Research
Asynchronous Prey Resources Create a Year-Round Energy Portfolio for Juvenile Salmonids
Freshwater rearing is a critical period in the life cycle of anadromous salmonids, known to produce carry-over effects mediating long-term growth and survival. Freshwater growth is primarily determined by food availability and temperature. While many species of salmon rear in freshwater for a full year or longer, most trophic ecology research is from a narrow window of time within the annual cycle. This work identified temporal biases in research, addressed gaps in understanding the trophic resources that support juvenile salmonids during key phases of freshwater rearing, and examined seasonal variability in asynchronous resource pulses and terrestrial-aquatic interactions. The first study in this thesis quantified temporal biases in the timing and duration of juvenile salmonid field research from the past 30 years. I found that across ecological topics, summer studies occurred 3x as commonly as winter studies and 57% of studies were focused on a single season. The second study in this thesis described the monthly variation in prey resources utilized by juvenile steelhead trout (Oncorhynchus mykiss) and coho salmon (O. kisutch) in the South Fork Skokomish River and its tributary Vance Creek in Hood Canal, Washington, USA. The results from this study suggest that stable in situ prey resources and ephemeral allochthonous prey resources create an asynchronous energy portfolio supporting juvenile salmonid freshwater rearing throughout the full annual cycle. Aquatic resources from the benthos and drift provided a relatively stable source of energy to juvenile salmonids year-round, but were most important during summer somatic growth, overwinter survival, and early spring prior to smoltification. Terrestrial subsidies contributed to fish diet over the course of spring, summer, and autumn; however, within the aggregate of terrestrial inputs, I found multiple ephemeral pulses of specific prey items. These ephemeral terrestrial invertebrates contributed heavily to fish diets and coincided with stressful developmental phases including smoltification in spring and lipid storage prior to the onset of winter: 66% of coho diet biomass in May came from rove beetles, 13% of coho diet biomass in October came from spiders, and 30% of steelhead diet biomass in October came from ground beetles. To an even greater extent, ephemeral marine subsidies provided energy to salmonids during a key development phase as they stored fat in preparation for overwinter survival. Multiple spawning events from three different species of salmon provided an extended resource pulse utilized by juvenile steelhead and coho with 61-96% of prey consumption during spawning months coming from marine subsidies. Moreover, despite the depressed size of salmon runs in this system, consumption of marine subsidies resulted in substantially larger rations than seen at any other point in the year. While summer research may be more common, the most interesting results from this field study came from spring and autumn. As salmon populations in the Pacific Northwest continue to decline, conservation and recovery efforts could benefit from incorporating knowledge of temporal variability in the trophic resources that juvenile salmonids use throughout freshwater rearing.
Master’s Thesis Presentation PDF of PowerPoint
_________________________
Missing pieces in the annual cycle of fish ecology: a systematic review of the timing of freshwater fish research focused on juvenile Pacific salmon and trout
In recent decades, fish ecologists have become increasingly aware of the need for spatially comprehensive sampling. However, a corresponding reflection on the temporal aspects of research has been lacking. We quantified the seasonal timing and extent of freshwater fish research reported in the literature. Since reviewing all prior work was not feasible, we considered two different subsets. First, we compiled the last 30 years of ecological research on juvenile Pacific salmon and trout (Oncorhynchus spp.) (n = 371 studies). In addition to the aggregate, we compared groups classified by subject matter. Next, to characterize whether riverscape ecology has embraced space at the expense of time, we compiled research across taxa for studies (n=46) that sampled fish in a spatially continuous manner, i.e., those that followed Fausch et al.’s 2002 plea for a ‘continuous view of the river…to understand processes interacting among scales.’ We found that the temporal distribution of ecological Oncorhynchus spp. research effort was biased towards summer (40% occurred during June-August) and the month of June in particular, at the expense of winter work (only 13% occurred during December-February). Riverscape studies were also biased in temporal distribution toward summer (47% of studies) and against winter (11%). It was less common for studies to encompass multiple seasons (43% of ecological Oncorhynchus spp. studies and 54% of riverscape studies) and most were shorter than 4 months (73% of ecological Oncorhynchus spp. studies and 81% of riverscape studies). These temporal biases may cause researchers to overemphasize ecological phenomena observed during summer and limit our ability to recognize seasonal interactions such as carry-over effects or compensatory responses. Full year and winter studies likely hold valuable insights for conservation and management.
