The Mediterranean is the most endangered sea on Earth

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Marine biodiversity in the Mediterranean is in danger - Credits: jpmiss (Flickr CC)
 - Marine biodiversity faces an alarming threat in the Mediterranean, according to an interim report published by the Census of Marine Life on Monday.

The report, pending a complete 2011 publication, claims that dense human population and activity are now the biggest and most immediate threat to the Mediterranean. The number of whales and dolphins has decreased significantly and the monk seal has nearly disappeared from the region.

"I feel like Diderot and the encyclopedists," said Jesse Ausubel, co-founder of the project that has brought more than 360 scientists worldwide to identify marine life since 2000.

Imported species

Species alien to a region can upset the balance of its ecosystem. Nearly 4% – over 600 out of 17,000 – of the observed species are exogenous, a percentage two to four times higher than in other examined bodies of water. Most of them have turned up accidentally from the ballast water of vessels going through the Suez Canal and Gibraltar strait. "The spread of Mnemiopsis leidyi (American jellyfish) from Israel to Spain in 2009 caused great concern because of its known impact on ecosystems and fishing areas," the report explains.

Species imported by man, such as Japanese oysters or clams, also endanger the balance of the Mediterranean’s ecosystem. The report underlines that “oyster farms have become real gateways to coastal waters for various kinds of algae."

Census identifies 230,000 species

The contributing researchers to the report encourage the authorities to implement preservation initiatives for marine life in the region, as invasions are causing a kind of “tropicalization.”

230,000 species, many of which remain unnamed, were identified in the report, and researchers suspect there are at least four times as many yet to be discovered. Of the “citizens of the sea,” crustaceans make up 19%; mollusks 17%; fish 12%; algae 10%; and jellyfish 5%, according to the report. Australia and Japan, the areas richest in biodiversity, are each home to 33,000 species, followed by China, the Mediterranean and the Gulf of Mexico. Although researchers regret the oil spill in the Gulf, at least they have "a good description of the species living before the disaster."

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