High-quality algae attached to leaf litter boost invertebrate shredder growth

Abstract

AbstractAlgae are higher-quality food resources than allochthonous plant litter for stream invertebrates, in part, because of their higher content of polyunsaturated fatty acids (PUFAs). We tested the hypothesis that algal biofilms on the surfaces of leaf litter improve the nutritional quality of terrestrial inputs for invertebrate shredders. We used a laboratory feeding experiment with 2 light levels (open and shaded) and 2 nutrient regimes (ambient and enriched) to manipulate the algal biofilms that form on leaf surfaces (Lophostemon confertus). We assessed how these treatments affected the fatty acid (FA) composition of these biofilms and the somatic growth of a stream invertebrate shredder (Anisocentropus bicoloratus, Trichoptera) that feeds on the conditioned leaf litter. Shredders reached a significantly larger size when nutrients were added, and leaf mass loss was significantly greater in these treatments than in treatments without nutrients. Shredder growth was affected significantly by leaf PUFA ...