96

under the new regulation schedule will consistently be

approximately 2 ft higher than they would have been under

the old regulation schedule. The estimated acrage of

seasonally drying marsh under the new regulation schedule

was therefore the difference between the new average high

and the new extreme low. The loss in wading bird feeding

habitat was calculated by subtracting the acreage of

seasonally drying marsh under the new regulation schedule

from the acreage of seasonally drying marsh under the

present regulation schedule. Areal estimates were adjusted

to be consistent with recent measurements of the present

size of the marsh by G. Pesnell (pers. comm.), based on

aerial photographs and vegetation transects.



 Field Study in Corkscrew Marsh and Mud Lake Pond

 Periodic quantitative sampling of fish and aquatic

invertebrates was carried out from June 1974 through

September 1975 at a site in the northeastern section of

Corkscrew Swamp Sanctuary, the property of the National

Audubon Society. Preliminary to the sampling, a

topographic survey was made of the study site. Previous

topographic work by a professional surveyor (L. L. Hampton,

pers. comm.) made it possible to relate elevations at the

study site to the surrounding area. Periodic measurements

of water levels in a well at the site (M. Duever, pers.

comm.) and at Lake Trafford (U. S. Department of Interior.

Geological Survey. 1975, 1976) allowed seasonal changes in