_________________________
Nisqually River Tributaries Habitat Assessment
Completed a salmon and steelhead habitat assessment for the Muck Creek basin, a major tributary to the Nisqually River; completed a preliminary design for a high priority passage barrier. Our team of 3 staff worked together to create the study plan, conduct field work, complete data analysis, and write a final report that incorporated our data as well as the data of hired consultants and past studies.
Recreation and Conservation Office Project Snapshot Page
_________________________
GIS Annotated Bibliography: An annotated bibliography project for Oregon State University’s GEOG 560: GIScience 1 – Introduction to Geographic Information Science
The continued decline of Pacific salmon is often attributed to four factors: habitat, hydropower, harvest, and hatcheries. I believe that the most important of these is juvenile rearing habitat. Estimating the productivity of individual reaches of rivers often is a time-consuming effort to collect data on fish abundances and distributions, land-use and habitat characteristics, abiotic factors such as temperature, slope, substrate type, and stream flow, and energy supply through the availability of food items. Geographic Information Systems (GIS) offer an alternative view by looking at landscape-scale data in place of or in conjunction with site-scale data. In some cases, landscape-level features may provide a more accurate assessment of the habitat available for juvenile salmonid rearing. The spatial analysis tools in a GIS also offer the potential to identify at-risk areas, areas that should be prioritized for restoration, areas where monitoring should be focused, or the potential effects of climate change.
_________________________
Run Timing of Spring vs Fall Chinook Salmon Using Otolith Chemistry
Worked for Washington Department of Fish and Wildlife as a genetics field technician as part of a project using otoliths to differentiate between spring and fall Chinook salmon. Independently carry out carcass surveys and genetic sampling efforts for Chinook salmon in the Chehalis River basin (Upper Chehalis River, Newaukum River, South Fork Chehalis River). Primary role as genetics specialist, removing otoliths and taking DNA samples from spawned salmon as part of a project utilizing otoliths to differentiate between spring and fall Chinook salmon. Wrote otolith collection protocol document.
My otolith collection protocol document PDF link
Final WDFW Otolith Report PDF link
Final WDFW Genetics Report PDF link
_________________________
Intraspecific variation of root mycorrhizal colonization among genotypes of Populus fremontii
Undergraduate Thesis. Common garden experiment investigating intraspecific genetic variation and ecosystem processes with two hypotheses: 1) the percentage of ectomycorrhizal (ECM) colonization of root-tips varies among different P. fremontii genotypes and 2) mycorrhizal colonization positively relates with tree survival and productivity. Hypothesis 1 supported with one-way ANOVA and Tukey’s HSD (tree genotype explained 41% of variation in ECM colonization). Hypothesis 2 was unsupported with bivariate linear regressions.
_________________________
Hood Canal Steelhead Project
I worked as a research technician on the Hood Canal Steelhead Project, a 17-year before-after-control-impact experiment that tests the effects of hatchery supplementation on natural steelhead populations in Hood Canal by monitoring adult and juvenile abundance, life history, and genetic diversity. I worked with the Hood Canal Salmon Enhancement Group operating rotary screw traps on control streams (Little Quilcene River, Tahuya River) and a supplemented stream (Dewatto River). Screw traps were operated each March to June to monitor outmigrating salmonid smolt abundance, collect genetic samples to assess changes from supplementation, collect scale samples for age determination, look at the proportion of resident rainbow trout vs anadromous steelhead (both Oncorhynchus mykiss), and determine if changes in resident vs anadromous O. mykiss populations occur as a result of hatchery supplementation.
My juvenile salmonid ID poster for Hood Canal Steelhead Project image link
_________________________