Trophic level index

The trophic level index (TLI) is used in New Zealand as a measure of nutrient status of 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 typeTrophic levelChla (mg m−3)Secchi depth (m)TP (mg P m−3)TN (mg N m−3)
Ultra-microtrophic0-10.13-0.3331-240.84-1.816–34
Microtrophic1-20.33-0.8224-151.8-4.134–73
Oligotrophic2-30.82-2.015–7.84.1-9.073–157
Mesotrophic3-42.0-5.07.8-3.69.0-20157–337
Eutrophic4-55.0-123.6-1.620-43337–725
Supertrophic5-612-311.6-0.743-96725–1558
Hypertrophic6-7>31<0.7>96>1558

See also

References

  1. ↑ New Zealand Ministry for the Environment Archived 2010-05-22 at the Wayback Machine - Trophic Level Index for lakes
  2. ↑ Burns, Noel; Graham Bryers; Eddie Bowman (March 2000). Protocol for Monitoring Trophic Levels of New Zealand Lakes and Reservoirs. Retrieved 9 May 2017.
  3. ↑ Burns, Noel; McIntosh, John; Scholes, Paul (2005). "Strategies for Managing the Lakes of the Rotorua District, New Zealand". Lake and Reservoir Management. 21 (1): 61–72. doi:10.1080/07438140509354413. S2CID 86767838.