Freshwater Marshes

by

Dr. Paul Keddy

Introduction

Wetlands are produced by flooding, and as a consequence, have distinctive soils, microorganisms, plants, and animals. The soils are usually anoxic or hypoxic, as water contains less oxygen than air, and any oxygen that is dissolved in the water is rapidly consumed by soil micro- organisms. Vast numbers of microorganisms, particularly bacteria, thrive under the wet and hypoxic conditions found in marsh soils. These microbes transform elements including nitrogen, phosphorus, and sulfur among different chemical states. Therefore, wetlands are closely connected to major biogeochemical cycles. The plants in wetlands often have hollow stems to permit movement of atmospheric oxygen downward into their rhizomes and roots. Many species of animals are adapted to living in shallow water, and in habitats that frequently flood. Some of these are small invertebrates (e.g., plankton, shrimp, and clams), while others are larger and more conspicuous (fish, salamanders, frogs, turtles, snakes, alligators, birds, and mammals). (Extracted from: Keddy, P. 2008. Freshwater marshes. p. 1690-1697 in S. E. Jørgensen and B.D. Fath (editor-in-chief), Ecosystems. Vol. 2 of Encyclopedia of Ecology. Elsevier, Oxford, UK.)

To read the complete article on Freshwater marshes. including discussions on the six types of wetlands, the distribution of marshes, plant and animal diversity in wetlands, and much more, click here.