Bandar Seri Begawan - Rivers and streams are part of Brunei‘s natural landscape. However not much thought is given to the interesting and intriguing processes that occur in these water bodies and most people probably do not fully appreciate the complexity of these ecosystems.
During my PhD study at the University Brunei Darussalam, I have grown to appreciate the diversity and complexity of Brunei streams. I have also discovered the different factors that affect the delicate balance in these habitats.
Due to their location in the tropical areas, Brunei rivers and streams contain a high biodiversity. One major group of organisms which are abundant in the rivers and streams in Brunei are the macro-invertebrates.
They include a range of organisms like snails (Mollusca), small crustaceans (Crustacea), insect larvae (Insecta), leeches (Euhirudinea) and aquatic worms (Oligochaeta) that have a wide range of environmental tolerances, survival strategies and preferences. Because part or all of their life cycles take place in water, they are in consequence directly dependent on adequate habitat and water quality for survival.
Aquatic insects are very useful in environment assessment due to their differing water quality requirements. Abundance and types of organisms present can be used to assess water quality and this is termed ‘biomonitoring‘.
For example a high abundance of the chironomids larvae (midges) in streams indicates that the water is moderately or highly polluted. This is because chironomids can tolerate a polluted river with lower oxygen levels.
Conversely a high abundance of Mayfly (Ephemeroptera), Caddisfly (Trichoptera) or Stonefly (Plecoptera) larvae will indicate that the water quality is very good (with high oxygen levels).
These are the three most pollution-sensitive aquatic insect orders and are very sensitive to oxygen level in the water. If oxygen levels in the stream are low, they will not survive. Monitoring these three kinds of insect larvae thus provides a quick method to assess water quality in streams.
Water quality in the rivers in Brunei-Muara District can be compared with conditions in the Temburong river.
The clear waters of the Temburong river has a high water quality and a correspondingly high invertebrate biodiversity.
Some rivers in Brunei-Muara have a lower diversity as a consequence of being moderately polluted, due to their proximity to urban and settlement areas.
Many factors determine the water quality in Brunei streams and their consequent community structure.
These include local stream geomorphology, rainfall, flow, organic pollutants, land use, channel modification, solid waste dumping, substratum characteristics and bank stability.
Indiscriminate dumping of solid waste in the streams and rivers in Brunei, especially in the Brunei-Muara District, is a problem that needs serious attention.
Disposal of solid and organic waste from houses situated close to rivers and streams contributes to the lowering of water quality and subsequent alteration to the invertebrate community structure and function.
Education programs aimed at creating awareness of the need for river protection are very important. A lot has been done in Brunei to educate the public about the importance of river protection. This approach should be continued more systematically and perhaps included in the school curriculum.
We should not only create awareness of river protection but also try to change people‘s attitude to make them appreciate the beauty, the ecological complexity and the sensitivity of Brunei river ecosystems.
Let‘s together protect this feature of Brunei‘s treasured heritage, its rivers.
Source: www.brunei-online.com (24 Oktober 2007)
