Assessing the current state of ecological connectivity in a large marine protected area system.

Jutta Beher,Kelsey E Roberts,Eric A Treml,Carly N Cook

doi:10.1111/cobi.13580

Abstract

The establishment of marine protected areas (MPAs) is a critical step in ensuring the continued persistence of marine biodiversity. Although the area protected in MPAs is growing, the movement of individuals (or larvae) among MPAs, termed connectivity, has only recently been included as an objective of many MPAs. As such, assessing connectivity is often neglected or oversimplified in the planning process. For promoting population persistence, it is important to ensure that protected areas in a system are functionally connected through dispersal or adult movement. We devised a multi‐species model of larval dispersal for the Australian marine environment to evaluate how much local scale connectivity is protected in MPAs and determine whether the extensive system of MPAs truly functions as a network. We focused on non‐migratory species with simplified larval behaviors (i.e., passive larval dispersal) (e.g., no explicit vertical migration) as an illustration. Of all the MPAs analyzed (approximately 2.7 million km2), outside the Great Barrier Reef and Ningaloo Reef, <50% of MPAs (46‐80% of total MPA area depending on the species considered) were functionally connected. Our results suggest that Australia's MPA system cannot be referred to as a single network, but rather a collection of numerous smaller networks delineated by natural breaks in the connectivity of reef habitat. Depending on the dispersal capacity of the taxa of interest, there may be between 25 and 47 individual ecological networks distributed across the Australian marine environment. The need to first assess the underlying natural connectivity of a study system prior to implementing new MPAs represents a key research priority for strategically enlarging MPA networks. Our findings highlight the benefits of integrating multi‐species connectivity into conservation planning to identify opportunities to better incorporate connectivity into the design of MPA systems and thus to increase their capacity to support long‐term, sustainable biodiversity outcomes.

Highlights

In an effort to halt the global decline of marine biodiversity, conserve ecosystem function, and help promote sustainable fisheries, the establishment of marine protected areas (MPAs) has rapidly increased over the past decade
Relative to the rest of Australia’s ecoregions, the Bassian ecoregion has very low levels of reef habitat protected (3%) as well as fewer and smaller MPAs distributed across the seascape
The global expansion of MPAs over the last few decades has been labeled a conservation success, there are growing concerns that many MPAs have been established without sufficient reference to the distribution of biodiversity (Jantke et al 2018) or the connectivity of habitat (Schill et al 2015), creating challenges for their ability to genuinely support the persistence of marine populations

Summary

Introduction

In an effort to halt the global decline of marine biodiversity, conserve ecosystem function, and help promote sustainable fisheries, the establishment of marine protected areas (MPAs) has rapidly increased over the past decade. MPAs rely on a design process guided by systematic conservation planning principles. This process can ensure that MPAs collectively represent the species and ecosystems in need of protection in order to maximize biodiversity outcomes (Margules & Pressey 2000). The movement of individuals (or larvae) among protected areas, termed ecological connectivity, significantly influences persistence through dynamic processes, such as self-recruitment and colonisation, and leads to evolutionarily significant outcomes such as the flow of adaptive genes in the face of environmental change (Hoffmann & Sgrò 2011; Matz et al 2018; Balbar & Metaxas 2019). In the context of marine spatial planning, ensuring connectivity among local populations should be an important consideration rather than relying on local areas to be self-persistent (White et al 2010; Burgess et al 2014)

Objectives

Methods

Results

Conclusion