AQUATIC INSECT DIVERSITY AND SEASONALITY OF THE LOWER YASUNI NATIONAL RESERVE OF THE ECUADORIAN AMAZON

K. Galacatos¹ and R. Barriga-Salazar². ¹Department of Environmental and Forest Biology, S. U. N. Y. - E. S. F. , Syracuse, NY 13210, ²Escuela Politecnica Nacional, Quito, Ecuador

Aquatic insect diversity and seasonality were studied in blackwater habitats of the lower Yasuni National Reserve of the Ecuadorian Amazon. Floating macrophytes within lagoon and river habitats and two forest streams were sampled with an aquatic dip net with 1000 micron mesh during the dry, transitional and wet seasons in 1996 and 1997. Specimens were preserved in 70% ethanol, identified to morpho-species and characterized into functional feeding groups. 2,859 individuals from 37 families representing 85 morpho-species were collected.

The aquatic insects of the lower Yasuni were characterized by habitat and seasonal variability. Species richness and abundance were higher within floating macrophyte than in forest stream habitats. Floating macrophyte and forest stream habitats shared 8% of morpho-species. Lagoon and riverine floating macrophyte habitats had 37% morpho-species similarity throughout all seasons. Within the forest stream habitats 29% morpho-species similarity occurred between the dry season samples and all other seasons. The percent of total individuals within functional feeding groups varied little among habitats and seasons. Predators dominated throughout the three seasons in all but two samples where collector-gatherers were dominant. Collector-gatherers dominated in the blackwater riverine floating macrophytes during the transitional season and one blackwater stream during the dry season.