A recent study has found that approximately half of Alaska’s common murre population was killed off by a marine heat wave, marking the largest recorded die-off of a single species in modern history. The event, known as “the Blob,” spanned the ocean ecosystem from California to the Gulf of Alaska in late 2014 to 2016.
Researchers tracked extreme population declines at 13 colonies across the Gulf of Alaska and Bering Sea, which found that by the end of the heat wave, over 62,000 common murre carcasses were counted. However, biologists monitored the rate at which common murres were dying and reproducing after the event and found no signs of recovery.
The study suggests that changes in marine environments driven by warming ocean temperatures are rapidly restructuring ecosystems and inhibiting the ability of animals like murres to thrive. The researchers determined that the scale of this catastrophic population loss was particularly alarming, with about 4 million common murres dying in Alaska within the period from 2014 to 2016.
The decline of common murre populations has significant implications for the marine food web in the Northern Hemisphere, as these predators play a critical role in regulating energy flow. While murres have experienced smaller die-offs in the past due to environmental and human-induced factors, they typically recover quickly when favorable conditions return.
However, this event was different, with temperatures rising by 2.5 to 3 degrees Celsius above normal levels. The study found that before the start of the heat wave, Alaska’s murre population made up 25% of the world’s population of seabird species, but declined anywhere from 52% to 78% in the seven-year span following the event.
While further research is necessary to fully understand why murres are not bouncing back, scientists believe that changes in the marine ecosystem, especially those associated with food supply, may be contributing to the species’ lack of rehabilitation. Reproductive challenges and relocation difficulties also may be playing a role.
The study highlights the need for long-term monitoring and research to better understand how climate events affect marine life. As temperatures continue to rise, animals like murres will face significant challenges in adapting to changing environments, and it is essential to consider other factors such as microplastics, ocean acidification, sea levels rising, and chronic oil spills that may be contributing to these changes.
The impact of the marine heat wave on Alaska’s murre population serves as a warning about the potential consequences of climate change on marine ecosystems and the species that depend on them.
Source: https://www.yahoo.com/news/record-heat-wave-killed-half-153746127.html