Chapter 16: Phytoplankton of the reservoirs of Central and North Patagonia

CASCO, M. A.,; LABOLLITA, H.A.; CANO, M.G

Freshwater phytoplankton from Argentina

Schweizerbartsche Verlagsbuchhandlung

Año: 2014; p. 293 - 307

The basins of the Limay, Neuquén, and Negro rivers comprise the greatest hydrographic system developed in its entirety in Argentina. The reservoirs constructed in this basin are distinguished by their numbers, dimensions and unitary system of management. Altogether 394 species were determined within the framework of environmental-monitoring programs carried out from 1977 to the present. Only 30 taxa were common to all the reservoirs; with Anabaena spp. (toxic complex), Ceratium hirundinella, Gymnodinium sp., Asterionella formosa, Aulacoseira ambigua var. ambigua f. spiralis, Aulacoseira pseudogranulata, Aulacoseira subarctica, and Stephanodiscus niagarae being included among the dominant taxa at some moment within the seasonal cycle. In the majority of the reservoirs the Chlorophyta were the group present in the highest numbers of species identified, while the Chrysophyta contributed the greatest percentage of taxa present. The Cyanobacteria have played a significant role. Two agendas for monitoring algal blooms were developed in the basin: (a) at one sampling station on the Limay River (near Arroyito Reservoir), (b) in the Mari Menuco reservoirs of the Neuquén River Anabaena spp. (toxic complex) was seen to exhibit the greatest abundance between the spring, the summer, and the beginning of the autumn. Another reservoir that has been the object of limnological investigations since 1990 is the Florentino Ameghino, situated within the eastern-central region on the Chubut River. The most abundant group identified there was the centric diatoms?principally Aulacoseira granulata, Stephanodiscus sp., and Cyclotella sp. The phytoplankton were composed of species characteristic of mesotrophic to eutrophic lakes.