Biodiversity Changes of Benthic Macroinvertebrates in Tamjin river system by Jangheung Dam Construction

Benthic macroinvertebrates in freshwater include Nematoda, Annelida, Mollusca, and Arthropoda etc. Insects in arthropoda are among the most conspicuous inhabitants of streams and rivers and occupy up to 95% of macroinvertebrates. In most cases, it is the larval stages of these insects that are aquatic, whereas the adults are terrestrial. Tamjin river system was surveyed seasonally for 13 years (1998–2010) to study the biodiversity changes of macroinvertebrtes by Jangheung Dam construction. Total macroinvertebrates consist of 139 species, 101 genera, 59 families, 19 orders, 6 classes in 4 phylums. To start 57 species in 1998 before the dam construction, 41 species were in 1999 which is the first year of construction. After the construction the number of species increased gradually and 73 species emerged in 2009 and 2010. The individual number fluctuated annually and it is difficult to infer the comprehensive results, but ephemerids decreased dramatically after the construction and then they increased gradually since 2006, whereas caddisflies increased rapidly and decreased. Among the studied taxa Ephemeroptera showed the highest diversity relatively, and the next was Trichoptera and Coleoptera. The species occurrence pattern was stable in Ephemeroptera as 15–24 species and fluctuated in Trichoptera ranged from 4 species (2001) to 15 species(2008). In Diptera, 8 species emerged up in 2003 and 2007 and 3 species in 1998 and 1999 and in Coleoptera, 3–6 species emerged in stable pattern.