Billions of snow crabs have disappeared from the ocean around Alaska in recent years, and scientists now say they know why: Warmer ocean temperatures likely caused them to starve to death.
Billions of snow crabs have disappeared from the ocean around Alaska in recent years, and scientists now say they know why: Warmer ocean temperatures likely caused them to starve to death.
They found that warmer temperatures and population density were significantly linked to higher mortality rates among mature crabs.
The reason behind the mortality event: hungrier crabs.
Snow crabs are cold-water species and found overwhelmingly in areas where water temperatures are below 2 degrees Celsius, though they can function in waters up to 12 degrees Celsius, according to the study. Warmer ocean water likely wreaked havoc on the crabs’ metabolism and increased their caloric needs.
The amount of energy crabs needed from food in 2018 — the first year of a two-year marine heat wave in the region — may have been as much as quadrupled compared to the previous year, researchers found. But with the heat disrupting much of the Bering Sea’s food web, snow crabs had a hard time foraging for food and weren’t able to keep up with the caloric demand.
Cause, warm water event allowed pacific cod to move to where the crabs were located. Eating portion of crab population.
Warming of oceans, letting predators reach crabs that are in coolet areas of ocean.
Normally, there is a temperature barrier in the ocean that prevents species like Pacific cod from reaching the crabs’ extremely cold habitat. But during the heat wave, the Pacific cod were able to go to these warmer-than-usual waters and ate a portion of what was left of the crab population.
In warmer water their metabolism goes up and they need to forage more food to survive. While they were attempting to do that, the were getting eaten by predators that typically couldn’t enter their region.