Understanding the connectivity patterns of marine populations is essential for their management and conservation . In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects early-life stages dispersal, but also by the spawning stock attributes that affect  reproductive output (e.g., passive eggs and larvae) and its survivorship , constituting the so-called spatial temporal spawner-recruit system. Despite these key properties of marine populations, the design of networks of MPAs often disregard connectivitypatterns. In this context, connectivity networks' properties, can provide valuable input for MPA network design to achieve conservation and fisheries objectives. We performed a step-by-step analysis, increasing the level of network complexity, to assess connectivity patterns of early life stages of marine species from a MPAs network in the Western Mediterranean. A hydrodynamic model was coupled to evaluate the dispersion of eggs and larvae after 21 days of transport, obtaining a connectivity network of hydrodynamic distances. Then, the painted comber, a sedentary and coastal fish with ca. 21 days of pelagic larval duration, was selected as model species to address questions related to a specific spawner-recruit system. The hydrodynamic network was updated by coupling information on the total egg production per site and available habitat for spawning and nursery. This biophysical network illustrates how the demographic characteristics impact the properties of the spawner-recruit system. New network properties emerged when centrality measures from graph theory were studied. Finally, a hypothetical scenario explored alternative MPA network configurations , demonstrating how simple spatial decisions based on connectivity measures could improve recruitment and average network connectivity  .
Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA networks design frequently disregards the importance of connectivity patterns . In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects early-life stages dispersal, but also from the spawning stock attributes that affect the reproductive output (e.g., passive eggs and larvae) and its survivorship . Early-life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled to egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may be different depending on the type of connectivity considered; consequently, the prioritisation of sites for marine populations' conservation might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. We use as a case of study a network of open-access areas and MPAs, off Mallorca Island (Spain), and test its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis are used to: (1) identify critical areas for improving overall larval connectivity; (2) assess the impact of species' biological parameters in network connectivity; and (3) explore alternative MPA configurations to improve average network connectivity . Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network which are relevant for increasing protection efficiency .
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Understanding the connectivity patterns of marine populations is essential for their management and conservation
Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA networks design frequently disregards the importance of connectivity patterns
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, constituting the so-called spatial temporal spawner-recruit system. Despite these key properties of marine populations, the design of networks of MPAs often disregard connectivitypatterns. In this context, connectivity networks' properties, can provide valuable input for MPA network design to achieve conservation and fisheries objectives. We performed a step-by-step analysis, increasing the level of network complexity, to assess connectivity patterns of early life stages of marine species from a MPAs network in the Western Mediterranean. A hydrodynamic model was coupled to evaluate the dispersion of eggs and larvae after 21 days of transport, obtaining a connectivity network of hydrodynamic distances. Then, the painted comber, a sedentary and coastal fish with ca. 21 days of pelagic larval duration, was selected as model species to address questions related to a specific spawner-recruit system. The hydrodynamic network was updated by coupling information on the total egg production per site and available habitat for spawning and nursery. This biophysical network illustrates how the demographic characteristics impact the properties of the spawner-recruit system. New network properties emerged when centrality measures from graph theory were studied. Finally, a hypothetical scenario explored alternative MPA network configurations , demonstrating how simple spatial decisions based on connectivity measures could improve recruitment and
. Early-life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled to egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may be different depending on the type of connectivity considered; consequently, the prioritisation of sites for marine populations' conservation might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. We use as a case of study a network of open-access areas and MPAs, off Mallorca Island (Spain), and test its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis are used to: (1) identify critical areas for improving overall larval connectivity; (2) assess the impact of species' biological parameters in network connectivity; and (3) explore alternative MPA configurations to improve
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. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network which are relevant for increasing protection efficiency