Author(s): P. I. A. Gomes; O. W. H. Wai
Linked Author(s): Pattiyage Ishan Ayantha Gomes, Onyx W.H. Wai
Keywords: Concrete lined streams; Diversity; Macroinvertebrates; Water quality
Abstract: Benthic macroinvertebrates are an important part of lotic systems such as stream and rivers. The sensitivity of macroinvertebrates to the changes in lotic environmental quality is one of the major reasons that macroinvertebrates are commonly used as ecological quality indicators. The present spatiotemporal study carried out in a characteristic concrete lined stream network in the northwest region of Hong Kong had an objective of studying benthic macroinvertebrate assemblages based on a functional classification. Also, the influence of water quality on macroinvertebrates was studied. Results indicated that concrete lined stream was not ecologically dead and it contained low but sizable macroinvertebrate populations. Out of the five macroinvertebrate functional groups, two to four groups were identified in the study area. As expected, most of the observed macroinvertebrates were pollutant tolerant in many reaches. Nevertheless, pollutant intolerant and native species were also observed in a few reaches. The diversity and pollution tolerance index did not show a good correlation as high diversity was due to reach specific combinations of pollutant tolerant and intolerant species. Similarly, low diversity was due the presence of a few types of pollution tolerant or intolerant species. Water quality was able to explain 46% of the macroinvertebrate variation by the first two axes. Nitrate-nitrogen, DO and pH were the most significant water quality parameters. While acknowledging the potential of restoring concrete lined streams to perform ecohydraulic functions similar to natural waterways, it is also imperative to focus more on water quality related inputs. This is essential as concrete lined streams have weak assimilation and attenuation processes.