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5.1 Introduction

The larvae of non-biting aquatic midges ( Chironomidae: Diptera ) are considered as ideal beings for bio-assaies because they spend most of their developmental clip in deposits ‘ surface where they remain open to different poisons ; besides, they are comparatively easy to civilization and have a short life rhythm. These standards make them suited beings for ecotoxicological monitoring ( Warwick 1985, Ingersoll and Nelson 1990, Vermeulen 1995 ) . When continuously exposed to emphasize or pollution, late instars of some chironomid larvae often develop malformations in the mouthparts, particularly the mentum. An bing hypothesis based on field observations is that the malformations in benthal midge larvae are a contemplation of the environmental pollution due to heavy metals, radiation, organic pesticides, and other xenobiotics ( Bird 1994, Servia et Al. 1998, Watanabe et Al. 2000, Vermeulen et Al. 1995, Martinez et Al. 2004 ) . The happening of developmental malformations in chironomids appears to be a general emphasis response to a broad scope of environmental contaminations ( Vermeulen 1995 ) , however, morphological malformations in chironomid larval populations in uncontaminated environments could besides happen but are comparatively less terrible and less frequent than those happening under the stressed conditions ( Warwick 1985 ) . The larval malformations could supply a utile tool for measuring aquatic pollution, specifically that relates to industrial wastes and agricultural overflow ( Wiederholm 1984, Warwick 1985, Warwick and Tisdale 1988, Janssens de Bisthoven et Al. 1992, Lenat 1993, Vermeulen 1995, Dickman and Rygiel 1996, Hamalainen 1999, Bhattacharya et Al. 2005, MacDonlad and Taylor 2006 ) .

Attempts to show the relationship of malformation incidence in chironomid larvae with H2O and deposit quality have been made ( Vermeulen 1995 ) . The application of chironomid malformations as bioindicators of pollution emphasis has been reviewed and illustrated chiefly for bioassessment intents ( Hamalainen 1999 ) . In this context, many research workers have developed several malformation indices based on different types of chironomid larval caput capsule malformations to better understand the causes. For illustration, the open uping Index of Severity of Antennal Deformities ( ISAD ) of Warwick ( 1985 ) was based on antennary malformations of Chironomus larvae, whereas the Toxic Score Index ( TSI ) proposed by Lenat ( 1993 ) was based on deformity of the mentum of Chironomus larvae. The latter writer categorized the malformations of mentum into three categories: Class I includes little malformations which are hard to divide from the “ chipped ” dentitions ; Class II consists of larvae with more conspicuous malformations, such as excess dentitions, losing dentitions, big spreads, and distinguishable dissymmetry ; and in Class III are included the larvae that suffer terrible distortion, including at least two Class II characters. Harmonizing to Lenat ( 1993 ) , the TSI can be computed as follows:

[ No. Of Class I +2 ( No. Of Class II ) + 3 ( No. Of Class III ) ] x 100 / Total Number of Larvae.

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The pollution of aquatic ecosystems in Malaysia has emerged as a major ecological job co-occuring with rapid industrialisation and urbanisation. In 1994, Malaysian Department of Environment ( DOE ) classified the Juru River ( situated in northeasterly peninsular Malaysia ) as “ really contaminated ” based on the Water Quality Index ( WQI ) classification by DOE ( DOE 1994 ) . Lim and Kiu ( 1995 ) pointed out that the Juru River is one the most contaminated rivers in Malaysia, with deposits extremely contaminated with non-residual heavy metals, such as Cd, Cu, Pb, and Zn. These contaminations in the river are most likely a consequence of discharges from the visible radiation and heavy industries in the Prai Industrial Estate ( established in the early 1970s ) , Penang, Malaysia ( Mat and Maah 1994 ) .

In Malaysia, considerable attempts have been made in the past two decennaries to analyse chemical pollution in several rivers ( including the Juru River basin ) ( e.g. , Mat and Maah 1994, Lim and Kiu 1995 ) , nevertheless, comparatively much less attending is paid to use aquatic beings for intents of environmental bioassessments ( Morse et al. 2007 ) . The available surveies refering effects of contaminations on aquatic invertebrates in Malaysia at present chiefly focal point on diverseness and copiousness of benthal macroinvertebrates populating contaminated rivers ( Azrina et al. 2006 ) .

