By Jonathan Pearlman
Australian scientists sequenced the DNA of samples of the giant seagrass, Posidonia oceanic, from 40 underwater meadows in an area spanning more than 2,000 miles, from Spain to Cyprus.
The analysis, published in the journal PLos ONE, found the seagrass was between 12,000 and 200,000 years old and was most likely to be at least 100,000 years old. This is far older than the current known oldest species, a Tasmanian plant that is believed to be 43,000 years old.
Prof Carlos Duarte, from the University of Western Australia, said the seagrass has been able to reach such old age because it can reproduce asexually and generate clones of itself. Organisms that can only reproduce sexually are inevitably lost at each generation, he added.
“They are continually producing new branches,” he told The Daily Telegraph. “They spread very slowly and cover a very large area giving them more area to mine resources. They can then store nutrients within their very large branches during bad conditions for growth.”
The separate patches of seagrass in the Mediterranean span almost 10 miles and weigh more than 6,000 tons. But Prof Duarte said that while the seagrass is one of the world’s most resilient organisms, it has begun to decline due to coastal development and global warming. “If climate change continues, the outlook for this species is very bad,” he said.
“The seagrass in the Mediterranean is already in clear decline due to shoreline construction and declining water quality and this decline has been exacerbated by climate change. As the water warms, the organisms move slowly to higher altitudes. The Mediterranean is locked to the north by the European continent. “They cannot move. The outlook is very bad.”