Charophyte and ostracod distribution in Laguna Llancanelo catchment and their ecological characterization

D'AMBROSIO, SABINA; GARCIA, ADRIANA; CLAPS, MARIA CRISTINA

Mendoza

Simposio; 6th International Symposium on Extant and Fossil Charophytes; 2012

The Laguna Llancanelo is located in the south-west of Provincia de Mendoza (35° - 36°30´ S, 68° 30´ - 70° W), at 1330 m above sea level and about 70 km east from Cordillera de los Andes. The lake is an endorheic basin in the Huarpes depression, at the North of Payenia volcanic field. The Llancanelo Lake basin is very flat, with mean water depth of 30 cm although deeper sections can reach up to 170 cm. The catchment of Laguna Llancanelo is formed by Rio Malargue (with four creeks joining it before reaching the lake), Arroyo Chacay, Arroyo El Mocho , Arroyo Malo and Arroyo El Alamo (the last two usually dry), and Bañados (local term for spring) Carilauquen, Carapacho, La Porteña and Los Menucos. Samples of benthos were collected seasonally at 18 sites within the basin, with charophytes, ostracods and molluscs being the more abundant remains. The samples were washed through a 100 μm mesh size sieve, then analysed with a binocular microscope to obtain the charophytes and ostracods. To analyse the spatial distribution the Olmstead and Tukey’s test was used. Preliminary results show Limnocythere as the dominant genus in Laguna Llancanelo, Iliocypris ramirezi is common, and Darwinula stevensoni, Sarcypridopsis sp. and Cypridopsis sp. aff. C. fuhrmanni are rare. The dominant species of charophytes are Chara halina and Lamprothamiun haesseliae, while Nitella sp., Chara contraria, Chara vulgaris and Chara hornemannii are rare. In the springs, the dominant species are Darwinula stevensoni, Iliocypris ramirezi, Cypridopsis sp. aff C. fuhrmanni and Chara vulgaris, while Limnocythere staplini., Sarcypridopsis sp., Potamocypris sp., Stenocypris sp., Chara contraria, Chara halina, Chara hornemannii, and Lamprothamnium sp. are rare. Finally, in the rivers and creeks Iliocypris ramirezi, Limnocythere staplini and Chara vulgaris are dominant, 29 Darwinula stevensoni, Sarcypridopsis sp., Cypridopsis sp. aff. C. fuhrmanni, Potamocypris sp., Stenocypris sp. and Chara hornemannii are rare, while Chara contraria is common. The distribution of these taxa is related to the salinity of the waterbodies: Laguna Llancanelo characterised by hyposaline to mesosaline (9,3 – 44,3 g L -1) water, shows an abundance of Limnocythere staplini, Chara halina and Lamprothamiun haesseliae ; the freshwater rivers, creeks and springs, have an abundance of Iliocypris ramirezi and Chara vulgaris.