Effects of Deployment Period on Decomposition and Colonization of Leaf Litter of Differing Quality by Invertebrates
Detritivorous invertebrates play major roles in organic matter processing and nutrient cycling in headwater streams. In this study, three common leaf species in upland Kenyan streams (Vernonia myriantha, Syzygium cordatum and the exotic Eucalyptus globulus) were used to determine the influence of deployment period (14 vs 28 days) on relative decomposition rates and colonization by detritivorous invertebrates in headwater streams of the Nzoia River Basin. Leaf decomposition rates were measured by placing 216 litterbags made of coarse- and fine-mesh in six streams draining forested (n =3) and agricultural (n = 3) land-use during the dry months of February- March 2020. For each stream, physico-chemical water characteristics and habitat quality were determined. Measurements of electrical conductivity, pH, temperature, dissolved oxygen concentration and salinity were performed in situ using portable probes. There were no major differences in physical and chemical characteristics between forested and agricultural streams, except for significantly higher canopy cover (p < 0.05) in forested streams, and electrical conductivity and mean water temperature in agricultural streams. Decomposition rates were faster during the first 2 weeks (day 14), and differences between fine- and coarse-mesh litterbags were significant for Vernonia and Syzygium, but not for Eucalyptus. After 14 days, differences between microbial and shredder + microbial breakdown of leaves were clearer than after 28 days, suggesting that short deployment periods (14 days) are enough to establish relative roles of shredders and microbes in leaf litter decomposition experiments in tropical streams. There were inter-specific differences in colonization rates of the leaves by detritivores (shredders) with Vernonia having the highest number of shredder taxa and abundance followed by Syzygium and Eucalyptus. However, there were minimal differences in taxon richness and abundance of shredders and non-shredders between day 14 and day 28. Therefore, this study recommends shorter deployment periods of 14 days rather than long periods of one month or more when studying leaf litter decomposition and colonization by detritivores in tropical streams
Benfield, E. F. (1996). Leaf breakdown in stream ecosystems. Methods in Stream Ecology, 579-590.
Boulton, A. J., & Boon, P. I. (1991). A review of methodology used to measure leaf litter decomposition in lotic environments: time to turn over an old leaf. Marine & Freshwater Research, 42(1), 1-43.
Boyero, L., Pearson, R. G., Hui, C., Gessner, M. O., Pérez, J., Alexandrou, M. A., & Barmuta, L. A. (2016). Biotic and abiotic variables influencing plant litter breakdown in streams: a global study. Proceedings of the Royal Society Biological Sciences, 14,283-296.
Boyero, L., López-Rojo, N., Tonin, A. M., Pérez, J., Correa-Araneda, F., Pearson, R. G., ... & Yule, C. M. (2021). Impacts of detritivore diversity loss on instream decomposition are greatest in the tropics. Nature Communications, 12(1), 1-11.
Cotrufo, M., Galdo, I., & Piermatteo, D. (2010). Litter decomposition: Concepts, methods and future perspectives. In W. Kutsch, M. Bahn, & A. Heinemeyer (Eds.), Soil Carbon Dynamics: An Integrated Methodology (pp. 76-90). Cambridge: Cambridge University Press.
Day, J. A., & I. J. de Moor. (2002a). Guides to the freshwater invertebrates of southern Africa. Volume 5: Non-arthropods (the protozoans, Porifera, Cnidaria, Platyhelminthes, Nemertea, Rotifera, Nematoda, Nematomorpha, Gastrotrichia, Bryozoa, Tardigrada, Polychaeta, Oligochaeta and Hirudinea). WRC Report No.TT 167/02. Water Research Commission, Pretoria, South Africa.
Day, J. A., & I. J. de Moor. (2002b). Guides to the freshwater invertebrates of southern Africa. Volume 6: Arachnida and Mollusca (Araneae, Water Mites and Mollusca). WRC Report No.TT 182/02. Water Research Commission, Pretoria, South Africa.
Dobson, M., Magana, A., Mathooko, J. M., & Ndegwa, F. K. (2002). Detritivores in Kenyan highland streams: more evidence for the paucity of shredders in the tropics? Freshwater biology,47(5), 909-919.
Ferreira, V., Encalada, A. C., & Graça, M. A. (2012). Effects of litter diversity on decomposition and biological colonization of submerged litter in temperate and tropical streams. Freshwater. Science, 31(3): 945-962.
Gessner, M. O., & Chauvet, E. (2002). A case for using litter breakdown to assess functional stream integrity. Ecological applications, 12(2), 498-510.
Gonçalves Jr, J. F., Graça, M. A., & Callisto, M. (2006). Leaf-litter breakdown in 3 streams in temperate, Mediterranean, and tropical Cerrado climates. Journal of the North American Benthological Society, 25(2), 344-355.
González, J. M., & Graça, M. A. S. (2003). Conversion of leaf litter to secondary production by a shredding caddis‐fly. Freshwater Biology, 48(9), 1578-1592.
Graça, M. A. S. (2017). The Role of Invertebrates on Leaf Litter Decomposition in Streams, a review. International Review of Hydrobiology, 86:386-393.
Graça, M. A., Ferreira, V., Canhoto, C., Encalada, A. C., Guerrero‐Bolaño, F., Wantzen, K. M., & Boyero, L. (2015). A conceptual model of litter breakdown in low order streams. International Review of Hydrobiology, 100(1): 1-12.
Graça, M.A. S., Cressa, C. M. O. G., Gessner, T. O., Feio, M. J., & Callies, K. A. (2001). Food quality, feeding preferences, survival and growth of shredders from temperate and tropical streams. Freshwater. Biology, 46(7): 947-957.
Irons, J. G., Oswood, M. W., Stout, R. J., Pringle, C. M. (1994). Latitudinal patterns in leaflitter breakdown: is temperature really important? Freshwater Biology 32, 401–411.
Janke, H., & Trivinho-Strixino, S. (2007). Colonization of leaf litter by aquatic macroinvertebrates: a study in a low order tropical stream. Acta Limnologica Brasiliensia, 19(1), 109-115.
Manzoni, S., Trofymow, J.A., Jackson, R.B., Porporato, A. (2010). Stoichiometric controls on carbon, nitrogen, and phosphorus dynamics in decomposing litter. Ecological Monographs, 80, 89–106.
Masese, F. O., Kitaka, N., Kipkemboi, J., Gettel, G. M., Irvine, K., & McClain, M. E. (2014a). Litter processing and shredder distribution as indicators of riparian and catchment influences on ecological health of tropical streams. Ecological Indicators, 46, 23-37.
Masese, A. F. O., Kitaka, N., Kipkemboi, J., Gettel, G. M., Irvine, K. (2014b). Macroinvertebrate functional feeding groups in Kenyan highland streams: evidence for a diverse shredder guild. Freshwater Science, 33(2), 435-450.
Masese, F. O., Raburu, P. O., & Muchiri, M. (2009). A preliminary benthic macroinvertebrate index of biotic integrity (B-IBI) for monitoring the Moiben River, Lake Victoria Basin, Kenya. African Journal of Aquatic Science, 34(1), 1-14.
Merritt, R. W., Cummins, K. W., & Berg, M. B. (2008). An Introduction to the Aquatic Insects of North America. 4th (Edition). Kendall Hunt Publishing. Dubuque, Iowa, USA.
Nyadawa, M. O., & Mwangi, J. K. (2010). Geomorphologic characteristics of Nzoia River basin. Journal of Agriculture, Science & Technology, 12(2):145-161.
Patrick, C. J. (2013). The effect of shredder community composition on the production and quality of fine particulate organic matter. Freshwater Science,32 (3):10261035.
Reis, D. F., Machado, M. M. D., Coutinho, N. P., Rangel, J. V, Moretti, M. S., & Morais, P. B. (2018). Feeding preference of the shredder Phylloicus sp. plant leaves of Chrysophyllum oliviforme or Miconia chartacea after conditioning in streams from different biomes. Brazilian Journal of Biology, 79(1): 22-28.
Sitati, A., Raburu, P. O., Yegon, M. J., & Masese, F. O. (2021). Land-use influence on the functional organization of Afrotropical macroinvertebrate assemblages. Limnologica, 88, 125875.
Tank, J. L., Rosi-Marshall, E. J., Griffiths, N. A., Entrekin, S. A., & Stephen, M. L. (2010). A review of allochthonous organic matter dynamics and metabolism in streams. Journal of the North American Benthological Society, 29(1), 118-146.
Vannote, R. L., Minshall, G. W., Cummins, K. W., Sedell, J. R., & Cushing, C.E. (1980). The river continuum concept. Canadian Journal of Fisheries & Aquatic Sciences, 37, 130–137.
Wabusya, M., Nyongesa, H., Konje M., & Agevi, H. M. T. (2015). Effects of land-use practices on soil organic carbon, nitrogen and phosphorus in river Nzoia drainage basin, Kenya, Agriculture, Forestry and Fisheries, 4(4): 153-158.
Wantzen, K.M., Yule, C.M., Mathooko, J.M., & Pringle, C.M. (2008). Organic matter processing in tropical streams. In: Dudgeon, D. (Ed.), Tropical Stream Ecology. Academic Press, London, pp. 44–65. Webster, J. R., & Benfield, E. F. (1986). Vascular plant breakdown in freshwater ecosystems. Annual review of ecology and systematics, 17(1), 567-594.
Wetzel, R. G., & Likens, G. E. (2013). Limnological analyses. Springer Science & Business Media.
Young, R.G., Matthaei, C.D., & Townsend, C.R. (2008). Organic matter breakdown and ecosystem metabolism: functional indicators for assessing river ecosystem health. J Journal of the North American Benthological Society 27, 605–625.
Zhang, M., Cheng, X., Geng, Q., Shi, Z., Luo, Y., & Xu, X. (2019). Leaf litter traits predominantly control litter decomposition in streams worldwide. Global Ecology and Biogeography, 28(10), 1469-1486.