The stoneflies of Saguaro National Park: “drought-proof survivalists” or “canaries in the climate-change coal mine”?
Authors: Michael T. Bogan
Year: 2014 (xlvi)
Abstract
Stoneflies (Plecoptera) are usually associated with cold, clean water, and are often used as sentinel species in stream health assessment. Despite their frequent association with cold water, some stoneflies can also be found in desert regions. While Saguaro National Park (SNP) was designated to preserve Sonoran Desert vegetation, the park also supports many kilometers of intermittent streams and a few perennial water sources. Little is known about the aquatic invertebrates of SNP, including the distribution of stoneflies in the park. In 2012 and 2013, I surveyed aquatic invertebrate communities at 24 intermittent and perennial stream reaches in SNP, with an emphasis on documenting the distribution of sensitive stonefly species. I found over 100 aquatic invertebrate taxa in SNP, including four stonefly species. The stoneflies Mesocapnia arizonensis and Capnia californica were found in intermittently-flowing reaches of streams throughout the park. Both are known to have desiccation-resistant diapause stages that confer survival through dry periods, including for multiple consecutive dry years. The other two species, Capnia decepta and Malenka coloradensis, were restricted to ~100m of stream at Manning Camp, the park’s highest elevation perennial water source. Both of these species, along with a suite of co-occurring caddisfly and mayfly species, are drought-intolerant and are at risk of being lost from SNP if Manning Camp Spring were to dry. Several other stonefly taxa (e.g. Chloroperlidae, Perlidae) occur at similar elevations in neighboring mountain ranges with more perennial water than SNP, suggesting that the current stonefly assemblage of the park is fairly depauperate. Thus the stonefly fauna of SNP includes both "drought-proof survivalists" (e.g. Mesocapnia arizonensis) and "canaries in the climate-change coal mine" (e.g. Malenka coloradensis), and populations of the latter should be closely monitored.
Resumen
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