Distribution And Diversity Of Zooplankton As Bioindicator Of Water Quality Status In Air Itam Reservoir, Penang, Malaysia
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Date
2009-05
Authors
Intan Sari
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Zooplankton composition and abundance, and water quality parameters were studied in Air Itam Reservoir from May 2006 to February 2007. This study investigates the community structure of zooplankton as indicators of water quality of the reservoir, which was constructed for domestic water supply. Zooplankton was sampled with a Wisconsin plankton net of 80 μm mesh size, from five meters vertical intervals. Physicochemical parameters used as the indicators of water quality were dissolved oxygen (DO), temperature, pH, biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, nitrates, nitrites, orthophosphates, total suspended solids (TSS), total dissolved solids (TDS), water transparency and total coliform bacteria. Five sampling stations were designated including three stations located in the reservoir (Stations A, B and C) and two stations in the upstream and downstream (Stations D and E) respectively. A total of 26 taxa, with 18 belong to Rotifera, six Cladocera and four Copepoda, were recorded. The most common and dominant species were Polyarthra vulgaris, Ceriodaphnia cornuta, Moina micrura, Mesocyclops leuckarti and Thermocyclops crassus while Filinia opoliensis, Alona karua and Tropocyclops prasinus were rare species recorded. These species are considered as the indicators of low level of organic pollution. Lower number and diversity of zooplankton were recorded at Stations D and E. A Canonical Correspondence Analysis (CCA) revealed a strong contribution of
NH4-N (P=0.061), temperature (P=0.28), PO4-P (P=0.001), NO2-N (P=0.003), NO3-N (P=0.05), TDS (P=0.86), COD (P=1.68), TSS (P=0.018) and pH (P=0.19) to the association of zooplankton assemblage and water quality parameters. Shannon-Weiner’s Diversity Index was the highest at Station C (2.06 ± 0.08 bits/individual) and the lowest at Station D (0.90 ± 0.40 bits/individual). Water Quality Index (WQI) was calculated by using the WQI recommended by Malaysian Department of Environment (DOE). The WQI of Stations A, B and C which lies between 92.02 – 93.64 were classified as clean to very clean water conditions. Stations D and E recorded the WQI values of 91.55 and 88.46 respectively which were classified as clean. Mean total coliform at Stations A, B and C was lower than Stations D and E. The highest value was at Station E (96.10 ± 34.31 MPN/100 ml) and the lowest value was at Station B (2.29±1.31 MPN/100 ml). Based on zooplankton community structural analysis and water quality parameters, it can be concluded that Air Itam Reservoir was in good conditions and clean throughout the sampling period. Therefore, the status of water quality in this reservoir is acceptable for water supply and human consumption.
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Keywords
The community structure of zooplankton , as indicators of water quality of the reservoir