Spatiotemporal structuring factors in the Chironomidae larvae (Insecta: Diptera) assemblages of an ultraoligotrophic lake from northern Patagonia Andean range: implications for paleolimnological interpretations

Abstract

Chironomid larvae assemblages and their seasonal variations were analyzed in several substrate types from Lake Moreno Oeste (Northern Patagonia) in order to understand the spatiotemporal patterns controlling its community. Information on the factors structuring chironomid communities is important to understand their ecological aspects and to improve the interpretation of paleolimnological records based on the analyses of subfossil assemblages. The chironomid community of Lake Moreno Oeste exhibited spatial heterogeneity, with four distinctive groups of taxa associated with different substrate types: (1) macrophyte Myriophyllum sp. (mainly represented by Parapsectrocladius escondido, Parachironomus sp. and Apedilum griseistriatum); (2) submerged riparian leaves (Ablabesmyia sp.); (3) deep sediment (Cryptochironomus sp. and Polypedilum sp.2.); and (4) littoral and sublittoral sediment (Riethia truncatocaudata and Djalmabatista). Along the sampling period, significant seasonal changes in chironomid composition were observed in substrates from sublittoral and littoral zones; however, a relatively stable community was recorded in the deeper zone. In Lake Moreno Oeste, the spatiotemporal structure of chironomid larvae assemblages is mainly driven by the substrate type and environmental factors associated with depth, such as organic matter content, sediment granulometric composition, and dissolved oxygen. The results presented here contribute to our understanding of chironomid ecology in North Patagonia and constitute an essential step forward to improve biomonitoring and paleolimnological studies in lacustrine environments in the region.