Effects of Deployment Period on Leaf Litter Decomposition and Colonization by Invertebrates
Aquatic macroinvertebrates play a major role of nutrient cycling in freshwater ecosystems as primary consumers processing live organic material and function as detritivores by consuming decomposing organic matter. In this study, the breakdown rate of three common leaf species; Syzygium cordatum, Vernonia myriantha and Eucalyptus globulus were examined in six headwater streams of Nzoia River Basin during the dry months of February- March 2020. Leaf decomposition rates were measured by placing 216 litterbags made of coarse- and fine-mesh in the six streams, three draining forested land and three draining agricultural land. For each stream, physical characteristics, physico-chemistry, leaf litter decomposition rates and macroinvertebrate community composition were measured. Leaf decomposition rates were measured by placing litterbags made of coarse- and fine-mesh in the six streams, three draining forested land and three draining agricultural land. Streams did not differ significantly in physical characteristics (p > 0.05) between the two land uses, except for canopy cover which was significantly higher (p = 0.044) in forested streams. Physico-chemistry differed significantly, with forested streams showing higher values (p < 0.05) for coarse particulate organic matter (p = 0.014) but lower for fine particulate organic matter (p = 0.053), total suspended solids (p = 0.014) and electrical conductivity (p = 0.043). Leaf decomposition rates differed significantly (p > 0.05), with forested streams showing faster rates by the end of 28 days. The results showed similar trends on leaf litter decomposition on day 14 and 28. Therefore this study recommends shorter deployment periods of 14 days rather than prolonged ones in studying leaf litter decomposition and longer deployment periods in studying macroinvertebrate colonization.
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