Paper Title
Influence of Physıcochemıcal Parameters on Abundance of Aquatıc Insects ın Rivers of Perak, Malaysıa

The effect of physicochemical factors on the abundance of aquatic insects has been studied in Kuala Woh, LataKinjang, BatuBerangkai and Dipang Rivers, Perak, Malaysia. The focuses are to identify the aquatic insect families, to compare the abundance of aquatic insects in four sampling areas and to investigate the effect of physical factors (water temperature, depth of water, canopy, and water velocity) and chemical factors (pH and dissolved oxygen) of rivers on the abundance of aquatic insects. The samples were collected by using aquatic net. Physical and chemical parameters have been measured in situ and recorded. A total of 631 individuals classified into 6 orders and 18 families of aquatic insects were identified from four sampling sites. The largest percentage of samples collected is from order Plecoptera 35.8%, followed by Ephemeroptera 32.6%, Trichoptera 17.0%, Hemiptera 8.1%, Coleoptera 4.8%, and Odonata 1.7%. The aquatic insects collected from Dipang River have the highest abundance of 273 individuals from 6 orders and 13 families compared to Lata Kinjang which only have 64 individuals from 5 orders and 6 families. Dipang River has a moderate stream flow (0.11 m/s) of warm water (27oC), pH 7.5 and DO 8.21 mg/L with 0.95 m depth and not covered by canopy. Lata Kinjang has faster stream flow (0.84 m/s) with the temperature of 24oC, pH 7.2 and DO 5.86 mg/L, 0.36 m depth and covered by canopy. The results reveal that the abundance of aquatic insects is high when water temperature increases, low water velocity, high dissolved oxygen (DO) level, deeper water and the area that is not covered by canopy. Keywords - Aquatic insects, Physicochemical factors, River.