Title: Impacts of Climate Change on Columbia Basin Aquatic Ecosystems
1Impacts of Climate Change on Columbia Basin
Aquatic Ecosystems
- (aka a forecasting fools game)
- Bill Green
- Canadian Columbia River Inter-tribal Fisheries
Commission - Columbia-Kootenay Fisheries Renewal Partnership
- Cranbrook, B.C.
2Summary
- Anticipated climatic and hydrologic changes
- Briefly review observed streamflow changes
- General impacts on periphyton, invertebrates and
fish - Hypotheses and examples re salmonids
- Some ROBUST adaptation strategies
3Temperature changes
- Increase in annual average temperature 0.5 o C.
(2010 2039, NCAR PCM) to 5o C. (NCAR RCM,
2xCO2) - Observed 1.1o C. 1895 1995 (BC MWLAP.)
- Both warmer summers and warmer winters (no
consensus around which season warms more)
4Precipitation changes
- No consensus on average annual precipitation,
probably variable across region - But 4 per decade increase in annual average
precipitation 1929 1998 (BC MWLAP) - Increased winter precipitation?
- Reduced summer precipitation (but observed 6
per decade 1929 1998 (BC MWLAP) - Winter precipitation more rain/less snow
5Streamflow changes
- Earlier snowmelt and peak of freshet (2 6 wk.)
- Summer low flows longer duration and possibly
lower - Glacial melting will offset low flow impacts
until glaciers gone/reduced
6Observed streamflow changes
7Observed streamflow changes
8Other changes
- More extreme events multi-year droughts (NCAR
PCM) - Less river ice
- Later freeze-up and earlier break-up
9Consensus impact predictions
- Increased annual mean air temperature (and
water?) 1 5oC. - Earlier snowmelt and peak of freshet (but)
- Summer low flows longer duration (lower?)
- Less river ice
- Shorter ice season on lakes
10Warming Impacts on periphyton
- Shift from diatoms to green algae (20oC)
- Increased species diversity
- Increase in productivity (except nutrient
limitation!) - Increased biomass
- (DeNicola, 1996)
- Likely only significant at higher end of
predicted temperature increases
11Warming Impacts on invertebrates
- Hatching success
- Larval growth
- Adult size and fecundity
- Number of generations per year
- Timing of adult emergence
- (Oliver and Fidler, 2001)
- Generally, more food for fish
12Warming impacts on salmonids
- Accelerated egg development
- Alter the timing of emergence, growth and
downstream migration of juveniles - Reduce food conversion efficiency
- Alter timing of spawning migration and spawning
- Increase susceptibility to disease
- Shift competitive balance between salmonids and
non-salmonids - (Oliver and Fidler, 2001)
13Warming impacts in spring H1 reduced cutthroat
trout egg/alevin survival
Westslope Fisheries, 2001
14Warming impacts in springH2 Reduced survival
rainbow eggs/alevins
RLL, 1998
15Warming impacts in summerH1 Reduced growth and
increased stress for all indigenous salmonids
Beers, 2001
16Warming impacts in summerH1 Reduced growth and
increased stress for all indigenous salmonids
17Warming impacts in summer White sturgeon
eggs/larvae
Data RLL, 1999 Max. incubation temperature
criteria Parsley et al, 1993
18Warming impacts in summer White sturgeon
eggs/larvae
Data Canada/BC Water Quality Agreement Optimum
incubation temp range Parsley et al, 1993
19Warming impacts in fallH1 Reduced survival of
bull trout eggs and alevins
Data Chirico and Westover, 1998 Temp. criteria
McPhail and Murray, 1979
20Warming impacts in fallBrook trout egg/alevin
survival less affected than bull trout egg/alevin
survival
Data Westslope Fisheries, 2001 Temp criteria 1
(upper brook trout optimum) Hokanson et al,
1973 Temp criteria 2 (upper bull trout optimum)
McPhail and Murray, 1979
21Warming impacts in winterH1 Reduced survival
mountain whitefish eggs and alevins
Data RLL, 1999 Temp. criteria (max.) Ford et
al, 1995
22Warming impacts in winterH1 Increased
survival burbot eggs
Data Westslope Fisheries, 2002 Optimum temp
range Ford et al, 1995
23Summer/fall low flows
- Anticipated longer duration (earlier freshet
peak) - Possibly lower summer flows
- Compounding effects with increased temperatures
(lower streamflow increased warming, greater
daily variability)
24Summer/fall low flows
- Summer low flow conditions generally thought to
be a habitat bottleneck restricting the
productivity of salmonid populations - Example Oliver (2001) determined that Joseph
Creek (Cranbrook) flows below 0.08 m3/sec.
(Kinsmen Park) likely limiting to cutthroat trout
parr. Flows at or below 0.08 m3/sec occur
frequently in late summer in dry years. Low flow
condition AT LEAST extended in all climate change
scenarios
25Less river ice
- Bill Westover (MWLAP, pers. Comm.) has noted
increased fishing activity in river fisheries in
warmer winters when rivers (e.g. Kootenay) can
frequently be fished from shore
26Shorter ice season on lakes
- Increased duration of ice-free, productive season
more food production - Thermocline depth, duration of stratified season?
- Reduced ice fishing opportunity/harvest
- Reduced winterkill in shallow lakes?
27Mitigating temperature impacts
- Protect and restore riparian areas (shading)
- Protect and restore riparian areas (minimize
channel widening) - Conservation/restoration efforts for indigenous
fish species precautionary regulations, no
harvest population strongholds, education - Reduce other population stressors (e.g. toxic
contamination)
28Mitigating temperature impacts
- Maintain and improve habitat connectivity/fish
passage - MONITOR so we can identify increasing
temperature stress - In short, do what we are or should be doing, only
do it more and better!
29Mitigating summer low flow impacts
- Water conservation
- Water conservation
- Water conservation
- MONITOR
- And improved water management systems (incl. Time
limited water licenses)
i.e., Do what we are or should be doing now MORE
and BETTER