The public-service corporation of changes in chironomid larval caput capsule morphology, such as distortion, phenodeviations, dissymmetries, etc. , has proven to be utile in footings of bespeaking aquatic pollution-related emphasis in many states, such as Canada ( Warwick 1985, MacDonald and Taylor 2006 ) , Sweden ( Wiederholm 1984, Janssens de Bisthoven and Gerhardt 2003 ) , and India ( Bhattacharya et al. 2005 ) , but no such survey has applied this empirical tool in Malayan rivers.

The present survey was undertaken with the aim of clarifying the incidence of malformations in Chironomus spp. larvae collected from three little rivers in the Juru River Basin. Specifically, the incidence of morphological abnormalcies of the epipharyngis, aerial, mentum, and lower jaws of the fourth-instar larvae of Chironomus spp. collected from these rivers that differed in their nature of taint was studied. The badness of mentum dentition malformations was used as a standard to measure effects of pollution and was scored utilizing the TSI of Lenat ( 1993 ) .


5.2.1 Study Area and Sampling Sites

For the present survey, three little rivers, [ Permatang Rawa River ( PRR ) , Kilang Ubi River ( KUR ) , and Pasir River ( PR ) ] in the Juru River system were selected ( see Chapter 3 ( 3.2.1 and Figure 3.1 ) . In each river, one permanent site for roll uping chironomid larvae and H2O and deposit samples was established.

5.2.2 Physico-chemical Parameters of Water

See Chapter 3 ( 3.2.2 ) .

5.2.3 Sediment Samples

See Chapter 3 ( 3.2.3 ) .

5.2.4 Chironomid Larval Sampling

The chironomid larvae were collected from the three rivers from November 2007 to March 2008. See Chapter 4 ( 4.2.2 ) .

5.2.5 Chironomid Deformities Investigation

Permanent slide saddle horses of chironomid larvae were prepared to analyze morphological malformations in the larvae. The preserved larvae were transferred to a Petri dish incorporating 10 % KOH solution and left in the solution for 24-48 H to digest the larval musculuss. Thereafter, the lasting slide saddle horses of the larvae were prepared following the method of Epler ( 2001 ) . The slide-mounted larvae were identified to genus utilizing appropriate systematic keys ( Kikuchi et al. 1985, Hasegawa and Sasa 1987, Morse et Al. 1994, Merritt and Cummins 1996, Epler 2001, Cranston 2004 ) . No effort was made to place the larvae to species degree because of systematic troubles in the designation of chironomid immature phases ( Warick and Tisdale 1988 ) . Larval caput capsules of 4th instar Chironomus spp. were examined for malformations under a compound microscope, by and large at 400X magnification ; mentum, epipharyngis, lower jaws, and aerials were examined for malformation happening. Examination of the aerial was carried out merely for gross malformations, such as losing or excess section, or major differences in size of sections between both aerial. Harmonizing to Bird ( 1994 ) , epipharyngis and lower jaws are classified as deformed if they exhibit excess dentitions, losing dentitions including spreads, or are really asymmetrical or unnatural in form. Damaged aerial or lower jaws as a consequence of cleansing and mounting procedure of these oral cavities parts normally have disconnected interruptions that are readily seeable and easy distinguishable from deformed constructions ( Dermott 1991 ) .

The mentum of Chironomus spp. has 15 dark pigmented teeth consisting a three-party average agreement of one big tooth flanked on either side by individual smaller dentitions and two larger and four smaller outer dentition ( Cranston 1995 ) . The happening of mentum malformations in the present survey was scored harmonizing to Lenat ( 1993 ) .

5.2.6 Statistical Analysis

The incidence of distorted larvae ( mouth parts ) from the different rivers was expressed as the proportion A± criterion mistake ( SE ) of the entire larvae mounted from each river. Standard mistakes were calculated harmonizing to the binomial theorem, i.e. , SE= ( pq/k ) 1/2, where “ P ” is the proportion of distorted specimens, “ Q ” is the proportion of non-deformed persons, and “ K ” is the sample size ( Hudson and Ciborowski 1996 ) . The average per centum of malformations from single trying site was compared utilizing the non-parametric process ( Kruskal-Wallis Test ) and general additive theoretical accounts of the SPSS package bundle. The information of malformations incidence per centums were transformed utilizing the arc-sine a?sx transmutation prior to analysis. The Redundancy Analysis ( RDA ) of CANOCO plan ( ter Braak and Prentice 1988, ter Braak 1989 ) was used to look into influence of the environmental parametric quantities on the entire malformations incidence, including mentum, lower jaws, aerial, and epipharyngis malformations. Specifically, the RDA provides the dimensions of the influencing parametric quantities, bespeaking the strength and way of correlativity between these parametric quantities and incidence of the morphological malformations. In this analysis, all measured environmental parametric quantities were included and the plan performed forward choice of important parametric quantities.

