Standard Presentation (15 mins) Australian Marine Sciences Association 2022

Altered functions and phase-shifts for a rapidly warming temperate reef ecosystem (#48)

Scott D Ling 1
  1. Institute for Marine and Antarctic Science, University of Tasmania, North Hobart, TAS, Australia

The phenomenon of phase-shift from healthy to collapsed reefs is now widely documented globally and includes iconic Australian reef ecosystems. On the rapidly warming coast of eastern Tasmania, rocky reef ecosystems have undergone cascading changes during recent decades. From widespread loss of giant kelp forests to formation of extensive sea urchin barrens, the transformation of this reef-scape has been profound. In this presentation, I will examine the transition between surface-canopy giant kelp forests and lower-canopy kelp beds and the progressive collapse to urchin barren grounds. I will detail how altered ecosystem functions, including reduced natural predation and novel range-extending herbivores plus altered dominance hierarchies of competing canopy-kelps, are driving phase-shift and creating feedbacks locking-in alternative states. I will conclude by showing how this knowledge of altered ecosystem functioning is now being used to reinstate critical functions safeguarding against collapse, and how such knowledge is also critical for identifying opportunities for meaningful ecosystem restoration in a changing world.