Dinámica estacional de la comunidad de rotíferos en la Laguna de Chascomús. Empleando un Modelo Vectorial Autorregresivo (VAR)

DIOVISALVI, N; SALCEDO ECHEVERRY, G.E.; ZAGARESE, H. E.

Lujan

Congreso; 8vo Congreso Latinoamericano de Biomatemática; 2013

Temperate shallow lakes experience strong seasonal and inter-annual va- riability in environmental conditions and biological variables. In eutrophic systems with large populations of planktivorous sh, the zooplankton com- munity is typically dominated by rotifers. Here, we studied temporal uc- tuation in zooplankton community in a highly eutrophic shallow-lake, La- guna Chascomús, during four years (2005-2009). Emphasis was given to the dynamics of rotifers as affected by environmental conditions and food avai- lability. The zooplankton community was composed mainly by rotifers and the cyclopoid copepod Acanthocyclops robustus. Rotifers were dominated by Brachionus caudatus, B. havanaensis and Keratella tropica. The abundance of K. tropica and that of A. robustus did not displayed signs of seasonality. In contrast, the abundance of the two dominant Brachionus reached maxi- mum values on late summer and early autumn. A prolonged period of low water temperature resulted in a massive sh winterkill event (winter 2007), which purportedly allowed the development of unusually dense populations of the cladocerans Moina micrura and Bosmina huaronensis. We used vector autoregressive models (VAR) to analyze the rotifer time series. The model accounted for 76% of the variance in rotifer abundance and provided evi- dence for their dependence on temperature and Chlorophyll a. In addition, the impact of the sh winterkill on total rotifer abundance could be asses- sed through intervention analysis. The evidence collected here suggests that zooplankton community structure is controlled by sh planktivory (i.e., top- down), while rotifers´ population dynamics were mostly driven by tempera- ture and available food (bottom-up). Both processes seem highly responsive to forcing weather variables.