Untitled - Haliburton County Community Cooperative Inc

that at $11.58 per fish any mercury advisory that deters anglers with consumptive goals would quicklyadd up into larger figures. It can be assumed that at current consumption levels of fish, the currenthealth of watercourse is $13.79 million, a figure that has potential to rise if mercury decreases in somelakes prompting the removal of advisories and allowing for more anglers to consume harvested fish.2.2.2: Dams and Temperature ChangesTemperature changes within aquatic ecosystems both up and downstream of dams have beenreported as common occurrences. Associated temperature change due to a dam would therefore beanthropogenic in nature and has the potential of impacting fish communities. A US study analyzed theaffects of lowberm dams on water temperature and associated communities of fish and invertebrates instreams. Results showed warmer summer temperatures were present below dams and may slowlyreturn to pre-impoundment temperatures over the course of the waterway (2-3km downstream).Factors influencing the magnitude of the temperature change included the size of impoundment (depthand surface area), residence time, whether or not the impoundment stratifies, and the release depth.The warmer summer temperatures found downstream of impounds had a significant impact upon thetrout communities which prefer colder temperatures. Brook trout populations decreased 96% whilebrown trout saw a 54% decrease downstream of the studied dams. Other species did not notice adecrease and the fish communities as a whole saw an increase in richness (Lessard & Hayes, 2003). A96% decrease in brook trout for the entirety of zone 15 would represent a monetary loss of $1,557,120while a 54% decrease in brown trout is unmearsurable as this species is not heavily angled. In short,dams may be detrimental to trout communities on affected streams, but the overall downstream affectof an increase in species richness may counteract this from an economic standpoint. As temperaturesincrease below dams it could be speculated that sought after warm water species such as smallmouthbass would experience an increase in species richness. Studies should be conducted upon which speciesobserve increases in richness as it may be wholly possible that the richness is attributed to fish14