Tuesday, September 29, 2015

Adventures with cane toads

When we first arrived at La Selva Biological Station, I had no idea what kind of antics I would get up to in the name of science. The other night at around 9 pm, I found myself wading through the putrid mud of an area with former agrochemical exposure attempting to locate and capture cane toads (Rhinella marina). For those readers who have not had the singular pleasure of working with cane toads, I would like to note that they pee rather forcefully upon capture (a questionably effective defense mechanism). This particular characteristic, coupled with the impressive ability of mud to seize and retain rubber boots made for a hilarious, if not slightly catastrophic night.
The following day we placed the toads one by one onto a makeshift treadmill to measure their endurance. We also collected blood samples in order to perform blood counts and assess their parasite loads. Another group of students performed the same evaluations on cane toads collected from areas with no (or less) agrochemical exposure. The endurance levels and parasite loads of the two groups were compared to determine whether cane toads living in a region exposed to monocropping and agrochemicals differ from those living in a biological preserve. 
Cane toads collected from agrochemical exposure areas had both a higher parasite load and a lower white blood cell count. One potential explanation for this finding is that agrochemicals could be suppressing their immune responses. However, no difference was found in endurance of the groups, which makes sense given that cane toads are highly resilient to increased parasite loads.
Prior to this semester I had plenty of experience working in labs, but had never really experienced data collection in the field. This project opened my eyes to just how intense (and amusing) fieldwork can be. And on a totally unrelated note, we saw a juvenile puma on our drive back from collecting toads! I live in a region of California where puma sightings are not uncommon, and had always wanted to see one. It was an unexpectedly beautiful conclusion to a rather absurd evening. 

Rose Hinson
Duke University

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