From: University of Delaware
Published March 18, 2015 09:58 AM

The importance of methane seeps in microbial biodiversity of sea floor

A new study “provides evidence that methane seeps are island-like habitats that harbor distinct microbial communities unique from other seafloor ecosystems." These seeps play an important role in microbial biodiversity of the sea floor.

Methane seeps are natural gas leaks in the sea floor that emit methane into the water. Microorganisms that live on or near these seeps can use the methane as a food source, preventing the gas from collecting in the surrounding hydrosphere or migrating into the atmosphere.

“Marine environments are a potentially huge source for methane outputs to the atmosphere, but the surrounding microbes keep things in check by eating 75 percent of the methane before it gets to the atmosphere. These organisms are an important part of the underwater ecosystem, particularly as it relates to global gas cycles that are climate important in terms of greenhouse gas emissions,” said University of Delaware assistant professor of marine biosciences, Jennifer Biddle.

“Scientists know that certain areas of the deep sea experience bursts of energy and that microbes can grow there, but they aren’t sure what these microbes do or what environment they prefer,” Biddle said.

In the study, Biddle and her international colleagues analyzed microbial samples from 23 methane seeps across the globe, and compared them to the microbial communities of 54 other seafloor ecosystems, including sulfate-methane transition zones, hydrothermal vents, coastal sediments and deep sea surface and subsurface sediments.

While the researchers theorized that bacteria and archaea would vary by the amount of methane emitted by a given seep, what they found was that methane secretion wasn’t a determining factor; rather other energy sources from the surrounding environment were determined to have a greater role in determining what types of bacteria and microorganisms were present.

The scientists’ findings indicate that, globally, methane seeps share a core community of bacteria and archaea, but that they are locally specific.

As governments and industry contemplate mining the deep ocean as a potential industrial reserve for minerals and other important deposits, scientists like Biddle are considering climate change and how the warming of the ocean potentially could affect the deep water and the marine organisms that live there.

Biddle believes the data set created with her colleagues may offer an important window into understanding the current state of diversity and dispersal in the deep sea. This is particularly important, she said, because consumption of methane by microbes is an important control for methane concentrations from the seafloor.

The article "Global Dispersion and Local Diversification of the Methane Seep Microbiome,” is published in the journal Proceedings of the National Academy of Sciences (PNAS).

Read  more at the University of Delaware.

Sea floor image via Shutterstock.

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