Abundance And Diversity Of Ephemeroptera, Plecoptera, Trichoptera (Insecta) In Relation To Environmental Quality Of Upstream Rivers In Kedah, Malaysia
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Date
2011-07
Authors
Ab. Hamid, Suhaila
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
A relatively rich assemblage of Ephemeroptera, Plecoptera and Trichoptera (EPT) (17,315) (Insecta) immatures were collected from Tupah, Batu Hampar and Teroi rivers in the Gunung Jerai Forest Reserve. From monthly collections starting September 2007 until August 2008 using a kick-net sampling technique, 29 genera representing 19 families of EPT were identified. The EPT community structure and specific sensitivity of EPT genera were not influenced by river water quality (Class I - II of WQI) of which more than 20 taxa were collected from each river. The EPT was most abundant but less diverse in Teroi River while the reverse was recorded from Tupah River. The highest EPT abundance was recorded from Teroi River (9,667) followed by the Tupah River (4,298) and Batu Hampar River (3,350). High scores of EPT taxa richness (>10) indicated that all rivers were not impacted by human activities or natural disturbances. The CCA biplot showed that distribution of Etrocorema, Lepidostoma, Hydropsyche, Diplectrona and Chimarra were characterized by high temperature. Cheumatopsyche was regulated by high pH while Marilia and Thalerospyrus by high BOD. Centroptilum, Rhyacophylia and Platybaetis preferred low COD. The abundance of Plecoptera was not affected by seasonal changes but Ephemeroptera was more abundant in the wet season while more Trichoptera occurred during the dry season (z = -6.096, P = 0.00). EPT community function in Tupah River, measured as leaf breakdown rate, was faster in the two species leaf (28 days) than in single species leaf (35 days). In cages without these insects, the two-species leaf and single-species leaf took 35 and 42 days respectively to completely decompose. The EPT reduced the decomposition time by 7 days in both leaf packs. Based on distribution of body length, Thalerospyrus sp. (Ephemeroptera: Heptageniidae) had a trivoltine life cycle at lower altitude in Tupah and Batu Hampar rivers but a bivoltine life cycle occurred at higher altitude in Teroi River. Light trapping of EPT adults showed that Trichoptera was the most abundant and diverse in Tupah River.
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Keywords
Abundance and diversity of ephemeroptera , environmental quality of upstream rivers in Kedah