Page:Popular Science Monthly Volume 20.djvu/157

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THE

POPULAR SCIENCE

MONTHLY.

 

DECEMBER, 1881.


 

DETERIORATION OF AMERICAN OYSTER-BEDS.
By Lieutenant FRANCIS WINSLOW.
II.

AN oyster-bed, in its natural and undisturbed state, consists of a long, narrow ridge of shells and oysters, lying generally in brackish water, on and surrounded by sticky bottoms, a mixture similar to clay and mud being the most favorable.

The form and area of the bed are variable, but, naturally, the length is greater than the breadth, and the greatest dimension is usually in the direction of the current. The bed itself is made up of masses of shells and oysters, covering areas of different sizes, and separated from each other by mud or sand-sloughs, though frequently it is unbroken, and the animals spread evenly and continuously over the entire area. This separation and detachment of the groups of animals are much more noticeable upon a bed which has been much worked. Upon an unworked bed, or one in its natural state, the oysters grow in clusters, and are firmly cemented to the bottom. Upon a bed which has been frequently dredged, the animals are single, and have no hold upon the bottom.

The fauna of the bed varies with the locality; in the Chesapeake it is somewhat sparse.

The bottom is usually of clay or mud, and of sufficient consistency to support the oysters; certain varieties of bottom are more favorable than others, but, except within wide limits, the character of the bottom does not appear to be of great importance, so long as it is sufficiently firm to prevent the animal from sinking into it and thus smothering.

The oyster thrives best in slightly brackish water, and the finest varieties are usually found in water of a lower specific gravity than