Diet and functional feeding groups of Chironomidae (Diptera) in the Middle Paraná River floodplain (Argentina)

Abstract

The gut contents of nine genera of benthic Chironominae and Tanypodinae from the Middle Paraná River floodplain habitats (a lake and a secondary channel) were analyzed to determine their feeding patterns and functional feeding groups. Amorphous detritus, animal and vegetal tissues, and mineral materials (predominantly sand) were observed in the larval guts. Amorphous detritus were the main food item found for Polypedilum (Tripodura) sp., Chironomus gr. decorus sp., Endotribelos sp., Phaenopsectra sp., Cladopelma sp., and Pelomus sp. (Chironominae), while animal tissues (mainly oligochaetes) were the most important food item found for Ablabesmyia (Karelia) sp., Coelotanypus sp., and Procladius sp. (Tanypodinae). Dietary overlap was calculated for all pairs of genera. Within predators, the highest overlap was obtained between Coelotanypus sp. and Ablabesmyia (Karelia) sp., while within detritivores the highest niche overlap was obtained between Endotribelos sp. and Phaenopsectra sp.

Se analizó el contenido intestinal de nueve géneros de Chironominae y Tanypodinae bentónicos en ambientes de la llanura aluvial del río Paraná Medio (laguna y cauce secundario) para determinar su patrón alimentario y los grupos funcionales tróficos. En los contenidos intestinales se observaron detrito amorfo, material mineral (principalmente arena), tejidos vegetal y animal. El principal ítem alimentario encontrado en Polypedilum (Tripodura) sp., Chironomus gr. decorus sp., Endotribelos sp., Phaenopsectra sp., Cladopelma sp. y Pelomus sp. (Chironominae) fue detrito amorfo, mientras que en Ablabesmyia (Karelia) sp., Coelotanypus sp. y Procladius sp. (Tanypodinae) el ítem más importante fue tejido animal (principalmente restos de oligoquetos). Se calculó el solapamiento trófico entre todos los pares de géneros, obteniéndose el mayor solapamiento dentro de los depredadores entre Coelotanypus sp. y Ablabesmyia (Karelia) sp. y dentro de los detritívoros entre Endotribelos sp. y Phaenopsectra sp.