Utilization of the red mangrove prop root habitat by fishes in south Florida

The inherent difficulty of sampling the red mangrove prop root habitat has impeded our understanding of the utilization of this habitat by fishes. A block net and rotenone method was developed and used to sample 2 sites in each of 4 regions in Everglades National Park, Florida (USA). At each site a 3 mm mesh net was used to enclose 3 sides of a mangrove stand while an onshore berm formed the fourth side. Samples collected from the mangrove prop root environment were compared with samples collected using a 2-boat otter trawl in the immediately (8 to 10 m) adjacent, fringing seagrass habitat. The density and biomass of fish collected by the 2 gear were greater in the prop root habitat than in the adjacent fringing seagrass areas. There also were consistent differences in species composition between the 2 hab~tat types across all 4 geographic regions. Analysis of the stomach contents of gray snapper Lutjanus griseus suggested that smaller snapper tend to feed in the prop root habitat while larger snapper may forage out into adjacent areas to feed. The red mangrove prop root habitat is utilized by a wide variety of fish, and greater attention should be given to evaluating its contribution to fish production in south Florida and elsewhere.