Freshwater Biodiversity Conservation. Focus often on genetically distinct populations, species, and species communities. Wetla nds

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1 Freshwater Biodiversity Conservation Biodiversity = genes to ecosystems Focus often on genetically distinct populations, species, and species communities Wetla nds Why should we care? 1) valuable Ecosystem Goods and Services (Poff et al. 2002) 1

2 2) Unrivaled Biodiversity Compared to marine and terrestrial systems on a per unit area basis. United States contributes greatly to global freshwater biodiversity. (Strayer & Dudgeon 2010) Master et al (1998, Rivers of Life) Why is freshwater diversity so high? Naturally isolated nature of FW ecosystems combined with natural barriers to gene flow has facilitated great evolutionary diversification. - linear stream channels surrounded by hostile terrestrial matrix - upstream-downstream barriers Freshwater biodiversity is at disproportionate risk of extinction Vulnerable and Imperiled Species Projected extinction rates Freshwaters: 3.7% per decade Terrestrial vertebrates: 0.8% per decade (Master et al. 1998) (Ricciardi & Rasmussen 1999) 2

3 Freshwater Mussels have co-evolved with fish hosts v=w04wvaxttdi What are the major threats to FW Ecosystems? Many interacting factors contribute to global biodiversity crisis and FW ecosystem degradation. Over- Exploitation Water Pollution 5 major threat categories. Flow Modification Species Invasions Habitat Degradation Fig. 1. The five major threat categories and their established or potential interactive impacts on freshwater biodiversity. Dudgeon et al. (2006, Biol. Rev.) Special challenges for FW biodiversity conservation? 1) landscape position: FW systems lie at low points in landscape and thus concentrate pollutants. 2) High endemism: Many species have restricted ranges reflects evolutionary isolation. (Fish, mussels, crayfish, which are far more isolated than insects.) 3

4 Fundamentals of FW ecosystem function that provide context for vulnerability to climate change 1 Dynamic environments - Runoff amount, timing, extremes Vulnerabilities Hydrologic alteration 2 Temperature-dependent - Ectotherms with temperature optima and limits 3 Low points on landscape - Concentrate nutrients and sediment 4 Highly spatially structured - Naturally isolated, with regional and endemic species Thermal alteration Pollution, Eutrophication Fragmentation by dams Invasive species 4

5 Specific Threats to Fishes Richter et al.: Threats to imperiled freshwater fauna (1997) [Figure 5] Stressors for Historic declines Current limits to recovery Western Fishes: (1) Exotic interactions > (2) Agri diversions ( habitat, flows) > (3) Agri/hydro dams (habitat, flows) Eastern Fishes: (1) Nonpoint sedimentation > (2) toxics = nutrients = hydroelectric (habitat, flows) Threats posed by Exotics Terminology Extent of the Problem Exotic Species Effects TERMINOLOGY Native vs. Nonnative Indigenous, Endemic Exotic, Non-indigenous, Alien, Foreign Invasive vs. Exotic Invasives are exotics that become a nuisance (i.e., spread uncontrollably and alter ecosystems) Modes of nonnative introductions Intentional Non-intentional 5

6 Extent of Problem? [Allan Fig , 14.19] [ What Exotics Do (1) local extinction of native fauna a) biotic interactions (predation/competition) Non-native topminnow (Gambusia) in Arizona (Meffe s work) Brown trout eliminate native galaxiid fishes in New Zealand except in refuges above waterfalls Brook trout displace native cutthroat trout in western US 6

7 b) hybridization Box 13 (Minckley) Interspecific Hybridization Has been a contributing factor in 38% of the documented cases of fish extinctions in the US. Probably an underestimate because this is based on morphology, not genetic analysis Intraspecific Hybridization Spreading subspecies through stocking, e.g., cutthroat trout in West has led to loss of one genetically pure subspecies, the westslope cutthroat trout (Oncorynchus clarki lewisi) Review paper -- Perry et al. (2002). Systematic Biology 51: Pecos pupfish Sheepshead minnow c) disrupt food webs / overexploit resources example: Asian Carp species (especially silver carp) planktivore herbivore planktivore molluscivore 7

8 Efforts to keep carps out of Lake Michigan (2) alter ecosystem processes EXAMPLES: Rainbow trout in Japan (recall Baxter and Fausch research) New Zealand mud snail (Potamopyrgus antipodum) Invaded geothermal streams/rivers in Yellowstone National Park in 1994 Usurp primary production and truncate food web (recall Mary Power s work with Dicosmoecus) Range expansion rom 1995 (Green) to 2007 (Red) Hall et al. (2003, Front. Ecol. Environ.) 8

9 How to understand, even predict invasion success? Questions: Can we predict based on abiotic conditions alone? Do biotic interactions matter more than abiotic conditions? Are more diverse communities more resistant? 2 examples: New Zealand mudsnail California fish 9

10 Potamopyrgus antipodarum (New Zealand mudsnail) First discovered in U.S. in Snake River (ID) in 1987 In U.S., populations comprised of self cloning parthenogenetic females single female can lead to colony of 40 million snails in one year Have densities of up to 750,000 snails/m^2 in Yellowstone Can comprise up to 95% of invertebrate biomass, and consume up to 75% of food Consume but cannot be consumed hold no nutritional value for native fishes Rigid operculum and thick shell wall enable passage through digestive system of predators unharmed Can seal its shell, surviving out of water for several weeks Snails may spread locally on terrestrial wildlife and pets, or be consumed and defecated by local fishes Long distance dispersal may occur from ballast water discharge, movement of commercial aquaculture products, and transport of contaminated recreational gear Can crawl at rates of up to 1 m/hr, and perhaps 1 km/yr Spread of New Zealand mudsnail AnimatedMap.aspx?speciesID=1008 Loo et al. (2007) predicted range based on data in native range... Very little can be done to control or eradicate them However, habitat suitability may be reduced through high flow releases from dams Holomuzki & Biggs (2005) showed that current velocities of 1.5 m/sec dislodge 100% of mudsnails from bedrock and >80% from gravel...and invaded range. 10

11 Example 2: California fishes Moyle & Light s (1996) principles of invasion based on 22 years of observations of CA fish. Most lotic systems can be invaded, depending on 1) life history fit with hydrologic regime if hydrologic regime modified then different species favored (recall Fausch s study of success of rainbow trout invasion around the world) 2) stressed/depleted native assemblages more invasible a) habitat modification stresses native fishes b) poor management by agencies (harvest) 3) trophic position influences impact a) predators have large impact (naïve prey) b) omnivores/detritivores less impact Bottom line: Invasion is a property of: - the invader - the habitat invaded - the community invaded Challenges for freshwater biodiversity conservation and ecosystem sustainability Over- Exploitation Water Pollution Limited regulation under Endangered Species Act or state-level initiatives Flow Modification Habitat Degradation Regulations developed under federal Clean Water Act Species Invasions Fig. 1. The five major threat categories and their established or potential interactive impacts on freshwater biodiversity. Many active control measures and efforts to limit spread 11