Central Coast CA: Morro Bay lost 90% of its eelgrass. Here’s how scientists are trying to save the key plant
The Morro Bay National Estuary Program is working to restore eelgrass, which was decimated in recent years.
Near Coleman Park, Rachel Pass of the Morro Bay National Estuarine Partnership points out patches of eelgrass, whose unassuming blades sway with the waters of the bay.
Closer to the South T Pier, a sleeping sea otter naps in a floating eelgrass bed and stirs occasionally to scratch its belly.
Both are valuable parts of the bay’s nearly 20 acres of the aquatic plant, a remnant of what was once closer to 350 acres in the past.
And while the habitat is still a far cry from its historic scope, work to replant eelgrass in recent years appears to have stabilized the decline and is supporting new growth, local conservationists say.
The National Estuary Program in Morro Bay continues to lead the way for local restoration efforts, leveraging a rich network of scientific expertise and elbow grease from the local community.
During their struggle to keep and expand the grass that’s left, program staff have been learning what works and what doesn’t when it comes to restoration.
THE IMPORTANCE OF EELGRASS
Eelgrass is one of those aquatic species that is both an organism and a habitat — think of oyster and coral reefs.
According to Lexie Bell, executive director of the Estuary Program, eelgrass is “the foundation for how the bay functions.”
The grass provides a home for and sustains a wide community of living things.
“It supports some species that people care particularly about,” Bell says, including coastal birds migrating through the Pacific Flyway and species of fish like steelhead trout.
Indeed, one of the more visible examples of the loss of eelgrass has been on black brandt geese, which feed on the vegetation and have long used Morro Bay as a migratory stop.
“They teach their next generation where to stop,” Bell said, and “the next generation is not learning to stop here.”
Eelgrass provides a slew of other benefits, as well.
When it comes to water quality, the grass slows the flow of incoming water, which allows sediment to drop out and improves clarity. It assists with the job of removing extra nutrients that could otherwise lead to overgrowth of algae.
Eelgrass also “allows fish and all other critters to have oxygen to breath underwater,” Bell said.
And the plant helps maintain the vitality of the bay and its value as a tourism destination.
The city needs “a healthy bay that’s functioning, with otters floating in the eelgrass, and birds that are feeding on fish — and a bay that looks clean and smells clean,” Bell added.
EELGRASS IN DECLINE
So when eelgrass suffered a major die-off here a few years ago, alarms sounded.
From 2007 to 2012, Morro Bay lost about 90% of its eelgrass.
“We have a community that is out on the water all the time,” Bell explained. “People notice — ‘Oh, there’s not as much eelgrass as there used to be. What’s happening?’”
Multiple factors might have led to the eelgrass loss and could be hindering its recovery — some environmental and some associated with human activity.
In order to understand which are important, the Estuary Program has collaborated with scientists at Cal Poly.
For example, research led by former Cal Poly Professor Jennifer O’Leary — now Africa Oceans Strategy director with The Nature Conservancy — revealed that parts of the bay experience very different water quality conditions including temperature, salinity, and ability of light to reach deeper water, all of which could influence eelgrass growth.
Meanwhile, the program has also led aggressive efforts to replant eelgrass, starting in 2012, while at the same time working to further understand the problem.
“We didn’t want to lose it all,” Bell said.
Results are still incoming, but what they can say about the current state of eelgrass in the area now, Bell said, is that the acreage still is small, but “it has been relatively stable since 2013. We don’t appear to be losing anymore and we might be gaining a small amount.”
To evaluate progress, the Estuary Program conducts regular mapping, but it can be inherently challenging to tell how much eelgrass is actually in the bay.
Different mapping technologies can give conflicting results, and the weather and tide conditions need to be just right for the flights they typically use to gather data every other year.
The effort to replant eelgrass in the bay has definitely helped, and the Estuary Program said it continues to test how to best restore the habitat.
In the most recent phase of restoration which started in 2017, the Estuary Program has planted just under 6,000 plants at 16 different sites.
Restoration work in a given year can take 30 to 40 hours spread out over multiple days and weekends and has to be timed for the right tide. A particular day of restoration can involve 10 to 15 volunteers that help set the plants out in the muddy bottom of the bay.
Bell described a great variety of community members who come out because they want to help restore the eelgrass. Teachers, former scientists, kayakers, students, AmeriCorps members, and oyster farmers are just some who have joined the ranks.
This year’s efforts include more sites than they’ve had in the past — about 15 instead of the 7 or 8 that were the focus of 2017 and 2018.
“We scaled up quite a bit in 2019, just based on the overall success of the past years,” said Karissa Willits, the program’s monitoring coordinator.
Currently, the program is employing two types of restoration methods.
One, used more sparingly in places that are harder to access, involves tying eelgrass to a piece of rebar bent into an L-shape that can be anchored to the bay floor and removed when the grass sets.
In most plots, however, eelgrass rhizomes — the thick underground stem of an eelgrass plant — are criss-crossed and secured with garden stakes.
During the replanting process, the team has made discoveries about the bay’s eelgrass that can help instruct and sometimes boost their efforts.
For example, when comparing planting during spring and summer, it’s clear spring plantings thrive more. This may be because the grass is released from competition with the algae that pops up in local waters during summer heat.
Willits explains that eelgrass can either be more seasonal in harsher environments or persist year round. Though staff thought their grass was around all the time, observations they’ve made of restoration projects revealed both types exist in the bay.
“We were testing the season, the location and the method,” Willits said.
Cal Poly researchers have also confirmed that the bay’s population of eelgrass is genetically distinct from outside locations.
This means transplanting from places other than Morro Bay could result in ill-adapted plants that fail during restoration attempts.
It’s also a reason why restoration efforts can take a little longer — the low acreage of eelgrass present means fewer beds to borrow from in order to cultivate more.
The program benefits from being part of a nationwide network that includes 27 other sites, and the group has had opportunities to get feedback from experts across the country.
This has helped fuel experimentation around restoration within the bay, with the ultimate goal of giving eelgrass the advantage it needs to re-establish itself.