Achieving Full Representativity of Seafloor Biodiversity With Minimal Expansion: Exploring a Strategy for New Zealand Marine Conservation

ABSTRACT Aim A key element of the Global Biodiversity Framework Target 3 is ‘representativity’, which refers to the inclusion of the full range of existing ecosystems, ecological processes and regions within protected areas, with the aim of ensuring that the full spectrum of biodiversity is protected. Here we use the New Zealand Seafloor Community Classification (NZSCC), which depicts compositional turnover of 1716 taxa (demersal fish, reef fish, benthic invertebrates and macroalgae) classified in 75 groups representing seafloor communities, and the conservation planning software Zonation to explore how representativity of benthic communities could be enhanced across spatial management areas (including protected areas) in New Zealand's marine environment. Location New Zealand Exclusive Economic Zone. Methods 154 Spatial layers derived from the NZSCC [Correction added on 3 March 2026, after first online publication: “NZSSC” has been corrected to “NZSCC”] depicting within‐ and between‐ group similarity/dissimilarity and taxonomic richness, representing beta and alpha diversity respectively, are used to explore scenarios to provide an optimal expansion of the current network of spatial management areas. Results Results indicate that a relatively small increase in spatial protection (1.5%) to the existing spatial management network can result in large increases in the representativity of all NZSCC groups, including 46 groups (out of 75) currently underrepresented. Main Conclusions The use of within‐ and between‐group similarity/dissimilarity is a significant improvement on spatial prioritisation processes that consider groups within benthic classifications to be homogenous. These results provide a solid base for informing the development of improved future protection measures within New Zealand that can meaningfully contribute to the representativity element of the Global Biodiversity Framework Target 3, and the approach presented here can be applied to other regions.