Regresar

The role of flow shaping the functional and structural invertebrate diversity at a high altitude tropical stream

Abstract:

The absence of wide temperature changes in tropical streams suggests that the variations of benthic assemblages are related to other environmental variables. At high altitude tropical streams, the temperature is usually below 10 ºC along the year, which is a harsh environment for the development of aquatic insects. In this context, long developmental times would be expected with more dependence on hydrological variables. Our objective was to characterize the hydrological variation of a high altitude Andean stream and to relate this variation to the composition and diversity of taxa and traits of aquatic insects. Our hypothesis is that the hydrological variation plays a major role shaping the functional and structural diversity in this type of stream. We studied the Saltana creek located in the Western Andean ranges of Ecuador at 3800 masl. We took twelve random Hess benthic samples monthly from April 2009 to April 2010. From every sample we recorded the velocity, substrate and depth. With these variables we also calculated the Reynolds and Froude numbers. Stream flow was followed every hour by a depth logger located in a fixed transect in the stream. We related the composition, abundance and diversity (taxa and traits) to flow and hydraulic variables.