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Document Type

Book Chapter

Department/Program

Virginia Institute of Marine Science

Editors

Gretchen Rupp and Michelle D. White

Publication Date

2004

Book Title

Fish Physiology, Toxicology, And Water Quality - Proceedings of the Seventh International Symposium, Tallinn, Estonia May 12-15, 2003

Publisher

U.S. Environmental Protection Agency

Series

EPA/600/R-04/049

Abstract

Development associated with human populations has led to the globalization of many environmental problems. In marine systems, the most serious of these problems are directly related to the process of eutrophication. The increased production of organic matter in these marine systems associated with eutrophication is the primary factor impacting species abundance and composition and dissolved oxygen budgets. Oxygen, which is essential to maintaining balance in ecosystem processes through its role in mediating microbial and metazoan activities, has declined to critically low levels in many systems, which has led to the development of hypoxia (<2 ml O2/l) and anoxia (0 ml O2/l). Currently, most oxygen depletion events are seasonal, but trends toward longer periods that could eventually lead to persistent hypoxic or anoxic conditions are emerging. Over the last 50 years, there has been an increase in the number of systems reporting problems associated with low dissolved oxygen. Currently there are over 100 hypoxic/anoxic areas around the globe, ranging in size from <1 km2 to 70000 km2, that exhibit a graded series of responses to oxygen depletion, ranging from no obvious change to mass mortality of bottom fauna. Ecosystems currently severely stressed by eutrophication induced hypoxia continue to be threatened with the loss of fisheries, loss of biodiversity, alteration of food webs, and simplification of energy flows.

A Global Perspective On The Effects Of Eutrophication And Hypoxia On Aquatic Biota And Water Quality

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