CLBMON-58. Kinbasket Reservoir: Monitoring of Impacts on amphibians and Reptiles from Mica Units 5 and 6 in Kinbasket Reservoir

Author: V.C.K.N.Tuttle Hawkes, K.J. Meyers

In 2008, BC Hydro initiated a long-term monitoring program (CLBMON-37) to assess the life history and habitat use of amphibians and reptile populations in the Arrow Lakes and Kinbasket Reservoirs of the Columbia Basin. Monitoring populations of amphibians and reptiles in the drawdown zone will provide the necessary information to address management questions related to (1) their life history and habitat use, (2) the effects of reservoir operations on those populations, and (3) the potential to mitigate those impacts by using physical works (as per CLBMON-37). Monitoring efforts specific to Kinbasket Reservoir (as per CLBMON-58) will enable an assessment of the impacts of Mica Units 5 and 6 on amphibians using habitats in the drawdown zone of Kinbasket Reservoir. MQ10: Do increased reservoir levels in Kinbasket Reservoir during the summer months resulting from the installation of Mica 5 and 6 negatively impact amphibians populations in the drawdown zone through increased larval mortality or delayed development?

MQ1: Which species of amphibians and reptiles occur (utilize habitat) within the drawdown zone and where do they occur? Three amphibians species have been documented using the drawdown zone and adjacent upland habitat of Kinbasket Reservoir (Western Toad, Columbia Spotted Frog, Long-toed Salamander).
MQ2: What is the abundance, diversity, and productivity (reproduction) of amphibians and reptiles utilizing the drawdown zone and how do these vary within and between years? Abundances vary from year to year and in general, there are more detections in the spring than in the summer or early fall. Western Toad were the most abundant species. amphibians species diversity has not varied substantively by year, ranging from 0.34 to 0.41. Western Toad, Columbia Spotted Frog, and Long-toed Salamander use the DDZ for reproduction (inferring productivity), and data collected for two species (Western Toad and Columbia Spotted Frog) indicate that all life stages of this species (i.e., eggs, tadpoles, toadlets, and adults) use habitats in the drawdown zone.
MQ3: During what portion of their life history (e.g., breeding, foraging, and over-wintering) do amphibians and reptiles utilize the drawdown zone? Frogs and toads use the DDZ to fulfill most of their life history stages (e.g., breeding and foraging), while other species (e.g., Long-toed Salamander) appear to use the DDZ to fulfill specific life stages. Use of the drawdown zone for overwintering is considered unlikely for most species.
MQ4: Which habitats do reptiles and amphibians use in the drawdown zone and what are their characteristics (e.g., pond size, water depth, water quality, vegetation, elevation band)? Western Toad and Columbia Spotted Frog were typically detected in wetlands within wool-grassPennsylvania buttercup, buckbean-slender sedge, Kelloggs sedge or swamp-horsetail habitats. Pond characteristics varied by species with Columbia Spotted Frog using ponds situated at a higher elevation and with a higher abundance and percent cover of aquatic macrophytes compared to Western Toad. Western Toad breeds at elevations down to 743 m above sea level (ASL) in ponds that are typically devoid of vegetation or woody debris. It appears that the water physicochemical parameters measured (dissolved oxygen, conductivity, pH, temperature) do not affect distribution, occurrence, or development of either species.
MQ5: How do reservoir operations influence or impact amphibians and reptiles directly (e.g., desiccation, inundation, predation) or indirectly through habitat changes? Reservoir operations impact habitat through changes in availability of breeding and foraging habitat of amphibians and reptiles using the drawdown zone, both directly and indirectly. The number of amphibians and reptile observations often decreased as reservoir elevations increased. Although inundation affects habitat availability directly, we have consistently observed only minor changes in water physicochemical parameters over the years and all life stages of both anuran species were observed in 2017. Because amphibians are persisting in the drawdown zone, we can speculate that the annual reduction of habitat availability does not dramatically affect local amphibians populations; however, we do not know if the populations are supressed relative to populations in non-reservoir habitats.
