Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA network 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.

中文翻译：

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基于图论和幼虫扩散突现特性的MPA网络设计

尽管海洋保护区 (MPA) 网络作为生物多样性保护工具的有效性得到公认，但如今 MPA 网络设计经常忽视连接模式的重要性。就定居海洋种群而言，连通性不仅源于影响生命早期阶段扩散的物理环境的随机性，还源于影响繁殖输出的产卵种群属性（例如，被动卵和幼虫）及其幸存。在海洋中几乎不可能追踪生命早期阶段。因此，结合卵和幼虫拉格朗日传输模型的数值洋流模拟仍然是评估海洋幼虫连通性的最常用方法。根据所考虑的连接类型，推断的幼虫连接可能会有所不同；因此，海洋种群保护地点的优先顺序也可能不同。在这里，我们介绍了一个框架，用于基于使用图论分析识别连接热点来评估和设计 MPA 网络。我们将马略卡岛（西班牙）附近的开放式区域和海洋保护区网络作为研究案例，并测试其保护彩绘精梳机 Serranus scriba 的有效性。网络分析的输出用于： (1) 确定改善整体幼虫连通性的关键区域；(2) 评估物种生物参数对网络连通性的影响；(3) 探索替代 MPA 配置以改善平均网络连接。