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This past weekend, three members of the Johnson Lab presented at the Guild of Rocky Mountain Ecologists and Evolutionary Biologists (GREEBs) meeting at the Mountain Research Station. GREEBs brings scientists from across the southern Rocky Mountains together to discuss research in ecology and evolutionary biology. During the meeting, PhD student Paige McCreadie and honors student Emma Smith both gave oral presentations and PhD student Griffin Wagner gave a poster presentation about their research. More information about their presentations is below. Great job, everyone!

Paige McCreadie - "Assessing salinity impacts on parasites using laboratory and meta-analysis techniques"

• Paige presented results from two separate projects investigating how increased salinity affects parasites. The first is an ongoing meta-analysis exploring studies that look at how parasite and host fitness is impacted by changes in salinity. The second was a project that assessed trematode cercarial survival in different salt concentrations. Results from this work will contribute to our knowledge of how drought impacts freshwater parasitism, as changes in water chemistry (including increased salinity) occur in ponds during drought conditions.

Emma Smith - "Geographic and seasonal patterns in osprey diet revealed through web-based imagery"

• Emma presented her honors thesis, which examines regional and seasonal variation in osprey (Pandion haliaetus) diet across the Caribbean and the Florida Keys in the United States. Osprey's diet is dominated by fish (~99%), and numerous studies conducted in North America have shown that they consume both freshwater and marine fish. However, osprey diet in the Caribbean remains largely unknown, with little to no studies examining what prey they consume across this region. Additionally, ospreys are currently the only known bird host of the parasite Scaphanocephalus expansus, which can cause Black Spot Syndrome in fishes. This research can provide insight into the roles that osprey play in both aquatic food webs and parasite transmission across ecosystems.

Griffin Wagner - "Amphibians Beneath the Mat: Effects of Invasive Mosquito Fern (Azolla caroliniana) on Pond Ecosystems"

• Griffin's project focused on the ecological effects of A. caroliniana including macroinvertebrate richness, amphibian survival, and amphibian chytrid fungus prevalence. This work is the first to document the harmful ecological effects of the recent A. caroliniana invasion in California. Additionally, this poster presented preliminary findings from a spring and summer 2026 mesocosm experiment directly testing the mechanistic effects of A. caroliniana on amphibian survival.