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

Selection of planning unit size in dynamic management strategies to reduce human-wildlife conflict

Conservation planning traditionally relies upon static reserves; however, there is increasing emphasis on dynamic management (DM) strategies that are flexible in space and time. Due to its novelty, DM lacks best practices to guide design and implementation. We assessed the effect of planning unit size in a DM tool designed to reduce entanglement of protected whales in vertical ropes of surface buoys attached to crab traps in the lucrative U.S. Dungeness crab (Metacarcinus magister) fishery. We conducted a retrospective analysis from 2009 to 2019 with modeled distributions of blue (Balaenoptera musculus) and humpback (Megaptera novaeangliae) whales and observed fisheries effort and revenue to evaluate the effect of 7 planning unit sizes on DM tool performance. We measured performance as avoided whale entanglement risk and protected fisheries revenue. Small planning units avoided up to $47 million of revenue loss and reduced entanglement risk by up to 25% compared to the large planning units currently in use by avoiding the incidental closure of areas with low biodiversity value and high fisheries revenue. However, large planning units were less affected by an unprecedented marine heat wave in 2014-2016 and by delays in information on the distributions of whales and the fishery. Our findings suggest that the choice of planning unit size will require decision-makers to navigate multiple socioecological considerations-rather than a one-size-fits-all approach-to separate wildlife from threats under a changing climate.

Costs in conservation: Common costly mistakes and how to avoid them

There has been an increasingly prevalent message that data regarding costs must be included in conservation planning activities to make cost-efficient decisions. Despite the growing acceptance that socioeconomic context is critical to conservation success, the approaches to embedded economic and financial considerations into planning have not significantly evolved. Inappropriate cost data is frequently included in decisions, with the potential of compromising biodiversity and social outcomes. For each conservation planning step, this essay details common mistakes made when considering costs, proposing solutions to enable conservation managers to know when and how to include costs. Appropriate use of high-quality cost data obtained at the right scale will improve decision-making and ultimately avoid costly mistakes.

The minimum land area requiring conservation attention to safeguard biodiversity

Ambitious conservation efforts are needed to stop the global biodiversity crisis. In this study, we estimate the minimum land area to secure important biodiversity areas, ecologically intact areas, and optimal locations for representation of species ranges and ecoregions. We discover that at least 64 million square kilometers (44% of terrestrial area) would require conservation attention (ranging from protected areas to land-use policies) to meet this goal. More than 1.8 billion people live on these lands, so responses that promote autonomy, self-determination, equity, and sustainable management for safeguarding biodiversity are essential. Spatially explicit land-use scenarios suggest that 1.3 million square kilometers of this land is at risk of being converted for intensive human land uses by 2030, which requires immediate attention. However, a sevenfold difference exists between the amount of habitat converted in optimistic and pessimistic land-use scenarios, highlighting an opportunity to avert this crisis. Appropriate targets in the Post-2020 Global Biodiversity Framework to encourage conservation of the identified land would contribute substantially to safeguarding biodiversity.

Spatial Solutions and Their Impacts When Reshuffling Coastal Management Priorities in Small Islands with Limited Diversification Opportunities

In small islands, the potential for new coastal activities and management options are often spatially limited. To reduce dependence on external factors and increase the resilience of populations to global changes and fluctuations in international markets, a recommended pathway is to diversify activities. We used a systematic prioritization tool with single and multiobjective zoning to explore the feasibility of scenarios at various levels of spatial diversification in the Gambier lagoon (French Polynesia), where black pearl culture is economically and spatially dominant. Local managers are committed to economic, livelihood, and environmental sustainability and agree that prioritizing both artisanal fisheries, which provide local food security, and ecosystem conservation should also be considered. Diversification options included the optimized reallocation of farming concessions and the identification of different types of conservation areas while taking into account traditional management areas. The scenarios were set to minimize surface areas and loss of access to existing fishing grounds. The solutions were compared between the scenarios with different cost metrics, allowing further discussions with stakeholders and managers. The Gambier case study shows that exploring diversification options in small islands using systematic prioritization tools can provide local managers with tailor-made plans adapted to island development questions.

An appraisal of systematic conservation planning for Pacific Ocean Tropical Islands coastal environments

Systematic Conservation Planning (SCP) offers concepts and toolboxes to make spatial decisions on where to focus conservation actions while minimizing a variety of costs to stakeholders. Thirty-four studies of Pacific Ocean Tropical Islands were scrutinized to categorize past and current types of applications. It appeared that scenarios were often built on a biodiversity representation objective, opportunity costs for fishers was the most frequent cost factor, and an evolution from simple to sophisticated scenarios followed the need to maximize resilience and connectivity while mitigating climate change impacts. However, proxies and models were often not validated, pointing to data quality issues. Customary management by local communities motivated applications specific to the Pacific region, but several island features remained ignored, including invertebrate fishing, ciguatera poisoning and mariculture. Fourteen recommendations are provided to enhance scenarios' robustness, island specificities integration, complex modelling accuracy, and better use of SCP for island management.

