Leaf litter breakdown and benthic invertebrate colonization affected by seasonal drought in headwater lotic systems of Andean Patagonia

MARILUÁN, G.; DIAZ VILLANUEVA, V; ALBARIÑO, R.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2015

0018-8158

We aimed to establish the effect ofseasonal drought on leaf litter breakdown and invertebratecommunities. Differences in breakdown ratesof Nothofagus pumilio were experimentally comparedusing the litter bag method (coarse and fine mesh sizebags) in two first-order streams, one intermittent andone perennial, during two different hydrologicalperiods. Colonizing fauna found in coarse mesh bagswas quantified, identified and compared with benthicbiota from the same streams. Leaf litter decay rates inlow flow conditions revealed that breakdown wasprincipally a consequence of microbial action in theintermittent stream. In contrast, breakdown in highflow conditions was caused by invertebrate feeding inboth streams. Collector?gatherers constituted most ofthe abundance and biomass in bags from the intermittentstream, due to their rapid benthic recolonization.Shredders peaked at approximately 50% remainingleaf litter mass in both streams only during high flow,which coincided with general models of detritusbreakdown in streams. Considering global warmingscenarios, with drought and water temperature increasesexpected for many regions of the world, thesestudies on the consequences for the biota andecological processes of small streams will allow theprediction of negative effects on such vulnerableecosystems.