Parasite video featuring Chelsea Wood, nominated for an Emmy

The 2024 Northwest Emmy Nominees for Category 24, Environment/Science – Short Form Content – includes a video featuring SAFS Professor, Chelsea Wood, and her work on parasites. The video, produced by Grist, explores why nature can’t run without parasites, and what happens when they start to disappear.

The video was part of a video series profiling the science and scientists behind some of the environment’s most unexpected research.

Watch the video

 


Uncovering parasites in one of the world’s largest fish collections

Housed in a set of World War II artillery bunkers on the outskirts of New Orleans is a surprising, and gargantuan, fish collection. Home to the largest collection of post-larval fish specimens in the world – 7 million to be precise – the Royal D. Suttkus Fish Collection at the Tulane University Biodiversity Research Institute (TUBRI) was the destination for a group of UW researchers over the summer.

Led by Chelsea Wood, a parasitologist and Associate Professor at the School of Aquatic and Fishery Sciences, a team of eight undergraduates, graduate students, post-docs, and research technologists spent 10 weeks in New Orleans to collect the largest long-term dataset on parasites that exists for freshwater fish.

The team arrives for work at the Tulane University Biodiversity Research Institute, in the English Turn region of the Mississippi River, near Belle Chasse, LA.
Specimens of emerald shiner (Notropis atherinoides) originally collected from the Pearl River in 1971 float in a jar after being dissected and having their parasites counted and removed.

This is a shift away from the marine fishes that Chelsea usually works on, but no less fascinating. Interested in understanding how environmental change impacts the presence of parasites in wildlife, Chelsea and her team have been working with museums to develop long-term datasets by dissecting fish and inspecting their insides. “One of the things that makes the Tulane collection so special is how systematically the fish specimens have been collected over nearly half a century,” Chelsea shared.

“Some of these jars, which are organized in rows upon rows of shelving, hold thousands of individual fish collected from one place at one time,” she said. “They’re preserved so perfectly that as you look at them in the jar you can almost imagine them starting to swim. And this systematic, perfect preservation is invaluable for our parasite work, as the parasites are preserved right along with their host: the fish.”

One of the key questions driving the team’s work is: does pollution kill parasites or help them? “The Pearl River, which empties into the Gulf in New Orleans, has a lot of pollution inputs, including pulp mills, poultry farms and agricultural wastewater,” she shared.

A live tapeworm as seen through a stereomicroscope.

The team focused on seven fish species – Carpiodes velifer, Gambusia affinis, Hybognathus nuchalis, Ictalurus punctatus, Notropis atherinoides, Percina vigil, and Pimephales vigilax – chosen because they were common both above and below pulp mills, and before and after the Clean Water Act of 1972. “Due to the systematic sampling and preservation of fish above and below the pulp mills between 1963 and 2005, the Tulane fish collection is set up very well to help answer our questions,” Chelsea said. Setting their own lab record, her team dissected 1,200 fish in 10 weeks. “This was a fantastic outcome, and a true testament to the amazing team we had this year,” she added.

So, what did the team find out? Many things are too early to tell, but more than 36,000 individual parasites were found during dissection. One of the exciting things Chelsea highlighted about this project is its relation to other parasite datasets. “Our lab has learned a lot about how marine parasites change through time in response to things like climate change,” she said. “But we don’t know if what is true in marine environments also applies to freshwater fish or terrestrial animals. With this move to freshwater fish, it’s helping us to understand whether the kinds of change we’re seeing in marine fishes and their parasites are general or specific to marine ecosystems.”

REU intern and UW Marine Biology major, Jolee Thirtyacre, randomly selects fish for dissection from among several hundred in one jar.

Extending a special thanks to the team of scientists at Tulane, Chelsea shared that her team felt the welcoming spirit of New Orleans. “The TUBRI lab space is not huge, and our team of nine descended like an invading army. We are so grateful to Hank Bart, the current curator, Justin Mann who manages the collection, and all of the wonderful staff at TUBRI.”

“I like to describe this collection as a gift that’s been passed down through several generations of scientists,” Chelsea added. “Now we get to discover what’s been going in the fish housed here, many of which were collected before any of my research team, including me, were born!”

Funded through the National Science Foundation (NSF), Chelsea’s team included four members of the Wood Lab: Gabriella (Gabby) Commisso, Dakeishla (Daki) Diaz-Morales, Katie Leslie, and Connor Whalen, plus four undergrads whose participation was supported by the NSF Research Experience for Undergraduates (REU) program: Desmond Boyd (University of South Carolina), Shyanne Christner (Valdosta State University, Imani Jones (Tuskegee University), and Jolee Thirtyacre (University of Washington).

Director of the Tulane University Biodiversity Research Institute Hank Bart teaches SAFS graduate students Gabby Commisso and Connor Whalen how to seine fish near Pools Bluff Sill, Bogalusa, LA.

“Each member of team is leading the charge on their own part of the data analysis,” Chelsea said. “Daki is working on how multiple stressors combine to influence parasites, Gabby is looking at how the parasites of invasive hosts respond to environmental change, and Connor is investigating how parasites respond to extreme weather events, which are common in this region.” This project is part of a larger effort that will continue with a field expedition to Albuquerque, New Mexico, next summer.

For the undergrads, this was an incredible research experience which gave a real insight into how team science works. “Our undergrads were spectacular, moving their research projects forward at a pace we didn’t expect. From conducting their own statistical analyses in R, to learning and using GitHub, to finishing off poster presentations at the end of the summer, it was incredible to watch them take to this research like ducks to water,” Chelsea said.

What can we expect from the Albuquerque project in 2025? “It turns out that fish collections from urban areas are uncommon, and that’s where the Museum of Southwestern Biology, based at the University of New Mexico, is unique,” Chelsea shared. “We will be developing a time series of parasite burden starting from the 1920s, which spans before and after the urbanization of Albuquerque, and we’ll be looking above and below stream that brings stormwater into the Rio Grande.”

Stay tuned for 2025!

The team after seining fish near Pools Bluff Sill, Bogalusa, LA. From left to right: SAFS graduate student Connor Whalen, REU intern and UW Marine Biology major Jolee Thirtyacre, REU intern Shyanne Christner (Valdosta State), Director of the Tulane University Biodiversity Research Institute Hank Bart, SAFS postdoc Daki Diaz Morales, SAFS graduate student Gabby Commisso, SAFS professor Chelsea Wood, REU intern Imani Jones (Tuskegee University), REU intern Desmond Boyd (University of South Carolina).

Watch the video from their trip to New Orleans