. Inter-annual and habitat variation of the mayfly assemblage in grassland and pine afforested headwater streams (Córdoba, Central Argentina)

PRINCIPE R E; MONTILLA V.; MARQUEZ J. A.

Conferencia; International Conference on Ephemeroptera and XXI International Symposium on Plecoptera.; 2022

Mayflies are widely used as indicators of stream condition since their presence and abundance are closely associated with changes in environmental characteristics. We aim to analyze richness and abundance patterns of mayflies in headwater streams of the Ctalamochita river basin in central Argentina. In this region, some sub-basins have been fully afforested with exotic pines which may alter distribution of instream mayfly larvae. We sampled 3 grassland streams and 3 pine afforested streams in 2008, 2012, 2014 and 2015. We took surber samples in riffles and in 2012 we also sampled 2 additional habitats: pools and macrophyte patches. We found 9 mayfly genera. Americabaetis sp. were the most frequent and abundant and Cloeodes sp., Farrodes sp. and Tricorythodes sp. were the lest ones, with a relative frequency < 3%. Richness and abundance was higher in grassland streams (ANOVA, p < 0.05), but the abundance pattern of the different mayfly genera varied. In 2012 mayfly abundance was higher in pools and macrophytes in the afforested streams (ANOVA, p < 0.05), but it was similar among habitats in grassland streams. Americabaetis sp. dominate in macrophyte patches and Baetodes sp. and Nanomis sp. in riffles. Caenis sp. dominated in pools but it was also abundant in macrophytes in the afforested streams. Leptohyphes sp. dominates in riffles but it was also abundant in macrophytes in the grassland streams. Callibaetis sp. were only found in grassland streams in pools and macrophyte patches. Distribution patterns are influenced by microhabitat characteristics which may be conditioned by changes in riparian land uses.