Comparison of emergence and taxonomic composition of chironomidae (Insecta: diptera) in Tortuguero National Park, Costa Rica.

Abstract

Traditional methods of collecting aquatic macroinvertebrates can be time consuming and expensive. One efficient form of sampling involves collection of surface floating pupal exuviae (SFPE) of a group of aquatic flies of the family Chironomidae. Previous studies have shown the efficacy of the SFPE collection technique to determine chironomid taxonomic composition and temporal organization in small streams of northwestern Costa Rica. However, the methodology has never been employed in a Neotropical brackish water setting and its efficacy was unknown in this context. The primary goal of this study was to test the SFPE method in a Neotropical brackish water setting and to expand the knowledge base of chironomid taxonomy and ecology in Costa Rica. The objectives of this research were to determine the economy of the SFPE method for studies in Neotropical brackish waters and the variability of Chironomidae emergence and taxonomic composition. Collections of chironomid SFPE were made in the brackish water estuary, Laguna del Tortuguero, and freshwater stream, Quebrada, in Tortuguero National Park, Costa Rica on seven consecutive days during both the dry and wet seasons. The SFPE method appears to be a reasonably economical method for sampling Chironomidae in Neotropical brackish waters and it is successful in detecting spatial differences in emergence between sites in the dry and wet season. The results indicate that Chironomidae SFPE sampling could be employed as part of a rapid biomonitoring program for monitoring water and sediment quality in Tortuguero National Park, Costa Rica. Generally, these data will expand the knowledge base of Neotropical Chironomidae taxonomy and ecology, which will facilitate entomological and aquatic ecology research and teaching in Latin America.