Using novel genomic technology, marine biologists have found troubling clues that marine life could be extremely vulnerable to climate change. By mimicking future ocean climes and using gene chips to detect how marine organisms respond, the researchers can evaluate how well different organisms deal with environmental stress. The findings, while still preliminary and incomplete, are worrisome.
“What we’re doing is linking the predictions that are released by IPCC [the Intergovernmental Panel on Climate Change] with genomics to assess how changes in ocean chemistry will impact these ecosystems,” says Gretchen Hoffman, a marine biologist at the University of California, Santa Barbara.
Scientists predict that in the next 100 years, the ocean will become warmer and increasingly acidic–environmental changes that together could wreak havoc on marine creatures from krill to killer whales. Marine biologists want to know how organisms will respond to this stress: under what conditions can they adapt to climate changes, and when will they simply surrender?
Hoffman studies simple animals such as mussels and sea urchins, which are the ocean’s version of canaries in a mine. “They can tell you what’s happening in the bigger ecosystem,” she says. The urchins and mussels are grown in large buckets in Hoffman’s lab under atmospheric conditions that mimic those predicted by the Intergovernmental Panel on Climate Change. For example, by 2100, atmospheric carbon levels could increase from 375 to 540 parts per million–the so-called best-case scenario–or to 970 parts per million, the business-as-usual scenario.
The researchers then use a specially built DNA microarray–a small slide speckled with carefully chosen sequences of DNA–to measure which genes are activated in response to specific conditions, such as changes in temperature or acidity.
So far, the team has focused its attention on a set of proteins, known as heat-shock proteins, which kick in when an animal is under stress. Almost all animals carry copies of these proteins, which can repair other proteins that have been bent out of shape by heat and additional environmental stresses. According to early results from gene-chip studies, sea-urchin larvae raised at current carbon levels activate their heat-shock proteins when faced with warming water temperatures. But larvae raised at the best-case-scenario carbon level no longer activate these genes under stress and therefore can’t respond to a warming climate. “I don’t want to say we will lose all sea urchins,” says Hoffman. “But there will be some part of the population that can’t develop.”