First evidence of testate amoebae in Lago Fagnano (54 S), Tierra del Fuego (Argentina): Proxies to reconstruct environmental changes.

CAFFAU, M.; LENAZ, D.; LODOLO E.; ZECCHIN, M.; COMICI, C.; TASSONE A.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 27 - 41

0895-9811

We report here the first findingsof testate amoebae at high southern latitudes (54  S) from four gravity cores recovered in theLago Fagnano (Tierra del Fuego, Argentina), where twelve taxa have beenrecognized. Among them, Centropyxis constricta ?constricta?, Centropyxiselongata, Difflugia globulus, Difflugia oblonga ?oblonga?, and Difflugiaprotaeiformis ?amphoralis? are always present, while other taxa are randomly distributed.According to the sand/silt ratio in the different cores, the Total OrganicCarbon content and the Carbon/Nitrogen ratio, as well as thepresence/disappearance and abundance of testate amoebae from cluster analysis,we infer a correlation between major textural/granulometrical changes found inthe cores and environmental changes. A seismic event occurred on 1949, whichsubstantiallymodified the morphology of theeastern Lago Fagnano shoreline and the supply pattern from two main easterntributaries of the lake, is recorded in the studied cores. This event has inpart modified the distribution of testate amoebae taxa within the studiedcores. Present results show that testate amoebae represent important indicatorsto detect changes occurring in the environment in which they live.