Distribution of ostracods in west-central Argentina related to host-water chemistry and climate: implications for paleolimnology

D'AMBROSIO, D. SABINA; GARCIA, ADRIANA; DÍAZ, ANALIA R.; CHIVAS, ALLAN; CLAPS, MARIA CRISTINA

JOURNAL OF PALEOLIMNOLOGY

SPRINGER

Lugar: Berlin; Año: 2017 vol. 58 p. 101 - 117

0921-2728

Ecological and biogeographicalstudies of Neotropical non-marine ostracods are rare, although such informationis needed to develop reliable palaeoecological and palaeoclimaticreconstructions for the region. An extensive, yet little explored SouthAmerican area of palaeoclimatic interest, is the arid-semiarid ecotone (AridDiagonal) that separates arid Patagonia from subtropical/tropical northernSouth America, and lies at the intersection of the Pacific and Atlanticatmospheric circulation systems. This study focused on the Laguna Llancanelo basin, Argentina, aRamsar site located within the Arid Diagonal, and was designed to build amodern dataset using ostracods (diversity, spatial distribution, seasonality,habitat preferences) and water chemistry. Cluster andmultivariate analysis of the data indicated that salinity is the mostsignificant variable segregating two ostracod groups. Limnocythere aff. staplini is the onlyspecies that develops abundant populations in the saline ephemeral LagunaLlancanelo during almost all seasons, and is accompanied by scarce Cypridopsisvidua in summer. The latter species is abundantin freshwater lotic sites, where Ilyocypris ramirezi, Herpetocypris helenae,and Cyprididae indet. are also found in large numbers. Darwinulastevensoni, Penthesilenula incae, Heterocypris incongruens, Chlamydotheca arcuata, Chlamydotheca sp., Herpetocypris helenae, and Potamocyprissmaragdina preferfreshwater lentic conditions (springs), with C. arcuata and Chlamydotheca sp. found only inthe Carapacho warm spring, which has a year-round constant temperature of ~20°C. Seasonal sampling was necessary because some taxa display a highly seasonaldistribution. Species that were recorded have either subtropical or Patagonianaffinities, although a few taxa are endemic or common to both regions. Thesedata can serve as modern analogues for reconstructing the late Quaternaryhistory of the area, and to investigate the extent and position of thearid/semiarid ecotone (Arid Diagonal) during past glacial/interglacial cycles.