Using individual-based movement information to identify spatial conservation priorities for mobile species

The optimal design of reserve networks and fisheries closures depends on species occurrence information and knowledge of how anthropogenic impacts interact with the species concerned. However, challenges in surveying mobile and cryptic species over adequate spatial and temporal scales can mask the importance of particular habitats, leading to uncertainty about which areas to protect to optimize conservation efforts. We investigated how telemetry-derived locations can help guide the scale and timing of fisheries closures with the aim of reducing threatened species bycatch. Forty juvenile speartooth sharks (Glyphis glyphis) were monitored over 22 months with implanted acoustic transmitters and an array of hydrophone receivers. Using the decision-support tool Marxan, we formulated a permanent fisheries closure that prioritized areas used more frequently by tagged sharks and considered areas perceived as having high value to fisheries. To explore how the size of the permanent closure compared with an alternative set of time-area closures (i.e., where different areas were closed to fishing at different times of year), we used a cluster analysis to group months that had similar arrangements of selected planning units (informed by shark movements during that month) into 2 time-area closures. Sharks were consistent in their timing and direction of migratory movements, but the number of tagged sharks made a big difference in the placement of the permanent closure; 30 individuals were needed to capture behavioral heterogeneity. The dry-season (May-January) and wet-season (February-April) time-area closures opened 20% and 25% more planning units to fishing, respectively, compared with the permanent closure with boundaries fixed in space and time. Our results show that telemetry has the potential to inform and improve spatial management of mobile species and that the temporal component of tracking data can be incorporated into prioritizations to reduce possible impacts of spatial closures on established fisheries.

Addressing transboundary conservation challenges through marine spatial prioritization

The Adriatic and Ionian Region is an important area for both strategic maritime development and biodiversity conservation in the European Union (EU). However, given that both EU and non-EU countries border the sea, multiple legal and regulatory frameworks operate at different scales, which can hinder the coordinated long-term sustainable development of the region. Transboundary marine spatial planning can help overcome these challenges by building consensus on planning objectives and making the trade-offs between biodiversity conservation and its influence on economically important sectors more explicit. We address this challenge by developing and testing 4 spatial prioritization strategies with the decision-support tool Marxan, which meets targets for biodiversity conservation while minimizing impacts to users. We evaluated these strategies in terms of how priority areas shift under different scales of target setting (e.g., regional vs. country level). We also examined the trade-off between cost-efficiency and how equally solutions represent countries and maritime industries (n = 14) operating in the region with the protection-equality metric. We found negligible differences in where priority conservation areas were located when we set targets for biodiversity at the regional versus country scale. Conversely, the prospective impacts on industries, when considered as costs to be minimized, were highly divergent across scenarios and biased the placement of protection toward industries located in isolation or where there were few other industries. We recommend underpinning future marine spatial planning efforts in the region through identification of areas of national significance, transboundary areas requiring cooperation between countries, and areas where impacts on maritime industries require careful consideration of the trade-off between biodiversity conservation and socioeconomic objectives.

Challenges in rendering Coral Triangle habitat richness in remotely sensed habitat maps: The case of Bunaken Island (Indonesia)

The Coral Triangle is the epicenter of marine biodiversity, yet the numbers of habitats that can be found on coral reefs remain poorly described. First surveys for habitat mapping in Indonesia revealed a high number of habitats (>150) even for structurally simple reefs. To be able to represent all these habitats, typical habitat mapping procedures and performances are poorly effective even using very high resolution satellite images. Using Bunaken Island (North Sulawesi, Indonesia) as a case study, we devised a way to maintain all the in situ habitat information in remote sensing habitat map products without loss and with mapping procedures based on photo-interpretation. The result is a product which is consistent with a per-polygon fuzzy classification. As such, it is a complex product that meets our habitat representation goal, but its complexity can also limit its immediate use by managers and conservation planners when analyses per habitat are needed.

Designing connected marine reserves in the face of global warming

Marine reserves are widely used to protect species important for conservation and fisheries and to help maintain ecological processes that sustain their populations, including recruitment and dispersal. Achieving these goals requires well-connected networks of marine reserves that maximize larval connectivity, thus allowing exchanges between populations and recolonization after local disturbances. However, global warming can disrupt connectivity by shortening potential dispersal pathways through changes in larval physiology. These changes can compromise the performance of marine reserve networks, thus requiring adjusting their design to account for ocean warming. To date, empirical approaches to marine prioritization have not considered larval connectivity as affected by global warming. Here, we develop a framework for designing marine reserve networks that integrates graph theory and changes in larval connectivity due to potential reductions in planktonic larval duration (PLD) associated with ocean warming, given current socioeconomic constraints. Using the Gulf of California as case study, we assess the benefits and costs of adjusting networks to account for connectivity, with and without ocean warming. We compare reserve networks designed to achieve representation of species and ecosystems with networks designed to also maximize connectivity under current and future ocean-warming scenarios. Our results indicate that current larval connectivity could be reduced significantly under ocean warming because of shortened PLDs. Given the potential changes in connectivity, we show that our graph-theoretical approach based on centrality (eigenvector and distance-weighted fragmentation) of habitat patches can help design better-connected marine reserve networks for the future with equivalent costs. We found that maintaining dispersal connectivity incidentally through representation-only reserve design is unlikely, particularly in regions with strong asymmetric patterns of dispersal connectivity. Our results support previous studies suggesting that, given potential reductions in PLD due to ocean warming, future marine reserve networks would require more and/or larger reserves in closer proximity to maintain larval connectivity.