Climate News Network

Sea urchins refine survival instincts as oceans change

December 16, 2014, by Tim Radford

Bright orange sea urchins in the waters off the Antarctic Peninsula.
Image: British Antarctic Survey

As climate change adds to the threat of extinction faced by many species, new research shows how sea urchins can adapt to the increasing temperature and levels of acidity in Antarctic waters. LONDON, 17 December, 2014 − The sea urchins of the Southern Ocean could be safe from the threat of extinction. They may not enjoy global warming and the increasingly acid oceans, but new research indicates that they can adapt to climate change. Researchers from the British Antarctic Survey and Bangor University in Wales − in what they describe as the largest study of its kind − collected 288 urchins of the species Sterechinus neumayeri from waters off the Antarctic Peninsula, carried them to Cambridge in the UK, and tested them in aquarium tanks over a two-year span, covering two full reproductive cycles. During this time, they report in the Journal of Animal Ecology, they changed the water chemistry and turned up the temperature. The environment was made less alkaline and the thermometer notched up another 2°C − which are the conditions sea creatures could expect by 2100 if the world goes on burning fossil fuels and pumping greenhouse gases under the notorious business-as-usual scenario.

Intricate network

Research like this matters because it helps scientists to better understand the intricate network of environmental conditions that underwrite life on the planet, and because it provides answers to one of the big questions of climate change: how will it affect the estimated seven million species with whom humans share the planet? According to the journal Nature, the lowest estimate is that 10 species become extinct every week, and the number could be as high as 690 a week. The uncertainty is an indicator of how little is known about the diversity of life on the planet. The oceans, in particular, have been hard hit by human action. Other marine survival studies have not been encouraging: ocean acidification promises to be very bad news for corals, and therefore for the rich and diverse communities that depend on coral reefs. It also offers a survival threat to bivalves that exploit ocean chemistry to build protective shells. Other experiments have shown that it can affect the survival behaviour of fish, and can even affect the lugworms that anglers favour as bait for fish. But the news from the laboratory aquarium in Cambridge is encouraging. It took the sea urchins six to eight months to acclimatise and adjust to the new acidity levels and temperature − but they survived. Artificial insemination experiments suggested that the urchins could spawn successfully under the new conditions, but to be sure of this, the researchers need more time. Antarctic invertebrates mature very slowly and sea urchins could live for 40 years or more. “With predictions of warmer, more acidic waters in the future, this work shows how resilient these animals are to climate change,” said Melody Clark, project leader for the Adaptations and Physiology Group at the British Antarctic Survey. “It also emphasises the importance of conducting long-term experiments in making accurate predictions. These animals live a long time, and so they do everything really slowly. They take around eight months to get used to new conditions, and two years to produce gonads (sexual organs). If we had stopped this experiment at three or even six months, we would have got very different results.”

Change habitat

Sea urchins cannot easily change their habitat: they must adapt or perish. But four-legged, warm-blooded terrestrial creatures have another option. In another instance of long-term research, scientists have established that small mountain mammals are prepared to move uphill as the climate warms. Karen Rowe, biodiversity research fellow at Museum Victoria in Melbourne, Australia, and colleagues report in Proceedings of the Royal Society that they looked at records of observations of small mammals, made between 1911 and 1934 at 166 sites in the Californian mountains. Then, between 2003 and 2010, they surveyed the same species in the same locations.

Warmer winters are bad for hibernating mammals such as the chipmunk. Image: Vlad Lazarenko via Wikimedia Commons

Warmer winters are bad for hibernating mammals such as the chipmunk.
Image: Vlad Lazarenko via Wikimedia Commons

Altogether, they looked at 30,000 observations that recorded the foraging and breeding ranges of 34 species of chipmunk, gopher, pika, shrew, deer mouse, woodrat and squirrel at altitudes that varied from sea level to about 4,000 metres.

Moving uphill

Since the first, historic set of systematic measurements, the average temperatures in the region have climbed by 0.6°C, and many mammals have shifted their range accordingly – by moving uphill. The pattern wasn’t consistent, but the researchers identified a problem for those animals that normally hibernate: warmer winters could be very bad news for creatures adapted to the chillier mountain slopes. And those animals that live at the highest altitudes might soon have nowhere to go. “While mammals can avoid heat stress by behavioural means (such as shifting daily activity), warming winters lead to increased energy expenditures for hibernators and reduce the snow layer, which acts as insulation for non-hibernators,” they conclude. “Global climate projections suggest that disappearing climates will be an increasing challenge for predicting future species’ responses.” – Climate News Network

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