Some physical and biological factors affecting a spring-summer phytoplankton dynamics in a shallow, temperate lake of South Andes (Argentina)

QUEIMALIÑOS, CP

INTERNATIONAL REVIEW OF HYDROBIOLOGY

Wiley-VCH

Lugar: Weinheim; Año: 1997 vol. 82 p. 147 - 160

1434-2944

The phytoplankton dynamics of Laguna Ezquerra (Río Negro, Argentina) was analysed on the basis of high frequency sampling, each 3-4 days during a spring-summer period, in relation to physical factors and to the zooplankton community structure. The phytoplankton biomass presented a marked seasonality, accompanied by similar seasonal patterns in temperature and zooplankton dynamics. Community variations were reflected in the diversity, dominance and equitability values. The greatest change was associated during a short flooding period produced in late spring. The wind exposure was irregular during the whole study period, and was assumed to be a factor of stress for the phytoplankton growth. During spring and early summer, the phytoplankton community was dominated by nanoplanktonic forms like Rhodomonas lacustris, and the large sized Asterionella formosa presented an exponential increment at late summer. This Asterionella growth permitted to affirm that the community evolved towards plagioclimatic stages, attending the highly disturbed conditions of the shallow and wind exposed environment.