Can seabirds make a cooler climate?

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Southern Ocean seabirds contribute to global climate regulation, study suggests.

Far-ranging seabirds, a top predator of the Southern Ocean, are linked to global climate regulation as well as the health of the ocean ecosystem.  According to a study conducted by Matthew Savoca and Gabrielle Nevitt at the University of California, a mutual relationship between seabirds and phytoplankton could help save the planet.

When phytoplankton are eaten by krill in the Southern Ocean, a chemical is released that signals frill-eating birds.  This chemical signal, known as dimethyl sulfide (DMS)- forms compounds that are released into the atmosphere and promotes cloud formation.  This process ultimately helps to cool down the earth.  Clouds are able to help cool the earth because they help to reflect sunlight, often referred to as a negative feedback loop to control the planet’s temperature.

Seabirds’ mutualistic relationship with phytoplankton occurs because the birds consume the krill, and the phytoplankton are fertilized with iron, a scarce nutrient in the Southern Ocean.  This new study suggests that the top marine predators are important in climate regulation, which is different than previous beliefs.  These results demonstrate the importance of future research on how ecological systems can impact climate, rather than how organisms are responding to climate change.

Nevitt and Savoca have found that DMS is not only is an important chemical signal for birds, but also for possibly various species of penguins, seals, sharks, sea turtles, whales, and other top predators of the ocean.  Phytoplankton is such a crucial organism in the ocean because they absorb carbon dioxide and also release an enzyme which generates DMS.

The firsts DMS hypothesis in regulating climate change was proposed in the 1980s, which states that warming oceans lead to growth of phytoplankton, which in turn release a precursor to DMS when they die.

The number of these birds is declining, with almost half the species listed as vulnerable, endangered, or critically endangered.  This new discovery of their influence on a cooler climate means that this decline could have a significant effect on marine productivity.

 

To read more on this study, visit the journal article here

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Savoca, Matthew; Nevitt, Gabrielle.  Evidence that dimethyl sulfide facilitates a tritrophic mutualism between marine primary producers and top predators.  PNAS 2014 ; published ahead of print March 3, 2014, doi:10.1073/pnas.1317120111

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