Impact of rising sea temperatures on marine life – sciencedaily



Global warming or climate change. It doesn’t matter what you call it. What matters is that right now this is having a direct and dramatic effect on the marine environments of our planet.

“The increasing frequency and severity of the extreme ‘underwater heat waves’ that we already see in the world today are more urgent than future climate change,” Lauren Nadler, Ph.D., assistant professor at Nova Southeastern University (NSU) Halmos College of Arts and Sciences. “This phenomenon is what we wanted to both simulate and understand.”

Nadler is the co-author of a new study on this topic, which you can find published online at eLife Scientific journal.

In order to better document the impact of rising temperatures in our oceans on marine life, Nadler and a team of researchers collected two common coral reef fish – the five-lined cardinalfish and the red-tailed fusilier. yellow – from northern Australia’s Great Barrier Reef. Then, under controlled laboratory conditions, the team gradually raised temperatures 3.0 degrees Celsius above the region’s average summer temperatures. But don’t worry, they didn’t boil the fish, instead they increased the temperatures so that they could realistically measure how each species reacted to these warmer conditions over a five-week period.

Researchers point out that these underwater heat waves can cause increases of up to 5 degrees C above average seasonal temperatures in just a few days and can last for several weeks. This rise in temperature can cause rapid physiological changes in these reef fish, which could have long-term effects on survival.

“We found that the fusilier responded quickly to heat stress, with almost immediate changes detected in gill shape and structure and blood parameters, however, the cardinal fish exhibited a delayed response and was much less able to adapt. at high temperatures, ”said Jacob Johansen. , Ph.D., study co-author and assistant research professor at the Institute of Marine Biology at the University of Hawaii at Manoa.

“Most importantly, we have identified seven parameters in the two species that may be useful as biomarkers to assess how quickly and to what extent coral reef fish can cope with increasing temperatures. Our results improve dramatically. our current understanding of physiological responses to ongoing threats and thermal disturbances, including which species may be most threatened, ”said Johansen.

The research team points out that the study is timely, given the rapid decline of tropical coral reefs around the world, including repeated events of coral bleaching and mass mortality on the Great Barrier Reef in 2016, 2017 and 2020, all caused by summer heat waves. Nadler indicated that the “winners and losers” of climate change will ultimately be determined by the ability to compensate for heat stress both in the short term (days, weeks and months), as in response to heat waves, as we have shown, and in the longer term. term of years, decades and centuries.

“Our results are extremely useful for scientists but also for managers, conservation planners and policy makers responsible for protecting important ecosystems, such as coral reefs, as well as communities that depend on coral reefs for food,” culture, jobs and their livelihoods, “said Jodie Rummer, Ph.D., associate professor at the James Cook University ARC Center of Excellence for Coral Reef Studies and co-author of the ‘study. “Collectively, we need to be able to predict which species will survive and which will be most vulnerable to climate change so that we can take action, because the decisions we make today will determine what coral reefs will look like tomorrow. “

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Materials provided by Southeast Nova University. Note: Content can be changed for style and length.


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