Assessment of fish community distribution and composition in the Perak river in order to determine biological indicators for freshwater health
Loading...
Date
2005
Authors
Mat Rosli Yeup, Zainudin
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A one-year research had been carried out to study the correlation between fish biodiversity
and water quality in terms of the differences in distance from estuary, altitudes, bottom
substrates and seasons. Seven study sites were chosen and located in the main channel of
the Perak River comprising the lower zone, middle zone and upper zone of the river system.
The water quality and bottom substrates were determined by using the standard methods.
The fish populations were sampled by using the standard fishing gear and technical
methods. Several fishing gear, such as five sets of gill net with various mesh sizes (2.5 cm,
5.0 cm, 7.5 cm, 10.0 cm and 12.5 cm), five sets of hoop net and a cast net were used. A
total of 92 species comprising 12 orders, 33 families and 63 genres were identified among a
total of 4733 specimens. Response of population for each of the 92 species had been
analyzed at the multi level of fish production, taxonomic and trophic compositions. The lower
zone has 11 orders (29 families, 63 species) while the middle zone has 8 orders (15 families,
48 species) and the upper zone has 6 orders (12 families, 33 species), showed a ratio of
2.86 : 1.67 : 1.00 in total species, 2.16 : 1.00 : 1.60 in total abundance and 3.01 : 1.00 : 3.05
in total biomass, whereas for Cyprinidae was 1.05 : 1.44 : 1.00 in total species and 1.29 :
1.00 : 1.62 in total abundance, which are some of the examples for the different ecological
processes in each zone respectively. This was also shown by the difference in species
composition, whereby 71% of species composition is different between the lower zone and
middle zone, 69% different between the lower zone and upper zone while between the
middle zone and upper zone it was 58%, based on Jaccard’s Coefficient. Overall, the water
quality has decreased in the flowing water from the upper zone towards the lower zone,
influenced the increase of the number of species towards the lower zone and influenced the
biocriteria as above. As the response of fish population towards the difference in habitat
criteria, four trends of species distribution had been identified, namely that are present in a
specific zone (65.2%), similar abundance either in 2 or 3 zones (24.0%, p>0.05), population
increased towards the upper zone (9.8%, p<0.05) and lower zone (1.0%, p<0.05). The total
species, total abundance, total biomass, taxonomic composition (order, family, species) and
trophic level composition (feeding-groups, consumers) showed a different pattern of changes
of functional entities as their response to the environmental changes such as water quality
and habitat criteria in terms of changes in distance from estuary, altitude, pollution or local
disturbance and characteristic of certain areas. Overall, the composition of endangered
species reached to 84% of fish species. A total of 41 species of freshwater fish (63%)
showed tolerance to the decrease of water quality towards the lower zone. Significantly, a
total of 8 species have been chosen as the best indicator species, based on the correlation
with 12 water quality parameters, distance from estuary and altitude among the 92 species
studied. The biological integrity of the 8 indicator species, showed the condition of
freshwater health has decreased about 83.6% in the lower zone and 62.7% in the middle
zone compared to the upper zone, which was used as the local benchmark quality and
identified as an important reference site with higher primer productivity. Meanwhile, the
middle zone took the role as the transportation channel and the lower zone as the nutrient
richness area. The pattern of changes in biocriteria had been assessed in seven
approaches, and they are proposed for the evaluation of river ecosystem and evolution of
habitat functions and entities of fish community and water quality. These were based on
cluster analysis of fish community, facial models, graphic representatives, ratios at the multilevel
of assessment and percentage of quality at the test sites from the reference site, which
the undisturbed area of the upper zone.
Description
Master
Keywords
Biological Science , Fisheries