Effects of parasites and predators on heart rates of Daphnia laevis using an innovative electronic stethoscope

Lutchie M. Carrasquillo, a student at the University of Puerto Rico at Arecibo, worked with Christian Hurd and Dr. Andy Davis to study the effects of parasitism on Daphnia heart rate using a new methodology.

Abstract: Daphnia are a model organism often used in investigations of chemical toxicity, and for biology classes. Measuring changes in heart rate is a commonly-used approach to assess responses to toxins. However, these assessments are usually done manually, which is time consuming and tedious. We developed a novel apparatus for monitoring changes in Daphia heart rates in real-time, without harming the animals. We used this approach to investigate how heart rate changes in response to naturally-occurring parasites (epibionts) and a natural Daphnia predator (glassworms). Our results showed Daphnia heart rates were not greatly affected by these, but we did discover an unusual diurnal effect, where the heart rate response differed between the morning trials and the evening trials.