Development Of Malaysian Water Quality Indices Using Aquatic Macroinvertebrates Population Of Pahang River Basin, Pahang, Malaysia
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Date
2016-02
Authors
Wan Abdul Ghani, Wan Mohd Hafezul
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
In this study, a large macroinvertebrates and water parameters data were collected
from fifty Pahang River Basin (PRB) tributaries. Initially, the efficiency of three
samplers; D-frame and square nets and Surber sampler, for collections of aquatic
macroinvertebrates were tested in three rivers. Low relative variation (RV) of
macroinvertebrates collected by square net in two rivers (15% and 19%,
respectively) indicated its highest efficiency among the samplers. Although the
square net required a longer time to process each sample (18.31 min) it recorded the
highest macroinvertebrate diversities (Alphaaverage = 13.5). Consequently, the square
net was selected to collect macroinvertebrates for comparison of biotic index
performances and the derivation of their tolerance values (TVs). Eleven biotic
indices were chosen; Family Biotic Index (FBI), Biological Monitoring Working
Party (BMWP), BMWP-Thai, BMWP-Viet, Average Score Per Taxon (ASPT),
ASPT-Thai, ASPT-Viet, HKHBios, South African Scoring System version 5
(SASS5), SingScore and EPT Index and their performances were compared.
Distribution and abundance of macroinvertebrates and hence the performance of
biotic indices were not influenced by Malaysian wet and dry seasons (Mann-
Whitney, P>0.05). Among the indices, FBI and all BMWPs tended to classify most
of the rivers into better water quality, ASPT-Thai and ASPT-Viet moderately
polluted while the SingScore and EPT showed most rivers had been polluted. Using
WQI as a reference, it was found that adjusted water quality categories of all biotic indices paralleled the tolerance of macroinvertebrates to pollutants. All BMWP
indices and SASS5 were positively influenced by varied levels of DO and pH in dry
season and COD in wet season which justified their reliability for water quality
assessment. Among these indices, BMWP-Viet was identified as the most suitable
due to close similarity of its macroinvertebrate fauna to Malaysian taxa. The TVs of
Malaysian aquatic macroinvertebrates were estimated by computing the weighted
average of macroinvertebrate abundance that responded towards NH4-N and pH, the
most important water parameters in Malaysian rivers (identified through forward
selection). The TVs of these two stressors were averaged to finally obtain single TV
for each taxon (genus or family). The values ranged from 0 (tolerant) to 10
(sensitive) and named as Malaysian Tolerance Value (MTV). These MTVs were
used to derive the Malaysian Biotic Index (MBI) and Malaysian Family Biotic Index
(MFBI) by dividing the cumulative sum of products of tolerance value (TV) of each
taxon multiplied by its number of individual with the total individuals in the sample.
Since the performances of the MBI and MFBI were not statistically different (Mann-
Whitney, P>0.05), the cluster analysis was used to assign MFBI scores into 5 water
quality classes, very good (> 5.9), good (4.5 – 5.8), moderate (3.8 – 4.4), bad (2.7 –
3.7) and poor (< 2.7) water quality. Their boundaries were separated using box plot
analysis. The MFBI scores were positively influenced by DO, and negatively by
NH4-N, BOD, TN and Pb, which validated their reliability. Accordingly, the MFBI
performed better than BMWP-My (BMWP-My calculated using MTV), BMWP and
WQI. Based on the findings of this study, the MFBI was the most suitable index to
be adopted in Malaysian river water assessment along with the WQI.
Description
Keywords
River water quality