerl, and will be the last to go … right after the cockroaches.