request of local government agencies, studies on biological
and engineering aspects of the proposed airport were made

(Tabb and Michel, 19689 Michel, 1970). These reports con-

tain information on the distribution of the major organism

in the area and on the importance of the existing unique

tidal and current regimes to the sustenance of the Lagoon.

Michel (1970) presents data on salinity distributions, tidal

cycles, and flushing rates of the Lagoon and proposes engi-

neering structures to be incorporated into the proposed runway

designs to maintain the critical water flow. Additional hydro-

graphic data are contained in Dammann (1970).

Description of the Study Area

 The study was conducted in Benner Bay and Mangrove

 Lagoon to the west. The area is on the southeast coast of

 St. Thomas (Figure 1) and is open to the Caribbean Sea on

 the south. Field work was confined to the area bounded by
 Patricia and Cas Cays on the south and Coculus Rocks on the

 east. Sampling stations are shown in Figure 3. Bovoni and

 Patricia Cays, as well as the low land to the north and west

 of the Lagoon are alluvial material (Donnelly & Whetten, 1968)

 deposited by the Turpentine Run gut. This stream is pre-

 sently the largest surface water producer remaining on
 St. Thomas. Although it now runs into the Lagoon only after

very heavy rains, that portion of it below Mt. Zion, and


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