Comparison of Benthic Macroinvertebrate Community Structure in Relation to Different Types of Human Disturbance along the Pong River, Khon Kaen Province(Thai)

Abstract

Benthic macroinvertebrates were seasonally sampled from 17 stations along the Pong River, Khon Kaen Province, Thailand during 2002 and 2003. Six replicates of samples were taken by Ekman Grab from each sampling site. Three phyla, 15 orders, 65 families, 123 genera and 123 species were identified and were dominated by aquatic insect larvae. Data on biological metrics showed that the total number of taxa of the benthic macroinvertebrates varied through time, space and distance over the study sites. It increased in the zone after the dam (z1) and the zone of fish cages (z3) and declined in the zone of the pulp and paper mill factory (z2), the sugar mill factory and urban areas (z4, z5, z6). ET (Ephemeroptera and Trichoptera) taxa and % ET declined in the zone of the pulp and paper mill factory (z2), the zone of the fish cage culture (z3), the zone of the sugar mill factory and urban area (z5) and the zone after the sugar mill factory and urban area (z6), whereas they increased in the zone after the dam (z1) and the zone before the sugar mill factory and urban area (z4), particularly in November 2002. Canonical correspondence analyses (CCA) were used to determine macroinvertebrate distribution related to environmental variables. In 2002, most community structures of macroinvertebrates at z2, z5 and z6 were categorized as the same group and were 40% different from the other groups. From CCA, BOD was significantly correlated with axis (r>0.05) and BOD at z2 and z6 increased. The community structure of macroinvertebrates at z2, z4, z5 and z6 however was designated as the same group as in 2003. Data on CCA showed that the color of water was significantly correlated with axis (r>0.05), particularly color of water at z2, z5 and z6 which increased in April 2003. This result may suggest that the benthic macroinvertebrate community can be used to qualify characteristics of the Pong River as less impacted sites (z1 and z3) and impacted sites (z2, z4, z5 and z6) and to assess the effects of human disturbances.