Climate change ecology: Salmon behaving badly

Projected future CO2 levels reduce the growth of juvenile salmon and alter their behaviour, with implications for the productivity of coastal ecosystems unless populations can adapt.

Pink salmon (Oncorhynchus gorbuscha) are anadromous fish that start life in fresh water but spend the majority of their juvenile and adult lives out at sea. Writing in Nature Climate Change, Ou et al.1 report that CO2-induced acidification of aquatic habitats could dramatically affect the performance of young pink salmon during the transition from a freshwater to marine lifestyle.

Pink salmon are remarkable fish — they hatch from eggs buried in the gravel of rivers and streams, emerging into a freshwater environment. The tiny hatchlings, with a yolk sac still attached to their belly, remain close to their birth place for a few months. Once the yolk sac is consumed they migrate downstream to the ocean, where they transition to a saltwater lifestyle. The juvenile salmon grow rapidly in the ocean and in less than two years they return as adults to their natal streams where they spawn and complete their lifecycle2. All of the complex physiological changes that enable juvenile salmon to survive in saltwater, after starting life in fresh water, occur while they are just a few centimetres long and weigh less than a quarter of a gram. This is a time of rapid change in the salmon’s life and they are also at high risk of predation from larger fishes and other predators. (…)

Munday P. L., 2015. Climate change ecology: Salmon behaving badly. Nature Climate Change 5:915–916. Article (subscription required).


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