The effect of sunlight on leaf litter quality reduces growth of the shredder Klapopteryx kuscheli

ALBARIÑO, RICARDO, DÍAZ VILLANUEVA, VERÓNICA & CANHOTO, CRISTINA

FRESHWATER BIOLOGY (PRINT)

Blackwell Publishing Ltd

Lugar: Oxford; Año: 2008 vol. 53 p. 1881 - 1889

0046-5070

The direct effect of sunlight on the conditioning, breakdown and incorporation of leaf litter in stream food webs has not yet been considered. The aim here was to evaluate the effects of light intensity on the colonization of leaf litter by microorganisms and its resulting quality as food for the stonefly shredder Klapopteryx kuscheli. Leaf litter was conditioned for two months in an open reach of a second order stream in litter bags either exposed to or shaded from direct sunlight. Subsequently, we performed laboratory experiments to test larval consumption, growth, growth efficiency and feeding preference fed on both leaf litter treatments. Leaf litter in the unshaded treatment had three times more Chl-a than that in the shaded treatment, 50% lower fungal biomass and similar bacterial abundance. Although larvae did not prefer either food and fed at the same rate on both leaf litter treatments, they grew twice as fast on the shade-conditioned leaves and attained a two-fold higher growth efficiency. Sunlight can have significant effects on detritus-based food webs. Riparian modification induced by human activities in forested catchments increases the potential for sunlight to influence detritus dynamics.