Marine heat waves 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

Ocean heatwaves are getting hotter, and all common sea stars could die by the end of this century.

Fabian Wolf and his colleagues at the GEOMAR Helmholtz Center for Ocean Research in Germany tested what these orange Atlantic starfish or “starfish” look like (Asterius Rubens) During an ocean heat wave – A short period of time when the ocean 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. Current mean temperature for starfish ranges, hypothetical conditions without a marine heatwave, and temperatures expected in a marine heatwave by the end of 2019. century under three warming scenarios. The coldest conditions included no heat waves as a baseline and a steady temperature of 18.4°C (65°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 heatwaves in coastal areas. During the two-month study period, the researchers fed the sea stars mussels and measured their size and weight regularly. They also recorded the time it took for each starfish to bounce back after being flipped onto 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. In the three future warming scenarios, starfish ate less mussels, but animals in the absence of heat waves and in current conditions maintained healthy appetites and weights. The starfish in the scenario took the longest to grow back after being flipped over. “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 endured heat waves in each scenario were more likely to survive subsequent cold water shocks that mimic upwellings that can stress animals by depleting oxygen. I thought it would build up stress, but it was the other way around,” says Wolf.

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