Conservation strategies, such as the establishment of Marine Protected Areas (MPAs), aim to safeguard biodiversity and to promote resilience of ecosystems by increasing their capacity to maintain key functions and processes following disturbance. However, the extent to which ecosystems in MPAs exhibit resilience remains debated. To address this question, we evaluated changes in reef fish species and functional diversity over time in relation to environmental and anthropogenic disturbances at multiple locations in the Gulf of California, Mexico. From 2005 to 2017, we assessed reef fish species richness and abundance in three MPAs: one no-take marine reserve (Cabo Pulmo) and two multi-use marine protected areas (MUMPAs: Espíritu Santo and Loreto). To examine change in functional diversity and composition, we calculated three functional diversity indices – functional richness, functional dispersion and functional originality – using six biological traits (size, mobility, period of activity, gregariousness, water column position, and diet). Species richness, density and functional diversity were maintained over time (resilience) in the no-take marine reserve. In contrast, MUMPAs showed temporal decline in species richness, which translated into decreases in functional richness and increases in functional dispersion. These differences were also observed at the species level: in Cabo Pulmo, only two ‘loser’ species declined in density, while Espíritu Santo and Loreto showed declines of 12 and 17 species, respectively. The two MUMPAs also shared 9 of the total 22 ‘loser’ species, which are generally abundant and common in the Gulf of California. Density declines were attributed to the combined effect of environmental (sea surface temperature and Chlorophyll-a anomalies) and anthropogenic (fishing, tourism and coastal population density) disturbances. Given the regional decline and the ecological importance of dominant species, long-term decreases in their populations can profoundly modify processes and reef ecosystem services in this region. Thus, local management strategies should be implemented to try to reverse the observed recent decline in fish diversity in MUMPAs.

保护战略，例如建立海洋保护区 (MPA)，旨在通过提高生态系统在受到干扰后维持关键功能和过程的能力来保护生物多样性和促进生态系统的复原力。然而，海洋保护区中的生态系统在多大程度上表现出复原力仍然存在争议。为了解决这个问题，我们评估了墨西哥加利福尼亚湾多个地点与环境和人为干扰相关的珊瑚鱼物种和功能多样性随时间的变化。从 2005 年到 2017 年，我们评估了三个海洋保护区的珊瑚鱼物种丰富度和丰度：一个禁止捕捞海洋保护区（Cabo Pulmo）和两个多用途海洋保护区（MUMPA：Espíritu Santo 和 Loreto）。为了检查功能多样性和组成的变化，我们使用六种生物学特征（大小、移动性、活动期、群居性、水柱位置和饮食）计算了三个功能多样性指数——功能丰富度、功能分散性和功能独创性。禁捕海洋保护区的物种丰富度、密度和功能多样性随着时间的推移（恢复力）得以保持。相比之下，MUMPA 表现出物种丰富度的暂时下降，这转化为功能丰富度的下降和功能分散度的增加。在物种水平上也观察到了这些差异：在 Cabo Pulmo，只有两个“失败者”物种的密度下降，而 Espíritu Santo 和 Loreto 的物种密度分别下降了 12 和 17 个。这两个 MUMPA 还共享 22 个“失败者”物种中的 9 个，这些物种在加利福尼亚湾普遍丰富且常见。密度下降归因于环境（海面温度和叶绿素-a 异常）和人为（捕鱼、旅游和沿海人口密度）干扰的综合影响。鉴于优势物种的区域衰退和生态重要性，其种群的长期减少会深刻改变该地区的进程和珊瑚礁生态系统服务。因此，应实施当地管理战略，以试图扭转最近观察到的 MUMPA 鱼类多样性下降的趋势。其种群数量的长期减少会深刻改变该地区的进程和珊瑚礁生态系统服务。因此，应实施当地管理战略，以试图扭转最近观察到的 MUMPA 鱼类多样性下降的趋势。其种群数量的长期减少会深刻改变该地区的进程和珊瑚礁生态系统服务。因此，应实施当地管理战略，以试图扭转最近观察到的 MUMPA 鱼类多样性下降的趋势。