Published October 26, 2007
This Week's Take:
Remember the bay's other filter feeders
Courtesy photo — The Capital
Dr. Erica Goldman of the Maryland Sea Grant
We mourn the loss of the bay's oysters, of their ecological
prowess and of the way of life they made possible. We mourn the
loss of the bay's great fisheries, of 100-pound sturgeon that
once cruised the waters and of shad that migrated up the Chesapeake
by the millions.
We don't mourn the less charismatic creatures — the sea
squirts, worms, mussels, and more. The other filter feeders that
lived in the crevices of oyster reefs, they too have declined
in diversity and abundance, along with the health of the bay.
But we don't miss them like we miss the oysters.
The oysters went noisily, amid conflict and gunfire.
The others, those creatures of the benthos, were the civilian
casualties of the oyster wars, of urbanization and pollution.
They left quietly, their absence as inconspicuous as their presence.
We don't even know exactly what species once thrived in great
numbers. We've only been keeping tabs recently, our records reflecting
times of scarcity, not of bounty.
During a recent visit to the National Museum of Natural History,
I was struck by a diorama showing the creatures of the Burgess
Shale as they might have looked living in ancient seas. The display
showcased a living reef structure, reconstructed from fossils
found in the Canadian Rockies in the early 1900s. Every nook
and cranny was filled with life, the bottom of the ocean carpeted
by ancient starfish-like crinoids and wriggling with crustaceans.
Did the bay's historic oyster reefs once look like this? While
historical reconstructions and maps of oyster reefs in the Chesapeake
offer clues to the shape and extent of these structures, we know
comparatively little about what animals lived with the oysters.
We may not know what the bay's ancient oyster reefs looked like,
but we do know what reefs can do for us now. Large vertical reefs
provide habitat for other species to live — several recent
studies make this point clear. When restored oyster reefs are
allowed to grow undisturbed, with oyster shells protruding high
into the water column, other species settle on and around the
reef in mind-boggling numbers.
Restored oyster reefs attract abundant and diverse life — sea
squirts, barnacles, mussels, insect-like amphipods, crabs and
more, according to a 2006 study by University of Maryland researchers
Kennedy Paynter and William Rodney published in the Journal of
Experimental Marine Biology and Ecology
. These researchers found that the density of animals was 10
times higher on a restored oyster bar than in an unrestored area — one
notable filter feeder, the hooked mussel, proved 200 times more
Like oysters, the forgotten filter feeders — the mussels,
sea squirts and more — remove algae from the water column.
Like oysters, they lock up nitrogen, sequestering it in their
body tissues. Like oysters, they help alter the flow of nutrients
through the bay's food web in a way that could help improve the
quality of the Chesapeake's polluted waters. And, along with
oysters, they could help make a difference in the health of the
Today, we've lost more than we ever knew we had. The Chesapeake
is a changed place — a product of human engineering, intended
or otherwise. The bay's ecology has been sculpted by years of
harvest, use, and often abuse.
The bay of the future will also be shaped by acts of engineering.
Its ecological state will reflect choices we make now to restore
or deplete aquatic resources, including the bay's natural buffers.
We're trying as hard as we can to bring back the native oyster.
We're even considering introducing a non-native one. But we rarely
allow reefs to grow to great heights, undisturbed and protected
from tongs, dredges, and boat anchors. In fact, when the oyster
season opened in the beginning of October, sanctuary reefs in
Virginia's Rappahannock River that had been untouched for some
10 years were again reopened to commercial harvest.
We rarely think about the other filter feeders that call an
oyster reef home. They've become collateral damage in the oyster
wars. We keep some track of their comings and goings through
surveys, but they've largely fallen to the sidelines of any active
If our goal for the Chesapeake is cleaner waters and healthier
fisheries, perhaps the forgotten filter feeders could lend a
hand, assisting oysters with the monumental task of filtering
the bay's murky water. For the Chesapeake's one species of oyster,
there are dozens of other species that could help remove algae
from the water column. Maybe the oyster will always reign supreme
among filter feeders. But aren't the others worth a closer look?