Selecting zones in a marine park: early systematic planning improves cost-efficiency; combining habitat and biotic data improves effectiveness

Systematic planning, using algorithm tools, can improve biodiversity representation in ‘no-take’ zones in a marine park while reducing costs of meeting conservation targets. The current zoning plan for the 870 km² Solitary Islands Marine Park (SIMP), designed without algorithm tools, provides an example to compare the efficiency of zoning scenarios that include or ignore the existing zoning scheme and to assess the utility of habitat and/or biotic data for planning. Marxan was used to compare representation of habitat categories and a selection of fish species using 3 scenarios for ‘no-take’ sanctuary zones: 1) clean slate; 2) building on the existing sanctuary zones; and 3) current sanctuary zones (2002 zone plan). Three target levels were considered (10%, 20% and 30% representation of habitats and fish species in sanctuary zones). The use of habitat and fish data combined was compared with results obtained using each dataset separately. The clean-slate option was the most cost-efficient. Extending the existing sanctuary zones to achieve equivalent representation required more area and longer boundaries. For both of these scenarios, a large cross-shelf sanctuary zone at the widest part of SIMP was an important requirement for achieving representation. Neither habitat categories nor reef fish assemblages were fully represented in the current zoning plan. Fish and habitat features combined were more effective than habitat alone at selecting areas known to have high conservation values in the SIMP. The fish data in isolation were too spatially constrained for systematic planning at this scale.