Amphibian Protection Strategies. Presented by: Linda Dupuis, M.Sc., R.P.Bio Wildlife Habitat Ecologist

Transcription

1 Amphibian Protection Strategies Presented by: Linda Dupuis, M.Sc., R.P.Bio Wildlife Habitat Ecologist

2 Vulnerability Biphase life histories and physiological limitations make aquatic-breeding amphibians particularly vulnerable to habitat loss and degradation

3 Protection Strategies Habitat Conservation (Avoidance) Environmental Mitigation Amphibian Salvages Wetland/Riparian Compensation

4 Conservation All wetlands are important Developments should avoid them

5 Conservation Temporary wetlands are critical breeding sites and/or stepping stones in the landscape

6 Conservation Temporary wetlands need to be properly identified and flagged during environmental impact assessments.

7 Conservation Aquatic For amphibians, wetlands and riparian zones are one inseparable habitat Refugia Terrestrial

8 Conservation Landscape Consideration

9 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

10 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

11 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

12 Mitigation Bathymetry Avoid disturbing shallow areas where amphibians reside)

13 Maintain step-pools Channel Morphology

14 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

15 Fibre rolls break slope grades and slow/disperse surface runoff Mitigation

16 Mitigation Check dams slow ditch flows (minimize erosion and promote sediment settlement)

17 Mitigation Riprap armouring protects underlying soil from erosion to flowing water

18 Mitigation Rock pits promote infiltration of ditch water and help settle sediments before they are discharged

19 Mitigation Large projects require settlement ponds

20 Mitigation Watershed-level considerations Ditches need to be properly configured: short ditch runs discharge disconnected from water bodies (streams and wetlands)

21 Landscape Consideration Mitigation

22 Mitigation Landscape Considerations Dispersal is key to metapopulation dynamics Habitat linkages Amphibian passageways

23 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

24 Mitigation Requires: On site supervision Knowledge of BMPs Knowledge of amphibian ecology Inter-disciplinary involvement

25 Salvages Timing Habitat Landscape Amphibian Salvages - Requires Context

26 Salvages Timing is species, year, and sitespecific Surface activity is necessary for an amphibian salvage to succeed

27 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.

28 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

29 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

30 Salvages Habitat dictates salvage techniques Active searches Aquatic traps Dipnets Pitfall traps Coverboards

31 Active searches are the most effective means of finding frogs of all ages and they require no set up costs Salvages

32 Salvages Active searches are the only effective means of capturing terrestrial and aquatic life forms of stream amphibians

33 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

34 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

35 Dipnets limited to simple habitats Ideal for inventories but not for salvages

36 Wetlands need to be excluded from construction sites with solid fencing Salvages

37 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

38 Salvages When development fully encroaches on a wetland RiparianZone Legend: Shallow water Mid level water Riparian Zone Exclusion Fence 30m Pitfalls (optional) Active Searches

39 Salvages Development in a stream environment Upstream exclusion fence Downstream exclusion fence

40 Gradual Reduced Flow Legend: Large Sandbags Shallow water (1) Mid level water (2) Deep Water (3) Exclusion Fence Bi-pass (pipe or diversion channel Stage 1 Stage 2 Stage 3 Downstream exclusion fence

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42 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)

43 Salvages All habitats have a carrying capacity. Crowding another wetland can defeat the purpose of a salvage

44 Relocating individuals can contribute to the spread of disease in wetlands Salvages

45 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

46 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

47 Wetland Compensation Several small wetlands provides more lentic habitat and increases potential metapopulation dynamics

48 Wetland Compensation Geometry Complex shoreline increase length of lentic habitat and mimics natural edges

49 Wetland Compensation Shallow Slope is critical for sustained lentic habitat through the spring and summer (3:1 to 5:1) France, 2003

50 Wetland Compensation Orientation Maximize southern shoreline through east-west alignment

51 Stream Compensation

52 The End Mark Johannes