Relative abundance and temporal variation of macroinvertebrates in a Venezuelan cloud forest habitat

Abstract

Tree-hole phytotelmata encompass the internodal water pools that form in many species of bamboo (Gramineae). Using bamboo traps, we sampled macroinverte-brate communities in a habitat within the subtropical cloud forest of Henri Pittier National Park, Rancho Grande, north-central Venezuela, and quantified the temporal differences in their abundance and composition. In total, 1024 invertebrates were collected during the 7 months between February and August 2008. The insect orders Diptera and Coleoptera were abundant, particularly Culex (Anoedioporpa) conservator Dyar & Knab, Culex (Culex) mollis (Dyar & Knab), Wyeomyia (Wyeomyia) arthrostigma (Lutz) and Toxorhynchites (Lynchiella) theobaldi (Dyar & Knab). The traps also contained predators, detritivores and collectors (filtering and gathering). Macroinvertebrate abundance in the traps was higher during the rainy season. This observation was attributed to a greater abundance of Ephydridae, Blattaria and Culicidae during wetter months, and an increased availability of potential new breeding sites in the environment, which resulted in increased adult eclosion, and higher rates of oviposition in the bamboo traps. Temporal differences in pH and dissolved oxygen levels of trap water were observed.