LAUSR

Abstract Disease outbreaks and mass mortality events in terrestrial and marine taxa are increasing as a result of human influence, pollution, and climate change. Sea Star Wasting has become more common on the west coast of the United States, with increasing numbers of asteroids affected since 2013. Rising temperatures have traditionally been linked to mass mortality events, but other factors such as the effect of diet on individual susceptibility to Sea Star Wasting have not been examined. Here, we use laboratory experiments to test the frequencies of SSW sign onset and death of a native sea star when exposed to diets of two invasive ascidians. We show that prey identity affects mortality rates of affected predators. Sea stars that consumed Diplosoma listerianum experienced SSW signs, but 0% mortality, whereas animals that consumed Botrylloides violaceus, or no prey experienced 41% mortality. We expect that invader induced shifts in community species composition will increase the frequency of these mass die offs on both the west and east coasts.