Presentation Type

Poster

Faculty Mentor’s Full Name

Art Woods

Faculty Mentor’s Department

Division of Biological Sciences

Abstract

The Giant Salmonfly (Pteronarcys californica), the largest species of stonefly in the world, are vital to streams in western North America. Understanding their diet may shed light on interactions between invertebrates and common riparian trees such as alder, cottonwood, chokecherry, dogwood, and willow. P. californica consume primarily fungal and microbial colonies on decomposing ‘conditioned’ leaves in streams. The rate and timing of leaf decomposition varies due to the toughness and chemistry of the leaves and the communities of microbes that colonize them. There are multiple species of leaves in the stream at any time, but they decompose with different dynamics. Leaves that quickly decompose disappear from the streams, leaving only tougher leaves during winter and the following spring and summer seasons. Because of this variability, P. californica may prefer leaves that decompose faster, such as chokecherry and alder, under short conditioning periods, but may prefer tough leaves, such as cottonwoods, under longer conditioning periods. We first asked whether stoneflies choose strongly among leaf type (based on either leaf species or conditioning time). We then assessed the consequences of those choices by measuring stonefly growth in no-choice assays (individuals given single leaf types). I also quantified leaf mass area for each leaf species as a proxy for toughness. This study showcases the complex interactions between riparian species and invertebrate growth. With the results of this study, restoration efforts on western streams may include planting a variety of riparian tree species to improve growth and winter survival of P. californica, and thus improve fisheries of western streams.

Category

Life Sciences

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Leaf Choice of Pteronarcys californica in Rock Creek, Montana

The Giant Salmonfly (Pteronarcys californica), the largest species of stonefly in the world, are vital to streams in western North America. Understanding their diet may shed light on interactions between invertebrates and common riparian trees such as alder, cottonwood, chokecherry, dogwood, and willow. P. californica consume primarily fungal and microbial colonies on decomposing ‘conditioned’ leaves in streams. The rate and timing of leaf decomposition varies due to the toughness and chemistry of the leaves and the communities of microbes that colonize them. There are multiple species of leaves in the stream at any time, but they decompose with different dynamics. Leaves that quickly decompose disappear from the streams, leaving only tougher leaves during winter and the following spring and summer seasons. Because of this variability, P. californica may prefer leaves that decompose faster, such as chokecherry and alder, under short conditioning periods, but may prefer tough leaves, such as cottonwoods, under longer conditioning periods. We first asked whether stoneflies choose strongly among leaf type (based on either leaf species or conditioning time). We then assessed the consequences of those choices by measuring stonefly growth in no-choice assays (individuals given single leaf types). I also quantified leaf mass area for each leaf species as a proxy for toughness. This study showcases the complex interactions between riparian species and invertebrate growth. With the results of this study, restoration efforts on western streams may include planting a variety of riparian tree species to improve growth and winter survival of P. californica, and thus improve fisheries of western streams.