Miss Celia Balemi1, Dr Nick Shears1, Dr Richard Taylor1, Dr Chris Battershill2
1University Of Auckland, Leigh, New Zealand, 2University of Waikato, Tauranga, New Zealand
Climate change is modifying the distribution and abundance of species worldwide, often causing substantial ecosystem changes. Long-term ocean warming has allowed Centrostephanus rodgersii, a subtropical sea urchin, to extend its range into Tasmania where it has destroyed large expanses of kelp forests and reduced associated biodiversity. Emerging evidence from offshore islands in northeastern New Zealand has demonstrated a large increase in C. rodgersii density on shallow reefs over the last 23 years. While the impacts of C. rodgersii on kelp forest biodiversity has been well documented and can be expected, unlike other sea urchin species, C. rodgersii also commonly occur on rock walls, caves and archways that are typically dominated by highly diverse encrusting invertebrate assemblages. However, the potential ecological impact of C. rodgersii on these assemblages is currently unknown. We resurveyed seven wall sites at the Poor Knights Islands to examine how both C. rodgersii and associated wall assemblages have changed after 36 years. Lab-based feeding experiments and stable isotope analysis were also carried out to compare the diet and feeding preferences between C. rodgersii and the common sea urchin Evechinus chloroticus. C. rodgersii densities increased on rock wall habitats at five of seven sites and were associated with significant grazing impacts on wall communities. Furthermore, feeding studies found C. rodgersii had a broader diet than E. chloroticus, feeding at a higher trophic level. These findings indicate that future warming-induced increases in C. rodgersii could have large-scale consequences on the biodiversity of rockwall, cave and archway communities.
Presentation Slides – Celia Balemi
Biography:
Celia is a PhD candidate at the Leigh Marine Laboratory in Auckland, New Zealand. Her current research focuses on assessing the long term population dynamics and ecological impacts of Centrostephanus rodgersii in northeastern New Zealand. Her current research interests include climate change impacts and temperate reef ecology.
