Browsing by Author "Wiseman, William J., Jr."
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Item Characterization of Hypoxia(NOAA Coastal Ocean Program, 1999-05) Rabalais, Nancy N.; Turner, R. Eugene; Justic, Dubravko; Dortch, Quay; Wiseman, William J., Jr.Nutrient overenrichment from human activities is one of the major stresses affecting coastal ecosytems. There is increasing concern in many areas around the world that an oversupply of nutrients from multiple sources is having pervasive ecological effects on shallow coastal and estuarine areas. These effects include reduced light penetration, loss of aquatic habitat, harmful algal blooms, a decrease in dissolved oxygen (or hypoxia), and impacts on living resources. The largest zone of oxygen-depleted coastal waters in the United States, and the entire western Atlantic Ocean, is found in the northern Gulf of Mexico on the Louisiana-Texas continental shelf. This zone is influenced by the freshwater discharge and nutrient flux of the Mississippi River system. This report describes the seasonal, interannual, long-term variability in hypoxia in the northern Gulf of Mexico and its relationship to nutrient loading. It also documents the relative roles of natural and human-induced factors in determining the size and duration of the hypoxic zone.Item Effects of Reducing Nutrient Loads to Surface Waters within the Mississippi River Basin and the Gulf of Mexico(National Oceanic and Atmospheric Administration National Ocean Service Coastal Ocean Program, 1999-05) Brezonik, Patrick L.; Bierman, Victor J., Jr.; Alexander, Richard; Anderson, James; Barko, John; Dortch, Mark; Hatch, Lorin; Hitchcock, Gary L.; Keeney, Dennis; Mulla, David; Smith, Val; Walker, Clive; Whitledge, Terry; Wiseman, William J., Jr.The overall goal of this assessment was to evaluate the effects of nutrient-source reductions that may be implemented in the Mississippi River Basin (MRB) to reduce the problem of low oxygen conditions (hypoxia) in the nearshore Gulf of Mexico. Such source reductions would affet the quality of surface waters-streams, rivers, and reservoirs-in the drainage basin itself, as well as nearshore Gulf waters. The task group's work was divided into addressing the effects of nutrient-source reductions on: (1) surface waters in the MRB and (2) hypoxia in the Gulf of Mexico.Item Nutrient Enhanced Coastal Ocean Productivity in the Northern Gulf of Mexico - Understanding the Effects of Nutrients on a Coastal Ecosystem(National Oceanic and Atmospheric Administration National Ocean Service, 1999-04) Wiseman, William J., Jr.; Rabalais, Nancy N.; Dagg, Michael J.; Whitledge, Terry E.This publication is a synthesis of the findings and management implications of research sponsored by the National Oceanic and Atmospheric Administration's (NOAA) Coastal Ocean Program (COP) through its Nutrient Enhanced Coastal Ocean Productivity (NECOP) study. Enhanced nutrient enrichment from anthropogenic sources is one of the major stresses imposed on the sea. This is particularly true in the northern Gulf of Mexico where the nation's largest river discharges into an otherwise oligotrophic sea. This report contains six chapters devoted to syntheses of specific topics important to understanding the oceanography of the area and the cumulative impact of river-borne nutrients on the coastal ecosystem.