Complementarity of community indices in characterizing aquatic macroinvertebrate assemblages

Community indices are commonly used in ecology to characterize and track species assemblages. However, their use is also critically discussed. Unclarities remain about what the various community indices actually represent, their appropriateness in representing ecological status, and their drawbacks. Therefore, the present study aimed to elucidate the context-specificity of aquatic macroinvertebrate community index scores in lotic and lentic water bodies. To this end, a large set of macroinvertebrate distribution data in surface waters of the Netherlands was analysed. Five indices were considered, including the diversity indices species richness, Shannon diversity, and Simpson diversity, and two diagnostic indices, the number of rare species and the number of indicator species. Patterns in index scores were compared between lotic waters, lentic waters, and the combined dataset. We observed that the correlation between index scores was not as strong as often assumed. In addition, patterns in index scores differed between lotic and lentic waters, with deviating ranges in scores. These results showed that the interpretation of the patterns in macroinvertebrate community indices scores is dependent on the water type. This highlights the importance of reporting multiple community index scores and of careful interpretation of their meaning within the appropriate context. This should be considered to make appropriate choices in the use of these indices in future water quality assessment and environmental management.