ERC Consolidator Grant to investigate seagrass symbionts

The European Research Council (ERC) awarded a Consolidator Grant to DOME group leader Jillian Petersen to delve into the biodiversity and ecological functions of a widespread group of microbial symbionts inhabiting coastal marine ecosystems, like seagrass meadows and salt marshes. The project aims to test the theory that Sedimenticolaceae symbionts provide their hosts with a natural ‘fertilizer’ by fixing nitrogen, and that they cleanse the environment of toxic sulfides.

You have probably seen seagrass meadows while holidaying at the beach. What you might not have seen is the range of essential services seagrasses perform for the health of our coastal oceans. They anchor the sand, preventing beaches from washing away. They provide a home for hundreds to thousands of other species, including some that are important fisheries resources. They also cleanse the water of excess nutrients pumped into the sea from farms on land, and they oxygenate their surroundings – hence their labelling as the ‘lungs of the sea’.

Seagrasses are flowering plants, descended from land plants that (re-)colonized the oceans nearly 100 million years ago. Like land plants, they also need communities of microbial symbionts to help maintain their health and productivity, but these have not been nearly as extensively studied as those on land.

In her project SeaSym, Jillian Petersen and her team will investigate the biodiversity and ecological functions of a very widespread type of microbial symbiont in coastal marine ecosystems, including seagrass meadows and salt marshes, which are also essential to ocean health. This symbiont group is called Sedimenticolaceae.

Petersen and her team will test the theory that Sedimenticolaceae symbionts provide their hosts with a natural ‘fertilizer’ through their nitrogen-fixing activity, and that they cleanse the environment of toxic sulfides, promoting plant health. They will test how the function of such symbioses might adapt to future oceans that are becoming warmer. One additional feature of these remarkable symbionts is their ability to colonize both animal and plant hosts. Understanding how such a unique lifestyle has evolved is another exciting aspect of the planned research.

The ERC will fund the SeaSym project for the next 5 years with a prestigious Consolidator Grant, amounting to 2 million Euros. Consolidator Grants support mid-career researchers to strengthen their research teams and advance their excellent scientific track record. They empower recently established independent research groups to pursue innovative and high-impact questions.

“The idea for this project grew out of discoveries we made during the ERC Starting Grant project EvoLucin,” explains Professor Petersen. “We realized that the same symbionts were colonizing both marine animals (lucinid clams) and plants (seagrasses) in coastal meadows where both co-occur.”

“Our idea is these symbionts, Sedimenticolaceae, are the most widespread symbionts of the sea,” she says. “The Consolidator Grant will allow us to test this theory!”