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Whales Vanish, Seabirds Scatter: Ocean Heatwave's Grim Warning
31 Jul
Summary
- Humpback whale numbers plunged 60% below normal during their migration.
- Rare seabirds appeared far from their usual feeding grounds in poor condition.
- Marine heatwaves can alter ocean currents, weather, and prey availability.
In late June, whale watchers in southwest Western Australia reported a 60% decrease in humpback whale numbers during their typical migration period. Around the same time, unusual sightings of albatrosses and petrels occurred off Australia's east coast, thousands of kilometers from their usual Southern Ocean foraging areas, with many birds in poor condition. These observations raise concerns about altered ocean conditions.
Marine heatwaves can impact even Antarctic regions, disrupting ecosystems accustomed to cooler temperatures. Since February, a persistent marine heatwave has affected waters around Australia's Heard Island and McDonald Islands, extending to the edge of Antarctica's sea ice. The southern Tasman Sea has also experienced a marine heatwave since at least April. These warming trends, exacerbated by climate change, can affect prey availability for marine life.
Past marine heatwaves, like 'the Blob' in the North Pacific between 2014 and 2016, caused widespread ecosystem disruption, including kelp forest disappearance and mass die-offs of marine life. Research indicates that warmer waters can shift zooplankton distribution, a crucial food source for seabirds, whales, and fish. This also impacts marine mammal populations, with Antarctic fur seals facing difficulties finding prey, and South Atlantic populations declining significantly.
