Abstract
ABSTRACTIchthyofauna and fish community were investigated at 17 representative stations of the Dongjin River drainage system from spring to fall in 2014. The survey resulted in a list of 53 species belonging to 14 families structured into 4 distinctive parts along the river: uppermost-stream, upper-stream, mid-stream, and lower-stream. Comparison of species lists with 30-year interval exhibited significant decreases in peripheral freshwater fishes, Acheilognathinae, endemic, and indigeneity species, but increases in exotic, epipelagic, and lentic species. Moreover, in the estuary of the Dongjin River drainage system, peripheral freshwater fish species were replaced by pure freshwater fish species due to the Saemangeum sea-wall project. In the upper region of the river, introduced eight alien species from Seomjin River via water diversion tunnels. In the mid-lower region, the construction of floodgates and numerous small weirs caused expansion of lentic water areas, facilitating the spread of problematic exotic species such as Micropterus salmoides, Lepomis macrochirus, and Carassius cuvieri. Also, water deterioration in this region resulted in an increase of tolerant species and a decrease of sensitive and endemic species. Our results suggest that a recovery strategy for a healthy ecosystem in the Dongjin River drainage system should reflect this compartmentalized cause and effect on the changes of icthyofauna.
Highlights
Natural distribution of temperate fishes is affected by multiple factors, including Pleistocene events, zoogeographic barriers, physiological factors, and biological interactions (Moyle & Cech 2000)
Introduction and dispersal of exotic fish species such as Lepomis macrochirus and Micropterus salmoides have been reported (Kim & Lee 1984; Kim 2000). Given these most notable and unique environmental changes in the Dongjin River, the objectives of this study were: (i) to present recent investigation results of ichthyofauna, the fish community and river health assessment in the entire Dongjin River in 2014, (ii) to compare these results with the results of previous investigations completed by Kim and Lee (1984), Kim (2000) and Kim et al (2009), and (iii) to discuss the causes and changes in the past 30 years
The present study investigated the changes of ichthyofauna in the Dongjin River drainage system in the past 30 years and explained faunal changes in the light of major influential environmental factors of that river
Summary
Natural distribution of temperate fishes is affected by multiple factors, including Pleistocene events, zoogeographic barriers, physiological factors, and biological interactions (Moyle & Cech 2000). Rapid industrialization and modernization of South Korea since the 1960s have brought in parallel pollution and construction of many large dams, weirs, and sea walls in rivers. These anthropogenic changes have caused severe deterioration of water quality as well as alteration in flows of rivers and streams in many places of Korea (Kwater 2007, Jang et al 2010). Health assessment of the river has been dependent on chemical factors, such as organic, toxic, and nutrient materials. Biological and physical factors are added in assessment of the river health (Barbour et al 1999). Biological assessment since the development of the index of Biological Integrity (IBI), many countries assess the river health using fish, benthic invertebrates, attached algae, and waterside vegetation (Oberdorff & Hughes 1992; Lee & An 2014)
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