: Seasonal zooplankton dynamics and its relations with environmental factors in Dalcar Urban Lake (Córdoba, Argentina)

Abstract

Seasonal zooplankton dynamics and its relations with environmental factors in Dalcar Urban Lake (Córdoba, Argentina). Urban lakes are frequently used for recreation and tourism, in addition to their aesthetic value. They are also important as a refuge for biodiversity. They are generally small and shallow, so they are strongly influenced by human activities. In Argentina, the ecology of urban lakes has not received much attention. The objective of this study was to identify the zooplankton and their relationships with environmental parameters in Dalcar (33° 06'S; 64° 22'W), an artificial lake of Río Cuarto City (Córdoba province). Seasonal samples were taken in 2017, when the lake had partial coverage of macrophytes and abundance of fish. The pH and conductivity were 8.97 (±0.19) and 0.81 mS/cm (±0.06), respectively. The water transparency was 0.72 m (±0.25), and the trophic status index was 64.73. Eight cladocerans, 3 copepods, and 25 rotifers were recorded. This high richness could be due to the reduced salinity, the presence of species associated with macrophytes and to the protection provided by these against predation. The dominance of rotifers, especially of the genera Brachionus, Keratella, and Lecane and the presence of cladocerans, such as Moina micrura and Bosmina longirostris are indicators of high trophic level. The zooplankton density was lower than that of other urban lakes in Central Argentina. Since Dalcar's zooplankton is dominated by small organisms and predation would prevent large species with high grazing rates from thriving, in absence of any event that modifies the current characteristics of the lake, the influence of zooplankton on the amount of phytoplankton and water transparency is not expected to change.