A study led by UW Biology Professor Jennifer Ruesink, in collaboration with Kerry Naish of the University of Washington’s (UW) School of Aquatic and Fishery Sciences and doctoral student Bryan Briones Ortiz, provides the first evidence that the life history strategies of eelgrass are genetically determined. This study, funded by Washington Sea Grant (WSG), has important implications for eelgrass restoration work, as they indicate managers will need to be careful in selecting appropriate sources for restoration projects.

Excerpt from Washington Sea Grant article:

Native Washington eelgrass (Zostera marina) is in trouble. Due to declines in some areas of the Salish Sea and Pacific coast over the last 20 years, restoring eelgrass – and the crucial habitat and ecosystem services it provides – is a high priority for Washington state. 

Restoring eelgrass meadows often looks like simply taking eelgrass from one location and replanting it in another. But for resource managers looking to maximize the impact of these efforts, many questions remain unanswered. Will eelgrass taken from one meadow really survive in another area? How similar or different are Washington’s eelgrass meadows from one another?

A study funded by Washington Sea Grant (WSG) seems to have revealed a piece of the puzzle. Led by Kerry Naish of the University of Washington’s (UW) School of Aquatic and Fishery Sciences, Jennifer Ruesink of UW Biology, and doctoral student Bryan Briones Ortiz, research published last month in Molecular Ecology provides the first evidence that the life history strategies of eelgrass are genetically determined.

Though it grows underwater, in many ways, eelgrass is similar to terrestrial plants. Each eelgrass plant can have one of two types of life cycles, annual or perennial. Annual plants complete their entire life cycle in one year, while perennial plants return to flower over multiple years.

“Annual eelgrass is reported in the literature, but it only lasts from April when it germinates to September when it senesces after flowering. No one had applied modern genetic techniques to evaluate its relationship to the more common perennial form,” explains Ruesink. “Here in Washington we had an opportunity to compare the life histories because they’re found close together in some of our larger coastal bays.”

It was believed that these life history strategies were based not on genetic differences but on the environment the plant happened to be in, and that the annuals were cued to flower by the more extreme environments they occupied. 

The new findings say differently. The research team first applied genetic analyses to eelgrass collected from 16 sites to describe extensive population structure around Washington state. In the next part of the study, seedlings from annual and perennial plants were taken from their locations of origin – only a few hundred meters apart – and swapped. Instead of the plants adopting new life history strategies, as may have been expected from the previous hypotheses, the plants kept the ones they had. The researchers found that the two life history strategies are genetically distinguishable, and that the plants were more closely related to each other than to more distant eelgrass elsewhere in the state.    

Read the full article here.