Excerpt:

"INTRODUCTION

Strictly speaking an estuary is a partially enclosed body of water in which fresh water from a river or stream mixes with the salt water of the sea . Most of the well-known estuaries are located at the mouths of major rivers. Yet, the greater number of estuaries are found where numerous small rivers or streams flow into a bay or inlet. Much of the fresh water flowing into these estuaries may seep into the bay or inlet as ground water. The importance of an estuary is related to its size, the quantity of fresh water pouring into it, the degree to which it is enclosed and its location relative to major cities.

Estuaries provide habitats for countless organisms. The fresh water carries nutrients that are flushed from the watershed. The sea water carries marine nutrients. Where the two waters mix, a unique habitat is formed in which organisms are supported by nutrients from both sources. Estuaries may support a remarkable abundance of life, from microscopic algae to fish, wildfowl and mammals. The large quantities of organisms in the food web of an estuary result in complicated dependencies among life forms. This balance can easily be disturbed by human interference through development, dredging and recreational use of estuaries.

The abundance and diversity of organisms in an estuary is partly a result of the quantity of nutrients available. However, this profusion of life forms reflects the enormous variety of estuarine conditions as well. For instance, many life forms thrive because of the complex mixtures of salt and fresh water. In addition to the gradients of salt and other minerals, other gradients involve the respective temperatures and the degree to which light can be transmitted through the two types of water."

Information about the resource can be found at:
ANKN Clearinghouse
P.O. Box 756730
Fairbanks, AK 99775-6730

Tel: (907) 474-5897
or email: ANKN Clearinghouse

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