Poster Presentation Freshwater Sciences 2023

Aquatic macroinvertebrate communities of central Arizona highland streams (#651)

Aaron Klarenbach 1 , David A Lytle 1
  1. Oregon State University, Corvallis, OREGON, United States

Streamflows in the arid southwestern United States, particularly in high elevation catchments, are expected to decline in the coming decades due to increasing water extraction and drought. Aquatic macroinvertebrates, which are a critical part of the riparian food web and are used as bioindicators of stream health, are one of many communities that will be affected by reduced streamflows. We seek to quantify how communities shift under possible future streamflow scenarios to inform conservation and management decisions. Aquatic macroinvertebrates were sampled in spring 2022 from four tributaries in designated Wilderness areas in the Central Arizona Highlands, an ecoregion known for geological and ecological diversity. A hierarchical sampling method was employed, with replicate samples taken from both riffles and pools, at two reaches, from each of the four tributaries, for a total of 48 samples. Environmental data, including depth, water velocity, substrate size, water chemistry, and canopy cover, were collected from each macrohabitat. Preliminary results show taxonomic richness does not differ between riffles and pools, despite each macrohabitat harboring distinct communities. Riffles contained a higher proportion of terrestrially available taxa with complex life cycles, such as Ephemeroptera, Plecoptera, and Trichoptera. Nonmetric Multidimensional Scaling (NMDS) ordinations will be utilized to examine how environmental variables influence community structures, as well as how communities compare between sampling reaches. Additionally, hydrological models will be used to determine how proportions of riffles and pools shift under reduced streamflow scenarios. Better understanding how different habitats influence aquatic macroinvertebrate abundance and diversity allows us to quantify how these communities will change in response to declining streamflows, as well as provide a baseline for future comparisons.