Emphasis on eelgrass

Local scientists continue work to restore a critical habitat

Local scientists are lending their expertise to offset the global decline of seagrass by studying and restoring eelgrass.

“The amount of eelgrass that is being lost is huge,” John Vavrinec, senior research scientist and dive officer at the Marine Sciences Laboratory, said. “In 2009, it was estimated about 30 percent the eelgrass meadows in the world had been lost since the 1940s.”

To help address this decline, scientists at Pacific Northwest National Laboratory’s Marine Sciences Lab in Sequim are working with the state toward a sound-wide goal to restore eelgrass throughout the Puget Sound.

Eelgrass (Zostera marina) is recognized by the Puget Sound Partnership, the state agency tasked with coordinating a variety of partners toward shared goals to restore and protect Puget Sound, as both “critical habitat” and a “vital sign” of Puget Sound because changes in its abundance or distribution reflect changes in environmental conditions.

As the amount of seagrass, including eelgrass, disappears on a local and global scale, so does an important piece of the overall marine habitat that supports many ecosystem processes.

As a flowering, rooted and most widespread species of seagrass, eelgrass provides a variety to ecosystem functions, Ron Thom, lead for the Coastal Ecosystem Research technical group at Marine Sciences Laboratory, said.

Examples include its ability to act as feeding grounds and food source, provide habitat for invertebrates and microbes, be a nursery and spawning area for some fish and shellfish, protect shorelines from erosion, improve water transparency, provide oxygen to the water, trap nutrients and cycle it and sequester carbon.

Seagrass meadows occupy less than 0.2 percent of the area of the world’s oceans, but it’s estimated that they bury roughly 10 percent of the ocean’s carbon, Thom said.

“This is important for climate change and really important for sequestering carbon in sediments.”

Reasons for the overall decline in eelgrass beds “are not yet fully understood,” according to Puget Sound Partnership, but local stressors like shoreline alteration, pollution and direct physical damage have impacts on the amount and health of eelgrass.

 

State goal

In reaction to the overall decrease in eelgrass, the state goal is to increase the area of eelgrass in Puget Sound by 20 percent by 2020.

“In places I think it (restoration) has gone well, but to make that goal by 2020 is going to be pretty difficult,” Vavrinec said.

For the past five years scientists at the Marine Sciences Laboratory have worked with state agencies to try to achieve this goal, Vavrinec said, but both his and his colleagues’ work with eelgrass prior to their collaboration with the state account for many more years.

If met, the goal would total 64,000 acres of eelgrass throughout Puget Sound, relative to 2000-2008 baseline of about 53,300 acres of eelgrass estimated to be within the sound. According to the 2015 State of the Sound (an annual report of analysis and findings) the 2011-2013 estimate is about 7 percent higher than the 2000-2008 baseline, but has a wide range of uncertainty.

“We looked all around Puget Sound for good (restoration) spots and the areas we’ve pursued are just one the ones that floated to the top of our list,” Vavrinec said. “We’ve been targeting the larger areas first, but we need to continue to improve our methods because most of the easy sites have been addressed,” Vavrinec said.

The eelgrass beds near Sequim are fairly healthy and seemingly self-sufficient, but the work and research done at the lab supports restoration projects throughout the sound, including two projects underway in Port Gamble and Quilcene bays. Eelgrass neighboring the Marine Sciences Laboratory have allowed scientists at the lab to long study established eelgrass beds and create long-term data sets, Vavrinec said, which is used to increase restoration success.

The lab also is equipped with large outdoor tanks fed with water from Sequim Bay to temporarily hold eelgrass intended for a restoration project, sometimes propagate plants and occasionally conduct experiments to better understand the physiological response of eelgrass to temperature, light, flow or amount of carbon dioxide given climate change.

Because of the space limitation of the tanks and the scale of most of the restoration projects, the eelgrass used to plant and restore an area is taken from natural donor sites, Vavrinec said. Although scientists err on the side of caution when taking plants from donor sites, there’s a study underway to establish the threshold for the amount of plants that can be removed from a healthy eelgrass population before its negatively impacted.

 

Improve data

Modeling is used when selecting areas to restore eelgrass, Vavrinec said. After modeling the shorelines, potential areas are identified, a field survey is conducted, test plots are placed and evaluated — if successful, Vavrinec will pursue a full-scale restoration.

“Science is a process,” he said. “We’re always trying to improve our chances for success and one of the biggest problems we run into with the model is the data.”

Although modeling can target areas ideal for eelgrass, the data used isn’t always reflective of the actual nearshore environment where eelgrass is able to grow given its sensitivity to both light and temperature. To improve the data used by the models, Vavrinec hopes to install light sensors throughout Puget Sound.

Funding for the supplies and installation still is needed, but Vavrinec hopes to pilot the project this year with five sensors. To regularly maintain and collect the information gathered by the light sensors, Vavrinec plans to network and partner with existing organizations like the Port Townsend Marine Science Center, Feiro Marine Life Center, the Seattle Aquarium, universities and citizen scientists.

“The idea is to get continuous data,” he said. “This would provide two things.”

First, Vavrinec said, it would provide much better estimates of where eelgrass would most likely thrive. Secondly, it would provide long-term data sets.

“That same data also could help us monitor changes in water quality,” he said.

Beyond the hands-on efforts and research being done to restore eelgrass beds, Vavrinec said, the biggest things that would help eelgrass is to increase both nearshore habitat restoration and water quality.

 

Reach Alana Linderoth at alinderoth@sequimgazette.com.