Ryan S. Mohammed
The University of the West Indies, Trinidad and Tobago
Title: Parasite-host interactions at elevated temperatures- Getting into hot water: Sick guppies frequent warmer thermal conditions
Biography
Biography: Ryan S. Mohammed
Abstract
One of the major predicted effects of climate change within fifty years is a 4 - 6°C projected increase of ambient temperature. Many of the effect of these increases to tropical freshwater ecosystems are still unknown. One particular importance is the interaction of ecto-parasites and their ichthyofaunal host during this increase in temperature. This project proposes a series of experiments at elevated temperatures investigating fish behavior on a model species, the Trinidadian guppy (Poecilia reticulata), parasite tolerance, parasite interactions and parasite transmissions (Gyrodactylus turnbulli). A choice chamber experiment was used to investigate the thermal preferences of P. reticulata, when infected with a common helminth ectoparasite G. turnbulli, in female-only and mixed-sex shoals. The temperature tolerance of G. turnbulli was also investigated by monitoring parasite population trajectories on guppies maintained at a continuous 18, 24 or 32oC. Regardless of shoal composition, infected fish frequented the 32oC choice chamber more often than when uninfected, significantly increasing their mean temperature preference. Parasites maintained continuously at 32oC decreased to extinction within three days, whereas mean parasite abundance increased on hosts incubated at 18 and 24oC. We show for the first time that gyrodactylid-infected fish have a preference for warmer waters and speculate that sick fish exploit the upper thermal tolerances of their parasites to self medicate. The implications of this on tank based aquaculture will be discussed as a potential mechanism for extoparasite control on fish