Influence of geographic distance and local environmental factors in shaping small eukaryote community structure along a latitudinal gradient of lakes

SCHIAFFINO, M. R.; LARA, E.; BALAGUÉ, V.; IZAGUIRRE I.

Granada

Congreso; 2015 Aquatic Sciences Meeting ASLO; 2015

ASLO

Small eukaryotes of pico- and nanoplanktonic size (0.2-5 µm, hereafter named picoeukaryotes -Peuk-) are responsible for numerous ecosystem functions and processes in most aquatic ecosystems. However, despite their recognized importance, the factors governing their community structure and spatial distribution or biogeography patterns are still poorly understood. We studied the latitudinal variation of Peuk in 45 freshwater bodies from Argentinean Patagonia (45°S) to Maritime Antarctica (63°S), to find out the factors that influence Peuk community composition (PeukCC). PeukCC was assessed by a 18S rRNA fingerprinting (denaturing gradient gel electrophoresis -DGGE-) and a next-generation sequencing (MiSeq Illumina). The abundance of Peuk (both autotrophic and heterotrophic) decreased significantly towards higher latitudes and increased significantly with increasing trophic status of the water body. The number of dominant operational taxonomic units (OTUs) decreased toward higher latitudes albeit not significantly, and increased significantly with increasing trophic gradient. The partial canonical ordination showed that not only local environmental factors, but also geographic distance exerted influence on PeukCC. Significant differences were found in PeukCC between Antarctic and Patagonian water bodies.