Page 124 - Environment: The Science Behind the Stories

CEnTRAl CaSE STUDy

The Vanishing Oysters

of the Chesapeake Bay

Baltimore
Washington, D.C.
UNITED “I’m 60. Danny’s 58. We’re the young ones.”
STATES —Grant Corbin, Oysterman in Deal Island, Maryland
Chesapeake Bay

“The Bay continues to be in serious trouble. And it’s
really no question why this is occurring. We simply
Atlantic haven’t managed the Chesapeake Bay as a system
Ocean
the way science tells us we must.”
—Will Baker, President, Chesapeake Bay Foundation

A visit to Deal Island, Maryland, on the Chesapeake Bay reveals oyster industry was all but ruined. Perpetual overharvesting,
a situation that is, unfortunately, all too common in modern habitat destruction, virulent oyster diseases, and water pollu-
America. The island, which was once bustling with produc- tion had nearly eradicated this economically and ecologically
tive industries and growing populations, is suffering. Economic important species from bay waters. The monetary losses asso-
opportunities in the community are few, and its populace is ciated with the fishery collapse have been staggering, costing
increasingly “graying” as more and more young people leave to the economies of Maryland and Virginia an estimated $4 billion
find work elsewhere. In 1930, Deal Island had a population of in lost economic activity from 1980 to 2010 alone.
1237 residents. In 2010 it was a mere 471 people—and only One of the biggest impacts in recent decades on oysters
75 of them were under age 18. is the pollution of the bay with high levels of the nutrients nitro-
Unlike other parts of the country with similar stories of gen and phosphorus from agricultural fertilizers, animal manure,
economic decline, the demise of Deal Island and other bayside stormwater runoff, and atmospheric compounds produced by
towns was not caused by the closing of a local factory, steel fossil fuel combustion. Oysters naturally filter nutrients from
mill, or corporate headquarters. It was caused by the collapse water, but with so few oysters today, elevated nutrient levels
of the Chesapeake Bay oyster fishery. have caused phytoplankton populations in the bay to increase.
The Chesapeake Bay was once a thriving system of inter- When phytoplankton die, settle to the bay bottom, and are
acting plants, animals, and microbes. Blue crabs, scallops, decomposed by bacteria, oxygen in the water is depleted (a
and fish such as giant sturgeon, striped bass, and shad thrived condition called hypoxia), which creates “dead zones” in the
in the bay. Nutrients carried to the bay by streams in its roughly bay. Grasses, oysters, and other immobile organisms perish in
168,000 km (64,000 mi ) watershed—the land area that dead zones when deprived of oxygen. Crabs, fish, and other CHAPTER 5 • Envi R onm E n TA l S y STE m S A nd E C o S y STE m E C ology
2
2
funnels water to the bay through rivers—nourished fields of mobile organisms are forced to flee to habitats where oxy-
underwater grasses that provided food and refuge to juvenile gen levels are higher, but they face smaller food supplies and
fish, shellfish, and crabs. Hundreds of millions of oysters kept increased predation pressure. Hypoxia, along with other human
the bay’s water clear by filtering nutrients and phytoplankton impacts on the Chesapeake Bay, cause it to be included on the
(microscopic photosynthetic algae, protists, and cyanobacteria Environmental Protection Agency’s list of highly polluted waters.
that drift near the surface) from the water column. Recent events in the Chesapeake have, at long last, given
Although oysters had been eaten locally for some time, reason for hope for the recovery of the Chesapeake Bay system.
the intensive harvest of bay oysters for export began in the The EPA agreed in 2010, for the first time in the region, to hold
1830s, and by the 1880s the bay boasted the world’s larg- bay states to strict pollutant “budgets” that aim to substantially
est oyster fishery. People flocked to the Chesapeake to work reduce inputs of nitrogen and phosphorus into the bay by 2025.
on oystering ships or in canneries, dockyards, and shipyards. Further, oyster restoration efforts are finally showing promise (see
Bayside towns prospered along with the oyster industry and The Science behind The STory, pp. 136–137) in the Chesapeake.
developed a unique maritime culture that defined the region. If these initiatives can begin to restore the bay to health, Deal
But by 2010 the bay’s oyster populations had been Island and other communities may again enjoy the prosperity
reduced to a mere 1% of their historical abundance, and the they once did on the scenic shores of the Chesapeake. 123

M05_WITH7428_05_SE_C05.indd 123 12/12/14 2:56 PM