Development of a Macroinvertebrate - based Index of Biotic Integrity (M-IBI) for Colombo-Sri Jayawardhanapura Canal System (A new approach to assess stream/ wetland health)

Macroinvertebrates have been identified as excellent indicators of stream (wetland) health as they respond rapidly to environmental changers and provide short to medium term pollution history records. Current study was aimed to develop a Macroinvertebrate-based Index of Biotic Integrity (M-IBI) to monitor stream health of Colombo-Sri Jayawardhanapura canal system. Macroinvertebrates were sampled using a D-framed kick net from ten stations during the period of Nov 2008 to June 2009. Habitat characteristics and some water quality parameters also recorded. For the index development, those ten stations were grouped into two as ’Reference’ and ‘Degraded’ based on their habitat characteristics and some water quality parameters. Then 41vcandidate metrics were nominated for statistical analysis process. After considering their sensitivity to stream impairment, ability of showing exceptionally strong discrimination between reference and degraded sites and less redundancy, ten candidate metrics were selected for M-IBI development. Validity of the index was tested with a new independent data set. Scores acquired for these data set were positively correlated with DO values (r = 0.578). That concluded the potential of using M-IBI developed for biological monitoring and improving biotic integrity of streams and wetlands.