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AB prepress abstract   -  DOI:

Assigning functional feeding groups to aquatic arthropods in a Neotropical mountain river

Cesar E. Tamaris-Turizo, Gabriel A. Pinilla-A. , Cristian J. Guzmán-Soto*, Cristian E. Granados-Martínez

*Corresponding author:

ABSTRACT: The importance of aquatic arthropods in the processing of organic matter in fluvial systems is well-known, but this topic has been poorly studied for Neotropical rivers. In this research, we studied the composition of functional feeding groups (FFGs) associated with differences in elevation in a tropical river in northern Colombia during the wet and dry seasons. Between 2008 and 2013, we collected benthic arthropods at three sites located in the upper (San Lorenzo), intermediate (La Victoria) and lower (Puerto Mosquito) sections of the Gaira River. We found some differences in the gut contents and FFGs of the animals from different sites and between the climatic seasons. The dominant food source was fine particulate organic matter (FPOM) at all the sites and seasons. At La Victoria, the genera Leptonema, Smicridea and Phylloicus (all belonging to Trichoptera) presented significant differences in the consumption of coarse particulate organic matter (CPOM) between the rainy season and the dry season (p < 0.05). At San Lorenzo, Leptonema had the highest animal tissue consumption value (p < 0.05). A discriminant function analysis based on gut contents suggested that some taxa may have been assigned to the wrong FFGs. We concluded that the diets of the aquatic arthropods in our study tended to present high trophic plasticity. Consequently, our results suggested that Neotropical rivers need to be re-evaluated in terms of traditionally established FFGs, which heretofore have been based on information from other regions of the world, producing incorrect assessments of aquatic systems.