Research

Research program

Two invaders now overlap with a native species in Oregon rivers. Non-native Smallmouth Bass are established predators in the Willamette and Umpqua systems; invasive Ringed Crayfish (Faxonius neglectus) are spreading into the range of native Signal Crayfish (Pacifastacus leniusculus). My dissertation asks whether predation by one non-native species alters the establishment of another — an invasive-on-invasive biotic resistance framing — and what that means for the native crayfish caught in the middle.

The three chapters move from what is eaten in the field, to why, to where it matters.

Dissertation chapters

Chapter 1

Diet and trophic position in the field

Research question. What do Smallmouth Bass eat across the invasion front, and how much of that diet is crayfish?

Approach. Field diet analysis paired with stable isotope work (δ¹³C and δ¹⁵N) to resolve trophic position and long-term resource use across sites in the Willamette and Umpqua basins.

Placeholder: add a site map, sampling summary, and one representative figure here.

Chapter 2

Temperature and predator–prey interactions

How does temperature influence Smallmouth Bass predation on native Signal Crayfish and non-native Ringed Crayfish?

Experimental design. Controlled predation trials across a temperature gradient spanning conditions measured in the field (approximately 20–27 °C during June fieldwork at stations UMP001–UMP005).

Species studied. Micropterus dolomieu, Faxonius neglectus, Pacifastacus leniusculus.

Tank setup. A three-compartment mesocosm (120 × 40 × 50 cm) separating the predator, a shared arena, and the crayfish, allowing controlled encounters and behavioral observation.

Methods. Trial protocol, prey selection metrics, behavioral scoring, and the statistical models used to analyze consumption rates.

Placeholder: add tank photos, the schematic, and preliminary results here.

Once published, this section will carry: publication · dataset · R code · conference presentation · DOI.

Chapter 3

Distribution and the range contact zone

Research question. Where do the two crayfish species actually meet, and what stream conditions predict overlap?

Approach. Spatial stream network modeling and distribution analysis. A national occurrence comparison found no shared hexagonal cells between F. neglectus and P. leniusculus, which makes the study reach a novel contact zone rather than a long-established one.

Placeholder: add distribution maps and model output here.

Methods and tools

Area Tools
Field sampling Diet collection, temperature loggers, site surveys
Laboratory Stable isotope analysis (δ¹³C, δ¹⁵N), mesocosm predation trials
Quantitative R, mixed models, spatial stream network models, species distribution modeling
Reproducibility Quarto, Git and GitHub, Zotero with Better BibTeX