MQ6: Can minor adjustments be made to reservoir operations to minimize the impact on amphibians and reptiles? The limited amount of breeding habitat available in the drawdown zone should be considered relative to reservoir operations. Some ponds at lower elevations in Bush Arm are used by Western Toad for breeding (e.g., breeding ponds at KM88). These ponds are situated between 735 and 744 m ASL, and although they comprise a small number of ponds, they could be considered for protection to minimize impacts to toads. By protection, we suggest that delaying the inundation of elevations between 735 and 736 m ASL into late June would likely afford enough time for eggs to hatch into tadpoles and provide enough time for the tadpoles to grow such that the effects of inundation would be minimized. A management strategy to avoid involves rapidly filling the reservoir in the spring when amphibians are breeding in ponds in the drawdown zone. Doing so would likely affect the annual fecundity of all species of pond-breeding amphibians.
MQ7: Can physical works projects be designed to mitigate adverse impacts on amphibians and reptiles resulting from reservoir operations? Yes. The removal of wood debris from wetlands, which was done as part of a physical works project in Kinbasket Reservoir improved the suitability of those wetlands for amphibians. The use of physical works to mitigate adverse impacts on amphibians and reptiles resulting from reservoir operations will be limited in scale as only certain portions of the drawdown zone can be manipulated to improve habitat suitability.
MQ8: Does revegetating the drawdown zone affect the availability and use of habitat by amphibians and reptiles? Np. revegetating the drawdown zone does not affect the availability and use of habitat by wildlife. CLBWORKS-1, revegetation program did not include improvements to amphibians habitat suitability as a primary objective.
MQ9: Do physical works projects implemented during the course of this monitoring program increase the abundance of amphibians and reptiles abundance, diversity, or productivity? The physical works implemented in Kinbasket Reservoir in 2015 have resulted in Western Toad using previously unavailable wetlands for breeding. As such, there is evidence to support an increase in productivity for certain species via the removal of wood debris from wetlands.
MQ10: Do increased reservoir levels in Kinbasket Reservoir during the summer months resulting from the installation of Mica 5 and 6 negatively impact amphibians populations in the drawdown zone through increased larval mortality or delayed development? Based on reservoir operations between 2011 and 2017, an increase in reservoir elevation of 0.6 m is unlikely to have a large effect on amphibians and reptile populations that use the drawdown zone of Kinbasket Reservoir. However, the anticipated increase in reservoir surcharging is not likely to directly affect amphibians populations, but indirect effects are likely. Important habitats will be impacted, particularly those ponds situated above 751 m ASL (which represents ~64 per cent of all ponds mapped in the drawdown zone). Impacts will be mainly related to changes in habitat suitability caused by wood deposition and changes to aquatic and riparian vegetation communities that could affect the primary productivity of wetlands.

MQ1: Which species of amphibians and reptiles occur (utilize habitat) within the drawdown zone and where do they occur? Three amphibians species have been documented using the drawdown zone and adjacent upland habitat of Kinbasket Reservoir (Western Toad, Columbia Spotted Frog, Long-toed Salamander).
MQ2: What is the abundance, diversity, and productivity (reproduction) of amphibians and reptiles utilizing the drawdown zone and how do these vary within and between years? Abundances vary from year to year and in general, there are more detections in the spring than in the summer or early fall. Western Toad were the most abundant species. amphibians species diversity has not varied substantively by year, ranging from 0.34 to 0.41. Western Toad, Columbia Spotted Frog, and Long-toed Salamander use the DDZ for reproduction (inferring productivity), and data collected for two species (Western Toad and Columbia Spotted Frog) indicate that all life stages of this species (i.e., eggs, tadpoles, toadlets, and adults) use habitats in the drawdown zone.
MQ3: During what portion of their life history (e.g., breeding, foraging, and over-wintering) do amphibians and reptiles utilize the drawdown zone? Frogs and toads use the DDZ to fulfill most of their life history stages (e.g., breeding and foraging), while other species (e.g., Long-toed Salamander) appear to use the DDZ to fulfill specific life stages. Use of the drawdown zone for overwintering is considered unlikely for most species.
