Research Project Details
The impacts of a worldwide invasive tunicate (Didemnum vexillum) on estuarine and coastal marine ecosystems
Science communication as service: Managing diverse citizen science projects in a marine context
A multifaceted, highly resolved investigation into the trophic role of small pelagic fishes on the Northeast US Continental Shelf
Characterizing the diaphragm of deep-diving beaked whales (Mesoplodon spp.)
Microbial diversity in restored urban and natural freshwater habitats in Central Arkansas: A foundation for a research-based curriculum
Oregon Institute of Marine Biology
My interest in invasion trophic ecology is somewhat happenstance. During my senior year of college, I was applying for graduate school and an assortment of fellowships. The internship I had recently completed at WHOI broadly piqued my interest in trophic ecology, but I had not developed specific questions of interest. For inspiration, I turned to Google Scholar, where I found the paper of Vergés et al. (2014) on tropicalization, and so began my fascination with the food web dynamics of invasion events.
Didemnum vexillum (Kott, 2002; from here, D. vex) is a colonial tunicate native to Japan. Tunicates are filter feeders. Evolutionarily, they are a bridge of sorts between the invertebrates and vertebrates: as larvae, they have the four chordate characteristics, but as adults they are solitary invertebrates. I chose D. vex as my proposed model organism for several reasons. Most obviously, it is impractical to study tropical herbivorous fish on the Oregon Coast, where I have incredible potential field sites in my backyard. Further, the Galloway Lab emphasizes the importance of feeding trials in its fatty acid (FA) analyses to distinguish when organisms are biosynthesizing or selectively retaining FAs, rather than obtaining them from their diet (Kelly and Scheibling, 2012). Performing feeding trials on vertebrates is challenging; D. vex proliferates rapidly relative to vertebrates and is a global invader with local impacts, lending itself to being a strong model.
While my graduate research is still in its early stages, my working objectives are to:
1. Elucidate the diet of D. vex using stable isotope analyses and fatty acid biomarkers;
2. Quantify D. vex's competition for resources by measuring its ability to convert food sources into body mass and surface area; and,
3. Develop an end-to-end model of how D. vex impacts estuarine and coastal marine food webs and socioeconomics.
Perhaps one of the most flattering pictures of D. vex, whose common names include 'carpet sea squirt' or 'marine vomit'. The above view is of a colony's branchial apertures. Photo credit: Dann Blackwood (USGS).
PTMSC's spring SoundToxins training. Citizen scientists learn how to tow for their quantitative plankton sample. Photo credit: Betsy Carlson.
Carolyn Woods and I deploying our strong 'mussels' for the RSMP. Photo credit: Katie Conroy.
Port Townsend Marine Science Center
Port Townsend, WA
Citizen science (CS) brought me out to the Pacific Northwest. Echoing the above, I learned of CS through the 'let's throw spaghetti at a wall and see what sticks' tactic (which, upon reflection, is proving to be quite useful). The CS Educator position was posted on the Texas A&M Fisheries and Wildlife Job Board. Though I had not previously heard of CS, I quickly recognized its alignment with my ideals of science communication.
CS invites the community to participate in the scientific research process. Empowering coastal communities with CS can result in powerful learning outcomes that promote conservation and stewardship, informed advocacy, science literacy, cross-cultural understanding, and trust between stakeholders and scientists. PTMSC's CS program is robust: it has engaged over 3,500 volunteers since its inception over two decades ago.
As the CS Educator during my AmeriCorps term, I supported citizen scientist volunteers working on over ten projects. Below, I have highlighted a few of these projects. For a more comprehensive list, visit PTMSC's website. Because of my experience with CS at PTMSC, I intend to incorporate CS into my graduate research.
Puget Sound Seabird Survey
On the first Saturday of every month from October to April, PTMSC volunteers bestow their ornithology skills on three Jefferson County shorelines as part of the Puget Sound Seabird Survey. During these 30-minute surveys, managed by our partner Seattle Audubon, our volunteers collected data on local wintering seabird populations. Species-specific sightings for each of the 120 total survey-wide sites (accounting for 2,400 acres of nearshore saltwater habitat!) and abundance charts for key ecosystem indicator species are reported on the PSSS 2015-2016 summary website.
SoundToxins (ST) is one of PTMSC's longest-running CS projects, now entering its 11th year. Coordinated by Washington SeaGrant, this study aims to act as an 'early warning system' for the impacts of Harmful Algal Blooms (HABs) on the shellfish humans consume. PTMSC volunteers sample four sites weekly year-round, looking specifically for Pseudo-nitzchia, which causes amnesic shellfish poisoning, Alexandrium, which causes paralytic shellfish poisoning, Heterosigma, which causes neurotoxic shellfish poisoning, and Dinophysis, which causes diarrhetic shellfish poisoning. For up-to-date information on shellfish closures in Washington, visit the Department of Health's website. In Oregon, visit the Department of Agriculture's website.
