calculate_ASPT          The Average Score Per Taxon (ASPT) represents
                        the average tolerance score of all taxa within
                        the community, and is calculated by dividing
                        the BMWP by the number of families/taxa
                        represented in the sample.
calculate_BMWP          The Biological Monitoring Working Party score
                        (BMWP) This index provides single values, at
                        the family level (with exception of Oligochaete
                        which is to the order level), representative of
                        the organisms’ tolerance to pollution.
calculate_EPT           This index is calculated based on the number of
                        families belonging to three macroinvertebrate
                        orders: Ephemeroptera, Plecoptera and
                        Trichoptera.
calculate_FBI           Assigned tolerancevalues range from 0 to 10 for
                        families and increase as water quality
                        decreases
calculate_SWRC          SWRC - Biotic index (Stroud Water Research
                        Centre - Biotic index)
