Mr Thomas Falconer1, Mr Shawn Gerrity1, Distinguished Professor David Schiel1
1Marine Ecology Research Group, University of Canterbury, Christchurch, New Zealand
The 2016 Kaikōura earthquake was a cataclysmic event that affected over 130 km of intertidal rocky reefs and resulted in the local collapse of a suite of culturally and ecologically significant large brown algae. The magnitude and scale of the earthquake allowed us to study recovery trajectories of algal assemblages within the intertidal zone at 16 sites with varying degrees of uplift (-0.3 – 6.0 m). Immediately following the earthquake, large brown algal cover dropped from 61 to 33 % in the intertidal low zone. Upper and mid tidal zones were mostly destroyed. After 5.5 years, there has been little recovery in the mid-tide zone, primarily because the reef platforms are inhospitable for large algae and the new zone is short and vertical. The low tidal zone has had considerable recovery of large brown algae, but the distribution and species composition are still in flux across all sites. A community shift saw fleshy red algae replace large browns in many sites, and Durvillaea replaced by smaller fucoids at others. The former dominance by bull kelp (Durvillaea spp.) has not returned except in one site. We predicted that ‘recovery’ would take at least 8 years because smaller scale experiments showed poor recruitment of Durvillaea when in competition with dense understory red algae and occasional heavy grazing by butterfish. There are ongoing site-specific issues relating to elevated temperatures and sediments at many sites, which make it difficult to predict what the algal communities will look like over the next few years.
Presentation Slides – Thomas Falconer
Biography:
Tom is a research assistant at the University of Canterbury with a background in animal physiology. His current research focuses on the recovery of communities inhabiting the rocky intertidal along the Kaikoura coastline.
