Presentation Title

Comparison of Post-Monsoon Aquatic Invertebrate Communities in the San Pedro River, AZ

Faculty Mentor

Steven Merkley

Start Date

23-11-2019 10:00 AM

End Date

23-11-2019 10:45 AM

Location

99

Session

poster 3

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

The San Pedro River, located in Southeast Arizona, is home to hundreds of migrating and residential birds and many species of mammals, amphibians, and reptiles dwelling within the riparian area. Terrestrial consumers in the San Pedro rely upon freshwater insects emerging from the river as a food source. Within the river, there are variable levels of stream flow due to unique environmental conditions. Understanding the effect of stream flow on aquatic insect communities will provide insight into how riparian consumers may respond to changing environmental conditions. We predict that there will be less freshwater invertebrate diversity in intermittent sites compared to perennial sites. We compared USGS discharge data with post-monsoon season sampling of invertebrates from various sites along the river. Two weeks post-monsoon, aquatic invertebrates were collected from both riffles and pools at two sites in the upper San Pedro River (near Fairbank, AZ and near Charleston, AZ).In riffles, we used a Surber sampler (30 x 30cm, 1mm mesh). For pools used a D-net (~500µm) with an effort of 10 s/m2. We identified invertebrates to the finest taxonomic level possible (Family or Genera). When comparing the USGS data, it was noted that the intermittent site (Fairbank) received significantly less discharge (ft3/s) compared to the perennial site (Charleston). We used Shannon Diversity Index to test our hypotheses that intermittent sites have less diversity in riffle habitats. Although we found differences in the mean (1.26 at perennial sites and 0.74 at intermittent sites), the difference was not statistically significant (t=2.31, df=3.99, p=0.082). Additional samples will be collected seasonally and between years to further test our hypotheses that community composition of freshwater invertebrates in the San Pedro River is impacted by stream flow.

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Nov 23rd, 10:00 AM Nov 23rd, 10:45 AM

Comparison of Post-Monsoon Aquatic Invertebrate Communities in the San Pedro River, AZ

99

The San Pedro River, located in Southeast Arizona, is home to hundreds of migrating and residential birds and many species of mammals, amphibians, and reptiles dwelling within the riparian area. Terrestrial consumers in the San Pedro rely upon freshwater insects emerging from the river as a food source. Within the river, there are variable levels of stream flow due to unique environmental conditions. Understanding the effect of stream flow on aquatic insect communities will provide insight into how riparian consumers may respond to changing environmental conditions. We predict that there will be less freshwater invertebrate diversity in intermittent sites compared to perennial sites. We compared USGS discharge data with post-monsoon season sampling of invertebrates from various sites along the river. Two weeks post-monsoon, aquatic invertebrates were collected from both riffles and pools at two sites in the upper San Pedro River (near Fairbank, AZ and near Charleston, AZ).In riffles, we used a Surber sampler (30 x 30cm, 1mm mesh). For pools used a D-net (~500µm) with an effort of 10 s/m2. We identified invertebrates to the finest taxonomic level possible (Family or Genera). When comparing the USGS data, it was noted that the intermittent site (Fairbank) received significantly less discharge (ft3/s) compared to the perennial site (Charleston). We used Shannon Diversity Index to test our hypotheses that intermittent sites have less diversity in riffle habitats. Although we found differences in the mean (1.26 at perennial sites and 0.74 at intermittent sites), the difference was not statistically significant (t=2.31, df=3.99, p=0.082). Additional samples will be collected seasonally and between years to further test our hypotheses that community composition of freshwater invertebrates in the San Pedro River is impacted by stream flow.