HR: 10:30h
AN: NB12A-01 INVITED     [Abstracts]
TI: NABS Plenary: Shifts in River Dynamics Translate to Shifts in Coastal Ecosystems
AU: * Rabalais, N N
EM: nrabalais@lumcon.edu
AF: Louisiana Universities Marine Consortium, 8124 Hwy. 56, Chauvin, LA 70344 United States
AB: Certainly the Mississippi River is not what it was in the early 1800s when settlers crossed the expanse of the continent. The locks, dams and reservoirs along its tributaries have changed the quantity and quality of flow and its constituents. Humans have altered the landscape, river channel and flood plain. Pollutants and contaminants are added along the way. The recipient of the changed effluent is the northern Gulf of Mexico. As the river and the processing of materials along the transit have changed, so has the adjacent continental shelf ecosystem. There the long-evolved ecosystem is subject to different hydrology, somewhat in amount and certainly in frequency, altered nutrient loads, and altered sediment loads. The gradual changes over the last century and a half and acceleration of change in the watershed in the last half of the 20th century are paralleled by similar changes in the coastal ecosystem adjacent to the river effluents. Basic shifts have occurred in the ecosystem from the primary production base and its composition and subsequently through the trophic structure to the fisheries. Eutrophication has resulted, and widespread, severe seasonal hypoxia is now present on the continental shelf where all indicators point to its absence historically.
DE: 4834 Hypoxic environments
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly