Ecosystem course 2011

Compiled by Silvio Zuluga and Gabriel Pinilla, Biology Department, Universidad Nacional de Colombia

During the 'Continental Regional Ecology' course of the Biology Department of the Universidad Nacional de Colombia, limnology and vegetation sampling were conducted in the western sector of the Natural National Park (NNP) El Cocuy, from 30 August to 16 September 2011. We wanted to evaluate the ecosystems of the region from the point of view of the structure of plant communities and ecological aspects of its rivers and lakes, in order to relate these components with the scales of biome and region, to which they belong. Samplings in high Andean forest, subpáramo, páramo and superpáramo were made.

Students participating in the course taking samples in the Rio Corralitos

Preliminary results of the limnological component

Physico-chemical analysis of water: aquatic environments of the NNP El Cocuy are characterized by being slightly acidic, with low amounts of nitrogen and phosphorus, high oxygen concentrations and low conductivity, characteristics that allow their classification as oligotrophic. The classification analysis of physico-chemical variables showed that three groups were formed: systems with higher pH and conductivity, water bodies with low ammonium, and environments with higher temperatures and lower pH.

Macroinvertebrates: the most diverse biomes, rich and populated with aquatic invertebrares, were located in the páramo and high Andean forest. The most representative functional groups were collectors and filter feeders, although the last mentioned could be promoted by human activities in the disturbed aquatic environments. The most common families were Leptoceridae, Hyalellidae, and Chironomidae, being the last of high representativeness, especially in the lotic systems.

Periphyton: diversity indices showed ecosystems that stand out for their diversity and low dominance. However Cyanobacteria were abundant in some aquatic ecosystems, indicating nitrogen limitation; other major groups were Bacillariophyceae (diatoms) and Zygnematophyceae (desmids), typical of oligotrophic and demineralized environments. Prostrate and filamentous-thalloid life forms of periphyton algae dominated aquatic systems at high Andean forest level and subpáramo, with high levels of dissolved oxygen and moderate turbidity.

Phytoplankton: in the studied lakes diatoms predominated due to the scarce depth and low nutrients, followed by Cyanobacteria and Chlorophyceae. In the lakes of the high Andean forest, phytoplankton functional groups were represented by small flagellated algae (Chrysophyceae), and filamentous algae with aerotops (Cyanobacteria); the páramo lakes had predominance of flagellated unicellular algae of medium to large size, tolerant to low concentration of nutrients.

Barbero, M.P., F. Castiblanco, S. Díaz, D. Duarte, L.M. Fierro, P.V. Fontanilla, L.E. Holguín, F.G. Márquez, N. Molano, A. Morales, C.F. Morantes, F.F. Moreno, M.K. Ontiveros, R.F. Paternina, A. Pinto, D.F. Ramírez, B.H. Rodríguez, L.S. Toro, G.A. Pinilla & S. Zuluga. 2011. Estudio de ecosistemas acuáticos y terrestres en el PNN el Cocuy. Componentes de vegetación y limnología. Cordillera Oriental sector occidental. — Universidad Nacional de Colombia. Departamento de Biología