May 29, 2020

Morro Bay Eelgrass Restoration Update: May 2020

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Eelgrass in Morro Bay grows at a range of intertidal and subtidal depths throughout the estuary. Intertidal areas are exposed at high tide, while subtidal locations are always under water. Over the last few years, the Estuary Program has focused on transplanting eelgrass at intertidal locations. Focusing on shallower intertidal locations has been ideal for getting access to the mudflats on foot, and has allowed us to maximize our volunteer support. (Thank you, volunteers!) This spring, we are excited to have additional funding to expand our planting efforts to subtidal locations, too, as many intertidal areas off the main tidal channel in the estuary are now growing strong with eelgrass (hooray!).

Subtidal Eelgrass Plantings

With support from Tenera Environmental, we were able to plant eelgrass in deeper areas of the forebay and midbay using scuba gear. Tenera staff used planting methods similar to those used in our earlier intertidal plantings. In three transplant sites, they anchored eelgrass with garden stakes, rebar pieces, and bamboo pieces to test the success of different anchoring techniques while using scuba.

Tenera Environmental staff plant subtidal eelgrass in spring of 2020.
Tenera Environmental staff plant subtidal eelgrass in spring of 2020.

 

Eelgrass is tied to three-foot long bamboo pieces or lengths of rebar to anchor the plants while their roots begin to grow. We will remove the rebar once the roots are established, and the bamboo will decompose.
As you can imagine, planting underwater creates new challenges. It can be difficult to use equipment in the current, and murky water can make it hard to see what you are doing. Luckily, the water clarity at this planting site allowed for good visibility and smooth planting of this rebar piece.
As you can imagine, planting underwater creates new challenges. It can be difficult to use equipment in the current and murky water can make it hard to see what you are doing. Luckily, the water clarity at this planting site allowed for good visibility and smooth planting of this rebar piece.
A ½ meter eelgrass plot planted using scuba.
This half-meter eelgrass plot was planted using scuba.
Tenera staff marking an eelgrass plot for future monitoring. We will monitor these plots approximately every three months to track their survival and health.
Here, Tenera Environmental staff marking an eelgrass plot for future monitoring. We will monitor these plots approximately every three months to track their survival and health.

2020 Eelgrass Restoration Monitoring

This year, we planted 3,000 eelgrass plants across ten subtidal and intertidal sites. So far, all of our sites look pretty good. We will report again on how both the intertidal and subtidal plantings are doing in a future blog post. Please stay tuned!

Eelgrass planting locations map
This map shows eelgrass planting locations from 2017 through spring of 2020.

 

Eelgrass is visible on top of the bay water, which reflects sunlight.
Calm early-morning low tides this week have allowed us to monitor our plots easily and enjoy the beautiful bay.

Eelgrass Dwellers

With more eelgrass growing in the bay, it has been great to hear about community members seeing leopard sharks, bat rays, and other wildlife finding home in the new eelgrass patches.

Estuary Program staff found this nudibranch in one of the intertidal restoration plots planted this past spring.

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