For photos, videos, and species identification guides from our 2026 mission, click here!
In July and August 2026, with generous support from the Tetiaroa Society, our team made its first scientific expedition to Tetiaroa to investigate a question with implications far beyond this remarkable atoll: what happens to parasites when biodiversity changes?
Parasites are among the most abundant and diverse organisms on Earth, yet they are often overlooked when we think about the consequences of biodiversity loss. Predators, for example, may influence parasite transmission in surprising ways. By controlling the abundance of their prey, sharks could reduce the number of hosts available to parasites – or, through cascading effects across the food web, they could actually increase parasite transmission. By contributing nutrients in the form of their feces, birds could amplify the abundance of parasites. Tetiaroa provides an extraordinary natural laboratory for resolving this question because predator abundance varies naturally among its lagoon habitats.
Our expedition was designed as a first step: could we develop a rigorous, large-scale sampling program capable of testing these ideas in the real world? The answer is an emphatic yes.
Over two weeks, four scientists sampled nine sites across the atoll, collecting 53 individual fish representing 15 species. We conducted complete parasitological examinations of 26 fish on the island, with the remaining specimens now awaiting dissection at our laboratory at the University of Washington. We also collected 212 invertebrates representing 19 species, every one of which was examined for parasites. Along the way, we documented an extraordinary diversity of reef and intertidal invertebrates – including 51 species of marine molluscs, 13 crab species, echinoderms, polychaetes, and others – providing the ecological foundation for understanding how parasites move through the Tetiaroa food web.
We are now working on identifying the parasites we discovered – and describing a few new species. The next phase will take these discoveries from exploration to experiment. We will complete the remaining fish dissections, sequence the suspected new species, analyze our preliminary data, and develop an expanded sampling program for Tetiaroa. Our goal is to return to the atoll in March 2027.
What began as an opportunity to explore an understudied ecosystem has already revealed a hidden world of extraordinary diversity – and potentially species new to science. More importantly, it has given us the tools to ask a much bigger question: how does the biodiversity of an ecosystem shape the parasites within it, and what happens to those parasites as the ecosystem changes?
