A recent study published in the journal Science sheds light on the devastating impact of the 2014-2016 Pacific marine heatwave “the Blob” on Alaska’s common murre seabirds (Uria aalge),

Key Takeaways from the study

• Massive Die-Off:
• • The marine heatwave (2014–2016)  caused the death of over 4 million common murres (Uria aalge), wiping out more than half of Alaska’s population of these seabirds.
    • It is the largest documented vertebrate die-off linked to warming oceans.

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• Population Decline:
  • Researchers observed a 52-78% decline in common murre populations across 13 colonies from 2008-2022.
    • This equates to the loss of 4 million birds in less than two years.
  • Causes of the Decline
    • Impact of Rising Temperatures:
      • Higher ocean temperatures disrupted marine ecosystems.
      • A sudden reduction in the quality, quantity, and accessibility of forage fish led to mass starvation among the murres.
    • Pre-Existing Stress:
      • Some murre colonies showed signs of population decline before the heatwave, indicating additional stress factors.
  • There were no signs of population recovery during  (2016-2022). 
    • It shows that  heatwaves likely caused a long-term ecosystem shift, reducing the ability to support seabird populations.
  • Decline in Other Species
    • Pacific Cod:
      • Population dropped by 80% between 2013 and 2017, leading to fishery closures.
    • Humpback Whales:
      • After recovering from whaling, numbers dropped by 20% during the heatwave.
      • Climate-induced food shortages now limit their population growth.
  • Long-Term Effects
    • A persistent drop in top predator populations like murres signals a major ecological shift due to global warming.
    • Ecosystems may face reduced carrying capacity, permanently altering their structure.

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