Temperature Dependent Urchin Grazing of Temnopleurus alexandri and Salmacis belli on two algal species of Stradbroke Island, Australia

Background/Question/Methods: Temperature may affect urchin grazing activity due to their differential metabolic rate as ectotherms and has variable ecological significance based on seasonal variation of net primary productivity.    Additionally, increasing temperature has the potential to alter urchin preference from a specialist to generalist grazer (as food becomes limited due to increases in grazing activity). We observed the grazing of two urchin species under different temperatures and compared this for two algae species to understand the preference of urchins under multiple temperature regimes.

Results/Conclusions: Our results showed a trend with increasing temperature there is an increase in grazing rate. Our data also demonstrates that Salmacis belli grazed at a higher rate than Temnopleurus alexandri regardless of species consumed or temperature with a significance of  p=0.036. Both these factors, grazing activity and preference, can act as an ecological disturbance keeping a single species from dominating the landscape, most notably, urchin grazing has the potential to keep algae from competitively excluding seagrasses