Scientists ponder Cockburn Sound's ecological mysteries

Oct 01, 2013 by Chris Thomas
Scientists ponder Cockburn Sound’s ecological mysteries
Dr Laverock says seagrass can take-up nutrients directly from the water/sediment via their leaves or roots. Credit: Ria Tan

Little is known about the microbial ecology of Cockburn Sound – but researchers from the University of WA and Edith Cowan University are investigating its seagrass root and rhizome sediments and how the presence of seagrasses enhances microbial functions.

UWA Indian Ocean Marine Research Centre research fellow Dr Bonnie Laverock is exploring how microbes contribute to both the success and productivity of seedlings and adult plants.

"I'm interested in carbon and nitrogen cycling microorganisms and how their processing of organic matter and inorganic , such as nitrate or nitrite, may affect seagrasses," she says.

"I research microbes using molecular techniques with DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) to investigate the abundance and activity of specific microbial genes.

"Seagrasses are known to have closely associated communities of nitrogen-fixing in their root/rhizome systems – these bacteria 'fix' nitrogen gas, therefore making it biologically available for uptake by the seagrasses.

"I'm also interested in the overall community structure of the bacteria and how it varies between and in comparison to bare sediments."

Working with colleagues, Dr Laverock aims to link these changes in to differences in carbon mineralisation and nutrient fluxes inside and outside of seagrass beds to better understand microbial processes in seagrass meadows.

Seagrasses can enhance the exchange of carbon and nutrients from the sediment to the in several ways.

Dr Laverock says seagrass can take-up nutrients directly from the water/sediment via their leaves or roots.

"These are then converted into seagrass biomass which can be decomposed by microbial communities in the sediment, releasing nutrients and carbon back into the water column," she says.

"The seagrasses also directly exude small dissolved compounds such as sugars and it's thought these sugars allow bacteria to chemotactically locate the roots."

Cockburn Sound has several unique features that enable researchers to study marine and draw comparisons to other areas on WA's coastline.

"The Sound is sheltered from large changes in tides and wave action compared to some areas that are continually disturbed by strong currents and waves," Dr Laverock said.

"This allows us to compare how seagrasses and other sediment organisms respond to physical disturbance from waves, such as during storm events.

"Cockburn Sound also has some good depth gradients, going from shallow to very deep, and some gradients of nutrient enrichment from industrial/agricultural outflow.

"The balance of nutrients in coastal regions is extremely important for ecosystem health and the ways in which microbes process these nutrients could be a key component of that ongoing health."

Explore further: New technique helps biologists save the world's threatened seagrass meadows

add to favorites email to friend print save as pdf

Related Stories

Nitrogen retained through loss

May 22, 2008

The nitrogen cycle plays a major role in seagrass fields. Dutch researcher Arie Vonk studied the nitrogen dynamics of seagrasses in Indonesia. He discovered that the interaction between seagrasses, animals and microorganisms ...

Solving the seagrass crisis

Sep 24, 2013

The world's seagrass meadows are in diabolical trouble – but Australian scientists say we can still save them if we act early, even as sea levels rise.

Humble plants may save the planet

Aug 16, 2013

Marine ecologists call them seagrass meadows. They once wrapped Australia's coastline providing sanctuary and food for dugongs and turtles, habitats for fish to breed and myriad other ecosystem services such ...

Tiny grazers play key role in marine ecosystem health

Apr 02, 2013

Tiny sea creatures no bigger than a thumbtack are being credited for playing a key role in helping provide healthy habitats for many kinds of seafood, according to a new study by the Virginia Institute of ...

Recommended for you

New water balance calculation for the Dead Sea

10 hours ago

The drinking water resources on the eastern, Jordanian side of the Dead Sea could decline severe as a result of climate change than those on the western, Israeli and Palestinian side. This is the conclusion ...

Studying wetlands as a producer of greenhouse gases

16 hours ago

(Phys.org) —Wetlands are well known for their beneficial role in the environment. But UConn Honors student Emily McInerney '15 (CAHNR) is studying a less widely known role of wetlands – as a major producer ...

User comments : 0