Hypoxia in the Northern Gulf of Mexico

verfasst von: Virginia H. Dale, Donelson Wright, Catherine L. Kling, Walter Boynton, Judith L. Meyer, Kyle Mankin, James Sanders, James Opaluch, Daniel J. Conley, Holly Stallworth, William Crumpton, Hans Paerl, Thomas Armitage, Kenneth Reckhow, Mark David, Denis Gilbert, Andrew N. Sharpley, David Wangsness, Robert W. Howarth, Thomas W. Simpson, Thomas Bianchi, Alan Blumberg, Richard Lowrance, Clifford S. Snyder

Verlag: Springer New York

Buchreihe : Springer Series on Environmental Management

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

Since 1985, scientists have been documenting a hypoxic zone in the Gulf of Mexico each year. The hypoxic zone, an area of low dissolved oxygen that cannot s- port marine life, generally manifests itself in the spring. Since marine species either die or ee the hypoxic zone, the spread of hypoxia reduces the available habitat for marine species, which are important for the ecosystem as well as commercial and recreational shing in the Gulf. Since 2001, the hypoxic zone has averaged 2 1 16,500 km during its peak summer months , an area slightly larger than the state 2 2 of Connecticut, and ranged from a low of 8,500 km to a high of 22,000 km . To address the hypoxia problem, the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force (or Task Force) was formed to bring together represen- tives from federal agencies, states, and tribes to consider options for responding to hypoxia. The Task Force asked the White House Of ce of Science and Technology Policy to conduct a scienti c assessment of the causes and consequences of Gulf hypoxia through its Committee on Environment and Natural Resources (CENR).

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

Nutrient over-enrichment from anthropogenic sources is a major stressor of aquatic, estuarine, and marine ecosystems. Nutrients enter ecosystems through off-target migration of fertilizer from agricultural fields, golf courses, and lawns; disposal of animal manure; atmospheric deposition of nitrogen; erosion of soil containing nutrients; sewage treatment plant discharges; and other industrial discharges. Excessive nutrients promote nuisance blooms (excessive growth) of opportunistic bacteria, cyanobacteria, and algae. When the available nutrients in the water column have been sequestered in plant biomass, the nuisance blooms die, decompose, and deplete dissolved oxygen in the water column and at the sediment water interface. This oxygen depletion, known as hypoxia, occurs when normal dissolved oxygen concentrations in shallow coastal and estuarine systems decrease below the level required to support many estuarine and marine organisms (≤ 2 mg/L).

Virginia H. Dale, Walter Boynton, Catherine L. Kling, Daniel J. Conley, Judith L. Meyer, William Crumpton, James Sanders, Holly Stallworth, Mark David, Thomas Armitage, Denis Gilbert, David Wangsness, Thomas Bianchi, Robert W. Howarth, Alan Blumberg, Richard Lowrance, Kyle Mankin, Andrew N. Sharpley, James Opaluch, Thomas W. Simpson, Hans Paerl, Clifford S. Snyder, Kenneth Reckhow, Donelson Wright

Chapter 2. Characterization of Hypoxia

Abstract

The hypoxic region along the northern Gulf of Mexico (NGOM) extends up to 125 km offshore and to 60 m water depth, has substantial variability with an average midsummer areal extent of 16,500 km² (2001–2007), and extends in some years from the Mississippi River mouth westward to Texas coastal waters (Rabalais et al., 2007). This hypoxic region (Fig. 1.1) occurs along a relatively shallow, open coastline with complex circulation and water column structure typical of many coastal regions and includes massive inputs of freshwater, weak tidal energies, seasonally varying stratification strength, generally high water temperature, wind effects from both frontal weather systems and hurricanes, and mixing of river plumes from the Atchafalaya and Mississippi Rivers and other smaller sources (DiMarco et al., 2006; Hetland and DiMarco, 2007).

Chapter 3. Nutrient Fate, Transport, and Sources

Abstract

The Study Group was asked to review the available literature and information, especially that developed since 2000, that would allow them to assess any changes and improvements in the understanding of nutrient sources and flux estimates within the Mississippi and Atchafalaya River basins (MARB) (see Fig. Fig 1.2) and the current ability to use watershed models to route and predict nutrient delivery to the Gulf of Mexico. The following sections discuss the current levels of understanding and provide brief summaries of the Study Group’s key findings and recommendations.

Chapter 4. Scientific Basis for Goals and Management Options

Abstract

Adaptive management offers a way to address the pressing need to take steps to manage for factors affecting hypoxia in the NGOM in the face of uncertainties. The authors of a recent study undertaken by the National Research Council of the National Academy of Sciences identified six elements of adaptive management that are directly relevant to goal setting and research needs (National Research Council, 2004): (1) resources of concern are clearly defined; (2) conceptual models are developed during planning and assessment; (3) management questions are formulated as testable hypotheses to guide inquiry; (4) management actions are treated like experiments that test hypotheses to answer questions and provide future management guidance; (5) ongoing monitoring and evaluation is necessary to improve accuracy and completeness of knowledge; and (6) management actions are revised with new cycles of learning.

Chapter 5. Summary of Findings and Recommendations

Abstract

This book responds to questions in three general areas: characterization of hypoxia; characterization of nutrient fate, transport and sources; and the scientific basis for goals and management options. In the sections below, these questions (shown in italics below) are addressed very briefly with references to those sections of this book where more detailed science on that particular question may be found.

Backmatter

Titel: Hypoxia in the Northern Gulf of Mexico
verfasst von: Virginia H. Dale
Donelson Wright
Catherine L. Kling
Walter Boynton
Judith L. Meyer
Kyle Mankin
James Sanders
James Opaluch
Daniel J. Conley
Holly Stallworth
William Crumpton
Hans Paerl
Thomas Armitage
Kenneth Reckhow
Mark David
Denis Gilbert
Andrew N. Sharpley
David Wangsness
Robert W. Howarth
Thomas W. Simpson
Thomas Bianchi
Alan Blumberg
Richard Lowrance
Clifford S. Snyder
Verlag: Springer New York
Electronic ISBN: 978-0-387-89686-1
Print ISBN: 978-0-387-89685-4
DOI: https://doi.org/10.1007/978-0-387-89686-1