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Figure 10.5: Trophic (nutrient) level (most recent to 2005) and trends (1990–2006) of monitored lakes

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Tropic level of 134 monitored lakes

Tropic level trends of 49 lakes

 

Note:

Lakes have been categorised in this figure using the Trophic Level Index and trends have been calculated using the Burns methodology (Burns et al, 2000).

Source: Adapted from Ministry for the Environment, 2006b and Ministry for the Environment, in press c.

Text description of figure

Figure showing (1) map of locations of 134 monitored New Zealand lakes colour coded according to trophic status (7 categories from microtrophic to supertrophic), (2) a bar graph showing numbers of the same lakes in each category, and (3) a bar graph showing the numbers of 49 monitored lakes that are either deteriorating, not changing, or improving over time.

Key feature of map is that most lakes in the nutrient-enriched trophic categories are in the north of the North Island or the lowlands of the South Island while the least nutrient enriched lakes are most commonly found in high country of both island (eg Taupo and the Southern Lakes).

Tropic level of 134 monitored lakes

 

Number of lakes

Hypertrophic

18

Supertrophic

13

Eutrophic

44

Mesotrophic

21

Oligotrophic

25

Microtrophic

13

Tropic level trends of 49 lakes

 

Low nutrients
(Oligotrophic/ Microtrophic)

Moderate nutrients
(Eutrophic/ Mesotrophic)

High nutrients
(Supertrophic/ Hypertrophic)

Deterioration

1

6

3

No Change

9

13

11

Improvement

0

4

2