Tropical Fish Cause Troubles as Climate Change Drives Them Towards the Poles

By Doug Struck for National Geographic 
Published July 25, 2014

Marine ecologist Adriana Vergés emerged from a scuba dive in Tosa Bay off the coast of southern Japan last week and was amazed at what she'd seen: A once lush kelp forest had been stripped bare and replaced by coral.

The bay is hundreds of miles north of the tropics, but now "it feels like a tropical place," said Vergés, a lecturer at New South Wales University in Australia.

This spotlight parrot fish (Sparisoma viride) was spotted grazing on coral near the island of Bonaire in the Caribbean.

This spotlight parrot fish (Sparisoma viride) was spotted grazing on coral near the island of Bonaire in the Caribbean.

The undersea world is on the move. Climate change is propelling fish and other ocean life into what used to be cooler waters, and researchers are scrambling to understand what effect that is having on their new neighborhoods. They are finding that the repercussions of the migration of tropical fish, in particular, are often devastating. Invading tropical species are stripping kelp forests in Japan, Australia, and the eastern Mediterranean and chowing down on sea grass in the northern Gulf of Mexico and Atlantic seaboard.

"The faunas are mixing, and nobody can see what the outcome will be," said Ken Heck, a marine scientist at the University of South Alabama in Mobile. But the consequences of that mixing are already trickling up the food chain. Click to read more.