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Effects of Climate Change on Aquatic Ecosystems John Gunn Canada Research Chair for Stressed Aquatic Systems How will climate change affect water quality and quantity in Ontario? 1. Increased evaporation – leading to lower water levels (surface and groundwater) – drought 2. Increased concentration of nutrients and contaminants – increased algal bloom, bacteria and beach closures 3. Longer ice free period – increased end of summer anoxia and macrophyte growth 4. Changes in time, intensity of precipitation events – winter thaw, floods , erosion, sewer overflows 5. Loss of wetlands – release of stored sulphur and metals Declining lake levels Declining Ice Cover January 10, 2007 J. Houle Extreme Events Swan Lake Wetland Millions of tons of stored sulfur in wetland soils: Our 100 year legacy SO4-2 pH 6.0 5.5 5.0 Drought and Re-acidification of Swan Lake 4.5 4.0 82 84 86 88 90 92 94 96 98 Year How will climate change impact aquatic ecosystems? 1. Distribution and abundance of fish 2. Changes in contaminant flux ( Hg) 3. Changes in nutrient cycling Kelly Lake 2005 Extreme Temperature 29-30°C Heat shock mortality in Ontario’s Far North 40 Air Temp. °C 35 30 2001 Daily Maximum Temperature at Peawanuck 25 20 15 10 5 0 15-Jun 22-Jun 29-Jun 06-Jul 13-Jul 20-Jul 27-Jul 03-Aug 10-Aug Small mouth bass invasion in Ontario Current - Historic [Hg] (ppm) Temporal change (~ 1979 to 2009) in muscle [Hg] for seven fish species across northern Ontario lakes (at 1 kg) 0.2 Ontari o 0.1 0.0 -0.1 WALL NP LT BUR SMB LWF WS Photo courtesy of Friends of Ramsey Lake What are invasive species, how are they getting here, and what types of impacts do they have? 1. Non indigenous species ( milfoil) and expanding native species (smallmouth bass) 2. Boats, aircraft, intentional human-assisted introductions, floods, etc. 3. Increased competition and predation and often elimination of some native species Invasive Species Non-native Native E. Engbretson Borrowman 2010 How will climate change affect Ontario's overall aquatic biodiversity? The fishing industry? 1. Loss of many coldwater species ( lake trout, brook trout) 2. Expansion of warmwater species 3. Decline of commercial and recreational harvest opportunities for coldwater species 3.5 3.0 2.5 Lake charr CPUE 2.0 (n/net) 77% 1.5 1.0 0.5 0 Reference (No bass No roads) Bass and Roads Kaufman et al 2008 CJFAS What kind of adaptation measures are there to decrease the risks to aquatic ecosystems? 1. Reduce overall water use and the harvest of vulnerable species 2. Protect and restoration of key habitat features – wetlands, riparian and shoreline buffers 3. Reduce contaminants and nutrient additions 4. Eliminate the movement of non native species Is this good enough? Will this work?