Assemblage-based biomonitoring of freshwater ecosystem health via multimetric indices: A critical review and suggestions for improving their applicability

Robert L. Vadas, Robert M. Hughes, Yeon Jae Bae, Min Jeong Baek, Orestes Carlos Bello Gonzáles, Marcos Callisto, Débora Reis de Carvalho, Kai Chen, Maria T. Ferreira, Pablo Fierro, Jon S. Harding, Dana M. Infante, C. J. Kleynhans, Diego R. Macedo, Isabela Martins, Norman Mercado Silva, Nabor Moya, Susan J. Nichols, Paulo S. Pompeu, Renata RuaroDeborah R.O. Silva, R. Jan Stevenson, Bianca de Freitas Terra, Christa Thirion, Douglas Ticiani, Lizhu Wang, Chris O. Yoder

Research output: Contribution to journalReview articlepeer-review

19 Citations (Scopus)


Freshwater biota are more comprehensive and direct indicators of biological impacts, and more meaningful to the public than water quality or physical habitat surrogates. Freshwater biotic data and the multiple biological indicators developed from them offer a much richer array of data for assessing the impacts of pollution controls than a limited set of physical or chemical measures. In recent decades, assemblage-based assessments by ecologists, environmental scientists, and water quality agencies have been employed globally for determining the condition of, and threats to, freshwater ecosystems. A key step in this advance has been the development of multimetric indices (MMIs) or indices of biotic integrity (IBIs) based on quantitative assessments of algae, macrophyte, macroinvertebrate, fish or riparian bird assemblages. In Europe, where biological assemblages are mandated for assessing freshwater ecosystem health, many indices are multimetric. However, the proliferation of MMIs globally has not always occurred through the application of rigorous study designs and monitoring protocols, nor have they always effectively incorporated functional metrics, stressor assessments, and statistical analyses. Therefore, in this review, we discuss eleven major concerns with the development and application (including logistical limitations) of multimetric indicators based on freshwater biota to encourage more rigorous and widely applicable (transferable) MMI use and implementation. Specifically, our concerns focus on reference conditions; sampling effort, methods, and season; trophic guild definition; metric comprehensiveness, options, screening and scoring; and MMI validation. MMIs could also benefit from increased attention to ecological mechanisms and metric development, to further improve our understanding of anthropogenic impacts as well as rehabilitation effects on freshwater ecosystems globally. Paying closer attention to study designs, ecological mechanisms and metric development should further improve our understanding of anthropogenic impacts and better facilitate rehabilitation of degraded freshwater ecosystems, as well as aiding in the conservation of healthy freshwater ecosystems globally.

Original languageEnglish
Article number100054
JournalWater Biology and Security
Issue number3
Publication statusPublished - 2022 Aug


  • Algae
  • Biological monitoring
  • Fish
  • IBI
  • Lakes
  • MMI
  • Macroinvertebrates
  • Rivers
  • Streams
  • Wetlands

ASJC Scopus subject areas

  • Water Science and Technology
  • Aquatic Science
  • Animal Science and Zoology
  • Agricultural and Biological Sciences (miscellaneous)


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