image: These are commonly named thick lucine, Phacoides pectinatus, collected from sediments near Fort Pierce, Fla. Ongoing research focused on P. pectinatus is revealing a much more diverse assemblage of chemosymbionts than previously recognized, including bacteria associated with nitrogen and methane, in addition to sulfur cycling. view more
Credit: Annette Engel, University of Tennessee
Millions of unique clams lie in seagrass beds worldwide. Despite their having being around for millions of years, little is known about them except that they are resilient and key to coastal biodiversity.
Annette Engel, the Jones Associate Professor of Aqueous Geochemistry in the Department of Earth and Planetary Sciences, at the University of Tennessee, Knoxville, has been awarded a National Science Foundation grant for $794,000 to lead a research group to learn more about these clams, called lucinids, and the role they play in the ecosystem. The project is part of the NSAF's Dimensions of Biodiversity program.
Findings could have implications for the recovery and management of fast-disappearing coastal environments.
Engel will collaborate with Laurie Anderson at the South Dakota School of Mines and Technology and Barbara Campbell at Clemson University on the project over the next five years, with a total project budget of $1.6 million.
Lucinids play a key role in detoxifying coastal environments for other creatures such as fish, crabs and manatees. They do this through a process called chemosymbiosis, a form of symbiosis in which a bacterium provides chemically derived energy and nutrients to a higher organism. Lucinids have bacteria that live within their gills and allows them to convert toxic compounds such as hydrogen sulfide—a neurotoxin to humans—into less toxic versions such as sulfate.
"These clams show us how chemosymbiosis, a unique evolutionary adaptation, is very important to life on earth," said Engel. "The lucinids clean up environments for other animals and allow them to live. Yet little is known about their chemosymbioses and how they are affected by environmental changes."
Lucinids' symbiotic relationship also has allowed them to survive millions of years of extinctions and disturbances. Researchers will tap into a 400-million-year-old fossil record of the lucinids' past to reconstruct environments and relationships over time. They will collect modern-day lucinid data from biomes in Florida, California and the Bahamas with varying degrees of disturbance.
Their findings will uncover the genetic, taxonomic and functional diversity of modern lucinid chemosymbioses and ways to identify the distinctive features of lucinid-bacteria biodiversity through the past. The goals are to be able to predict future lucinid evolutionary adaptations and help save or recover seagrass beds being lost at tremendous rates due to climate change, pollution, sea level rise and other disruptions.
"Environmental managers are working to save these lands yet they do not know about all the living beings in the ecosystems," said Engel. "We will look at how the effect of human activities is changing water chemistry, how this change in water is impacting the clams and how this change is impacting the whole ecosystem."
This project will train graduate and undergraduate students in interdisciplinary research; involve students underrepresented in science, technology, engineering and mathematics; and provide mentoring and outreach to the public on the topics of symbiosis and biodiversity.
The Dimensions of Biodiversity awards are supported by NSF's Directorates for Biological Sciences and Geosciences along with NASA, which co-funds projects that use state-of-the-art remote sensing technologies. To learn more the program, visit http://1.usa.gov/1bMi7Bn.