As the ocean warms, marine species relocate toward the poles: study

MARCH 26, 2020

by University of Bristol

A global analysis of over 300 marine species spanning more than 100 years, shows that mammals, plankton, fish, plants and seabirds have been changing in abundance as our climate warms.

At the cool edge of species ranges marine life is doing well as warming opens up habitat that was previously inaccessible, while at the warmer edge species are declining as conditions become too warm to tolerate.

The study, conducted by researchers from the Universities of Bristol and Exeter, reviewed 540 published records of species abundance changes to investigate how marine plants and animals are responding to warming seas.

Martin Genner, Professor of Evolutionary Ecology at the University of Bristol's School of Biological Sciences, who guided the research, said: "We drew together an extensive collection of survey records that reported how species abundances have changed over the last century, as the world's oceans warmed by over 1°C. We then identified the location of each study in relation to the full global distribution of the species and asked if abundance changes depended on where a species was studied."

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Warming oceans lead to more fur seal deaths from hookworm infection

Date:  November 6, 2018

Source:  eLife

Rising ocean temperatures are putting fur seal pups at greater risk of death from hookworm infections, according to new findings published in eLife.

The results shed new light on how warmer oceans can alter specific physiological processes in marine mammals, and suggest that infectious diseases could cause higher mortality rates if temperatures keep rising.

"Increasing ocean temperatures are associated with changes in the patterns of wind and ocean currents, which cause a decrease in the cycling of nutrients and, by extension, the abundance of life including fishes," says first author Mauricio Seguel, Postdoctoral Associate in the Odum School of Ecology at the University of Georgia, Athens, US.

"Reductions in marine life have also been linked with the decline of marine mammal populations, as they rely on fish as their main food supply. Fur seals and sea lions may be included here, because although their pups live on land, they depend on their mother's' milk for survival, which can only be produced if the mothers eat enough fish."

To investigate how marine mammals may be affected by changes in ocean conditions, Seguel and his team studied the health and survival of a colony of fur seals in South America between 2004-2008 and 2012-2017. "As hookworm infection is a major cause of death in this group of animals, whereby the parasite gets into the intestine of seal pups and sucks their blood, we wanted to see if environmental change affects the pups' ability to respond to this parasite," Seguel explains.

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Reef fish inherit tolerance to warming oceans

April 30, 2018, ARC Centre of Excellence in Coral Reef Studies

In a rapidly changing climate, the decline of animal populations is a very real concern. Today, an international team of researchers report new evidence of reef fish adjusting to global warming conditions at the genetic level.

For the first time, researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) and the King Abdullah University of Science & Technology (KAUST), have found that reef fish can inherit from their parents the genetic tools to adjust to ocean warming.

"When parents are exposed to an increase in water temperature, we found that their offspring improved their performance in these otherwise stressful conditions by selectively modifying their epigenome," said senior author Prof Philip Munday of Coral CoE at James Cook University.

Epigenetic change refers to chemical modifications in the DNA that signals genes to be switched on or off. A range of factors, including disease, famine, or in the case of this research, heat stress, can stimulate these subtle changes.

In this study, when both parent and offspring experienced the same elevated water temperatures, responsive changes in their epigenome, via selective DNA methylation, were observed that enhanced the next generation's ability to cope with the new, warmer temperatures.

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Disease, warming oceans, rock lobster and sea star populations

Date: February 16, 2016

Source: Cornell University

Two new Cornell University studies show how diverse marine organisms are susceptible to diseases made worse by warming oceans.

The first study warns that warm sea temperatures in 2015 may increase the levels of epizootic shell disease in American lobster in the northern Gulf of Maine in 2016. The second provides the first evidence linking warmer ocean temperatures with a West Coast epidemic of sea star wasting disease that has infected more than 20 species and devastated populations since 2013. Both were published Feb. 15 as part of a marine disease-themed special issue of the journal Philosophical Transactions of the Royal Society B.

The first paper, "Improving marine disease surveillance through sea temperature monitoring, outlooks and projections," summarizes the cases where there are known links between disease outbreaks and temperature, including diseases that affect corals, turtles, lobsters, bivalves, starfish and eelgrasses. The paper proposes best practices to develop models that link disease risk with temperature. Increased disease threatens a diverse range of marine populations, including economically important species like the Maine lobster which could put at risk the New England fishing industry.

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