Life history and emergence patterns of stonefly species in mountain streams of the Futaleufú basin, Patagonia (Argentina)

The temporal dynamics in density, life histories, and emergence patterns were described for the first time for five Plecoptera species in tributaries of the Futaleufú River in Patagonia, Argentina. Benthic samples and adult collections were made in five low order Nothofagus forested streams. Four species of Gripopterygidae; Aubertoperla illiesi, Notoperlopsis femina, Antarctoperla michaelseni and Senzilloides panguipulli had simple, highly synchronized univoltine life histories. The austroperlid Klapopteryx kuscheli takes more than two years to develop. Emergence periods of most of the species were concentrated in late spring and summer (October to February), which suggests seasonal and synchronized life histories. Most N. femina adults were collected in mid spring indicating this species emerged first, whereas S. panguipulli emerged last from January to April. Aubertoperla illiesi showed a slightly delayed emergence at the high elevation site (La Hoya Stream) when compared to a piedmont stream, suggesting that temperature was an important control. Although we were unable to describe the life history of Limnoperla jaffueli (Gripopterygidae) its adult emergence period was November to January. Life histories of Plecoptera species in the studied streams seem to have a high degree of seasonality at least at this latitude, and are possibly determined by predictable temperature patterns and discharge regimes. This first contribution on the life histories of Plecoptera species helps us to better understand the dynamics and functioning of pristine but fragile aquatic environments in Patagonia