A novel system to examine whether climate change stressors affect interspecific predator-prey interactions

Predation is a strong structuring mechanism and selective force in ecological communities, however, there is relatively little known regarding how predator-prey relationships will be affected by climate change stressors. Ocean Acidification (OA), a result of anthropogenic carbon dioxide emissions, is known to affect the sensory ecology of marine animals, in turn altering behaviour.

However, the majority of this research has so far focussed on fishes and molluscs. On the rocky intertidal shores of south-eastern Australia, two asterinid seastar species Meridiastra calcar and Parvulastra exigua present a novel system to examine interspecific predator-prey interactions between echinoderms.

As such, this study aimed to characterise the predator-prey interaction between these two species, by 1) characterising the escape response of P. exigua, 2) assessing predator avoidance behaviour in P. exigua, and 3) assessing if M. calcar will forage for P. exigua as prey items. We then aimed to determine if the escape response of P. exigua is altered by OA.

This study shows that the escape response of P. exigua to its sympatric predator is mediated by the sensory modality of the cue they are stimulated by. This response is the strongest when they are presented with their predator, followed by a chemosensory cue.

Finally, we showed that there is little effect of OA on the escape response of P. exigua to its sympatric seastar predator M. calcar. Latency to respond to predators is higher pH 7.6, however, the primary elements an escape response are not altered. This study is the first regarding the behavior of seastars under OA conditions and shows there is little effect of ocean acidification on prey escape behaviours in Asterinids.

This study is being conducted by Emily Jane McLaren under the supervision of Prof Maria Byrne from the Coastal and Marine Ecosystems Group at the University of Sydney.