Amphibian Protection Strategies Presented by: Linda Dupuis, M.Sc., R.P.Bio Wildlife Habitat Ecologist
Vulnerability Biphase life histories and physiological limitations make aquatic-breeding amphibians particularly vulnerable to habitat loss and degradation
Protection Strategies Habitat Conservation (Avoidance) Environmental Mitigation Amphibian Salvages Wetland/Riparian Compensation
Conservation All wetlands are important Developments should avoid them
Conservation Temporary wetlands are critical breeding sites and/or stepping stones in the landscape
Conservation Temporary wetlands need to be properly identified and flagged during environmental impact assessments.
Conservation Aquatic For amphibians, wetlands and riparian zones are one inseparable habitat Refugia Terrestrial
Conservation Landscape Consideration
Mitigation Minimize the development footprint Aim for at least 30 m buffer Buffers against wind and sun Provides foraging habitat, refuge Filters sediment and other pollutants Screens noise and activity
Mitigation Replant disturbed soils with native grasses and shrubs as soon as possible Prevents colonization by invasive species Minimizes sedimentation and erosion Limit coarse armouring in habitat areas
Hydrology Surface outflows Evapotranspiration Changes in water volume Work with a hydrologist Groundwater outflows Mitigation Maintain hydroperiod so that lentic environment wetted until metamorphosis Net Precipitation Changes in water volume Surface outflows Groundwater outflows
Mitigation Bathymetry Avoid disturbing shallow areas where amphibians reside)
Maintain step-pools Channel Morphology
Mitigation Control sediment and erosion Silt fences are effective for intercepting sediments along the toe of slope or the upper boundary of a work site
Fibre rolls break slope grades and slow/disperse surface runoff Mitigation
Mitigation Check dams slow ditch flows (minimize erosion and promote sediment settlement)
Mitigation Riprap armouring protects underlying soil from erosion to flowing water
Mitigation Rock pits promote infiltration of ditch water and help settle sediments before they are discharged
Mitigation Large projects require settlement ponds
Mitigation Watershed-level considerations Ditches need to be properly configured: short ditch runs discharge disconnected from water bodies (streams and wetlands)
Landscape Consideration Mitigation
Mitigation Landscape Considerations Dispersal is key to metapopulation dynamics Habitat linkages Amphibian passageways
Mitigation Amphibian culvert design considerations: Local organic soil as substrate Variable rock size Cover objects Permanent ramps to culvert edge Barrier fencing Flush with slope Strategic placement
Mitigation Requires: On site supervision Knowledge of BMPs Knowledge of amphibian ecology Inter-disciplinary involvement
Salvages Timing Habitat Landscape Amphibian Salvages - Requires Context
Salvages Timing is species, year, and sitespecific Surface activity is necessary for an amphibian salvage to succeed
Salvages Onset of Breeding Season Species Red-legged and Oregon spotted frog Coast tailed frog and Pacific giant salamander Western toad Earliest activity varies with latitude and elevation Minimum 7 C water temp. Low summer flows with minimum 8 C water temp. Minimum 9 C water temp.
Salvages Spring considerations Breeding adults generally congregate in the littoral zone during the egg-laying season Liz Kovics Egg masses are easy-to-detect aggregations of larvae; relocation requires (1) similar ph, water temperature, habitat conditions; (2) fencing to prevent egg drift without restricting larval movement
Salvages Summer and fall considerations Older tadpoles are easier to detect than young ones and less numerous Juveniles and adults can become increasingly water bound as summer progresses
Salvages Habitat dictates salvage techniques Active searches Aquatic traps Dipnets Pitfall traps Coverboards
Active searches are the most effective means of finding frogs of all ages and they require no set up costs Salvages
Salvages Active searches are the only effective means of capturing terrestrial and aquatic life forms of stream amphibians
Salvages In some terrestrial settings (with complex CWD or shaded talus), active searches might be supplemented by a passive salvage technique Coverboards need to weather for at least a few weeks Pitfalls are labour intensive; not feasible in rocky terrain or areas of thin soil. Both of these techniques yield fewer captures than searches; they are costly and timeconsuming
Salvages Funnel traps are effective for capturing tadpoles in most BC wetlands A low recovery can be expected but this is the best one can achieve when salvaging tadpoles
Dipnets limited to simple habitats Ideal for inventories but not for salvages
Wetlands need to be excluded from construction sites with solid fencing Salvages
Salvages When development partially encroaches on a wetland Lentic habitat ( < 1m ) Legend: Shallow water Mid level water Riparian Zone Exclusion Fence Undisturbed 30m riparian Development Proposed disturbance
Salvages When development fully encroaches on a wetland RiparianZone Legend: Shallow water Mid level water Riparian Zone Exclusion Fence 30m Pitfalls (optional) Active Searches
Salvages Development in a stream environment Upstream exclusion fence Downstream exclusion fence
Gradual Reduced Flow Legend: Large Sandbags Shallow water (1) Mid level water (2) Deep Water (3) Exclusion Fence Bi-pass (pipe or diversion channel 1 2 2 1 3 Stage 1 Stage 2 Stage 3 Downstream exclusion fence
Relocation options can be limited Best to avoid having to salvage because wetlands are scarce in many areas, or of different types Salvages A landscape assessment is required before a salvage to determine relocation site(s)
Salvages All habitats have a carrying capacity. Crowding another wetland can defeat the purpose of a salvage
Relocating individuals can contribute to the spread of disease in wetlands Salvages
Wetland Compensation Restore/enhance other degraded wetland habitats Create wetland in other location to counterbalance loss Location priorities: As close as possible to site Same wetland type
Wetland Compensation Compensation ratios May be greater than 1:1 Increases with distance from site (Wetland Mitigation in Canada a Framework for Application) Wetland re-construction Involve multi-disciplinary team
Wetland Compensation Several small wetlands provides more lentic habitat and increases potential metapopulation dynamics
Wetland Compensation Geometry Complex shoreline increase length of lentic habitat and mimics natural edges
Wetland Compensation Shallow Slope is critical for sustained lentic habitat through the spring and summer (3:1 to 5:1) France, 2003
Wetland Compensation Orientation Maximize southern shoreline through east-west alignment
Stream Compensation
The End Mark Johannes