Factors influencing incidental representation of previously unknown conservation features in marine protected areas

Abstract

Spatially explicit information on species distributions for conservation planning is invariably incomplete; therefore, the use of surrogates is required to represent broad-scale patterns of biodiversity. Despite significant interest in the effectiveness of surrogates for predicting spatial distributions of biodiversity, few researchers have explored questions involving the ability of surrogates to incidentally represent unknown features of conservation interest. We used the Great Barrier Reef marine reserve network to examine factors affecting incidental representation of conservation features that were unknown at the time the reserve network was established. We used spatially explicit information on the distribution of 39 seabed habitats and biological assemblages and the conservation planning software Marxan to examine how incidental representation was affected by the spatial characteristics of the features; the conservation objectives (the minimum proportion of each feature included in no-take areas); the spatial configuration of no-take areas; and the opportunity cost of conservation. Cost was closely and inversely correlated to incidental representation. However, incidental representation was achieved, even in a region with only coarse-scale environmental data, by adopting a precautionary approach that explicitly considered the potential for unknown features. Our results indicate that incidental representation is enhanced by partitioning selection units along biophysical gradients to account for unknown within-feature variability and ensuring that no-take areas are well distributed throughout the region; by setting high conservation objectives that (in this case >33%) maximize the chances of capturing unknown features incidentally; and by carefully considering the designation of cost to planning units when using decision-support tools for reserve design. The lessons learned from incidental representation in the Great Barrier Reef have implications for conservation planning in other regions, particularly those that lack detailed environmental and ecological data.

Sympathy for the Devil: Detailing the Effects of Planning-Unit Size, Thematic Resolution of Reef Classes, and Socioeconomic Costs on Spatial Priorities for Marine Conservation

“…Similar findings have come from previous studies [9, 58, 73, 76]. As rare environmental classes or species tend to be at most risk of destruction or extinction [77, 78], this is a critical point to consider regarding the ability of coarse prioritisations to represent fine priorities.…”

“…Whilst some previous studies similarly found reasonable potential for coarse prioritisations to achieve fine-resolution objectives [9, 12], these did not consider variable socioeconomic cost data in their prioritisations. Bridge et al (2016) [73], however, found a significant negative relationship between planning-unit cost and incidental representation of environmental classes in the Great Barrier Reef marine reserve network, Australia. The less spatially-biased selection of planning units that occurs when no (or uniform) costs are considered allows a greater chance for incidental representation of finer-resolution objectives, with this effect being almost indistinguishable between the different levels of thematic resolution tested in this study.…”

The role of scale in designing protected area systems to conserve poorly known species

“…To the extent that this is true, the use of surrogates may be enforcing a hyperdispersed spatial arrangement of protected areas; our results show that, over some spatial scales, this could lead to improved conservation performance when compared to random protected area configurations, even if the surrogates have little biological relationship to the species distributions. In an analysis of why the Great Barrier Reef Marine Park rezoning was effective at protecting a set of conservation features that were undescribed at the time, Bridge et al (2015) found that ensuring representation within each of a number of geographically defined subregions was just as effective as ensuring representation within each of the ecologically defined bioregions used in the actual rezoning. We further explored this issue with the African mammal range data, constructing surrogates using 29 'natural' landcover types (including various classes of forest, shrub, herbaceous, grassland, aquatic, and deserts; Bicheron et al 2008), nested within 123 ecoregions (Olson et al 2001), for a total of 1875 conservation targets.…”

To what extent do mesophotic coral ecosystems and shallow reefs share species of conservation interest?

“…For example, the existing Coral Beach Nature Reserve in Israel was expanded in order to incorporate MCEs down to a depth of 50 m. It is unclear how this expansion in protection will impact MCEs and shallow-water reefs, as conditions may alter species depth distributions from site to site and affect the degree of community overlap between the shallow reefs and MCEs. In other instances, MCEs may have been serendipitously protected by the establishment of large off-shore no-take reserves [23].…”