Seasonal Changes in Mayfly Communities and Abundance in Relation to Water Physicochemistry in Two Rivers at Different Elevations in Northern Peninsular Malaysia

A field study was performed at rivers in Gunung Jerai forest reserve(Kedah,Malaysia) to assess seasonal changes in mayfly community structure and abundance in relation to altitude and water physicochemistry.Rivers at lower(Batu Hampar River) and higher(Teroi River) elevations were visited through dry and wet seasons in September 2007 to August 2008.Monthly visits were made to 20 sites on each river,and water and aquatic insects were sampled using D-pond aquatic nets.Water was warmer,more acid,and more turbid in Teroi River during wet season.Ammonia was the only nutrient exhibiting significant seasonal variations(greater during wet season).Chemical oxygen demand content was higher in Teroi River where biochemical oxygen demand content was low during wet season.Species richness was higher in Batu Hampar River,but displayed seasonal variations only in Teroi River.Among the eight families encountered,Baetidae was the commonest.Baetid abundance was usually high during wet season,and those belonging to the dominant genus(Baetis) were more abundant in Teroi River.Heptageniidae was the second commonest family;its predominant genus,Thalerospyrus was more abundant in Teroi River during dry season.Caenidae,Leptophlebiidae and Oligoneuriidae were only found in Batu Hampar River where their abundances peaked during dry season,i.e.,Habrophlebiodes sp.and Isonychia sp.Ephemerellidae and Teloganodidae occurred only in Teroi River,with the first found only during dry season.Mayflies were recorded under very distinct physicochemical conditions,illustrating their potential usefulness for assessing water quality.Caenids,leptophlebids,oligoneurids ephemerellids and teloganodids seem to be particularly sensitive to temperature,acidity,turbidity,chemical oxygen demand and biochemical oxygen demand,parameters that varied with river altitude.

Determination of Water Quality of Rivers under Various Land Use Activities Using Physico-chemical Parameters and Bacterial Populations in Northern Peninsular Malaysia

A study on water quality of rivers with different land use activities by using physico-chemical parameters and bacterial population was conducted around Kedah, Penang and Perak, Malaysia. The water quality parameters such as dissolved oxygen(DO), five-day biochemical oxygen demand(BOD5), chemical oxygen demand(COD), total dissolved solids(TDS), total suspended solids(TSS), nitrate, p H, ammonia-nitrogen, water temperature, water depth and velocity were measured and the densities of bacteria which were total coliform(TC) and fecal coliform(FC) were monitored simultaneously using IDEXX-Colilert?technique from selected rivers. The greatest population of TC and FC(>2 419.6 n MPN/100ml) were recorded from industrial rivers while the lowest reading recorded in less disturbed rivers with less than 1 MPN/100 ml. Total coliform count categorized all rivers into Class I and FC count showed five rivers fell into Class I(Sungai Sedim, Bukit Hijau, Teluk Bahang, Kurau and Tukun), two rivers fell into Class IIA(Sungai Batu Hampar and Salleh) and eight rivers fell into IIB categories(Sungai Jerejak,Pinang, Air Hitam, Kluang, Chelong, Titi Hayun and Cherok Tokun). There was a significant difference between the TC population with TSS content(r=0.43), TDS content(r=0.813), river depth(r=0.513) and DO level(r=-0.401) from all selected rivers.Fecal coliform population was greatly influenced by contents of BOD5(r=0.456), COD(r=0.531), TSS(r=0.813), TDS(r=0.724), and water temperature(r=0.711). The rivers with industrial land-use setting recorded the highest range of water quality index scores and fell into Class III(Sungai Jerejak, Air Hitam and Kluang) and Class V(Sungai Pinang). Both plantation rivers(Sungai Chelong and Sungai Salleh) fell into Class II and all recreational and less disturbed rivers fell into Class I.