A LONG-TERM ANALYSIS OF FISH SPECIES PROPORTIONS IN SONOITA CREEK, ARIZONA

Abstract

Desert streams are unique and fragile ecosystems that are extremely sensitive to system changes. Dams and diversions, introduction of exotic species, global warming, and pollutant runoff from cities and mines are all anthropogenic changes to stream behavior that have resulted in low flow, increased competition, increased temperature, and higher concentration of pollutants. Sonoita Creek, Arizona has experienced all of these stressors and we examined if the native and exotic fish species composition has shifted and the potential roll of these stressors. This paper follows a 36-year (1991-2017) meta-analysis of the proportions of three primary native fish species found in Sonoita Creek; desert sucker, Pantosteus clarki, longfin dace, Agosia chrysogaster,and speckled dace, Rhinichthyes osculus, In the beginning of these surveys in 1991, longfin dace was highly dominant in the creek but decreased over time, likely due to a change in discharge. This analysis shows us that there is a definitive change in species composition. While the trend does provide insight into the stream status, further studies need to be done to determine what surrounding covariates are affecting these changes the most.