A study of the impacts of anthropogenic activities on the distribution and biodiversity
of benthic macroinvertebrates and water quality of the Langat River (Peninsular Malaysia)
was conducted. Four pristine stations from the upstream and 4 stations at the downstream
receiving anthropogenic impacts were selected along the river. For 4 consecutive months
(March-June 1999), based on the Malaysian DOE (Malaysia Environmental Quality Report
2000, Department of Environment, Ministry of Science, Technology and Environment Malaysia.
Maskha Sdn. Bhd. Kuala Lumpur, 86pp; Malaysia Environmental Quality Report 2001, Department
of Environment, Ministry of Science, Technology and the Environment Malaysia) water
quality index classes, the upstream stations recorded significantly (P<0.05) higher
Biological Monitoring Working Party scores and better water quality indices than those
of the downstream. The total number of macrobenthic taxa and their overall richness
indices and diversity indices were significantly (P<0.05) higher at the upstream stations
(54 taxa) than at the downstream stations (5 taxa). The upstream of the Langat River
was dominated by Ephemeroptera and chironomid dipterans while other orders found in
small quantities included Trichoptera, Diptera, Plecoptera, Odonata, Ephemeraptera,
Coleoptera, and Gastropoda. On the other hand, the downstream of the river was mainly
inhabited by the resistant Oligochaeta worms Limnodrilus spp. and Branchiodrilus sp.
and Hirudinea in small numbers. The relationships between the physicochemical and
the macrobenthic data were investigated by Pearson correlation analysis and multiple
stepwise regression analysis. These statistical analyses showed that the richness
and diversity indices were generally influenced by the total suspended solids and
the conductivity of the river water. This study also highlighted the impacts of anthropogenic
land-based activities such as urban runoff on the distribution and species diversity
of macrobenthic invertebrates in the downstream of the Langat River. The data obtained
in this study supported the use of the bioindicator concept for Malaysian rivers.
Some sensitive (Trichopteran caddisflies and Ephemeraptera) and resistant species
(Oligochaeta such as Limnodrilus spp.) are identified as potential bioindicators of
clean and polluted river ecosystems, respectively, for Malaysian rivers.