Study suggests marine heatwaves getting more frequent, lasting longer

A new study suggests that heatwaves in the world's oceans are getting longer and more frequent, raising concerns about how the higher temperatures are affecting marine ecosystems.

Eric Oliver of Dalhousie University in Halifax, who led the research that included scientists in Australia, the U.S. and the United Kingdom, says it found that annual marine heatwave days have increased by 54 per cent from 1925 to 2016.

The oceanography professor says that means a marine ecosystem now experiences 45 marine heatwave days per year compared to 30 days of extreme heat annually in the early 20th century.

The study, released Tuesday in the journal Nature Communications, says the prolonged heat can harm an ecosystem's biodiversity, as well as fisheries and aquaculture.

For example, the authors say a marine heatwave off western Australia in 2011 altered the plant composition in an ecosystem once dominated by kelp.

A year later, high temperatures in the Gulf of Maine caused the lucrative lobster fishery to be flooded with cheaper early landings while persistent warm water in the North Pacific caused fishery closures and strandings of marine mammals from 2014 to 2016.