Client: Ministry of Primary Industries 

The term ‘trophic cascade’ is used to describe the indirect effect that changing the abundance of one species can have on other parts of a food web, as well as biodiversity and ecosystem function. Sea urchin (kina) ‘barrens’ are areas of rocky reef that would normally support healthy kelp forest but now have little or no kelp due to overgrazing by sea urchins. 

In 2023, Ministry of Primary Industries (MPI) commissioned e3Scientific to provide a comprehensive desktop analysis to inform the current state of knowledge on trophic cascades and sea urchin barrens across Aotearoa. This project support’s MPI’s wider integration of ecosystem considerations into management decisions, as required under the Fisheries Management Act 1996  

e3Scientific presented this work at a stakeholder workshop held in Wellington in March, 2023. The report was subsequently published as a peer reviewed Aquatic Environment & Biodiversity Report (AEBR) (see full reference below). Key points addressed within this work include an overview of key species and ecosystems, temporal and spatial factors influencing the development of urchin barrens, and key issues to consider for informing ecosystem-based management in Aotearoa.