DRIFT PATTERNS IN COSTA RICA STREAMS (a preliminary report)

Abstract

Tropical streams are not as well characterized as temperate streams. The types of benthic organisms and their abundances may or may not be different from temperate systems (COVICH 1988, FLOWERS 1991). Many more studies will have to be done to understand ecological principals and to answer the question of A whether tropical waters are more diverse than temperate ones. Drift behavior of aquatic invertebrates in tropical streams has achieved little attention in the last few years. Several studies from temperate (e.g. KOHLER & McPEEK 1989, FORRESTER 1992 unpubl.) and also from tropical streams (TURCOTTE & HARPER 1982, FLECKER 1992) show that drift behavior depends on presence or absence of predators and different types of predator communities (e.g. invertebrates, fish). Objective of this study is to evaluate factors effecting drift densities in low order tropical streams.