The second part of the experiments began this week. My experiment, however, has changed quite drastically because we did not see the Bd infection levels from the swabs that we thought we would. It is possible that swabbing is not a satisfactory method, or that PCR did not sufficiently amplify the DNA. In any case, because there has been so much tadpole mortality in the Bd treatments, I will probably now be investigating the effects of Bd infection on tadpoles.
Despite my own absence, the transmission experiment goes on. Will will be investigating the transmission of probiotics among tadpoles, and whether it is primarily through environmental or horizontal means. Horizontal transmission refers to the spread of chytrid via individual to individual contact, while environmental transmission refers to the ability of Bd to infect other individuals by spreading through the environmental medium (in this case, water). By isolating tadpoles in individual mesh bags, horizontal transmission should be eliminated so that the probiotics can only inoculate the other tadpoles by moving through the water. Tadpoles in the other treatment swim freely, so that both environmental and horizontal transmission are occurring. The object of this study is to see if probiotics can be transferred horizontally through tadpoles, and whether transmission also occurs through the environment. Will should have some interesting results from this tadpole experiment by the end of the summer that will hopefully help scientists to better understand the way that transmission of skin microbes occurs.