5.3 Consequence

5.3.1 The Incidence of Deformity in Chironomus spp. Larvae

A sum of 616 Chironomus spp. larvae collected from the three rivers was processed and examined for malformation incidence. Statistical analysis of the informations revealed a important difference between malformation incidence among the three rivers ( Kruskal-Wallis, n = 15, X2= 8.66, P & lt ; 0.05 ) . Overall, this incidence was the highest in the larvae collected from KUR, followed by PRR, and PR ( Table 5.1 ) . The ascertained monthly per centum larval malformation in Chironomus spp. in the three survey rivers is shown in Table 5.1. In KUR, merely 59 larvae were successfully mounted for the malformation probe. In this river, an overall malformation incidence of 47.17 % was recorded with monthly incidence runing from 0 % ( November 2007 ) to 68.42 % ( January 2008 ) . In November 2007, merely 3 larvae were collected from this river with no malformation noticed in them. In PRR, the overall per centum mean malformation amounted to 33.71 % among the entire 448 larvae collected, with monthly incidence runing from 26.6 % ( December 2007 ) to 40.9 % ( March 2008 ) . In PR, the overall ascertained malformation incidence was 30.34 % . In this home ground, the lowest malformation incidence was recorded in January 2008 ( 15.38 % ) and the highest ( 42.3 % ) in March 2008.

The malformations in Chironomus spp. larval menta ( Figure 5.2 ) amounted to 27.9, 20.87, and 30.19 % in the PRR, PR, and KUR, severally. However, incidence of malformation in lower jaws ( Figure 5.3 ) was comparatively low and amounted to 3.79 % ( PRR ) , 3.48 % ( PR ) , and 3.77 % ( KUR ) ( Figure 5.6 ) .

There was no statistically important difference ( P & gt ; 0.05 ) between malformations of menta or malformations of lower jaws in Chironomus spp. larvae collected from the three rivers. Among the malformation traits of mentum, Kohn spread, missed dentitions, fused dentition, and broken dentitions were the most dominant. Although malformations in lower jaws were comparatively rare, but where present, were terrible ensuing in broken or losing dentitions. The incidence of malformation in epipharyngis ( Figure 6.4 ) was by and large lower compared with mentum malformations, with the highest incidence ( 18.87 % ) happening in KUR and the lowest ( 6.96 % ) in PR. The highest per centum ( 10.43 % ) of antennary malformation ( Figure 5.5 ) was recorded in the PR and the lowest ( 4.91 % ) in the PRR. Statistical analysis revealed that the incidence of malformations in the epipharynges and aerial among the three rivers varied significantly [ Kruskal-Wallis, X2=21.46 ( n = 15 ) and 10.49 ( n = 15 ) , severally, at P & lt ; 0.05 ] . The differentiation in the incidence of malformations among the different caput capsule constructions of Chironomus spp. larvae in the three rivers is summarized in Figure 5.6.

Table 5.1: Larval malformation incidence ( per centum A± SE ) in Chironomus spp. sampled monthly ( November 2007-March 2008 ) from Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia. The entire figure of larvae processed and examined each month in each home ground is given in parenthesis






40.9A±4.61 ( 88 )

33.33A±2.16 ( 21 )

0.0A± 0.0 ( 3 )


26.6A± 4.28 ( 94 )

29.41A±1.88 ( 17 )

26.67A±1.71 ( 15 )


31.86A±4.95 ( 113 )

15.38A±1.30 ( 13 )

68.42A±2.03 ( 19 )


32.2A±4.45 ( 91 )

26.32A±2.71 ( 38 )

14.29A±0.93 ( 7 )


40.32A±3.86 ( 62 )

42.3A±2.52 ( 26 )

11.11A±1.25 ( 15 )

Overall mean

33.71A±10.01 ( 448 )

30.34A±4.94 ( 115 )

47.17A±3.63 ( 59 )

Table 5.2: Average A± SE values of selected physico-chemical parametric quantities of H2O and deposits measured monthly from November 2007 to March 2008 at a lasting sampling site in each of three rivers, Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) , in the Juru River Basin, Penang, Malaysia.





