Assessing alpha and beta diversities of benthic macroinvertebrates and their environmental drivers between watersheds with different levels of habitat transformation in Japan

Abstract

Little is known about differences in species diversity among ecological communities subject to different levels of human-caused habitat transformation and how this disturbance contributes to diversity through symbiotic dependencies with the environment in freshwater ecosystems. We estimated α and β diversities of benthic macroinvertebrates and relationships between diversity and environmental variables in Ado River (natural) and Yasu River (intermediately disturbed) watersheds, Japan. Alpha diversity was consistently slightly higher in the natural river watershed than in the intermediately disturbed one, but the spatial distribution was not equivalent. The opposite pattern was found for β diversity. Significant differences in environmental variables existed between the two river watersheds, with especially high chlorophyll-a concentrations detected in the intermediately disturbed watershed. Alpha diversity was not correlated with specific environmental variables, whereas water temperature and chlorophyll-a concentrations were the two most significant environmental variables influencing β diversity across sites in the two watersheds. These results suggest that diversity patterns in freshwater benthic macroinvertebrates are differentially influenced by levels of human-caused habitat transformation, especially that intermediately disturbed habitats may benefit species turnover, and further understanding how they relate to environmental variables is essential for protecting local to regional diversity and can provide useful information for conservation planning to maximise biodiversity at the watershed scale.

Rice paddy irrigation seasonally impacts stream benthic macroinvertebrate diversity at the catchment level

“…More importantly, the evenness of local communities was lower during the irrigation period than during the nonirrigation period, suggesting higher β‐diversity among the former. When comparing spatial patterns of benthic macroinvertebrate communities between the moderately disturbed Yasu River and the less disturbed Ado River within the Lake Biwa watershed, Ko et al (2019) found that the β‐diversity was higher for the former, despite the lower species richness. The Yasu River has a different pattern of land‐use types in its catchment (i.e., 57.7%, 22.5%, and 6.5% for forest, cropland, and urban land use, respectively) compared with that of the Ado River (91.5%, 3.7%, and 0.7%, respectively); thus, there is higher spatial heterogeneity of local stream environments in the former catchment.…”

“…Stream benthic macroinvertebrates, which are sensitive to environmental changes and serve as a useful indicator of water quality and habitat degradation, not only have important influence on nutrient cycles, primary productivity, decomposition, and translocation of materials, but also constitute an important source of food for fish in freshwater ecosystems (Wallace and Webster 1996, Ogbeibu and Oribhabor 2002). Studies have demonstrated the influence of environmental factors, including physical, biological, and chemical, on the distribution, abundance, and community composition structure of benthic macroinvertebrates and, consequently, leading to a certain change in benthic macroinvertebrate diversity (Rousi et al 2011, Ko et al 2019). For example, low water temperature but high DO formed suitable environments for high diversity and abundance of benthic macroinvertebrates in the Baltic Sea.…”

“…For example, low water temperature but high DO formed suitable environments for high diversity and abundance of benthic macroinvertebrates in the Baltic Sea. Water temperature and chlorophyll a (Chl‐ a ) concentrations significantly contributed to benthic macroinvertebrate diversity among watersheds with different levels of habitat transformation in Japan and in the Philippines (Ko et al 2019, Peralta et al 2020). Moreover, benthic macroinvertebrate communities may shift functional diversity during forest maturation or when experiencing deforestation (Stone and Wallace 1998, Kobayashi et al 2010, Ishikawa et al 2016).…”