Abstract:
Macroinvertebrates have been identified as excellent indicators of stream/ wetland health as they
respond rapidly to environmental changes and provide short to medium term pollution history records.
Current study was aimed to develop a Macroinvertebrate-based Index of Biotic Integrity (M-IBI) which
is a new approach to monitor stream/wetland health of Colombo-Sri Jayewardenepura canal system.
Sixty eight macroinvertebrate samples were obtained using a D-framed kick net from ten stations
namely Kotte, Nawala, OUSL, Kirimandala Mw., Wellawatta, Orugodawatta, St. Sebastian, Beira Lake,
Buthgamuwa and Royal Park representing main branches of the system and marshes covering dissimilar
environmental conditions of the canal system during the period of Nov. 2008 to June 2009 on monthly
basis. 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
environmental conditions. Then ten candidate metrics were selected out of 41 for M-IBI development
after evaluating their sensitivity and appropriateness. Validity of the index was tested with a new
independent data set. Scores acquired 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/ wetlands.
