Freshwater, Invasive species, and climate change.

BIO 294

Importance of F-W Ecosystems• F-W occupy < 1% of earth’s surface • Support 10% of all described sp. ( 125,000)• 1/3 of all known vertebrates can be found in F-W • Human uses of F-W • Ecosystem Services – estimated at 6.5 trillion usd/year

( Strayer and Dudgeon 2006)

Freshwater Ecosystems • Freshwater taxa more likely to suffer from biotic change (land use and

invasives) than climate change drivers relative to terrestrial biomes. ( Sala et al 2000)

Primary Concerns 1. Increased air temperature Inc. H20 temp.2. Shorter durations of snowpack and ice-cover3. Altered stream flows4.. Increase demand for water storage and transportation • Synergistic combinations- alter pools of potential colonizing

species • ex. Ag. Runoff nutrient addition cultural eutrophication

inc. habitat for eurythermic species to colonize.

Rahel and Olden 2008

1. Increased H20 temperature on F-W1.Displacement of species- non random composition shift

– Transition from cold water stenotherms to eurythermic species ( Krajick 2004)

– Eutrophication and species composition shift in fish ( smaller, faster reproducing fish)

Stagnant more stratified water

Less dissolved o2, more phosphorus release

Inc. algal abundance

Increased H20 Temp. Cont.2. Increased habitat for warm water aquaculture

– Can facilitate spread of invasives. • Ex- Catfish ( Ictalurus punctatus) farms projected to move 240 km

( 149 mi) north per every 1 degree celcius increase in S.E USA (McCauley& Beitinger 1992)

3. Most F-W organisms ectothermic - disrupt bioenergetics and foraging tendencies. - Increase water temps inc. metabolic rates and higher

consumption• ex. Bass predation on salmon in Columbia River inc. when water temp

increases. Rate of 1 degree celcius increase= 4-6 % inc. per capita consumption of salmon (Peterson and Kitchell 2001)

2. Reduced Ice Cover• Predict- Ice cover will reduce in N. Hemisphere. 1979-2012 - ~4% loss per

decade (IPCC 2013)1. Increased light cover• Could facilitate invasion of aquatic plants • Ex. Study found threadleaf-water crow foot ( Ranunculus trichophyllus)

recent invasion in Himalayan lakes due to reduced ice cover.(Lacoul & Freedman 2006)

• Inc. light cover increases water temperatures.

Reduced Ice Cover cont.2. Decreased low oxygen environment during winter. • Reduced hypoxic conditions• Rahel 1984- smaller fish occupy lakes w/ no predatorsdue to hypoxic conditions• Reduced ice cover could create suitable habitat for larger predatory fish

(Stefan et al. 2001) (Jackson & Mandrake 2002)

3. Altered Stream Flow Regimes• Changing precipitation, evapotranspiration, and runoff patterns will cause stream

regimes (frequency, duration, magnitude and timing ) to change.

• Timing and magnitude of these events important for ecosystem function and structure (Poff et al. 1997)

• Predict -earlier onset of peak flows from spring to late winter in mountainous regions – More winter floods and reduced summer flows in mountain streams.

Altered Stream Flows1.Increase in occurrence of opportunistic invasives • ex- non-native fish density increases during years of low spring and

summer discharge in San Juan River ( Propst and Gido 2004) 2. Increase in occurrence of invasives due to desiccation of streams• New Zealand mud snail- highly invasive and tolerant to desiccation 3. Presence of Dams prevents floods which historically wiped out non-native species.

4. Increased demand for H20 storage and transportation

• Decrease in annual runoff= less surface water for humans • Requires the construction of reservoirs to increase water storage• Increase demand for water transportation= construction of canals and

aqueducts

Increased demand for H20 storage and transportation cont.

1. Canals and aqueducts provide source of transportation for non-natives across long distances.

2. Reservoirs alter aquatic habitat. Flowing water Standing water. Enhanced habitat for non-native fish.

ex. Bluegill (L. macrochirus) introduction into Carolina river system.(Meffe 1991)3. Reservoirs provide human recreation opportunity. • Ex. Zebra mussels

Conclusions• Development of H20 technologies away from reservoirs and dams. • Lack of literature regarding freshwater sp. response to climate change relative to

marine and plant taxa. • Redefinition of invasive species

– range expansions/ contractions and shifts in abundance of species. Trend- sp. will expand ranges to more northern latitudes and at higher altitudes

Xenopolous et al 2005• River Discharge- volume of water flowing through river channel at given

time (cubic meters per sec.)

• Fish Data- Oberdoff et al 1995- Global scale patterns of fish species richness in rivers. – Fish Base- online appendix , largest most accessed fish database for

finfish• Current River Discharge- Water-Gap Model

– 1996 German University. Calculates flow and storage of water on all continents except Antarctica.

– Takes into account human influence of water abstraction and dams.– Used in IPCC reports, U.N World Water Development Reports

Xenopolous et al. 2005• Future River Discharge- HADCM3 model

- coupled atmospheric-ocean general circulation model - uses HADATM3 and HADOM3, alternate days of running ocean and

atm models. Measure fluxes ( heat, moisture, etc) and couple models by aligning grids together.

- Used in IPCC 3rd assessment report 2001.