Water deepness ( centimeter )




River breadth ( m )








DO ( mg/l )




Temperature ( °C )




TOM ( % )




TSS ( mg/l )




Phosphate-P ( mg/l )




Ammonium-N ( mg/l )




Nitrate-N ( mg/l )




Sulphate ( mg/l )




Chloride ( mg/l )




Aluminum ( mg/l )




Sediment Zn ( ppm )




Sediment Mn ( ppm )




Sediment Cu ( ppm )




Sediment Ni ( ppm )




n = 15, ND = non detected

5.3.2 Possible Influence of Selected Environmental Parameters on Chironomid Deformities

Data refering assorted H2O and deposits physico-chemical parametric quantities measured during the survey period are summarized in Table 5.2. The average H2O deepness at the sampling locations at PRR, PR, and KUR was 19.07, 25.87, and 20.43 centimeter, severally, bespeaking these sites to be comparatively shallow. Similarly, average river breadth at trying locations at PRR, PR, and KUR measured 3.36, 4.65, and 3.42 m, severally. The average value of H2O pH in three rivers ranged from 6.90 ( PR ) to 7.10 ( PRR ) . As expected, the average value of dissolved O degree was instead low in all three home grounds, with KR demoing the lowest average value of 1.14 mg/l. Water temperature by and large remained 2-3 A°C higher in the PRR ( average 30.15 A°C ) , compared to the other two home grounds. Entire organic affair demoing a average value of 8.57 % in the PRR was 2-3 crease higher in this home ground than KUR where a average value of 3.29 was recorded ; in the PR average value of entire organic affair amounted to 6.21 % . Total suspended solids were the highest in PRR ( average value of 81.07 mg/l ) , followed by KUR ( average value of 68.57 mg/l ) , and PR ( average value of 22.57 mg/l ) . The phosphate-P content of H2O in the three rivers ranged from 2.15 mg/l ( PRR ) to 3.97 mg/l ( KUR ) ; in PR, the average value amounted to 2.67 mg/l. Ammonium-N content in H2O of PRR and PR had average values of 3.83 and 3.30 mg/l, severally, while the highest average value ( 5.62 mg/l ) of this parametric quantity was recorded in KUR. In the PRR, average nitrate-N value was 1.5 mg/l, whereas in PR and KUR, the average value of nitrate-N was 0.85 and 0.96 mg/l, severally. The sulfate content in the three rivers showed a big fluctuation, with the lowest average value of 6.38 mg/l recorded in PR and the highest 27.69 mg/l in KUR. In PRR H2O, the average value of sulphate concentration was 13.29 mg/l. The average value of chloride in the PRR, PR, and KUR was 5.45, 3.25, and 4.24 mg/l, severally. The aluminium concentration in samples of H2O from the three rivers ranged from 0.08 to 0.22 mg/l, with the highest concentration happening in PRR and the lowest in PR ; in KUR, aluminium concentration amounted to 0.17 mg/l. The concentration of this metal was about three fold higher in PRR compared to PR.

In the deposits of PRR, concentrations of non-residual metals, Zn, Mn, Cu, and Ni were 38.83, 50.54, 3.13, and 2.92 ppm, severally ; Mn was highest in concentration and was the chief contamination in this home ground, followed by Zn. In PR deposits, concentration of Zn at 24.81 ppm was the highest, followed by Mn, Cu, and Ni, with average values of 16.78, 1.98, and 3.01 ppm, severally. In KUR, Ni was below the sensing degree of the instrument used but Zn, Mn, and Cu concentrations amounted to 44.72, 17.91, and 1.64 ppm, severally.

