Historical Zooplankton Composition Indicates Eutrophication Stages in a Neotropical Aquatic System: The Case of Lake Amatitlán, Central America

Abstract

This paper presents a study of freshwater zooplankton biodiversity, deemed as a reliable indicator of water quality. The Guatemalan Lake Amatitlán, currently used as a water source, has shown signs of progressive eutrophication, with perceptible variations of the local zooplankton diversity. Biotic and abiotic parameters were determined at four sites of Lake Amatitlán (Este Centro, Oeste Centro, Bahía Playa de Oro, and Michatoya) in 2016 and 2017. The local composition, the species richness and abundance of zooplankton, and the system environmental parameters were analyzed during both years surveyed. Biological data suggesting eutrophication of this tropical system were obtained, including a high rotifer abundance (11 species: the rotifers Brachionushavanaensis (109 ind L−1) and Keratellaamericana (304 ind L−1) were the most abundant species in this lake). The presumably endemic diaptomid copepod species, Mastigodiaptomusamatitlanensis, was absent in our samples, but we report the unprecedented occurrence of two Asian cyclopoid copepods (i.e., Thermocyclopscrassus and Mesocyclops thermocyclopoides) for Lake Amatitlán and Guatemala. The presence of larger zooplankters like adults and immature copepods (i.e., Arctodiaptomusdorsalis) and cladocerans (Ceriodaphnia sp.) at site “Este Centro” indicates a relatively healthy zooplankton community and represents a focal point for managing the conservation of this lake.