A Comparison of the Fish Populations and Habitat in Open and Closed Salt Marsh Impoundments in East-Central Florida

Abstract

Historical and recent biological surveys Including aerial and ground level photo- graphs reveal gross changes In vegetation and fish habitat associated with impoundment and flooding of salt marshes bordering the Indian River lagoon in east-central Florida. These studies show a depauperate Ichthyofauna and floral association in impoundments excluded from estuarine tidal influence. Monthly collections of fishes made during 1979 and 1980 are used to compare two marsh Impoundments: one closed to tidal Influence from the Indian River lagoon and the other re- opened to tidal influence through a single 80 cm diameter culvert. The closed impoundment was found to contain a depauperate ichthyofauna consisting of 12 species collected under stressed environmental conditions. Water temperatures ranged from 14 to 34° C, salinities fluctuated widely from 2.0 to 200 ppt and dissolved oxygen was measured as low as 1.2 and as high as 14.2 ppm. The open Impoundment contained a far richer ichthyofauna with 41 fish species captured at temperatures of 13.5 to 30° C, salinities of 25 to 38 ppt and dissolved oxygen levels of 2.2 to 7.5 ppm. The open impoundment also demonstrated extensive regrowth of marsh vegetation