Table 5.3 shows correlativity coefficient values between deformed mentum, epipharyngis, aerial, and lower jaws of Chironomus spp. larvae and assorted physico-chemical parametric quantities of H2O and deposits encountered in the three rivers. Among statistically important correlativities with mentum, entire organic affair, and entire phosphate-P were reciprocally correlated, while sediment Mn and Cu concentrations showed a positive relationship with mentum malformations. The epipharyngis malformations were negatively correlated with phosphate-P, ammonium-N, and sulphate concentrations in H2O, and positively correlated with dissolved O, and Mn in the deposits. The antennary malformations had a negative correlativity with phosphate-P, and positive correlativity with entire organic affair, and concentrations of Mn and Cu in the deposits. The lone statistically important correlativities between mandible malformations were a positive correlativity with entire organic affair, and opposite relationship with phosphate-P and sulfate in H2O.

The deliberate TSI for the three rivers based on the encountered frequence of Chironomus spp. larval mentum malformation is presented in Table 5.4. The information show that the highest TSI average value of 59.16 was recorded for PRR, followed by 46.15 for PR, and 44.05 for KUR.

Table 5.5 summarizes additive positive or negative relationship between TSI and assorted environmental parametric quantities in the three rivers. Among the statistically important correlativity coefficient values, in PRR, H2O pH, DO, and deposit Ni showed reverse relationship, while sediment Zn showed a positive relationship. Similarly, in PR, H2O pH, TOM, phosphate-P, and ammonium-N were negatively correlated with TSI, and DO had a positive relationship with TSI ; the deposit Cu was besides positively correlated with TSI in this home ground. In the KUR, the lone important correlativity was noted for deposit Mn holding a positive correlativity.

As shown in Figure 5.7, the RDA selected ( forward choice ) TSS, deposit Zn, Mn, Cu, and Ni, and H2O pH, dissolved O, H2O temperature, entire organic affair, nitrate-N, chloride, phosphate-P, ammonium-N, sulfate, and aluminium as parametric quantities that significantly affected some proportion of malformations. The first axis explained 75.1 % and the 2nd axis 15.5 % of the discrepancy and Montrcarlo substitution trial ( 499 substitutions ) was important ( P & lt ; 0.05 ) .

The entire malformations correlated closely with malformations of mentum but merely weakly with malformations in other parts of caput. The entire malformation incidence was strongly correlated with high contents of deposit Mn and Ni. The mentum and epipharyngis malformations incidence was extremely correlated with addition of TSS, entire aluminium, and ammonium-N, and lessening in pH and dissolved O.

Table 5.3: Non-parametric correlativity ( correlativity coefficient values ) between different types of malformations ( informations transformed utilizing arsina?sx2 ) in caput capsule oral cavity parts of Chironomus spp. larvae and H2O and deposit parametric quantities ( sampled from November 2007 to March 2008 ) in Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia.






Water deepness





River breadth

























Toxic shock



































Sediment Zn





Sediment Mn





Sediment Cu





Sediment Ni





*P & lt ; 0.05 ; **P & lt ; 0.01

Table 5.4: Calculated Lenat ‘s Toxic Score Index values ( Lenat 1993 ) based on frequence of mentum malformations in Chironomus spp. larvae sampled in Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia.

























Overall mean




Table 5.5: Correlation coefficient values between Lenat ‘s Toxic Score Index ( Lenat 1993 ) values based on frequence of mentum malformations in Chironomus spp. larvae and prevailing selected environmental physico-chemical parametric quantities in Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia.





















Toxic shock




























Sediment Zn




Sediment Mn




Sediment Cu




Sediment Ni




ND = Not detected

*P & lt ; 0.05







Figure 5.2: Deformities of mentum in Chironomus spp. larvae collected from three rivers in the Juru River Basin: A: Normal dentitions, B: Slightly broken median-lateral tooth, C: Badly broken average tooth, D: Kohn spread, Tocopherol: Amalgamate average dentition, F: Missing median-lateral tooth.




20 I?m

Figure 5.3: Deformities of larval lower jaw of Chironomus spp. collected from three rivers in the Juru River Basin: A: Normal mandible, B and C: Deformed lower jaw.

10 I?m



Figure 5.4: Deformities of pectin epipharyngis of Chironomus spp. larvae collected from three rivers in the Juru River Basin: A: Normal epipharyngis, B: Deformed epipharyngis.



Figure 5.5: Deformities of aerial of Chironomus spp. larvae collected from three rivers in the Juru River Basin: A: Normal aerial, B: Deformed aerial.

