Date of Graduation

Spring 5-19-2017

Document Type

Project/Capstone

Degree Name

Master of Science in Environmental Management (MSEM)

College/School

College of Arts and Sciences

Department/Program

Environmental Management

First Advisor

John Callaway

Abstract

Amphibian populations worldwide are experiencing precipitous declines as a result of disease, introduced species, habitat loss, and climate change. The mountain yellow-legged frog (MYLF), once considered the most abundant vertebrate in the Sierra Nevada, has suffered dramatic population declines in recent decades, and implications of their decline include biodiversity impacts throughout this region. Specifically, the distribution of MYLF has severely contracted within their geographic range, with an obvious shift in overall abundance to sites toward the upper reaches of their elevation range. MYLF occupying high-elevation habitats (i.e., lakes and ponds) must overwinter for especially prolonged periods, which decreases their ability to forage and develop. Conversely, MYLF occupying habitats at lower elevations (i.e., wet meadows, streams, lakes, and ponds) exhibit higher growth rates, better body condition, and increased longevity. Yet, most scientific efforts for MYLF, such as non-native fish removal and research on disease dynamics, are being conducted at high-elevation habitats. The purpose of this literature review was to evaluate the potential opportunities and constraints of wet meadow restoration for MYLF. An evaluation of literature was conducted to answer questions revolving around (1) the biological and ecological requirements of MYLF, (2) primary stressors threatening the survival and distribution of MYLF, (3) MYLF utilization of wet meadows, and (4) suitability of wet meadow restoration outcomes for MYLF. A review of the literature suggests that meadow restoration may increase the availability and connectedness of habitat for MYLF by providing key physical and biological features required by this species. Meadows may also promote MYLF persistence with the chytrid fungus via warm expansive aquatic habitat that reduces zoospore density and production, disincentivizes transmission through aggregations and overwintering, and promotes overall MYLF fitness. These results indicate that increased species resiliency may be a general opportunity of meadow restoration. Major constraints or limitations of meadow restoration include predatory species introductions and limited peer-reviewed data on MYLF overwintering, co-occurrence with non-native fish, and use of wet meadows, despite a moderate amount of meadow occupancy data presented by public resource agencies. Given the results of this literature review, abbreviated recommendations include: restoration planning and design that incorporates knowledge on MYLF dispersal abilities, overwintering and basking needs, and MYLF-non-native fish dynamics; adaptive management of non-native predators following MYLF natural reestablishment or repatriation in restored meadows; and further studies on MYLF in wet meadow habitats, including those that focus on disease dynamics and overwintering.

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