Chironomids community along Salix sp gradient in a stream of NW Patagonia

MONTES DE OCA, F.; MASSAFERRO, J.; BLACKHALL, M.; FRANSEZE, J.; RELVA, MA.

Esquel

Congreso; 9Congreso Argentino de Limnologia; 2020

Sociedad Argentina de Limnologia

Chironomids community along Salix sp gradient in a stream of NW Patagonia. Preliminary results.Montes de Oca. F (1); Massaferro, J (1); Blackhall, M (2).; Franceze, J (2). & Relva, A (2).(1) CENAC-Programa de estudios aplicados a la conservación del Parque Nacional Nahuel Huapi. montesdeocafernanda@gmail.com(2) INIBIOMA-Instituto de investigaciones en biodiversidad y medioambiente; (CONICET-UNComa)Spatial distribution of chironomids reflected morphological and trophic characters to particular environmental conditions.Chironomid (Insecta:Diptera) larvae from Chacabuco Stream, a lotic system located in the northern Patagonia steppe, was analyzed between December 2018 and March 2021. Samples were collected yearly during two hydrological (seasonal) periods: low water (spring) and high water (summer) periods. Four sites were selected for sampling: two, located in a disturbed area composed by non-native plants (mainly Salix sp) and two, located in an area surrounded by native species (Nothofagus antarctica, Discaria chacaye). Taxonomical and functional chironomid diversity was examined and compared at different levels: between sites and between seasonal periods. Limnological and climatic variables were also analyzed and were used to investigate potential drivers of the faunal composition. Benthic invertebrate communities was analysed to observe whether there were differences in aquatic insect community structure at spatial and temporal scales. The results show that the abundance and diversity of chironomids were higher during the summer or high water period. The group of chironomids belonging to ?collectors? such as Parapsectrocladius (in part), Tanitarsini and Chironomus feeding group were the dominant in the Salix plots. In contrast, ?scrapers? such us Stictocladius and Psectocladius, ?collectors-gatherers? such as Orthocladius sp, and Smittia and ?collectors-filterers? Parapsectrocladius were the feeding groups observed in native vegetation plots. These results show that the structure of native plants of the riparian areas provide particular microhabitat diversification, light conditions, organic matter supply, and other conditions, (related to the structure of the stream bed, patterns of river flow) (work in progress), which favors periphyton growth. Consequently, the appearance of other feeding groups such as scrapers, collectors-gatherers, collectors-filterers, and predators and a high chironomid taxa number. In contrast, plots with the presence almost exclusive of Salix spp. showed a severe reduction of light conditions leading to a poor substrate for algal growth and impoverishing the general fauna abundance and diversification.Palabras clave: Salix spp., Chironomids, northern Patagonia, ?Área temática: Impactos antrópicos / usos de la tierra, Ambientes acuáticos urbanosModo de presentación*: póster¿Solicita beca? NO