Integrating multiple species connectivity and habitat quality into conservation planning for coral reefs

Abstract

Incorporating connectivity into the design of marine protected areas (MPAs) has met with conceptual, theoretical, and practical challenges, which include: 1) the need to consider connectivity for multiple species with different dispersal abilities, and 2) the role played by variable habitat quality in determining the spatial patterns of connectivity. We propose an innovative approach, combining biophysical modeling with a routinely-used tool for marine-reserve design (Marxan), to address both challenges by using ecologically-informed connectivity parameters. We showed how functional demographic connectivity for four candidate reef-associated species with varying dispersal abilities and a suite of connectivity metrics weighted by habitat quality can be used to set conservation objectives and inform MPA placement. Overall, the strength of dispersal barriers varied across modeled species and, also across species, we found a lack of spatial concordance of reefs that were high-quality sources, self-persistent, and stepping-stones. Including spatially-heterogeneous habitat quality made a considerable difference to connectivity patterns, significantly reducing the potential reproductive output from many reefs. We also found that caution is needed in combining connectivity data from modeled species into multi-species matrices, which do not perform reliably as surrogates for all connectivity metrics of individual species. We then showed that restricting the habitat available for conservation has an inequitable impact on different connectivity objectives and species, with greatest impact on betweenness centrality and long-distance dispersers. We used Brazilian coral reefs as a case study but our approach is applicable to both marine and terrestrial conservation planning, and offers a holistic way to design functionally-connected reserves to tackle the complex issues relevant to planning for persistence.

Designing connected marine reserves in the face of global warming

“…We show that maintaining dispersal connectivity incidentally through representation‐only reserve design approaches is unlikely, particularly in regions with strong asymmetric dispersal connectivity patterns, such as the RGI. Previous studies have found similar results (Magris et al., ; White et al., ), but ours is the first to show benefits (in terms of maintaining larval connectivity) and potential costs of this approach under future ocean warming. Adjusting network designs to maintain connectivity assuming shorter PLDs prove effective to maximize connectivity under current and ocean‐warming scenarios.…”

“…We followed a graph‐theoretical approach to account for larval connectivity patterns in the design of marine reserve networks. This required mapping potential spawning and recruitment habitats of focal species and characterizing planning units by their potential contribution to the overall connectivity of networks (e.g., Magris et al., ; White et al., ) during spring‐summer. We used the ecosystems inhabited by each focal species (Table S6) to represent their spawning and/or recruitment habitats, and assumed they all have, potentially, equal per unit area contributions of larvae.…”

“…In step 5, we followed the method proposed by Magris et al. () to calculate representation objectives for connectivity features. We identified subsets of planning units with the highest contributions to connectivity, and used their summed values across all planning units to set representation objectives expressed as percentages of totals.…”

Landscape connectivity losses due to sea level rise and land use change

“…In recent years, the multispecies connectivity approach has been successfully demonstrated for marine-area conservation planning (Magris et al, 2015), examining rare mammal communities in tropical forests (Brodie et al, 2014), and for understanding past land use decisions on current bird distributions (Mimet et al, 2013). Most frequently, however, these studies employ deterministic metrics or occur over one time horizon.…”

A modified trait‐based framework for assessing the resilience of ecosystem services provided by coral reef communities

“…, Magris et al. ), if they consider traits at all. The framework highlights the traits and mechanisms that require investigating (Tables and ) such that multi‐trait models can be developed to better predict species‐specific performance.…”