Catastrophic anoxia in the Chesapeake Bay in 1984
In 1984, four climatic sequences combined to produce what may be a major anoxic catastrophe in the northern Chesapeake Bay, sufficient to severely threaten the major benthic species. These sequences are (1) the highest late-winter streamflow on record from the Susquehanna River watershed; (2) streamflows from the Susquehanna River for the consecutive months of June, July, and August that are higher by 2 standard deviations than the respective monthly mean values measured over the last 34 years; (3) a stationary high in August off the Atlantic Coast; and (4) an absence of strong storm events in summer. An empirical equation is proposed for the prediction of the monthly trend of dissolved oxygen decrease in terms of a temperature-dependent subpycnoclinal respiration and a modified estuarine Richardson number. As of 23 August 1984, the summer pycnocline of the northern bay had eroded upward from its historically recorded depth below 10 meters to an abnormally shallow 5 meters, with higher stratification than in earlier years. Dissolved oxygen concentrations directly below the pycnocline decreased to zero during June, 2 months earlier than for previous wet years. At present, oxygen-deficient waters containing significant concentrations of hydrogen sulfide have penetrated into Eastern Bay and the Choptank and Potomac rivers. Because most remaining shellfish-spawning and seed-bed areas in these tributaries are located at depths between 4 and 8 meters, the continued absence of major destratifying events will prolong the present anoxic trend and may result in high benthic mortalities. 11 references, 2 figures.
- Research Organization:
- Johns Hopkins Univ., Baltimore, MD
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5883315
- Journal Information:
- Science (Washington, D.C.); (United States), Vol. 228:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BENTHOS
MORTALITY
CHESAPEAKE BAY
ANOXIA
CLIMATES
EQUATIONS
FORECASTING
HYDROGEN SULFIDES
MIXING
MOLLUSCS
RESPIRATION
STORMS
SUSQUEHANNA RIVER
TEMPERATURE DEPENDENCE
WATERSHEDS
ANIMALS
AQUATIC ORGANISMS
ATLANTIC OCEAN
BAYS
CHALCOGENIDES
DISASTERS
HYDROGEN COMPOUNDS
INVERTEBRATES
RIVERS
SEAS
STREAMS
SULFIDES
SULFUR COMPOUNDS
SURFACE WATERS
520200* - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)
560304 - Chemicals Metabolism & Toxicology- Invertebrates- (-1987)