Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
shoreline, in particular on the south
shore of Kempenfelt Bay (Figure 5-7a).
While this area has a very small zone
available for aquatic plant colonization
due to the quick drop in depth, excess
nutrient run-off into Lake Simcoe (the
Barrie Creeks subwatershed
contributes an estimated 4.5 4 tonnes of
phosphorus per year, while Lovers and
Hewitt’s contribute 0.8 and 0.4 tonnes
of phosphorus per year, respectively 5
[values are based on modelled, three
year average from 2004-2007]), soft
substrates, and the high light
transparency of the water provide
optimal conditions for plant growth. If the aquatic plant community changes in this area
correspond to those in Cook’s Bay, then the biomass of aquatic plants has increased three-fold
since the 1980s as well. This is likely due to zebra mussels (Dreissenia polymorpha) clearing
the water and creating ideal habitat for plant growth. The invasive species, eurasian watermilfoil
(Myriophyllum spicatum), likely invaded this area and displaced any native species.
The second component being analyzed is the amount of phosphorus contained in lake
sediments, which was poorly understood prior to the initiation of the LSRCA Lake Science
Research and Monitoring Program. Monitoring of sediment phosphorus is undertaken because
of the potential for phosphorus release under low dissolved oxygen concentrations in the water
(less than 2 mg/L) and this is, thus far, an undetermined source of phosphorus loading. Along
the Barrie shoreline, mean sediment nutrient concentrations are relatively high with total
phosphorus (TP) ~1.1 mg/g, likely due to soft, muddy substrates which hold more nutrients than
coarser grained sediments (Figure 5-7c). For comparison, across the lake concentrations range
from TP ~0.35 mg/g in Cook’s Bay to ~1.4 mg/g near Beaverton. (For details on the total
phosphorus within the tributaries please refer to Chapter 3 -
Water Quality).
The last component of the LSRCA Lake Science Research and
Monitoring Program is monitoring invasive species with the
goals of assessing the impact on native biological
communities, tracking changes through time, and identifying
new risks (a complete list of invasive species within the
tributaries and within Lake Simcoe can be found in the
Stressors section of this chapter). While some exotic species
are studied under other projects (e.g. eurasian milfoil
(Myriophyllum spicatum) and curly-leaf pondweed
(Potomogeton crispus) with aquatic plant monitoring, spiny
waterflea (Bythotrephes longimanus) with our zooplankton
projects), a targeted survey was carried out in 2009-10 to
supplement the annual benthic invertebrate monitoring and
determine the extent of dreissenid mussel (zebra mussel,
Dreissenia polymorpha; quagga mussel, Dreissenia
rostriformis bugensis) impact on Lake Simcoe. Since their
4 This total does not include Water Pollution Control Plants (WPCP) or septic systems
5 This total does not include septic systems
Two invasive mussel species in
Lake Simcoe: (a) zebra mussel;
(b) quagga mussel.
Chapter 5: Aquatic Natural Heritage 221