Yesterday (8/28), we set up a 24 hr exposure with triploid and diploid C. Gigas oysters to an elevated temperature + desiccation stress. In total, we had 40 oysters (20 diploid, 20 triploid). 10 control animals were kept for both the diploid and triploid animals in mesh bags in the aquarium in regular seawater. We had to place a foam cover over the mesh so that sea stars wouldn’t get in and potentially interfere with the controls. The other 20 animals (10 diploid, 10 triploid) were transferred to an incubator at 27 degrees Celsius where they were also kept in mesh bags. Exposure began at roughly 12:00 PM. Additionally, we decided to take 2 animals from both the control and the desiccation + elevated temperature exposure at 24 hrs to expose to a 1 hr acute heat shock at 45 degrees Celsius (for a total of 8 oysters exposed to acute heat shock). Thus, our sample size is N = 8 for the diploid/triploid controls and the diploid/triploid desiccation + elevated temperature treatment group.
Originally, we were planning to do a factorial stress response experiment, examining the effects of hypoosmotic stress (low salinity), desiccation + elevated temperature, and the two stressors combined. However, we ultimately decided to go with a simpler experimental design that would be more robust and could give us a baseline stress response to work with. I’m still interested in investigating interactive effects between multiple stressors, especially in triploids, so once we have this baseline single-stressor trial completed, we can definitely think about doing a factorial design!
Today (8/29), we’ll be sampling the oysters at the 24 hr mark, collecting mantle, adductor muscle, and gill tissue for follow-up RT-qPCR. At around noon, we’ll take 2 oysters each from the diploid/triploid control and treated groups to do an acute heat shock at 45 degrees Celsius for 1 hour.