Estudio de la entomofauna acuática en la Quebrada Piedra Gorda - Cuenca Alta del Río Tunjuelo, Bogotá D.C.

Abstract

The high basin of Tunjuelo River is an important source of natural resources, characterized by the presence of high Andean forest vegetation, subparamo and paramo, which allows the formation of streams, lakes and streams in which there is a great diversity of species of both fauna and of flora, which thanks to its ecological functions maintain aquatic ecosystems in balance and correct functioning, providing drinking water to the southern area of the city of Bogotá. This research evaluated the structure of the aquatic entomofauna present in four zones with different anthropic intervention level in the Quebrada Piedra Gorda - Tunjuelo river upper basin located in the rural area of Usme, through the sampling and determination of specimens, estimation of diversity and determination of water quality through the evaluation of physical-chemical parameters in situ and laboratory from the use of multiparameters and spectrophotometry techniques. The samplings were made in a time of four months, in which two methods of collection were used, one of qualitative type, screen network and the other quantitative, type "D" network, covering both rainy and dry season. Taking as a result the following: the stream presented ideal physical-chemical characteristics for the support of life, classifying it as oligotrophic and unproductive waters, very common in high mountain areas and we stopped; parameters such as dissolved oxygen, temperature and concentration of orthophosphates obtained significant degree of variation among the evaluated zones, existing, thus, organisms closely related to them; a total of 9,749 individuals were collected, distributed in 5 orders, 24 families and 47 genera. The most abundant taxa were morphotypes of the subfamily Chironominae, Orthocladinae and Tanypodinae, and genera such as Andesiops Lugo-Ortíz & McCafferty (1999), Gigantodax Enderlein, 1925, Simulium and Neoelmis Hinton, 1941, among others. The orders with the greatest wealth were Trichoptera and Diptera, while the zone with the greatest diversity was the area with high density of riparian forest or zone classified as conserved, observing a pattern of increase in dominance and decrease in equity and equity as the riparian forest decreases, where the abundance of diptera of the family Chironomidae are benefited by this effect, while Rhionaeschna Förster, 1909, Smicridea McLachlan, 1871 and Marilia Müller, 1880 among others were the most vulnerable to these changes. Finally concluding that the community of insects present in this stream is distributed in relation to physico-chemical factors such as water temperature, level of flow and concentration of dissolved oxygen and orthophosphates, being able to detect some important genera for the bioindication of the state of conservation of these ecosystems.