Impacts of Climate Change on Columbia Basin Aquatic Ecosystems

1
Impacts 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.

2
Summary

• 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

3
Temperature 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)

4
Precipitation 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

5
Streamflow 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

6
Observed streamflow changes
7
Observed streamflow changes
8
Other changes

• More extreme events multi-year droughts (NCAR
  PCM)
• Less river ice
• Later freeze-up and earlier break-up

9
Consensus 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

10
Warming 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

11
Warming 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

12
Warming 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)

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Warming impacts in spring H1 reduced cutthroat
trout egg/alevin survival
Westslope Fisheries, 2001
14
Warming impacts in springH2 Reduced survival
rainbow eggs/alevins
RLL, 1998
15
Warming impacts in summerH1 Reduced growth and
increased stress for all indigenous salmonids
Beers, 2001
16
Warming impacts in summerH1 Reduced growth and
increased stress for all indigenous salmonids
17
Warming impacts in summer White sturgeon
eggs/larvae
Data RLL, 1999 Max. incubation temperature
criteria Parsley et al, 1993
18
Warming impacts in summer White sturgeon
eggs/larvae
Data Canada/BC Water Quality Agreement Optimum
incubation temp range Parsley et al, 1993
19
Warming impacts in fallH1 Reduced survival of
bull trout eggs and alevins
Data Chirico and Westover, 1998 Temp. criteria
McPhail and Murray, 1979
20
Warming 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
21
Warming impacts in winterH1 Reduced survival
mountain whitefish eggs and alevins
Data RLL, 1999 Temp. criteria (max.) Ford et
al, 1995
22
Warming impacts in winterH1 Increased
survival burbot eggs
Data Westslope Fisheries, 2002 Optimum temp
range Ford et al, 1995
23
Summer/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)

24
Summer/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

25
Less 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

26
Shorter 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?

27
Mitigating 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)

28
Mitigating 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!

29
Mitigating 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