Eelgrass, a plant critical to the ecological health of Morro Bay, has disappeared from much of the bay, and scientists are not sure what is causing what they call a crisis.
In an effort to turn this trend around, a group of volunteers and contractors spent much of last week transplanting eelgrass within the bay. The effort was a pilot program that organizers hope will be a springboard for future restoration efforts.
In all, divers transplanted some 8,000 eelgrass plants from Coleman Beach near the mouth of the bay to areas of the back bay where losses have been greatest, said Keith Merkel, with Merkel & Associates, a San Diego-based environmental consulting firm hired for the project.
Eelgrass is a form of sea grass with long, ribbon-like green leaves that grows in estuaries and other protected coastal water bodies. Worldwide, eelgrass numbers are dropping, but the rate of reduction in Morro Bay is particularly high.
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Between 2007 and 2010, the amount of eelgrass in the bay fell by nearly 50 percent. At its peak extent in the 1970s, eelgrass was estimated to cover nearly 500 acres of the intertidal flats and shallow areas of the bay. Today, fewer than an estimated 100 acres of eelgrass remains in Morro Bay, an 80 percent reduction since the 1970s. Most of the loss has been in the southern and central parts of the bay in areas with mudflats and shallow water.
“We have not been able to identify a single apparent cause for the declines we’re seeing in Morro Bay,” said Annie Gillespie, monitoring projects manager for the Morro Bay National Estuary Program. “More likely a long streak of diverse impacts has led to the losses in the southern areas of Morro Bay.”
Possible causes for the eelgrass decline include sedimentation and algae blooms, both of which reduce water clarity and hamper photosynthesis. Intense tidal surges over a three-day period caused by the March 2011 Fukushima tsunami may have also scoured out some of the eelgrass beds.
Whatever the cause, a wide variety of organizations are alarmed. In addition to the National Estuary Program, the Black Brant Group, an organization of local waterfowl hunters, and the Morro Coast Audubon Society have formed an uncommon alliance to back the restoration effort.
“This just shows how many people in the community are interested in eelgrass restoration for a variety of reasons,” said Adrienne Harris, executive director of the estuary program.
Benefits are many
Eelgrass provides numerous ecological benefits, making it what scientists call a foundation species. It offers shelter and spawning areas for many commercially valuable fish species and food for migrating birds, particularly black brant.
The brant is a small goose that feeds in sheltered bays along the coast as far south as Baja California during the winter and breeds in the Arctic tundra during the summer. As eelgrass acreages in Morro Bay have dwindled, so have the number of brant using the bay, in roughly the same proportion.
Morro Bay is one of only four major stopover sites for the brant in the state. Eelgrass is a crucial component because it is the brants’ primary food, said Andrea Jones, director of an Audubon Society bird program based in Morro Bay.As eelgrass has diminished, a variety of species of red algae have replaced it. From 2009 to 2010 alone, red algae acreage increased 334 percent to 220 acres from 51 acres.
Both the Black Brant Group and the Audubon Society funded one day of last week’s restoration work. Additional funding came from the Army Corps of Engineers as mitigation for extensive dredging operations done in 2010 that destroyed a number of eelgrass beds, Merkel said.
Replanting by hand
Last week’s replanting was a labor-intensive affair. Using their hands, divers removed eelgrass from the Coleman Beach donor site.
The grass was taken by boat to a processing site at the Coast Guard pier, where volunteers tied the plants into bundles of four to six. Each bundle was attached to a biodegradable lollipop stick that acted as an anchor when it was replanted.
Merkel selected 20 transects throughout the back bay where eelgrass was replanted. Each bundle was planted a meter apart, three abreast along each 66-meter transect. The wide spacing will encourage the eelgrass to send its roots — or rhizomes — out quickly over a large area.
Now that the transplanting is complete, the project moves into a monitoring phase. Monitoring will indicate how successful the transplanting was and offer lessons for fine-tuning the process in the future.
One goal is to simplify the process so in the future volunteers can do the replant-ing rather than professional divers, Harris said. The groups also hope to develop procedures for harvesting eelgrass seeds and dispersing them in transplant areas.
The estuary program plans to continue fundraising efforts to pay for future eelgrass restoration.
“Maintaining vibrant intertidal eelgrass meadows in Morro Bay remains a priority of the Estuary Program,” the group said in its 2010 report.