Figure 5.6: Percentage ( A± SE ) of malformation incidence in different constructions of caput capsule of Chironomus spp. larvae collected monthly ( November 2007 to March 2008 ) from Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia.





Entire Deformity




Lower jaws



Water Temp.


Toxic shock











Figure 5.7: First two axes from Redundancy Analysis ( RDA ) demoing the relationship between selected ( forward choice ) environmental parametric quantities and morphological malformation incidence in caput capsule constructions in Chironomus spp. larvae collected from Permatang Rawa River ( PRR ) , Pasir River ( PR ) , and Kilang Ubi River ( KUR ) in the Juru River Basin, Penang, Malaysia.

6.4 Discussion

None of the rivers investigated in this survey is perceived to be pristine or even clean because of their location amid countries of high alimentary lading from assorted industrial, agricultural, and anthropogenetic beginnings. These rivers are dominated by pollution-tolerant invertebrate taxa, such as Oligochaeta ( Tubifex sp. ) and Chironomus spp. ( informations non shown ) . The PRR is most likely contaminated with agricultural chemicals applied sporadically to the environing paddy Fieldss. The KUR receives industrial discharges from garment and gum elastic mills. The PR is polluted chiefly with domestic wastes ensuing from anthropogenetic activities in the environing residential countries of this river.

Application of populating beings in biomonitoring of aquatic ecosystems has several advantages over traditional chemical analyses for H2O quality. Freshwater organisms unrecorded about continuously in the H2O and respond to all environmental stressors, including interactive combinations of pollutants ( Morse et al. 2007 ) . Perturbation of the aquatic communities due to pollution is clearly proved ( Goodnight 1973, Kay et Al. 2001 ) . However, Hamilton and Saether ( 1971 ) suggested that probe of morphological abnormalcies in single beings might turn out peculiarly utile in finding the biological effects of contaminations in aquatic ecosystems although relatively small is known about how single beings react to contaminations. Petersen and Petersen ( 1983 ) stated that alterations at the organismic degree might be more utile than alterations at the community degree for intents of environmental monitoring. Individual response occurs before community responses and therefore could supply an earlier warning of pollution emphasis.

The larval caput capsule morphological malformations in Chironomus spp. observed in this survey are comparable to those reported earlier by Warwick and Tisdale ( 1988 ) , and Bird ( 1994 ) . The present survey clearly shows that distortion of the mentum is a widespread developmental anomalousness in Chironomus spp. larvae in all three sampled rivers. Agring with Vermeulen ( 1995 ) , it is assumed that Chironomus spp. midge larvae are extremely susceptible beings to morphological distortion, hence, they are potentially of import indexs of the effects of the H2O and sediment- edge contaminations ( Hudson and Ciborowski 1996 ) . Morphologic abnormalcies appear to ensue from the change in developing cells which may take to their improper operation and intervention with distinction, which renders their proper development ( Karmin 1988 ) . Therefore, incidences of malformations in beings at peculiar sites could bespeak overload of contaminations at such sites.

In the scientific literature it is mentioned that several substances entirely or together may do morphological distortion in chironomid larvae, specifically heavy metals and pesticides, but no specific substance ( s ) has been identified as being more causative of distortion than others ( Wiederholm 1984 ) .

In the present survey, the frequence of oral cavity parts malformations in Chironomus spp. larvae differed among the three rivers ; the beginning and nature of pollution in these home grounds differed every bit good. For illustration, the highest incidence of malformations in larval Chironomus spp. ( 47.17 % ) observed in the KUR may hold been due to the influence of some industrial discharges from the nearby gum elastic and garment mills. Deformities of this magnitude are much higher compared to the 1-30 % reported by Bird ( 1994 ) in a contaminated river in Canada.

Dermott ( 1991 ) stated that there is no distinguishable grounds that could find which of the assorted industrial and agricultural chemicals induce distortion in the chironomid larvae. However, Warwick ( 1985 ) and Warwick and Tisdale ( 1988 ) had reported the association between malformations in Chironomus spp. larvae and contaminated deposits. The incidence of malformations in Chironomus spp. larvae and the badness of their response were related to elevated concentrations of radioactive stuffs, metals, and pesticides ( Warwick 1985, Warwick and Tisdale 1988 ) .