MQ4: Which habitats do reptiles and amphibians use in the drawdown zone and what are their characteristics (e.g., pond size, water depth, water quality, vegetation, elevation band)? Western Toad and Columbia Spotted Frog were typically detected in wetlands within wool-grassPennsylvania buttercup, buckbean-slender sedge, Kelloggs sedge or swamp-horsetail habitats. Pond characteristics varied by species with Columbia Spotted Frog using ponds situated at a higher elevation and with a higher abundance and percent cover of aquatic macrophytes compared to Western Toad. Western Toad breeds at elevations down to 743 m above sea level (ASL) in ponds that are typically devoid of vegetation or woody debris. It appears that the water physicochemical parameters measured (dissolved oxygen, conductivity, pH, temperature) do not affect distribution, occurrence, or development of either species.
MQ5: How do reservoir operations influence or impact amphibians and reptiles directly (e.g., desiccation, inundation, predation) or indirectly through habitat changes? Reservoir operations impact habitat through changes in availability of breeding and foraging habitat of amphibians and reptiles using the drawdown zone, both directly and indirectly. The number of amphibians and reptile observations often decreased as reservoir elevations increased. Although inundation affects habitat availability directly, we have consistently observed only minor changes in water physicochemical parameters over the years and all life stages of both anuran species were observed in 2017. Because amphibians are persisting in the drawdown zone, we can speculate that the annual reduction of habitat availability does not dramatically affect local amphibians populations; however, we do not know if the populations are supressed relative to populations in non-reservoir habitats.
MQ6: Can minor adjustments be made to reservoir operations to minimize the impact on amphibians and reptiles? The limited amount of breeding habitat available in the drawdown zone should be considered relative to reservoir operations. Some ponds at lower elevations in Bush Arm are used by Western Toad for breeding (e.g., breeding ponds at KM88). These ponds are situated between 735 and 744 m ASL, and although they comprise a small number of ponds, they could be considered for protection to minimize impacts to toads. By protection, we suggest that delaying the inundation of elevations between 735 and 736 m ASL into late June would likely afford enough time for eggs to hatch into tadpoles and provide enough time for the tadpoles to grow such that the effects of inundation would be minimized. A management strategy to avoid involves rapidly filling the reservoir in the spring when amphibians are breeding in ponds in the drawdown zone. Doing so would likely affect the annual fecundity of all species of pond-breeding amphibians.
MQ7: Can physical works projects be designed to mitigate adverse impacts on amphibians and reptiles resulting from reservoir operations? Yes. The removal of wood debris from wetlands, which was done as part of a physical works project in Kinbasket Reservoir improved the suitability of those wetlands for amphibians. The use of physical works to mitigate adverse impacts on amphibians and reptiles resulting from reservoir operations will be limited in scale as only certain portions of the drawdown zone can be manipulated to improve habitat suitability.
MQ8: Does revegetating the drawdown zone affect the availability and use of habitat by amphibians and reptiles? Np. revegetating the drawdown zone does not affect the availability and use of habitat by wildlife. CLBWORKS-1, revegetation program did not include improvements to amphibians habitat suitability as a primary objective.
MQ9: Do physical works projects implemented during the course of this monitoring program increase the abundance of amphibians and reptiles abundance, diversity, or productivity? The physical works implemented in Kinbasket Reservoir in 2015 have resulted in Western Toad using previously unavailable wetlands for breeding. As such, there is evidence to support an increase in productivity for certain species via the removal of wood debris from wetlands.
MQ10: Do increased reservoir levels in Kinbasket Reservoir during the summer months resulting from the installation of Mica 5 and 6 negatively impact amphibians populations in the drawdown zone through increased larval mortality or delayed development? Based on reservoir operations between 2011 and 2017, an increase in reservoir elevation of 0.6 m is unlikely to have a large effect on amphibians and reptile populations that use the drawdown zone of Kinbasket Reservoir. However, the anticipated increase in reservoir surcharging is not likely to directly affect amphibians populations, but indirect effects are likely. Important habitats will be impacted, particularly those ponds situated above 751 m ASL (which represents ~64 per cent of all ponds mapped in the drawdown zone). Impacts will be mainly related to changes in habitat suitability caused by wood deposition and changes to aquatic and riparian vegetation communities that could affect the primary productivity of wetlands.