Key Takeaways:
– A marine heat wave has led to a massive reduction in seabird colonies, from millions to a mere quarter of their former size in some areas.
– The heat wave, known as the “Blob,” caused extreme differences in ocean temperatures, impacting the food chain and resulting in mass bird starvations.
– Monitoring reveals heat wave resulted in the loss of an estimated four million birds, half of the region’s murres, during a single winter.
– The fall in bird numbers and lack of recovery even seven years later suggest a long-term shock to the ecosystem.
– It is feared such extreme climate shifts are likely to become more common due to global warming.
– Conservation instances are important for these bird populations as their decimation can be a warning sign of potential drastic changes in the ecosystem.
Highest Recorded Wildlife Mortality Event
Across the high cliffs of the Northeast Pacific, the once vibrant and bustling bird colonies have plummeted following a devastating marine heat wave. Their numbers are down to one-fourth of their previous population in several places. The extreme reduction in bird populations may be the most significant wildlife death event recorded in modern times.
Pinning Down the Problem – the “Blob”
A brutal marine heat wave, nicknamed “Blob,” was the main culprit, distressing the Pacific northeast for nearly two years starting in late 2014. This heatwave brought the ocean temperature far higher than normal, sparking an ecological domino effect. Food chains were disrupted as phytoplankton populations dwindled, affecting the edible fish stock and causing seabirds to die from starvation.
Impacts of the Heatwave on Seabird Populations
Renner, part of a monitoring program that has been collecting seabird data for the last half a century, instantly recognized the crisis. Over 62,000 bird carcasses washed up on the beaches, stretching from the Gulf of Alaska down to California. Their team decided to quantify the mortality size, drawing on colony count data collected from 1995 to 2022 across 13 colonies along the border of the Bering Sea and the Gulf of Alaska.
Catastrophic Impact on Murres Population
After comparing bird counts before and after the heat wave, their findings were alarming. It is estimated that the heat wave wiped out four million murres between the Gulf of Alaska and Eastern Bering Sea. Astonishingly, half of the murre population died in just one winter season.
Long-term Impact on Ecosystem and Future Concerns
The fact that the bird populations have not regenerated even several years after the heat wave and that several colonies are still meagerly populated suggests that the event has triggered a potentially irreversible change in the ecosystem.
Such rapid and drastic changes have not been previously recorded, giving cause for concern. If the current trend of global warming continues, such heat waves could become more frequent, affecting various vulnerable animal populations. This could lead to even further harm to the already vulnerable ocean ecosystem, which is still reeling from the effects of the past heat wave.
Recognizing the Role of Conservation
As immediate human control over marine heat waves is limited, the significance of conservation efforts is heightened. These may include eliminating invasive predators or other species causing stress to seabird populations in combination with climate fluctuations. The loss of top-tier species in the food web could be a crucial warning sign of massive ecosystem changes, necessitating proactive action.