According to a new study, the 2014-2016 Pacific marine heatwave wiped out roughly four million of Alaska’s common murre (Uria aalge) seabirds, representing the largest documented vertebrate die-off linked to warming oceans.
Study Highlights
- Event: The 2014-2016 Pacific marine heatwave caused the largest documented vertebrate die-off linked to ocean warming.
- Impact: Approximately 4 million common murres (Uria aalge) perished, representing half the population.
- Significance: The study highlights how climate effects can be:
- Swift: Significant population decline within one year.
- Intense: High mortality rates, drastically altering population dynamics.
Ecological Effects
- Key Findings:
- Heatwaves destroy critical habitat-forming species like kelps and corals.
- Trigger cascading trophic effects, including:
- Displacement of lower-trophic-level species.
- Altered ecosystem productivity.
- Amplified food shortages for predators.
- Impacts on Common Murres:
- Depend on small schooling fish, juvenile predatory fish, and krill for food.
- Experienced extreme food shortages due to the disruption of marine food webs.
Marine Heatwaves (MHWs)
- Definition: Periods where sea surface temperatures rise 3-4°C above average for at least five days.
- Duration: Can last weeks, months, or even years.
- Effects:
- Reduce reproductive success and increase mortality for upper-trophic-level species.
- Broader population impacts remain poorly understood.
Species Characteristics
- Common Murres:
- Long-lived diving seabirds.
- Found in temperate and subarctic marine ecosystems in the Northern Hemisphere.
- Dive as deep as 200 metres to forage.
