Dong-Soo Kong

Development of Benthic Macroinvertebrates Streambed Index (BMSI) for Bioassessment of Stream Physical Habitat

This study was conducted to develop a Benthic macroinvertebrates streambed index (BMSI) based on the response of the community to the substrate type of streambed. Analyzing the seasonal (Spring and Fall) data (11,367 sampling units) surveyed and collected during 2008~2014 at 960 sites in South Korea, we estimated the lithophility of 191 taxa. BMSI was composed of the lithophilic value, indicator weight value and individual abundance frequency. It showed an extremely significant correlation ( = -0.8, p<0.001) with the mean grain size (in phi-value) of the streambed.

Korean stream types based on benthic macroinvertebrate communities according to stream size and altitude

ABSTRACT Type-specific stream assessment systems based on biotic indicators are considered a main focus of future stream assessment in many European countries. However, there is a lack of information on type-specific differences of freshwater eco-regions in South Korea. We aimed to classify the stream types characterized by stream size and altitude. Analyzing the relationship between physical environmental variables and benthic macroinvertebrates collected between 2008 and 2015 at 1,020 sites (i.e. 13,366 samples) on a national scale in South Korea, we classified a total of five Korean stream types. All streams were divided into wadeable and non-wadeable streams using stream order and width. Wadeable streams were classified as mountain, highland, or lowland wadeable streams based on altitude. Non-wadeable streams were divided into lowland non-wadeable streams or rivers based on width. Mountain and highland streams significantly correlated with altitude, whereas others were distinctly related to stream order and width. We selected 25 indicator species sensitive to stream size and altitude. These assessments will provide preliminary information for development of a future biotic stream assessment system based on stream typology.

Comparative Analysis of Benthic Macroinvertebrate Communities Before and After the Restoration Project in the Kyoungan Stream

This study aims to analyze the changes in the benthic macroinvertebrate community before and after a restoration project in a eutrophic stream. Species diversity and species richness increased at the points where the channel changed from standing water to running water. However, species diversity and richness decreased at the points where only riparian restoration was implemented, and the concentration of suspended solids increased, while biochemical oxygen demand and total phosphorus decreased and the concentration of dissolved oxygen increased. In such reaches, functional feeding groups went from collector-filterers to collector-gatherers, and habitat orientation groups changed from clingers to burrowers.

Disturbance of Korean Lake Ecosystems by Aquaculture and Their Rehabilitation

The many artificial, multipurpose reservoirs in the Republic of Korea (henceforth, Korea) have been used for water storage, flood control, hydroelectricity, sightseeing, fishing, aquaculture, and other activities. In 1978, cultured fish contributed 1,831 metric tons (t) of product per year to the inland fishery. By 1992, the cultured-fish contribution had drastically increased to 20,049 t per year. Aquaculture in reservoirs contributes most of this production. Most cultured fishes are alien fishes. Concomitant with the increase in the aquaculture industry, many ecological, limnological, and biological problems emerged. Among them, reservoir eutrophication and the spread of alien-fish species into Korean waterways are severe problems. Lake Soyang, the largest and the most important reservoir in Korea, was constructed in 1973 and has a water-holding capacity of 2.9 billion tons. From 1978 through 1997, the lake supported many fish farms for the production of alien species such as mirror carp (Israeli carp) (Cyprinus carpio), channel catfish (Ictalurus puntatus), and rainbow trout (Oncorhynchus mykiss). These fishes were raised with fish feed, which has a high phosphorus concentration. Prior to the introduction of aquaculture, the lake was very clean; Secchi-disk transparency was 9 m, and phytoplankton density was low. However, after 10 years of aquaculture, symptoms of eutrophication appeared, such as an anoxic zone in the hypolimnion, low dissolved oxygen layers in the metalimnion, increased Anabaena spp. density, and high phosphate concentration in the hypolimnion. It was believed that the eutrophication was due to an increase of phosphorus from the fish feed. In 1990, the annual total phosphorus (TP) loading into the lake from the watershed was 104 kg=yr, and that from the fish farms was 48 kg=yr. The critical TP loading for eutrophication of Lake Soyang is 87 kg=yr. The fish farms were thus believed to be a major cause of eutrophication. All of the fish farms were closed and removed between 1997 and 1999. The water quality of Lake Soyang should improve sooner or later. Also a new and different ecosystem will be established. Alien fishes also predominate in Lake Paldang, which is the major source of drinking water for 20 million people. Bluegill (Lepomis macrochirus), imported Crucian carp (Carassius cuvieri), largemouth bass (Micropterus salmoides), and other