Ichthyofauna of piedmont and savannah environments in the Casanare River drainage, Orinoco Basin, Colombia

This study considered two natural units, the Andean piedmont that comprises the Andean versant above 200 m a.s.l, and the savannahs and flooded forests below 200 m a.s.l (Lasso et al. 2010). For the delimitation of natural units, the layer intersection tool was used (slope, geo-shape, covers and climate), available in ArcGIS ©10.2.

Samplings took place during two hydrological seasons: low water (March-April 2015) and high water (August-September 2015). The collections were carried out at 35 sampling localities in the Casanare River drainage including rivers, streams, lakes, floodplain lagoons and morichales, of which 24 are in the piedmont and 11 in flooded savannahs (Figures 2–11). The coordinates follow the WGS84 system.

Collection in piedmont stations was carried out with transects of 75 meters in length using an electrofishing equipment (Samus 725G/550-600), complemented with six successive passes of a seine (5 m long, 2 m height and 0,1 cm mesh) and 20 throws of a cast net (3 m diameter and 2 cm mesh). In the savannah stations, sampling spanned a transect of 100 m, performing eight passes of a seine (7 m long, 2 m height and 0,1 cm mesh), 20 throws of cast net (diameter of 4 m and 2,5 cm mesh) and the installation of 20 hooks during two hours (hooks and lines of different size and bait types). Two “stationary” gillnets (23 m long, 2 m height and 5 cm mesh) were used along the main course of the Casanare River, which were installed during 4 hours and examined every half hour.

The specimens were anesthetized in-situ with benzocaine solution and fixed in 10 % formalin, and then preserved in 70 % ethanol. Specimens were identified and housed in the ichthyological collections of both the Instituto Alexander von Humboldt (IAvH-P) and the Museo Javeriano de Historia Natural Lorenzo Uribe Uribe S.J (MPUJ). Large-sized species and those under any national threat category, were identified in the field, photographed and posteriorly released in their capture site. Taxonomic identification was done at the species level using species descriptions, taxonomic revisions and specialized taxonomic keys (Lasso and Machado-Allison 2000, Vari and Harold 2001, Taphorn 2003, Armbruster 2003, 2005, Netto-Ferreira et al. 2009, Londoño-Burbano et al. 2011, Ballen and Vari 2012, Ballen and Mojica 2014, Menezes and Lucena 2014, Marinho and Langeani 2016). The list of species and the validation of the scientific names follow the classification of Eschmeyer et al. (2016 http://www.calacademy.org/scientists/catalog-of-fishes-classification/).

Species were categorized as endemic of Orinoco river drainage or some sub-drainage (Machado-Allison et al. 2010), migratory (Zapata and Usma 2013) and threatened (Mojica et al. 2012), in order to assess the conservation status of the fish fauna in the drainage.

Lastly, the complete dataset was uploaded to SiB Colombia’s (GBIF Colombia Node) Integrated Publishing Tool in order to increase the visibility and reach of the information produced herein. The Darwin Core standard (Wieczorek et al. 2012) was used as the biodiversity standard to structure the complete dataset. The shared dataset is identified by a DOI, provided by SiB Colombia and is available herein.