In the PRR, the entire per centum malformations in Chironomus spp. larvae amounted to 33.71 % . Presumably the chironomid population in this river is exposed to overflow of agricultural chemicals, including fertilisers, antifungals, weedkillers, and insect powders that are routinely applied to the environing Permatang Rawa rice Fieldss. Dickman et Al. ( 1992 ) reported that addition in frequence of malformations was correlated with high degrees of metal, coal pitch, urban or agricultural overflow, and pesticides. Madden et Al. ( 1992 ) reported a important correlativity between the antennary and mouth parts malformations in larval chironomids ( Chironomus spp. , Dicrotendipes conjunctus, and Procladius paludicola ) and the concentrations of DDT and the weedkiller, Dacthal.

It is known that heavy metals taint is a major cause of malformations in the chironomid larvae. For illustration, in a to a great extent polluted river in India, Bhattacharya et Al. ( 2005 ) reported 35.88 % antennary malformations in Chironomus circumdatus under deposit Zn and Cu concentrations of 165.79 and 51.33 ppm, severally. Janssens de Bisthoven and Gerhardt ( 2003 ) in their probe reported 14 % deformed larvae of Procladius choreus and interpreted this distortion of oral cavity parts as an consequence of metal-related pollution ; the concentration of some metals in H2O with acidic environment ( pH 6.4 ) in their survey was 0.01, 0.02, and 0.03 mg/l for Cu, Pb, and Zn, severally.

In a survey to measure sediment toxicity and sublethal effects on chironomid larvae, Meregalli et Al. ( 2000 ) reported high degrees of morphological malformations making 40, 10, and 20 % in menta, lower jaws, and epipharyngis, severally, under Zn and Cu concentrations of 212 and 28 ppm, severally. By comparing, per centum malformation in those three constructions of Chironomus spp. larvae in the present survey was much lower under the highest deposit Zn, Ni, and Cu concentrations of 44.72, 3.01, and 3.13 ppm, severally. However, such concentration degrees of these metals likely bring on some morphological malformations in Chironomus spp. as observed in the present survey.

The happening of caput capsule morphological malformations in Chironomus spp. larvae expressed as per centum in the present survey was unequal to quantify the environmental emphasis. Therefore, it was necessary to hit malformations of mentum for each home ground by utilizing TSI of Lenat ( 1993 ) . Harmonizing to Lenat ( 1993 ) , a average toxic mark of 49 classifies the home ground as “ Toxic Fair ” in footings of H2O quality. Based on Lenat ‘s TSI, the studied rivers fall under ( or near ) the “ Toxic Fair ” group as this mark ‘s calculated average value amounted to 59.16 ( scope: 37.17-88.71 ) , 46.15 ( scope: 18.42-69.23 ) , and 44.05 ( scope: 0.0-89.47 ) for PRR, PR, and KUR, severally. Although Lenat ( 1993 ) designed TSI to be applied in state of affairss of organic burden, the present survey shows that it is besides utile in heavy metals contaminated rivers.

Ordination technique facilitated designation of the influence of assorted environmental parametric quantities on malformations in Chironomus spp. larvae. Concentration of metals, peculiarly Ni and Mn were extremely correlated with larval malformations. There were important non-parametric correlativities between several environmental parametric quantities and mentum, epipharyngis, aerial, and mandible malformations ( Table 5.3 ) . Previously, the figure and badness of chironomid larval caput capsule malformations have been shown to be correlated with high degrees of Zn and Cu in the deposits ( e.g. , Warwick 1985, Warwick and Tisdale 1988, Hudson and Ciborowski 1996, Meregalli et Al. 2000, Bhattacharya et Al. 2005 ) .

In decision, the present survey demonstrates the possible influence of industrial and anthropogenetic contaminations in footings of malformations in assorted caput capsule constructions of Chironomus spp. larvae populating the studied Malayan rivers. The malformation incidence in larval menta in the investigated rivers is comparatively high compared to some similar earlier surveies reported from temperate parts ( e. g. , Bird 1994, Dickman and Rygiel 1996 ) . The identified malformations are declarative of certain environmental emphasiss on the studied home grounds and could function as an empirical tool for their appraisal. The survey besides provides baseline informations on some physico-chemical conditions predominating in the investigated rivers for future mention. Based on biomonitoring appraisal, the survey identifies some pollutants in the rivers that are damaging to populating beings, necessitating appropriate H2O quality betterments.