Invertebrate Community Index

Invertebrate Community Index

The invertebrate community index (ICI) is very similar to the IBI and measures the health of the macroinvertebrate community. This index is comprised of 10 metrics where sampled sites are also compared to relatively undisturbed sites with similar geographical features. Both IBI and ICI are useful tools for biological measuring of aquatic environments, but IBI is often the preferred method; fish are generally longer lived and can therefore represent environmental changes over a longer period of time.


Invertebrate Community Index Components

  Variable Measured
1. Total Number of Taxa
2. Total Number of Mayfly Taxa
3. Total Number of Caddissfly Taxa
4. Total Number of Dipteran Taxa
5. Percent of Mayflies
6. Percent of Caddisflies
7. Percent of Tribe
Tanutarsini Midges
8. Percent of Other Dipterans
and Non-insects
9. Percent of Tolerant Organisms
10. Total Number of EPT Taxa

EPT- Ephemroopters, Plecoptera, and Trichoptera (specific types of invertebrate taxa); ICI criteria as taken from Ohio EPA 1989

Modeled after IBI, ICI can receive a score of 6, 4, 2, or 0 depending on the undisturbed site comparison. Each site can therefore range between:

  • Total maximum ICI score of 10(variables) * 6(highest score) = 60
  • Total minimum ICI score of 10(variables) * 0(lowest score) = 0