Effect of Rotifer Community to Microhabitat Structure Changes Caused by Summer- Concentrated Rainfall in a Shallow Reservoir, South Korea | Chapter 4 | Modern Advances in Geography, Environment and Earth Sciences Vol. 1

 Empirical studies suggest that the diversity and abundance of macrophytes determine the structural heterogeneity of the microhabitat of the aquatic ecosystem. Excessive accumulation of free-floating macrophytes on the surface of the water will, however, reduce the biomass of submerged macrophytes, leading to a relatively simplified structure of the ecosystem. We hypothesised that heavy summer rainfall disrupts the growth of free-floating macrophytes covering most of the water surface of the Jangcheok Reservoir, contributing to a more complex structure of the ecosystem by enabling a more diverse macrophytic population to evolve. Long-term (2008-2017) monitoring data (rainfall, macrophytes, and rotifers) were split into two groups: rainy and dry years, referring to years with annual rainfall higher and lower than the overall annual average. We found that rotifers' summer densities dropped sharply in the Rainy Years, but steadily increased in the Dry Years. Which we have attributed to habitat changes associated with the development of differential macrophytes. By creating large areas of open water and thus a more complex autumnal microhabitat structure, moderate disruption of the water surface caused by high summer rainfall may encourage the growth of submerged macrophytes, resulting in seasonal variations in rotifer group structures and populations. In addition, a highly complex micro-habitat structure limits the foraging behaviour of fish preying on rotifers (i.e., Lepomis macrochirus). On the basis of these results, we propose that summer-concentrated rainfall plays an important role in promoting the diversity of rotifers in terms of density and organisms. We conclude that summer rainfall plays an important role in promoting rotifer diversity based on the findings of this analysis. While rotifer density is negatively affected by summer rainfall, we have found positive effects in terms of species diversity. We propose the diversity of high autumn rotifer species in the Rainy Years

Author (s) Details

Jong-Yun Choi
National Institute of Ecology, Seo-Cheon Gun, Chungcheongnam Province 325-813, South Korea.

Seong-Ki Kim
National Institute of Ecology, Seo-Cheon Gun, Chungcheongnam Province 325-813, South Korea.



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