The Heat Is Online

Small Temperature Rise Fuels Migrations of Sea Animals

Around the same time scientists announced the decline in the zooplankton population of the Pacific Ocean, other researches noted that rising water temperatures in Monterey Bay have triggered an exodus of cold water crabs, snails and other species and an influx of different populations of sea animals accustomed to warmer temperatures. Stanford University biologist Chuck H. Baxter said the findings indicate "there has certainly been a climate change at least at that site." The changing population of snails, crabs and other creatures was discovered when researchers repeated a survey of 45 species of sea animals that was first conducted 60 years earlier in a part of a cove near the Hopkins Marine Station in Monterey Bay. Baxter, co-author of a study published in March, 1995, the journal Science, said the new survey conducted in 1993 and 1994, found that northern species were in decline and the abundance of southern species had increased.

"The most dramatic change was in a snail that was not even detected in the earlier study," said Baxter. The snail is found on rocks in the intertidal areas of the cove. Another species, a predatory snail, was rare in the 1930s survey but now is abundant, he said. Species of crab and starfish that prefer cold water were severely reduced in number. A southern sea anemone moved in vigorously, while a northern variety was in decline, Baxter said. Also, a type of algae that prefers cold water has declined while a southern species of the plant has bloomed, he said. The scientist said instruments at the site indicate the annual mean temperature on the shoreline at the cove has increased by about 1.3 degrees Fahrenheit over 60 years and the maximum summer temperatures have increased by about 4 degrees. The temperature differences are small, but enough to fundamentally change the animal and plant communities in the cove, Baxter said.

"These species changes ... show that even a modest change in temperature can cause organisms to respond," he said. Subtle changes may be under way worldwide, and Baxter said research should be conducted wherever a record exists for a comparison of species types and numbers.

Citation: "Study Suggests Some Sea Creatures Responding to Changing Climate," Associated Press, March 2, 1995