1

The condition of some lakesin the southern part of the

Gatineau Valley RCM

Henri Fournier

Department of Natural Resources and Wildl ife

Wildlife Development Directorate

Direction régionale de l’Outaouais

Summit on Lakes and Rivers

Maniwaki September 14, 2007

2

Indicators used

1. An integrator: the habitat of the lake trout Living habitat Reproduction habitat

2. A precursor: phosphorus concentration in the water

3

Why should we be interested in the lake trout’s habitat?

1. Its habitat requirements are well known

2. A demanding species as far as its habitat is concernedIf the habitat is adequate for the lake trout, it will be for human use.

2. Major issue for those providing sport fishing services

4

How did we evaluate habitat quality?

1. Living habitat: Evolution of oxygen concentration at the depths of the lake since 1975

2. Spawning habitat: Bioassay Presence of young lake trout in the

population

3. Phosphorus: spring runoff

5

Evolution of dissolved oxygen at the bottom of a few lake trout-inhabited lakes

Oxy

gen

at

the

bo

tto

m o

f th

e la

ke

Adequate 42%

Probable loss of habitat (33%)

Loss of habitat (25%)

? ?? ?

6

Lakes and their level of dissolved oxygen at the bottom

7

The spawning habitat has already been destroyed by periphyton in a few lakesPeriphyton : vegetation that develops on

stones at the bottom of a body of water

Lakes where the spawning habitat has been destroyed:

1. Blue Sea

2. Petit des Cèdres

3. Davis Bay (Thirty-One Miles)

8

Total phosphorus in the water of certain lakes

Ph

osp

ho

rus

con

cen

trat

ion

Natural (23%)

Probable enrichment (54%)

Enriched (23%)

9

Total phosphorous concentration in certain lakes

10

In summary

1. The living habitat of the lake trout in some lakes has declined and others are heading in that direction.

2. The spawning habitat has been destroyed by periphytic vegetation in a few lakes.

3. In some lakes, phosphorous concentration points to certain enrichment.

4. Phosphorous concentration in several lakes seems to be above natural concentration and is an indication that these lakes are probably in the throes of enrichment.

11

Conclusion : eutrophization is already upon us!

1. The adverse effects of eutrophization are already being felt in some lakes (no oxygen on the bottom, strong phosphorous content)

2. The data indicates that the number of lakes affected could increase (decrease in oxygen levels on the bottom, concentration of phosphorous above natural concentrations)

And the Eurasian water-milfoil could accelerate the

process!