Consistent multi-level trophic effects of marine reserve protection across northern New Zealand

Abstract

Through systematic Reef Life Survey censuses of rocky reef fishes, invertebrates and macroalgae at eight marine reserves across northern New Zealand and the Kermadec Islands, we investigated whether a system of no-take marine reserves generates consistent biodiversity outcomes. Ecological responses of reef assemblages to protection from fishing, including potential trophic cascades, were assessed using a control-impact design for the six marine reserves studied with associated reference sites, and also by comparing observations at reserve sites with predictions from random forest models that assume reserve locations are fished. Reserve sites were characterised by higher abundance and biomass of large fishes than fished sites, most notably for snapper Chrysophrys auratus, with forty-fold higher observed biomass inside relative to out. In agreement with conceptual models, significant reserve effects not only reflected direct interactions between fishing and targeted species (higher large fish biomass; higher snapper and lobster abundance), but also second order interactions (lower urchin abundance), third order interactions (higher kelp cover), and fourth order interactions (lower understory algal cover). Unexpectedly, we also found: (i) a consistent trend for higher (~20%) Ecklonia cover across reserves relative to nearby fished sites regardless of lobster and urchin density, (ii) an inconsistent response of crustose coralline algae to urchin density, (iii) low cover of other understory algae in marine reserves with few urchins, and (iv) more variable fish and benthic invertebrate communities at reserve relative to fished locations. Overall, reef food webs showed complex but consistent responses to protection from fishing in well-enforced temperate New Zealand marine reserves. The small proportion of the northeastern New Zealand coastal zone located within marine reserves (~0.2%) encompassed a disproportionately large representation of the full range of fish and benthic invertebrate biodiversity within this region.

The use of spatial management tools in rights‐based groundfish fisheries

“…For example, in New Zealand, coastal marine reserves have led to increased spiny lobster ( Jasus edwardsii , Palinuridae) densities within and around the closed areas (Shears, Grace, Usmar, Kerr, & Babcock, ). Snapper ( Pagrus auratus , Sparidae) and blue cod ( Parapercis colias , Pinguipedidae) have similarly benefitted from New Zealand's marine reserves, and cascading effects of protection on other, non‐fished species have been demonstrated (Edgar, Stuart‐smith, Thomson, & Freeman, ). Similarly, the BPAs covering New Zealand's seamounts were originally designed to protect the country's unique and representative habitats, but have led to protection of important orange roughy spawning grounds as well (Clark & Dunn, ; Table ).…”

“…Other case-studies illustrate more typical MPA outcomes, with increases in key metrics (e.g., abundance or density of target stocks) inside protected areas relative to conditions before implementation or in nearby areas with fewer restrictions. For example, in New Zealand, coastal marine reserves have led to increased spiny lobster (Jasus edwardsii, Palinuridae) densities within and around the closed areas (Shears, Grace, Usmar, Kerr, & Babcock, 2006 (Edgar, Stuart-smith, Thomson, & Freeman, 2017). Similarly, the BPAs covering New Zealand's seamounts were originally designed to protect the country's unique and representative habitats, but have led to protection of important orange roughy spawning grounds as well (Clark & Dunn, 2012; Table 3).…”

Increase in Relative Abundance and Size of Snapper Chrysophrys auratus Within Partially-Protected and No-Take Areas in a Temperate Marine Protected Area

“…Multiple use MPAs have been established in many countries, such as Australia, which provide different levels of protection through zoning and allow some areas for fishing (partially-protected) and other areas that are total no-take which exclude all forms of fishing. No-take areas within MPAs often show an increase in abundance and size of harvested species and measurable changes in the trophic structure (Halpern et al, 2010;Sciberras et al, 2013;Edgar et al, 2017), although the size of the effect is strongly influenced by factors such as reserve size, location and age, levels of compliance, life-history characteristics, and population status of harvest species (Claudet et al, 2008;Edgar et al, 2014;Malcolm et al, 2016).…”

The influence of protection and temperature on subtropical reef fish assemblages in Cape Byron Marine Park

“…In particular, increases in the sparid species Acanthopagrus australis (‘bream’) and Chysophrys auratus (‘snapper’), both non‐tropical species, were not predicted by consideration of water temperatures in 2014. Sparids in general and C. auratus in particular have been shown to respond rapidly to protection from fishing with increased abundance and average size (Buxton & Smale, ; Edgar et al, ; Kelaher et al, ; Willis et al, ; ). Conversely, the tropical haemulids P. gibbosus and D. pictum were most commonly encountered in the coolest conditions of spring 2006.…”

“…In addition to the warmer temperatures, a second factor that and Chysophrys auratus ('snapper'), both non-tropical species, were not predicted by consideration of water temperatures in 2014. Sparids in general and C. auratus in particular have been shown to respond rapidly to protection from fishing with increased abundance and average size (Buxton & Smale, 1989;Edgar et al, 2017;Kelaher et al, 2015;Willis et al, 2001; In this study the locations were chosen to minimize inter-locational differences in depth, so movement into deeper or shallower locations cannot be demonstrated.…”