Regional Stormwater Monitoring Program
Broadly, the RSMP is designed to evaluate collective stormwater management. Participants encompass local municipalities, stakeholders, and state and federal agencies. The purpose of this study is to determine the degree of contamination in nearshore habitats; an analysis of the 2012-13 data is available on the Washington Department of Fish and Wildlife (WDFW) website. PTMSC volunteers transplanted cages of native mussels (Mytilus trossulus) at three local sites in October, then retrieved the cages in February. The mussels’ tissue were analyzed for the occurrence and magnitude of contaminants. A final report for the 2015-16 season is anticipated from WDFW in Summer 2017.
PTMSC citizen scientists (L to R: Bruce Marsten, Ron Sikes, and Bill Vogt) participating in the Puget Sound Seabird Survey at Pt. Wilson in Fort Worden State Park.
Woods Hole Oceanographic Institution
Woods Hole, MA
Spending a summer as a guest student at WHOI was significantly formative: it confirmed my interest in pursuing a graduate degree in marine science, and seeded my curiosity of food web relationships in the ocean. Growing up surrounded by freshwater (the Great Lakes) and attending a landlocked college limited my access to the marine environment. Woods Hole was the first small coastal town in which I had the opportunity to live. I've been hooked since, to say the least.
In the Llopiz Lab at WHOI, I studied the trophic ecology of small pelagic forage fish in the Northeast United States Continental Shelf Large Marine Ecosystem (NES LME). In this highly productive ecosystem, there are only a few species of fish through which energy flows from zooplankton to higher trophic levels: Atlantic herring (Clupea harengus), alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), Atlantic mackerel (Scomber scombrus), butterfish (Peprilus triacanthus), and sand lance (Ammodytes dubius). We used stable isotope analyses to elucidate the trophodynamic roles of these organisms. Specifically, we sought to tease out the nuanced seasonal, spatial, and among-consumer variability in trophic levels and the base of the food web.
We found that these organisms' trophic levels varied significantly over seasonal and spatial scales, but not over the scales of habitat temperature or body length. To complement these stable isotope analyses, later work on this project visually identified the gut contents of the organisms. For contents too far digested to identify visually, we used DNA barcoding techniques.
Top: NOAA's Henry B. Bigelow, the vessel that caught the fish used in my project. Bottom: Example of a dissection performed on S. scombrus, which had a nearly undigested A. dubius in its gut.
Top: ATPase stain of Mesoplodon spp. costal diaphragm section. Bottom: the same serial section stained for NADH with Type I fibers circled in pink and Type II in white.
Despite Hendrix, my undergraduate alma mater, being located in a landlocked state, I was able to complete marine research on campus--turns out it's not so hard if your study subject is dead! This charismatic megafauna-focused project was certainly diversified my research repertoire. I owe my ability to study marine mammology to my academic advisor extraordinaire, Dr. Jennifer Dearolf, who is a vertebrate physiologist and whose lab studies marine mammal breathing muscles. In fact, I owe the majority of my foundational zoology and marine biology knowledge to Dr. D.
During this project, we characterized the breathing muscles of the deep-diving beaked whale (Mesoplodon spp.) with the aim of using this characterization to better describe these whales' breath-holding behaviors. We serially sectioned and stained diaphragm muscle fibers for their myosin ATPase and NADH (oxidative enzyme) activities. In doing so, we demonstrated that these muscle fibers are predominantly Type I (slow-twitch) and had a low oxidative activity. We hypothesized that these characteristics correspond to high glycolytic activity, allowing these whales to contract their diaphragms even if their oxygen stores are depleted during their extended dives to depth.
My first undergraduate research project appropriately connected my interest in research and education. Under the advisement of Drs. Mark Sutherland and Richard Murray, I worked to revise the Cell Biology Lab curriculum. We designed the curriculum to be more research-focused, where units built upon each other rather than functioning as a series of independent, disjointed exercises. For more education-specific details on this project, visit my education page.
The curriculum is now centered around the Hendrix Creek Preserve, a recently (2011-12) restored urban watershed. Biodiversity can function to measure the health of an ecosystem. We thus modified standard biochemical, molecular, and microscopic techniques to track the microbial diversity of this young watershed over a span of many years. Results will ultimately be compared to older systems managed by the Nature Conservancy and Arkansas Game and Fish Commission.
Bottom: the Hendrix Creek Preserve, Fall 2013. Photo credit: Mark Sutherland. Top: Rhopaloida (L) and Mallomonas & Anabaena (R), sample microbes collected from the Preserve.
Kelly, J.R. and Scheibling, R.E. (2012). Fatty acids as dietary tracers in benthic food webs. Mar Ecol Prog Ser. 446: 1-22.
Kott, P. (2002). A complex didemnid ascidian from Whangamata, New Zealand. J Mar Biol Assoc UK. 82:625-628.
Vergés, A. et al. (2014). The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts. P R Soc B. 281:20140846.