Anthropogenic connectivity regulation in rivers, such as via weirs and dams, affects the plankton community. We hypothesized that the longitudinal similarity of the zooplankton community in a river could change in a river–reservoir hybrid system (RRHS). The impact of weir construction on zooplankton communities in terms of species diversity, abundance, and community structure was examined biweekly at six sites on the Nakdong River for 14 years (before construction: 2002–2008; after construction: 2012–2018). We checked time-series alignment using a dynamic time-warping method between longitudinal survey sites. After RRHS, the zooplankton community showed an increasing number of species. However, RRHS decreased the longitudinal similarity in terms of number of zooplankton species and population density. Our results demonstrate the negative effect of lateral infrastructures on zooplankton populations due to river fragmentation and habitat alteration.

This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging period from October 2010 to June 2012. The water quality, number of species, population densities, and biotic indices were compared for both dredging period and grouping type. Nine of 11 water quality parameters were changed by the dredging period. The results showed that the rotifer and planktonic groups were consistently dominant. In all groups, population density was the lowest during the dredging period. After dredging, both the number of species and population density increased only in the epiphytic group. The dominant species, including Polyarthra vulgaris, Brachionus calyciflorus, B. rubens, and Bosmina longirostris, were included in the planktonic group for 9 years. Evenness did not differ, but diversity increased after the dredging period. This study showed that zooplankton could be used as a supplemental biological assessment tool for evaluating the impact of river dredging.

Eui-Jeong Ko, Hyosun Leem, Junghyun Lee and Wooseok Oh*. J Ecol Environ 2024;48:. https://doi.org/10.5141/jee.23.074

In this study, we created a map to present the results of the third survey on national environment, following the ecological and natural map guidelines established by law. For the terrestrial areas of the Republic of Korea, we conducted three assessments, vegetation, landform, and endangered species, at a national scale. The results yielded an ecological map covering 99,138.5 km2. The map showed the area distribution of different grades as follows: 11.3% for grade 1, 31.4% for grade 2, and 57.3% for grade 3. Specifically, within grade 1, vegetation covered 90.5% of the area, endangered species covered 9.7%, and landform covered 1.3% (including overlapping areas). This map provides detailed information including habitats of endangered species that were previously inaccessible to the public. Additionally, it offers insights into management areas with separately managed zone that could not be identified in existing ecological and natural maps.