Marine heatwaves could wipe out all common sea stars by 2100

Ocean warming simulations show future ocean heatwaves lasting more than 13 days will kill all of the world’s common sea stars

To spider wetzel

An increasingly hot and prolonged ocean heatwave could kill all common sea stars by the end of the century. The loss of this important marine predator could lead to cascading ecological consequences, including an overabundance of mussels, their primary prey.

Fabian Wolf of the GEOMAR Helmholtz Center for Ocean Research Kiel in Germany and his colleagues tested what these orange Atlantic starfish or “starfish” look like (red star) A short period of time when the sea is unusually warm, usually caused by a pocket of hot air above.

Using ten saltwater tanks the size of large bathtubs, the team subjected 60 starfish to five temperature scenarios. Present-day average temperatures for starfish ranges, hypothetical conditions without marine heatwaves, and temperatures expected in marine heatwaves by the end of the century. under three warming scenarios. The coldest conditions did not include a heat wave as a baseline – a steady temperature of 18.4°C (65°F) – the hottest conditions peaked at 26.4°C (79°F) . .

They kept their fever constant for 13 days. This is the length of severe marine heatwaves expected by 2100. This was followed by several days of cold, low-oxygen water mimicking the deep-sea upwelling that often follows heat waves in coastal areas. During the two-month study period, the researchers fed the starfish mussels and measured their size and weight periodically. They also recorded the time it took for each starfish to get back up after laying on its back. This is an important ability for feeding.

In the most severe warming scenario, 100% of the starfish died before the 13-day heatwave ended. Starfish ate less mussels in all three future warming scenarios, but animals in the absence of heat waves and in current conditions maintained healthy appetites and weights. One scenario sea star also took the longest to get back up after being flipped. “The longer the heat wave lasted, the stronger its impact,” Wolff says.

The starfish used in this study were collected off the coast of Germany, and some members of the species from temperate regions of the Atlantic may have higher heat tolerance, implicated. Not so says Lloyd Peck of the British Antarctic Survey. At work.

Strikingly, sea stars that survived the heatwave in each scenario were more likely to survive subsequent cold water shocks mimicking upwellings that can stress animals by depleting oxygen. “I thought it would build up stress, but it was the opposite,” says Wolf.

He doesn’t yet know the mechanism behind this ability, but animals enduring elevated temperatures do not have higher expression of so-called heat shock proteins, which help protect existing proteins from stress-induced damage. I think