Carbon-Nitrogen mismatch in the leaf litter-shredder relationship of an Andean patagonian stream detritivore

BALSEIRO E.G. Y ALBARIÑO, R.J.

JOURNAL OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY

Allen Press

Lugar: Lawrence; Año: 2006 vol. 25 p. 607 - 615

0887-3593

Abstract.  Aquatic shredders depend mostly on terrestrial leaf litter as a food resource, and differences between the C:N ratio of their food resource and their bodies may affect nutrient excretion and the composition of their feces.  Laboratory experiments were used to test how the stonefly, Klapopteryx kuscheli, rebalances the high C:N ratio of its food.  An experiment was designed in which K. kuscheli was fed 5 different leaf litters across a gradient of C:N ratios and the elemental ratios of the food, insect bodies, and feces were analyzed.  Klapopteryx kuscheli regulated its internal elemental composition by changing its excretion of N depending on the N content of its food.  An inverse relationship was found between N content of most foods and excreted NH4+.  However, K. kuscheli feces were rich in N and the insect excreted very small amounts of NH4+ when fed Nothofagus pumilio, probably because of refractory N-based compounds in the leaves of this species.  Homeostatic regulation of N content by invertebrate shredders may influence N dynamics in small poor-nutrient streams.