Application of Fish-Integrity Biological Index and Water Quality Index to Assess the Ecological Health of the Pahang River, Malaysia

The development along the river has tremendously affected the ecological health of the river environment, where the changes and disturbance of the environment could lead to deterioration of water quality and habitat destruction. This study aimed to assess the ecological health of the Pahang River through the integration of the Fish-Base Index (FBI) and Water Quality Index (WQI). The fish community, habitat conditions, and water quality survey were conducted monthly from 2007 until July 2010 at twenty-one (21) sampling sites. There are four (4) related fish characteristics were used to calculate the fish index: (i) species richness and composition, (ii) trophic composition, (iii) habitat and spawning area, (iv) fish health and abundance, and eight (8) water quality parameters were measured and used to compute WQI. Based on the survey result, most of the sampled fish species are native to the Pahang River, with the cyprinid family as the dominant species. The water column species have decreased from upstream to downstream, while the demersal and/or benthic species have shown an increasing pattern toward the downstream area. The IBI result indicates that the value is high in the upstream area, followed by the downstream and middle stream area. The IBI result is consistent with the WQI results that clearly state the WQI is higher at the upstream and lowest at the middle stream area. Human activities were identified as one factor that reduced the biotic composition and water quality in certain areas, especially KM3. In contrast, extensive human activities such as logging, land use changes, wastewater discharge, agriculture, and aquaculture activities were recognized as the main pollution sources in the middle and downstream areas. The F-IBI and WQI results clearly show a positive correlation between increasing human activities and perturbation. The integration of these indices can offer a more accurate and safer evaluation of the ecological health of a river. Therefore, the combination of the fish base index and water quality index is a valuable tool for assessing the ecological health of a river, and its integration can provide a more reliable and comprehensive ecological assessment.