DI (density index). Density of marine macroinvertebrates as indicator of environmental status

Summary

DI (density index) is a new index for fauna density. DI was specially developed for classifying status of low-density faunas. Indices for diversity and sensitivity in those cases may function poorly, due to accidental fauna composition implied by scarcity of data. Low-density faunas especially occur at sites with depleted oxygen, or strong industrial pollution. Abnormally high densities of tolerant species indicate influence from organic pollution, common near municipal or aquaculture plants. DI signalizes abnormally high as well as abnormally low densities. Border values between status classes for DI are defined. DI is included in the revised Norwegian classification system 02:2013.