Lakes and reservoirs represent key freshwater ecosystems that host diverse aquatic organisms and perform essential functions such as water cycling, nutrient retention, and ecosystem service provision. Due to their semi-closed hydrological structure and limited inflow-outflow dynamics, lakes exhibit complex biological communities shaped by regional climate, topography, and land use. However, these ecosystems are increasingly exposed to multifactorial stressors-including climate change, urbanization, nutrient enrichment, and invasive species-that are causing significant structural and functional shifts in aquatic biodiversity. This review provides an integrative overview of (1) the structural and ecological characteristics of lake ecosystems and the primary drivers of biodiversity alteration, (2) the ecological functions and bioindicator potential of key organism groups including phytoplankton, zooplankton, aquatic macrophytes, benthic macroinvertebrates, and fish, and (3) the emerging role of environmental DNA (eDNA) metabarcoding in lake biodiversity monitoring. We highlight both the technical principles and challenges of eDNA analysis and discuss its potential to complement traditional survey methods for the development of integrated ecosystem health assessments. Positioned at the forefront of the 2025 special issue of Ecology and Environment, this article establishes a conceptual and methodological foundation for a national-scale freshwater biodiversity monitoring framework in Korean lakes.

This study investigated the fish fauna of Jeonjucheon and Samcheon Streams, flowing through the city of Jeonju, through surveys conducted at 10 sampling sites using kick net and cast net. The fish fauna collected included 10 families and 36 species, with a total of 2,064 individuals. Samcheon had 8 families and 30 species with 1,074 individuals, Jeonjucheon had 8 families and 26 species with 986 individuals. The dominant species was Zacco platypus with 1,202 individuals, and a total of 153 individuals of the subdominant were Pseudogobio esocinus. In Jeonjucheon Stream, a total of 567 individuals of the dominant species were collected as Z. platypus and 99 individuals of the subdominant species were collected as Pungtungia herzi, and there was no significant change in the stream environment except for the confluence site. Further expanded research covering the entire Jeonjucheon and Samcheon Streams region, accompanied by regular monitoring, is essential to record and understand fluctuations in fish fauna.