HR: 1330h
AN: NB33Q-09    [Abstracts]
TI: Importance of Riverine Energy Sources in Puerto Rican Estuaries
AU: * Smith, K L
EM: smithkat@uga.edu
AF: Institute of Ecology, University of Georgia, Ecology Building University of Georgia, Athens, GA 30602 United States
AU: Pringle, C M
EM: cpringle@uga.edu
AF: Institute of Ecology, University of Georgia, Ecology Building University of Georgia, Athens, GA 30602 United States
AU: Rodriguez Del Rey, Z
EM: zrodrig1@uno.edu
AF: University of New Orleans, 2000 Lakeshore Drive , New Orleans, LA 70148
AB: Studies conducted in temperate, deltaic systems suggest that freshwater energy sources contribute little to estuarine food webs. In contrast, small, riverine estuaries draining mountainous tropical islands may be more dependent on freshwater energy sources than temperate deltaic systems, due to differences in landscape characteristics. We used two methods to evaluate the importance of freshwater energy sources to fishes in two Puerto Rican estuaries. We used stable isotopes (C, N, S) to evaluate the relative importance of freshwater organic matter, estuarine primary producers, and mangroves to fishes and other estuarine macroconsumers. We also analyzed gut contents of fishes collected for stable isotope analyses. Preliminary carbon isotope data suggest that local production of phytoplankton and benthic microalgae provides the primary organic matter source for estuarine fishes. These results, however, appear inconsistent with gut content analyses which contained few benthic organisms. Gut contents of omnivorous fishes were dominated by pelagic larval fishes and larvae of amphidromous freshwater shrimps (found in estuarine pelagic littoral zones). Sulfur isotope data will further distinguish between primary producers supporting these estuarine food webs and may explain discrepancies between carbon isotopes and gut contents. This study emphasizes the importance of using multiple methods for ecosystem level food web analyses.
DE: 4235 Estuarine processes
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly