Author(s): John Claude Renan Salluta
Email (s): jbsalluta@up.edu.ph
Institution or organization of origin: University of The Philippines Diliman
Country: Philippines
Abstract
Agricultural lands are prevalent on Lake Sebu shores due to its high productivity, but intense farming may lead to the runoff of organic pollutants in adjacent rivers and streams. Assessing the impacts of organic pollution in rivers and streams requires using biological communities such as macroinvertebrates as biological indicators due to their varied response to stressors. But reliance on monitoring physicochemical parameters in countries such as the Philippines underestimates its stream ecosystem health. Thus, this study assessed the structural and functional diversity of stream macroinvertebrates from upstream and downstream reaches of six tributaries (n=12) in Lake Sebu from January, April, August, and November 2019. NMDS and ANOSIM revealed no distinct difference in the overall community structure.
PCA and cluster analyses further supported the lack of structural differences in the upstream and downstream reaches. Nonetheless, downstream areas have obligate parasites and filter-feeders. Downstream sites also had higher water conductivity and total dissolved solids, which may be attributed to the area’s intense agriculture and aquaculture activities. Despite the presence of sensitive taxa (Plecoptera) upstream, the dominance of mildly tolerant taxa such as Baetis spp. and Thiara spp. for upstream and downstream sites indicated a land-use gradient in the surrounding terrestrial environment of Lake Sebu. Moreover, the lack of dominant specialist taxa in the sampled sites supports the extent of habitat modification in Lake Sebu. Thus, the local government must enact policies that will rehabilitate the riparian zone of the tributaries for Lake Sebu to reduce the organic pollution load in the lake.