December 26, 2023 — The following was released by NOAA Fisheries:
New research suggests that warming of the Bering Sea Shelf affects algae blooms and the food web that relies on it. This is particularly true of the recent unprecedented and widespread warming during 2018–2019. Understanding the impacts of the timing of the bloom and its association with sea ice is essential to predicting ecosystem responses to climate change.
The Bering Sea shelf is a highly productive ecosystem that extends 500 kilometers offshore from the Alaska coast. It typically experiences large phytoplankton blooms in spring. In cold, high-ice years in the southern Bering Sea, and all but the warmest years in the northern Bering Sea, the timing of sea-ice retreat is a major driver of spring bloom formation.
At the start of spring, as light levels increase, ice-algae grows on the underside of the ice. As spring progresses and the ice melts, the surface water gets fresher, which creates stratification in the water. This allows the phytoplankton to remain in the well-lit surface layer to grow.
These ice-associated phytoplankton blooms feed zooplankton (e.g. copepods, krill) and other tiny creatures that are important fat-rich foods for young fish, birds and marine mammals. The phytoplankton that do not get eaten fall to the seafloor to support a diverse community of bottom-dwelling invertebrate species, like crab and clams. These species, in turn, are food for walruses and some whales.