Patagonia's fjords are home to spectacular biodiversity, with many endemic and endangered aquatic species. They are also an environment suitable for thriving fisheries that support food security and local economies, being the second largest producer of farmed salmon after Norway. However, climate change is impacting the ecosystem, in particular the increasing occurrence of droughts.
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In 2018, river discharge accounted for 74% of Total Exchange Flow, while tides and wind contributed 17% and 9%, respectively. During the 2016 drought year, though, the influence of tides and wind on Total Exchange Flow increased to 21% and 16% respectively, which highlights the increasing significance of their role in destratification when freshwater availability via river discharge is low.
Consequently, this wind interference caused the fjord's water to destratify, with increased mixing of the dense high-salinity water that usually sits below a thin layer of lower-salinity freshwater at the surface. This has significant implications for ecosystem dynamics and the scientists used this information to predict fjord stratification patterns linked to recorded incidences of harmful algal blooms over 40 years (1980-2021).
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The latter algal blooms can be harmful to the fjord ecosystem as their rapid growth at the surface can block sunlight from reaching organisms living below, as well as creating oxygen minimum zones when the decomposition of dead algae uses up the water's dissolved oxygen. The subsequent hypoxic conditions can make it severely challenging for other organisms to survive.
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