Of mudsnails, terrapins, and flukes: Use of trematodes as a field‐based project in parasitology research

Abstract

We present an exercise for counting trematode cysts on mudsnails that can be implemented as a field‐based project in course work by students or by volunteers. The exercise involves the digenetic trematode Pleurogonius malaclemys, which infects diamondback terrapins (Malaclemys terrapin) as its definitive host, and eastern mudsnails (Tritia obsoleta) as its intermediate host. The trematode forms macroscopic metacercarial cysts on the shells and opercula of the mudsnails, and the life cycle is completed when terrapins ingest the intermediate hosts with cysts. Previous research has suggested that quantifying cysts on mudsnails can be a relatively simple method to estimate terrapin population sizes where terrapins co‐occur with mudsnails. Three non‐professional scientist groups (including students and volunteers) were tested in their estimates of prevalence and intensity data compared to verified cyst counts. Prevalence data were relatively accurate (~76–78%) and reliable (68–89%) across the groups. The intensity of cysts (on shells and opercula of mudsnails) were mostly within 12% of the verified counts (total mean intensity of 1.81–2.97 cysts/parasitized mudsnail) but varied significantly in two cases due to false positives (likely due to sand grains or debris scored as cysts) or negatives (likely due to missed cysts behind the operculum). The exercise can be completed as a lab or series of labs in courses, and data from such projects could be used in terrapin conservation efforts, particularly in helping scientists determine where terrapins occur. We discuss modification of the exercise for other trematode species in regions around the world and hope this expands recognition by the public of the important role of parasites in ecosystems.

Providing interactive and field laboratories while teaching university marine biology classes in an era of COVID‐19

“…Some articles, such as Lindsay (2021) and Nova et al, 2021) provide ideas for situations in which the students retain some access to campus or to specialized equipment. Others, such as Eugene et al (2021), Middlebrooks and Salewski (2021), and Schulze et al (2021) work well for situations in which students cannot access campus but retain some access to the field sites being studied. Verdes et al (2021), The Virtual Field Project (https://thevirtualfield.org/), and this article present ways that students without access to campus, to specialized equipment, or to the field sites can nonetheless experience important aspects of research and field studies.…”

Innovation in teaching and learning invertebrate zoology in remote and online classrooms

“…Eugene et al (2021) present a field‐based independent research project where students survey the prevalence and intensity of cysts of the digenetic trematode flatworm Pleurogonius malaclemys . The definitive host of this parasite is the diamondback terrapin, which is classified as Near Threatened by the IUCN, and its intermediate host is the eastern mudsnail.…”