Ms Kelsey Miller1, Dr. Nick Shears
1University Of Auckland, ,
Globally, many kelp forests have been destroyed by sea urchin overgrazing, leaving behind depauperate “urchin barrens” with reduced habitat complexity, productivity, and biodiversity. In response, sea urchin removal provides a simple approach for kelp reforestation and is increasingly used worldwide, but these methods need to be evaluated for effectiveness, practicality, and ecological relevance. Few large-scale (>1 ha) removals have been conducted worldwide, and none within New Zealand.
This study evaluates the potential role of large-scale sea urchin (kina, Evechinus chloroticus) removal in kelp forest restoration in the Hauraki Gulf, northeastern New Zealand. Following trials of various removal methods, sea urchins were culled in situ between Oct 2020-Mar 2021 from four large areas of barrens (1.6-2 ha each; 7.1 ha total).
After one year, sea urchin densities remained low at all removal sites without additional culling. Within one year, kelp (Ecklonia radiata) and fucoids (Carpophyllum spp. and Sargassum spp.) increased dramatically (canopy cover and density) within all removal sites, while little change occurred in control sites. The effects on macroalgae, associated community (fishes, spiny lobsters, benthic community), and kina will be monitored for two years post removal.
This study showed that hectare-scale removal of sea urchins alone can lead to rapid (<1 year) recovery of kelp. However, if sea urchin removal is to be used to accelerate kelp recovery, restoration plans also need to address the causes of sea urchin overpopulation (e.g. overfishing of predators) to prevent reinvasion and to support ecosystem health, biodiversity, and resilience in the long-term.
Presentation Slides – Kelsey Miller
Biography:
Kelsey is a PhD candidate at the Leigh Marine Laboratory whose current research is on evaluating large-scale sea urchin removal as a tool for restoring the mauri (life force) of kelp forests in the Te Moananui a Toi (Hauraki Gulf), New Zealand. Her background is working collaboratively with scientists, indigenous peoples, fishermen, and community groups towards common goals to increase sustainability of fisheries. Her research has spanned the Pacific Ocean from Canada and the US to Australia and New Zealand, focussing on marine and fisheries ecology.
