Enhanced biodiversity and abundance of benthic invertebrate macrofauna in a New Zealand marine reserve

Abstract

Abstract No‐take marine reserves are an important management tool in the conservation and restoration of marine habitats around the world. They are intended to provide spatial refugia for exploited species and to protect sensitive habitat and biodiversity hot spots. Despite strong evidence that marine reserves enhance overall biodiversity, it is not clear that this effect extends to all taxonomic groups. Most marine reserves are designed to protect large mobile fauna. Their effect on small sessile benthic invertebrates is unclear, yet these organisms provide critical ecosystem functions. Three hundred and seventy‐eight images and associated faunal descriptions were compared from 2007 and 2018 in Ulva Island/Te Wharawhara Marine Reserve, Stewart Island/Rakiura, New Zealand (46.9°S, 168.1°E, 0–25 m depth, established 2004), to discern the effect of non‐extractive marine protection on a soft‐sediment temperate benthic community. Qualitative habitat types observed in the 2018 images were similar to those described in 2007. There was a significant positive effect of protection on benthic invertebrate abundance between 2007 and 2018 across Paterson Inlet/Whaka a Te Wera. Additionally, there were significantly more benthic invertebrates within reserve sites compared with sites outside the reserve in 2018. Based on these positive effects, it can be concluded that Ulva Island/Te Wharawhara Marine Reserve has facilitated an increase in the biodiversity of the benthic invertebrate community of Paterson Inlet/Whaka a Te Wera, Stewart Island/Rakiura. Interestingly, heavily calcified biogenic reefs were present within Paterson Inlet/Whaka a Te Wera, but not within the reserve itself. The re‐evaluation of marine reserve boundaries could result in more comprehensive and representative management of the rich marine environment around Stewart Island/Rakiura.