Sea Urchins Prepared For Future Climate Change
April 10, 2013

Purple Sea Urchins Evolve To Cope With Climate Change

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Lee Rannals for - Your Universe Online

Scientists have uncovered some surprising abilities in sea urchins living along the coast of California and Oregon.

A group from Stanford discovered that some purple sea urchins have the ability to rapidly evolve in acidic ocean water, which is a skill that could come in handy as climate change increases. This ability allows urchins to have healthy growth in water with high carbon dioxide levels.

“It´s like bet hedging,” Stephen Palumbi, a senior fellow at the Stanford Woods Institute for the Environment who co-authored the study, said. “Betting on multiple teams in the NCAA playoffs gives you a better chance of winning. A parent with genetic variation for survival in different conditions makes offspring that can thrive in different environments. In an uncertain world, it´s a way to have a stake in the Final Four.”

Scientists are worried about what increasing acidification could do for those who depend on the ocean for their sustenance and livelihoods. They also wonder what kinds of sea creatures will be able to survive or adapt to the changing ocean chemistry in the future. The team wrote in the Proceedings of the National Academy of Sciences that other marine species that have dealt with environmental stresses may have similar adaptive capacity as the sea urchins.

The scientists examined how purple sea urchins react to the acidification levels predicted for 2100. For the study, they sampled larvae at early and later stages in life and then used new DNA-sequencing and analytical tools to determine which elements of the urchins' genetic makeup changed through time in these conditions. By looking at the function of each gene, they were able to pinpoint which types of genes were critical for survival under future conditions.

“The high CO2 larvae showed almost no negative effects, and that was a surprise,” said Melissa Pespeni, the study´s lead author and a former Stanford postdoctoral fellow. “They didn´t suffer because among them were some individuals with the right genes to be able to grow well in those harsh conditions.”

Purple sea urchins live in cold water that wells up along the coast, which tends to bring seasonally higher CO2 levels. The team's findings suggest that this long-term environmental mosaic has led to the evolution of genetic variations enabling purple sea urchins to regulate their internal pH level.

“There are hundreds of West Coast species that similarly evolved in these conditions. Maybe some of these have the genetic tools to resist acidification, too,” Palumbi said. "We need to learn why some species are more sensitive than others.”

Researchers from the University of Gothenburg, Sweden have created huge plastic containers to help study ocean acidification. The team developed ten huge plastic containers called mesocosms as an experiment to determine the impact of climate change on marine ecosystems. Each mesocosm will enclose 55,000 liters of seawater, containing organisms from the winter waters of the Gullmar Fjord in Sweden.

The Swedish team plans to study the effects of different acidity levels on marine plants and animal plankton by monitoring the plankton over many generations.