The comparison of macroinvertebrates and diatoms as two biotic indices of water pollution

The value of macroinvertebrates and diatom communities as monitors of water quality was studied at 25 sites in the North East of England. The aim was to compare and contrast the two methods on their benefits as environmental quality indicators. Few studies have been made on a critical level between the two groups although similar reasons in support of their use have been made. Invertebrates were collected by a Standard kick sample and community quality was evaluated using a BMWP score. Diatom communities were scraped from stones and a Generic Diatom Index was applied to the result. Both methods appeared to give good indications of levels of organic pollution, though the correlation between the methods was poor. Multivariate analyses suggested that in both cases physical environmental factors overrode water quality in detecting community composition and that the precise nature of these was different for macroinvertebrates and diatoms. It does seem that diatom methods of water quality monitoring should be further studied as an addition to the solely used invertebrate methods