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Plant Life


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“Relationship between Environmental Factors and Aquatic Macrophyte Distribution in the Old Ausable River Channel” Johan Wiklund, M. Sc. Thesis, Univ. Western Ontario.  All photos © Johan Wiklund 

There are 29 species of large aquatic vegetation located in the Old Ausable River Channel. Six of these species dominate certain sections of the river. The six species include: Chara vulgaris, Elodea canadensis, Myriophyllum spicatum, Vallisneria americana, Wolffia spp. and Lemna minor.

Wiklund (2001) showed that there are differences in aquatic vegetation above and below the dam in the Pinery. 

Chara vulgaris - meadow
Chara vulgaris meadow

Chara vulgaris - Looking down upon a stand
Chara vulgaris  
Looking down upon a stand
Above the dam, the dominant species is Chara vulgaris, a plant species that creates a dense mat on the bottom of the river. This species is present due to the low turbidity and bicarbonate rich groundwater that feeds the system in this section of the river. 
Wolffia sp and Lemna minor - bloom covering water surface
Wolffia sp and Lemna minor 
bloom covering water surface
Above the dam, closest to Grand Bend two species, Wolfia spp. and Lemna minor become very abundant later in summer and cover the water surface (looks like algae bloom on surface).

 

 

 

 

All photos © Johan Wiklund 

Below the dam in the Pinery, the turbidity of the water in the channel increases. As well, the water conditions in this section of the channel are heavily influenced by the Ausable River Cut. The water from the “Cut” is higher in nutrients primarily because of inputs from agricultural land base.  Therefore, we observe two plant species that thrive under these conditions: 

Elodea canadensis - seen up close growing in shallow water
Elodea canadensis
seen up close growing in shallow water
Elodea canadensis is dominant where sediments are rich in nutrients. 
Myriophyllum spicatum - forming a floating canopy
Myriophyllum spicatum 
forming a floating canopy
Myriophyllum spicatum becomes abundant where sediments have low to moderate ammonium content. 
Vallisneria americana
Vallisneria americana
Vallisneria americana dominates near the confluence with the Ausable River Cut due to the increased velocity and turbidity of the water in this area.

Johan’s research on the sediments of the Old Ausable River Channel concluded that the centre of the channel is filling in with sediment. This is expected due to the slow flowing nature of the present channel. When there is no flow to carry the particles, they fall out of suspension and settle at the bottom of the river.


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Thank you to the funding partners for the OAC Management Project

Grand Bend Community Foundation
Ausable Bayfield Conservation Foundation
Gov of Canada's Habitat Stewardship Program (HSP)
Ausable Bayfield Conservation Authority

and also ...
Numerous local groups and volunteers that have offered their in-kind time and services

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