Biology Reference
In-Depth Information
Much of what is known about eelgrass comes from studies in other es-
tuaries such as Chesapeake Bay and Puget Sound. Though the species that
grows in these estuaries is the same, several aspects of each population are
very different. In Chesapeake Bay, where the waters are both clearer and
warmer, eelgrass beds tend to be relatively large, extending over several
dozen acres. But the plants themselves tend to grow just a few feet long. In
San Francisco Bay, the largest remaining bed is 1,500 acres, though most
beds are just tens of acres in size. Individual plants often sprout blades up
to eight feet long.
Although scientists can't be certain, human activities have likely con-
tributed to the disappearance of these marine meadows.
The most recent attempts at eelgrass restoration began with a loss of habi-
tats. To build the new eastern span of the Bay Bridge, the California De-
partment of Transportation had to sink supports right through an existing
eelgrass bed off Emeryville. As mitigation for this damage, the agency paid
for a survey by consultant Keith Merkel to map existing and potential eel-
grass habitat in the bay. He found that the largest bed, between Point San
Pablo and Point Pinole, consists of about 1,500 acres, or about half of the
remaining 3,000 acres of eelgrass in the bay. He also mapped two other
large beds and a number of smaller ones, mostly in the brisk currents and
moderate salinities of the Central Bay. Although this is an improvement
over 1987, when just 316 acres of eelgrass were found, Merkel estimates
that the right conditions exist to support 10 times more eelgrass acreage in
the bay.
Meanwhile, Katharyn Boyer, a professor of biology at San Francisco
State University and the Romberg Tiburon Center, has been experiment-
ing with how best to replenish local eelgrass meadows. After a year of
laboratory studies, she began planting new eelgrass beds at three half-acre
sites in Marin in 2006. One is within San Quentin's watery front yard, one
in the next inlet over at the Marin Rod and Gun Club, and the third at
Richardson Bay.
Though Richardson Bay appeared the most promising site at first, at-
tempts to establish eelgrass there failed. In retrospect, says Latta, the site
may have been too murky, requiring the plants to grow at shallow depths
that exposed them to heat stress during low tides. Plants at the other two
sites, however, flourished.
Boyer has used four different planting techniques, each designed to
take advantage of the plant's natural methods of propagation. The first
