Tuesday, May 27, 2008
198

Reference condition approach to assess tropical island streams integrity

Pablo J. Hernandez-Garcia, Biology, University of Puerto Rico, Río Piedras Campus, P.O. Box 21910, San Juan, PR 00931 and Luis A. Ramirez, Biology, University of Puerto Rico- Rio Piedras Institute for Tropical Ecosystems Studies, PO Box 21910, San Juan, PR 00931.

Bioassessment methods had been developed to evaluate and monitor water quality for over a century.  However, limited information is available on their applicability and performance to evaluate tropical streams.  The Reference Condition Approach (RCA) is a promising tool to assess tropical stream integrity, as it does not require information about the life history of aquatic fauna.  Our overall objective is to assess the potential applicability of the RCA concept to Puerto Rico.  Here, we assessed spatial variability in macroinvertebrate communities and its implications for establishing reference conditions for streams in Puerto Rico.  Samples were collected from forested streams of similar size at three elevations (<250m, 250-500m, >500m), and located in watersheds with and without migratory barriers (e.g. dams, waterfalls).  Macroinvertebrates were collected during the dry season from riffle micro-habitats (e.g., leaves, wood, cobbles). In addition, water physicochemistry was characterized at each site.  We found few significant differences among macroinvertebrate communities at the different elevations.  In contrast, streams in watersheds with migratory barriers presented higher abundance of insects than streams in watersheds without migratory barriers.  Overall, our study shows that the RCA can be applied to Puerto Rico by establishing different reference conditions for streams with and without migratory barriers.


Web Page: Bioassessment, tropical island streams, Puerto Rico

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