Claire Butler1, Scott Bennett1, Adriana Vergés2, Catriona Hurd1, Scott Ling1, Chris Brown1, Jordi Boada3, Jasmin Schuster4,5, Yanheng Wang1
1University of Tasmania, Australia - 2University of New South Wales, Australia - 3Centre d’Estudis Avançats de Blanes, Spain - 4Memorial University of Newfoundland, Canada - 5University of Victoria, Canada
The interaction between herbivorous sea urchins and their macroalgal food source plays a fundamental role in regulating community structure on temperate reefs across the globe. Water temperature strongly influences the strength of this interaction, and research predicts that herbivore pressure will increase as climate change accelerates. However, how this relationship manifests in natural settings and across broad-scale environmental gradients is poorly resolved. In this study we investigate thermal performance of two ecologically important sea urchin species (Centrostephanus rodgersii, Heliocidaris erythrogramma) and their macroalgal food (Ecklonia radiata) source at six locations across 8°C and 12 degrees of their latitudinal distribution in Australia, as well as over seasonal cycles at a single high-latitude site. Thermal performance was assessed by quantifying in-situ grazing rates as well as the acute thermal sensitivity of respiration (for urchins) and photosynthesis (for E. radiata) at 6-9 temperatures between 5-35 °C. C. rodgersii shows a clear peak in grazing in the centre of it’s range, and temperature is shown to be an important driver of grazing rates. C. rodgersii also shows increased thermal sensitivity of respiration rates towards its warm range-edge. Conversely H. erythrogramma shows no consistent pattern in grazing across latitude while respiration rates differ between populations in the cool range-edge relative to those in warmer locations. For E. radiata, decreased maximum photosynthetic rates were observed towards warmer latitudes. These contrasting patterns suggest each species occupies different thermal niches, and provide key insights into how the ecological impacts of these species may change across their distribution and in response to ocean warming.
Biography
Claire is a marine ecologist whose research focuses on understanding how patterns and processes change across broad spatial and temporal gradients in coastal temperate marine environments. Through a combination of comparative field and laboratory experiments, as well as remote sensing techniques, Claire seeks to understand the vulnerability of species to climate change, especially ocean warming, and its impact on ecological systems.