PENGGUNAAN ALGA PERIFITON DI DALAM PENILAIAN STATUS KUALITI AIR LEMBANGAN SUNGAI PINANG
Loading...
Date
2002-07
Authors
WAN OMAR, WAN MAZNAH
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Water quality status of Sg. Pinang Basin was determined by physico-chemical
monitoring and by periphytic algal indicators colonized on artificial substrates (glass
slides). Water quality index (WQI) that was computed based on the mean values of six
parameters (DO, BOD, COD, pH, ammonia-N and suspended solids) showed that station
A was clean, water quality at stations Band C were relatively good, and station I was
moderately polluted, whereas other downstream stations were highly polluted. Periphytic
algae attached on glass slides consisted of 80 species of Bacillariophyta, 13 species of
Cyanophyta and 18 species of Chlorophyta. The concept of bioindicators and the specific
saprobic zone of diatom species, expressed in the form of saprobic index (S-values),
showed that station A is clean (good water quality, S = 1.4), water quality at stations B
and C were fairly good (S = 1.962 and 1.781 respectively), station I was classified as
slightly polluted (S= 2.292) and other stations downstream were highly polluted
organically. with S-values ranging between 2.811 and 3.092. The sampling stations along
Sg. Pinang Basin could be divided into four zones of saprobic contamination, namely
Polysaprobic Zone (very heavily polluted stations; J and L), Alpha-mesosaprobic Zone
(heavily polluted stations), Beta- mesosaprobic Zone (moderately polluted station; I) and
Oligosaprobic Zone (clean stations; A, B and C). There was a marked trend in the
abundance of certain group of diatom species, namely saprophobous species (eg.
Achnanthes minutissima, A. woltereckii, A. oblongella, Cocconeis pediculus, C.
placentula, Fragilaria capucina, Psammothidium bioretii and Surirella linearis, saprobic
valency value 1), saproxenous species (eg. Diatoma sp., E. monodon var. a/pina,
Fragilaria sp. 1, Gomphonema gracile, G. subventricosum and Navicu/a cryptocepha/a,
saprobic valency value 2 - 3), and saprophilic species (eg. Gomphonema parvu/um,
Achnanthes exigua, A. exigua var heterovalva, Hantzschia amphioxys, Nitzschia
amphibia, N. pa/ea, Pinnularia biceps and P. biceps f. petersenii, saprobic valency value
3 - 4). In this study, saprophobous and saprophilic species could be indicator for clean
and polluted waters respectively.
In general, clean stations have higher species richness and diatom diversity
(Shannon-Wiener index, H') than the polluted stations downstream, except for stations
near estuary (G and H). The highly polluted station (station L) had the lowest values of
species richness (mean S = 9.941), evenness (0.645) and diversity (mean H' = 2.133).
Species diversities (H') at stations G and H (mean 3.563 and 3~537 respectively) were
higher than clean stations although WQI and S-values showed that these stations were
highly polluted.
Discriminant analysis using the density of diatom also successfully discriminate
sampling stations into clean, polluted and brackish waters. Autotrophic index (AI) that
was determined as the ratio of AFDW: chlorophyll a reflects the conditions of sampling
stations, with the lowest value (754.70) was recorded at the most cleanest station (A), the
value increases at polluted stations downstream, and the highest AI was recorded at
station L (1206.99). Although the occurrence of algal species on artificial substrate (glass
slides) were selective, but it remains possible that the use of artificial substrate reduces
the heterogeneity of the naturally occurring substrate and it was a standard means of
comparison between sites with differing substrates. The conditions of water quality in Sg.
Pinang Basin were clearly reflected both in physico-chemical parameters, as well as in
biotic indices and non-taxonomic measurements of periphytic algae.
Description
Keywords
PENGGUNAAN ALGA , PENILAIAN STATUS