The trophic level index (TLI) is used in New Zealand as a measure of nutrient status of lakes.New Zealand Ministry for the Environment - Trophic Level Index for lakes It is similar to the trophic state index but was proposed as alternative that suited New Zealand.
The system uses four criteria, phosphorus and nitrogen concentrations, as well as visual clarity and algal biomass weighted equally.
Lake type Trophic level Chla (mg m−3) Secchi depth (m) TP (mg P m−3) TN (mg N m−3) Ultra-microtrophic 0-1 0.13-0.33 31-24 0.84-1.8 16–34 Microtrophic 1-2 0.33-0.82 24-15 1.8-4.1 34–73 Oligotrophic 2-3 0.82-2.0 15–7.8 4.1-9.0 73–157 Mesotrophic 3-4 2.0-5.0 7.8-3.6 9.0-20 157–337 Eutrophic 4-5 5.0-12 3.6-1.6 20-43 337–725 Supertrophic 5-6 12-31 1.6-0.7 43-96 725–1558 Hypertrophic 6-7 >31 <0.7 >96 >1558
See also Water pollution in New Zealand Lakes of New Zealand Environment of New Zealand
External links New Zealand Ministry for the Environment - Trophic Level Index for lakes Definitions of the 5 trophic states - Oligotrophic, Mesotrophic, Eutrophic, Supertrophic and Hypertrophic lakes
References