HIGH PARK NATURE
HIGH PARK STEWARDS
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See also: Monitoring Water Quality
Excerpts from the Gartner Lee Report, 1995
The high levels of phosphorus in Grenadier Pond, in combination with high levels of nitrogen, relate directly or indirectly to many of the problems within the pond. High nutrient levels encourage the growth of both macrophytes and algae. In general, algae and aquatic macrophytes utilize nitrogen in the form of nitrate (ammonia can also be used, but is pH dependent). Some bluegreen algae have the ability to use molecular nitrogen as well, although this ability is enzymatically suppressed when concentrations of inorganic nitrogen are high.
A single analysis of the type of algae growing in Grenadier Pond was conducted by the MOEE in August 1994. Approximately 87% of the algae in the pond were blue-greens (mainly Aphanizomenon sp.), a less desirable food source of most zooplankton and only 6% were found to be green algae, which are readily consumed by zooplankton, with the remaining species a collection of diatoms and brown algae. Aphanizomenon sp. is known to be nitrogen fixer, however, it should be noted that their presence in the pond is not evidence that they are actually fixing nitrogen; appropriate
testing would have to be conducted to confirm the biological activity of this algae. The general implication of this is that the system currently favours the growth of blue-green algae over other species.
Recommended measures in the 1995 Gartner Lee report included:
The internal loading of phosphorus is one of the main sources of phosphorus contamination and therefore, all actions to remediate this loading are considered to be high priorities. Food web alteration can be applied through the stocking of the historically present predator fish, northern pike and largemouth bass. Funding from the. Canadian National Sportsmen's Show has allowed for the stocking of 200 largemouth bass and five northern pike in September 1994. Additional stocking of northern pike is scheduled for May 21, 1995. Although fish stocking will assist in the recovery of ecosystem balance, the successful reproduction of pike will likely not be observed until such time as the water levels are altered seasonally and shorelines are naturalized. Bass spawning can be enhanced by installing 50 spawning boxes along the south shore until such time as water quality improvements are realized.
More importantly, though, is the need to deal directly with the sediments in the pond. More information is required to allow a final determination of how to deal with the internal load. Specifically, additional information is required to delineate the depths, quality and consistency of the sediments to determine appropriate handling, as well as to obtain necessary permits or approvals. Trial plots for different sediment treatments could be undertaken to examine different alternatives prior to whole scale implementation.
Source: Gartner Lee Report, 1995
Nutrient loading in Grenadier Pond was studied early in the 1990s culminating in the 1995 Gartner Lee report (see above).
Comments by Leslie Gooding