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Macroinvertebrate diversity patterns in tropical highland andean rivers

Abstract:

We studied the macroinvertebrate diversity patterns at 44 sites in tropical highland streams (from 2600 to 4800 m a.s.l. and from northern Ecuador to southern Peru, South America) within six watersheds. The aquatic macroinvertebratealpha (α) diversity tended to decrease with increasing altitude and latitude. Moreover, a high variability existed in the local diversity, which was related to the local environment and habitat heterogeneity. A community composition analysis revealed changes associated with the transition from montane forest areas to páramo or puna areas (at altitudes close to 3500 m a.s.l.). The changes were related to the absence of vegetation in the basins and the absence of riparian areas above 3500 m a.s.l. Three areas could be clearly differentiated: The Northern Andes (Colombia and most of Ecuador), Central Andes (southern Ecuador and most of Peru up to the Altiplano area) and the Altiplano-Puna area. These differences are linked by the distance between basins, as well as biogeographic factors, such as the presence of the Huancabamba Depression between Ecuador and Peru. These three areas have distinct differences in composition, with some taxa more abundant in the south (some of them of Gondwanan origin) and others more prevalent in the north.