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OECD Fixed Boundary System or the Diagnostic Model

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

Updated: August 12, 2015          Trophic Terminology and Prediction

(cf. Mandaville, 2000; and  Vollenweider and Kerekes, 1982)

In this system, a certain arbitrariness is unavoidable, and the danger exists that the respective categorization is rigidly applied. To avoid this, judgment about allocation of a given lake to a trophic category should not be based on only one or two parameters but on the total information.

The advantage of a fixed boundary system is its easy application by managers and technical personnel with only limited limnological training. In particular, it is apt to prevent gross misuse of the trophic terminology, which has often happened in the past.

Trophic Category
(Annual Mean Values)
[P]λ[chl][max. chl][Sec]y[min. Sec]y
Ultra-oligotrophic .....≤ 4.0≤ 1.0≤ 2.5≥ 12.0≥ 6.0
Oligotrophic ...........≤ 10.0≤ 2.5≤ 8.0≥ 6.0≥ 3.0
Mesotrophic .......10 - 352.5 - 88 - 256 - 33 - 1.5
Eutrophic .......35 - 1008 - 2525 - 753 - 1.51.5 - 0.7
Hypertrophic .......≥ 100≥ 25≥ 75≤ 1.5≤ 0.7

Trophic Terminology and Prediction                                Soil & Water Conservation Society of Metro Halifax Master Homepage

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