Abstract
<p>The aquatic insects are important bioindicators of water quality in rivers and streams. The order Trichoptera is part of this group, plays an important role in aquatic systems and because of the multiple functions they fulfill, it is essential to know about their biodiversity. This study aimed to know the Trichoptera composition, and its spatial and temporal distribution, in close relationship with the available microhabitats, and some physical and chemical variables, in the middle and lower sections of the Manzanares river basin (Sierra Nevada of Santa Marta, Colombia). A total of eight microhabitats were sampled in three sites from August 2002 to February 2003, and during the rainy and dry seasons. A total sample of 3 316 Trichoptera larvae were collected, belonging to 10 family and 14 genera; six of these genera and one family are new records for the Magdalena department. The caddisflies presented the greatest abundance and richness on leaves in pool, leave in riffles and stones in riffle, where <em>Nectopsyche</em> (28%), <em>Leptonema</em> (17%) and <em>Smicridea</em> (15%) were the more predominant genus. Structure and composition of Trichoptera genus in each site changed in function to the rainfall pattern, and physical and chemical variables presented in the basin, showing the lowest abundance and richness during high rainfall period (October and November), and the greatest abundance and richness in low rainfall period (December, January and February). Likewise, stations with higher values of dissolved oxygen and lower in temperature and conductivity reported the greatest abundance of Trichoptera. The Trichoptera showed affinity to the specific microhabitats, variations in their composition in relationship whit climatic periods and pollution levels of the river. To know others aspects about the Trichoptera distribution, we recommended continuing these studies including annual cycles and increasing the altitudinal gradients.</p>
Highlights
Otros trabajos enfocados en aspectos taxonómicos (Rincón, 2002; Posada-García, & Roldán, 2003; Muñoz-Quesada, 2004) han registrado importantes contribuciones sobre la distribución de los géneros para Colombia
Variación temporal: Durante la época de lluvias (Agosto a Noviembre) la abundancia de los tricópteros disminuyó en todas las estaciones, la cual se evidenció especialmente en la estación La Cascada, donde se registraron abundancias menores a 200 individuos en agosto y septiembre, fecha que coincidió con el inicio de las precipitaciones
Los tricópteros presentaron la mayor abundancia y riqueza genérica en los microhábitats Hojarasca Corriente Lenta, Hojarasca Corriente Rápida y Piedra Corriente Rápida, donde Nectopsyche (28%), Leptonema (17%) y Smicridea (15%) fueron los géneros más predominantes
Summary
Área de estudio: El río Manzanares nace en la vertiente noroccidental de la SNSM en la cuchilla de San Lorenzo, a una altura de 2 300msnm en el departamento del Magdalena, Colombia (Fundación Pro-Sierra Nevada, 1998). Esta cuenca se localiza entre los 11°07’22” N - 74°01’14” W y los 11°14’27” N - 74°12’25” W. La primera estación de muestreo se denominó “Cascada”, se encuentra localizada entre los 11°11’00” N 74°05’47W a 360msnm; la segunda “Therán”, ubicada entre los 11°11’39” N - 74°06’02” W a 245msnm; “Paso del Mango” correspondió a la tercera estación (11°11’29” N - 74°06’04” W), a 230msnm; la cuarta estación, ubicada en una zona de balneario de “Bonda”, entre los 11°13’50” N - 74°06’36” W a 60msnm (Fig. 1). Los sitios presentaron variabilidad de sustratos, entre los que se encuentran gravas, grandes piedras y arenas, constituyendo diferentes microhábitats.
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