Diversity and abundance of littoral cladocerans and copepods in nine Ecuadorian highland lakes

Leticia E Torres,Kent Rylander

doi:10.15517/rbt.v54i1.13983

Abstract

The diversity and abundance of littoral cladocerans and copepods were studied in nine lakes at Reserva Ecológica Cayambe-Coca (Páramo de Guamaní), Ecuador. Six samples were taken in the littoral zone of each lake using a 500 microm mesh plankton conic net. One species of cladocerans (Ephemeroporus acanthoides) is reported for the first time in Ecuador. The diversity (H') and evenness (E) of the lakes were determined and correlated with PCA axes based on their environmental variables. The principal parameters that distinguished these lakes were altitude and pH, an unexpected finding considering that the altitudinal range was very small. Lake size is of secondary importance for this group of lakes. None of the environmental axes correlated with H' or E; nevertheless, a larger than expected species richness was found in a small oligotrophic lake with a high level of DO. Based on our results, we hypothesize that altitude and pH are important factors determining the zooplankton diversity (directly or indirectly) in highland lakes.

Highlights

The páramo, one of the various ecosystems in the northern Andean region, ranges in altitude between 3 200 and 4 700 m above the limit of Andean forests and below the limit of perpetual snow (Lauer 1979)
No studies on planktonic fauna of Ecuadorian high altitude lakes exist in spite of the importance of this group in the trophic chain of aquatic communities
The objectives of this study were to (a) survey the microcrustacean plankton fauna in the study area, (b) determine their diversity and abundance, and (c) attempt to determine the effect of environmental conditions on diversity

Summary

Introduction

The páramo, one of the various ecosystems in the northern Andean region, ranges in altitude between 3 200 and 4 700 m above the limit of Andean forests and below the limit of perpetual snow (Lauer 1979). The most notable studies of the ecology of plankton in high altitude Andean lakes occurred during the late seventies and eighties. They included surveys (Widmer et al 1975), preliminary studies of the relationship between zooplankton and environment (Colvinaux and Steinitz 1980), and preliminary assessment of the trophic relationships affecting the diversity of zooplankton (Hurlbert et al 1986). Most studies of freshwater ecosystems in the Ecuadorian páramos have focused on aquatic insects and their adaptation to lotic environmental variables. No studies on planktonic fauna of Ecuadorian high altitude lakes exist in spite of the importance of this group in the trophic chain of aquatic communities. The objectives of this study were to (a) survey the microcrustacean plankton fauna (cladocerans and copepods) in the study area, (b) determine their diversity and abundance, and (c) attempt to determine the effect of environmental conditions on diversity

Objectives

Methods

Results

Conclusion