Examination of Trophic Dynamics of the Mangrove Ecosystem in Port Everglades, Florida, USA, Using Stable Isotope Ratios

Mangrove communities are unique environments that line coastlines in tropical and subtropical latitudes. In Florida, four mangrove tree species dominate these communities and are accompanied by other primary producers, infaunal, epifaunal, and juvenile faunal species that together form the base of a complex, chiefly detritus-based food web. In an effort to evaluate mangrove communities in Port Everglades, Florida, tissue samples were taken from a diversity of mangrove- associated producer and consumer species from three mangrove sites. Stable carbon and nitrogen isotope ratios were used to establish patterns of energy flow of mangrove material, examine the influence of detrital material, and identify isotopic differences among mangrove species. R.mangle was the most depleted in δ13C, -34.11 to -26.19‰, while C.erectus was the most enriched, -29.91 to -25.30‰. This pattern mirrors the documented pattern of proximity to the waterline, but this pattern was not the same in δ15N, as C.erectus exhibited the narrowest range of δ15N values, -1.95 to 5.40‰. Significant differences were found in δ15N and δ13C signatures of the mangrove species among the tissue types, sampling sites, and trophic linkages among three sample sites, which could indicate differences between natural and anthropogenic influences, such as increased nitrate from a nearby residential area. Specifically, site 1, the only site located directly on the Intracoastal Waterway, differed significantly from sites 2 and 3, both of which were indirectly connected to the waterway. Results also established unique trophic levels, with primary producers at the bottom and carnivorous fish at the top. Slight differences among the trophic dynamics, such as a shift in diet specifically with fish species, among the sites revealed a possible influence of restricted tidal flow from mangrove communities