Even seaweeds can get sunburned

Washington, August 23 : A new research by scientists from the Alfred Wegener Institute on Spitsbergen in Norway has determined that even marine organisms like seaweeds can get sunburned.

The research says that too much sun is not only bad for humans, but many plants react sensitively to an increased dose of ultraviolet radiation as well.

With the help of pigments absorbing solar energy and light, plants produce their vitally important building blocks by means of photosynthesis.

However, this has its limits: too much sun means an over-abundance of energy and thus the destruction of the sensitive pigments.

The result is black spots, pale leaves and rotten parts.

Since algae cannot apply sun lotion like we do, they develop their own strategies to protect from the sun.

According to Dr. Christian Wiencke, marine biologist at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association, "A species of red algae, for instance, produces under increased ultraviolet radiation less red light-harvesting proteins, thus decreasing the absorption of radiation. The typical red colour of the alga fades and the plant gets white tips."

"The algae additionally produce substances which react similar to melanin in human skins: mycosporin amino acids (MAA)," he added.

Melanin absorbs ultraviolet radiation and thus protects the human skin - at the same time, it gives a natural suntan.

The ozone layer usually absorbs the major part of the hard and harmful solar ultraviolet radiation of short wavelength.

However, because of stratospheric ozone depletion, these dangerous rays increasingly penetrate to the earth's surface and therefore also to the seawater.

Extensive biological experiments are presently conducted on this complex of problems at the German French Research Base AWIPEV on Spitsbergen.

"We examine the harmful effects of ultraviolet radiation on algae and their protective mechanisms," said Wiencke.

The ultraviolet radiation particularly harms the algae's photosynthesis and their hereditary material. These organisms usually react with a decreased rate of growth or a reduction of reproductive success.

The spores and germ cells of the algae which drift through the water as unicellular organisms are particularly sensitive. Even small ultraviolet doses are damaging and inhibit their germination.

"Our investigations show that the distribution of certain species of brown algae is inhibited by the climate of ultraviolet radiation. The algae are displaced into deeper water layers if ultraviolet radiation increases," said Wiencke.

"We want to observe the development of marine coastal ecosystems in the face of global climate change. Not only an increased ultraviolet radiation plays a decisive role, but also the water temperature which has been increased by the greenhouse effect," he added.

ANI