| OYSTERS VITAL
TO ALABAMA’S GULF COAST
AUBURN – Oysters may seem to be passive creatures, but when it
comes to the economy and ecology of Alabama’s Gulf Coast, they’re
dynamic, vital players. Research underway through Auburn University’s
Peaks of Excellence Program is helping ensure that oysters can continue
to do their important work.
According to Rick Wallace, professor of fisheries and allied aquacultures
at Auburn, oysters have always been important to Alabamians. The Southeast’s
Paleo Indians used oysters for food, tools, jewelry and currency thousands
of years before the first Europeans arrived. Early European settlers
in America also used oysters for food and tools and even as construction
material for buildings and roads.
Oysters developed into a cash crop and today Alabama’s oyster
fishery contributes an estimated $3.4 million to the coastal economy
annually. However, oysters populations are declining.
Low oxygen events (such as the Mobile Bay “jubilee” phenomenon),
high sedimentation, a limited supply of newly hatched oysters (larvae)
and limited oyster shell substrate for larvae to attach to are also
suspected contributors to the decline of these once productive oyster
reefs.
To answer questions about the declines and fluctuations in oyster populations
and to increase oyster yield and quality for the food market, AU has
been studying a wide range of oyster management programs for many years.
David Rouse, now chair of the AU Department of Fisheries and Allied
Aquacultures, and Wallace have spent more than 20 years exploring oyster
issues.
In one Peaks project, AU researchers assessed Fish River Reef, which
once covered about 70 acres along the Eastern Shore of Mobile Bay. This
area contains several historically productive oyster reefs that are
not producing commercial quantities of oysters despite the fact that
these beds have not been fished commercially in many years.
According to Wallace, initial reef assessment studies in 1998 revealed
low oyster density (less than 0.1 oyster per square yard) and a lack
of shell substrate for larval oysters to settle on. Hatchery-produced
oysters planted on the oyster shell plots at the reef grew well for
more than a year and young oysters were found in the area.
In the second year of the study, low oxygen events (levels near zero)
occurred in bottom water at the study site. In addition, sediment accumulated
on the shell pads at rates greater than at productive reefs and killed
all the young that summer.
Results of this study indicate that oyster larvae are present and they
can attach and survive when adequate substrate is available. However,
periodic low oxygen concentrations and possibly high sedimentation rates
are contributing to the failure of some oyster reefs. Some of this problem
may simply be where the oysters are located in the water profile.
Last year oyster shells were added to the areas to raise the oyster
beds up off the bottom of the Bay and improve the survivability of the
oysters by changing their location in the water stream.
“We’re monitoring that situation now,” Wallace said,
“and this information is being used to formulate new strategies
for oyster reef restoration projects in Mobile Bay.”
By: Katie Smith
-30-
August 2002
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