THE BENTHIC OSTRACODS OF THE OJO DE AGUA URIBURU SALINE LAKE (LA PAMPA, ARGENTINA)

KIHN, ROMINA G.; VIGNATTI, ALICIA M.; ECHANIZ, SANTIAGO A.

Otro; XLI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2023

Although the phytoplankton and zooplanktonic communities of the shallow saline lakes of the province of La Pampa are relatively known,information regarding their benthos is considerably less. The objective of this study is to know the diversity of benthic ostracods in ahighsaline Pampean lake. In August 2023, sediment samples were collected at two sites in Ojo de Agua Uriburu (36°31´S, 63°53´W), locatedin the eastern region of the province of La Pampa, on the western limit of the Pampa Plains ecoregion. The lake is located in an arheic basin,fed by precipitation and groundwater, resulting in highly fluctuating, water levels due to dry and humid climatic cycles. Its contour is a beachwith patches of halophilic vegetation. The area is primarily used for cultivating cereals, oilseeds and, to a lesser extent, cattle farming. Thesamples were sieved with 63 µm mesh and then air-dried at room temperature. Specimens were recovered under a stereomicroscope, usingthe picking technique. The samples revealed a high density of ostracods, documenting four species: Limnocythere titicaca Lerner-Seggev,1973, Limnocythere cusminskyae Ramón Mercau, Plastani & Laprida, 2014, Amphicypris argentinensis Fontana & Ballent, 2005 andHeterocypris similis Wierzejski in Ramírez, 1967. Limnocythere cusminskyae and L. titicaca are typical of waters of high salinity and werethe most abundant species, since they reached densities of 2439 and 987 ind/100 gr of sediment, respectively. In both cases, completepopulations were recorded, made up of adult and juvenile individuals, both males and females. In the case of A. argentinensis, although itbelongs to a genus typically associated with freshwaters, it had been previously reported in the saline waters of La Pampa, with four specimensin juvenile stages recovered. Although H. similis is a common species in the center of the country, only three specimens were recorded.Given that the samples included in this study have a relatively high diversity and density, further collection during in the remaining seasonsof the annual cycle would be of significant interest.