Marine ecosystems are responsible for about half of global annual primary production and more than one billion people rely on fish as their primary protein source. Latest studies show that enormous warm water bubbles in the ocean are having a noticeable impact on ecosystems. How should we interpret these changes?
Heatwaves in the Northeast Pacific
An unusually long-lasting warm water bubble — nicknamed ‘The Blob’ — spread across the surface of the Northeast Pacific from winter 2013/2014 to the end of 2015. The warm water bubble at times measured up to 1,600 kilometres in diameter and had water temperatures of more than 3 degrees Celsius above the long-term average. Because warm surface water has a lower density than the cold deep water, the exchange of nutrient-rich deep water with warm surface water was reduced, especially along the west coast of North America. This had far-reaching consequences for marine organisms and ecosystems: the growth of phytoplankton decreased due to the reduced supply of nutrients, and some zooplankton and fish species migrated from the warm and nutrient-poor water to cooler regions. By contrast, researchers found pygmy killer whales in the North Pacific for much longer than usual: this tropical whale species is usually observed 2,500 kilometres further south.
Read more at: ScienceDaily
Photo courtesy: Cookaa via Wikimedia Commons
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