This study evaluates litter dynamics and its relation to macroinvertebrate communities (assemblages and feeding habits) at Piburja stream (3300 m, Ecuador). Annual litterfall (216 g AFDM/m2 ) was not related to rainfall, but differed significantly between months. Transport of Coarse Particulate Organic Matter (CPOM) did not differ between seasons, but retention was higher during the dry season. Thus, CPOM standing stock was higher in the dry (125.28 g AFDM/m 2 ) compared to the wet season (12.27 g AFDM/m 2 ). Macroinvertebrate richness and diversity were positively related to Coarse Benthic Organic Matter (CBOM) especially during the wet season. Gut content analysis revealed that, regardless of season, CPOM and Fine Particulate Organic Matter (FPOM) were the most important food items in the diet of most invertebrate taxa, including those that are not considered shredders or gathering collectors in the literature.
IntroductionInputs of leaf litter from riparian vegetation comprise a significant source of energy and nutrients for headwaters, (SICCAMA et al., 1970;ANDERSON and SEDELL, 1979; WAL-LACE et al., 1997; GRACA, 2001) where they are incorporated into secondary production by decomposers and detritivores (GESSNER et al. 1999;GRAÇA, 2001). In temperate streams, the interactions between organic matter inputs, decomposers, detritivores and physical factors are relatively well understood and have been widely studied (ANDERSON and SEDELL, 1979;SUBERKROPP and WALLACE, 1992;SUBERKROPP and CHAUVET, 1995;WALLACE and WEBSTER, 1996;GRAÇA, 2001). In contrast, tropical streams are understudied, and there is a lack of quantitative information on the inputs, storage and cycling of allochthonous organic matter, even though these streams often drain heavily forested catchments and leaf inputs represent a major potential energy source (GRAÇA et al., 2001a;COLÓN-GAUD et al., 2008). The rates and relative importance of the different pathways through which organic matter passes through in tropical mountain streams is virtually unknown (JACOBSEN, 2008