Seasonal Diversity of Microeukaryotes in the Han River, Korea Through 18S rRNA Gene Metabarcoding

Abstract

Freshwater ecosystems contain a large diversity of microeukaryotes that play important roles in maintaining their structure. Microeukaryote communities vary in composition and abundance on the basis of temporal and environmental variables and may serve as useful bioindicators of environmental changes. In the present study, 18S rRNA metabarcoding was employed to investigate the seasonal diversity of microeukaryote communities during four seasons in the Han River, Korea. In total, 882 unique operational taxonomic units (OTUs) were detected, including various diatoms, metazoans (e.g., arthropods and rotifers), chlorophytes, and fungi. Although alpha diversity revealed insignificant differences based on seasons, beta diversity exhibited a prominent variation in the community composition as per seasons. The analysis revealed that the diversity of microeukaryotes was primarily driven by seasonal changes in the prevailing conditions of environmental water temperature and dissolved oxygen. Moreover, potential indicator OTUs belonging to diatoms and chlorophytes were associated with seasonal and environmental factors. This analysis was a preliminary study that established a continuous monitoring system using metabarcoding. This approach could be an effective tool to manage the Han River along with other freshwater ecosystems in Korea.

Fungal Diversity in Nam River and Their Biodegradative Activities

“…Additionally, widespread distribution of genera like Aspergillus , Cladosporium , Penicillium , Epicoccum , Paraconiothyrium , Septoriella , and Talaromyces , regardless of aquatic conditions or marine environment, have been reported [ 5 ]. These fungal clusters exhibit diverse compositions and sizes based on seasonal and environmental variables, serving as valuable biological indicators of environmental changes [ 6 ]. Furthermore, fungi isolated from ecosystems represent crucial resources due to their potential for various beneficial purposes.…”

Metabarcoding by Combining Environmental DNA with Environmental RNA to Monitor Fish Species in the Han River, Korea

“…Importantly, the downstream area of the Han River is the main water source for the half of the Korean population who reside in the Seoul metropolitan area. Due to its value and significance, the health of the Han River is very important, and it is crucial to implement effective monitoring protocols for water quality management [25]. However, ecological surveys within the Han River basin have focused on the middle and upstream regions, with limited attention given to the downstream region [25,26].…”

“…Due to its value and significance, the health of the Han River is very important, and it is crucial to implement effective monitoring protocols for water quality management [25]. However, ecological surveys within the Han River basin have focused on the middle and upstream regions, with limited attention given to the downstream region [25,26]. Furthermore, previous studies conducted in this region have predominantly relied on observational methods, with a notable lack of molecular investigations that used eDNA and/or eRNA metabarcoding for studying fish species in this area.…”