ZOOPLANKTON COMMUNITY AND PHYSICO-CHEMICAL PARAMETERS OF THE UNAMUNO SHALLOW POND DURING THE SPRING

EMILIO JAVIER GARIBOTTI; PATRICIA MARTA CERVELLINI; MARIA CINTITA PICCOLO

Archbold Biological Station, Lake Placid, Florida (EEUU)

Workshop; VI Global Lake Ecological Observatory Network Workshop; 2008

University of Wisconsin, Center of Limnology

The objective of the present work was to study the zooplanktonic community and the physicochemical parameters of the Unamuno shallow pond, located on the southwest of Buenos Aires Province. Zooplankton was studied in a qualitative and quantitative form, the limnological conditions of the biotope were analyzed and the water body was characterized on the basis of the presence of characteristic species. The approach of the field work was centered in collecting biological material from October to December, 2006 every 15 days. A sampling station was selected (Station 1), where "in situ" measurements of the physicochemical water properties were taken. Meteorological conditions were observed from a nearby weather station. Zooplankton was collected with a net of 200 µm. Seven species were determined: two cladocerans (Moina eugeniae and Alona diaphana), four copepods (Boeckella poopoensis, Metacyclops sp., Microcyclops sp. and Cletocamptus sp.) and a ciliated (Strombidium sp.). The density of total zooplankton for the lagoon was variable, alternating from 221 to 1703 ind/l. The most abundant species was Moina eugeniae (70 %) and marked the tendency of total zooplankton, it was followed by the calanoid copepod Boeckella poopoensis (27 %). Zooplankton shows large size and a high dominance index, with absence of planktonics rotifers. The specific diversity was 2.69 bits/ind and the equitability 0.96 that would indicate a strong dominance of few species. There were no thermal stratification for the study period and water temperatures oscillated between 16.3 and 23.2 ºC (average = 19.4 ºC). Salinity values characterized the lagoon as oligohalin, with low concentrations of nitrates and silicates and high concentrations of nitrites and phosphates. The dominant cation and anion were Na+ and CL- , respectively, being able to classify it like bicarbonate sodic chlorinated. It shows highs values of chlorophyll, which would indicate high primary productivity.