Marine protected areas (MPAs) have been established with the aim of preserving and recovering marine environments, as well as managing fisheries activities. Some features of MPAs can enhance conservation goals, such as being completely no-take, well-enforced, large, old and isolated. The no-take area in the Alcatrazes Archipelago, southwestern Atlantic, was recently expanded from four separate small areas of 3 km (totalling 12.5 km) established in 1987, to a large continuous no-take reserve (NTR) of 675 km established in August 2016, allowing tourism activities. In this study, the aim was to detect recent changes in the reef fish assemblage following the expansion of the NTR using visual census samples in specific sites around the main island. The surveys were conducted before (2015–2016; n = 230 censuses) and after (2019–2020; n = 320 censuses) the expansion of the NTR. Generalized additive mixed models were fitted to predict fish richness, functional richness, abundance and biomass, considering factors like depth, year and specific sites. The most parsimonious models for mean richness, functional richness, abundance and biomass all included a negative relationship with protection after the expansion, but with an increase of unique species and unique functional entities. Beta diversity values between sites decreased after the expansion with a smaller contribution of nestedness, which indicates a greater sharing of species among the reef areas around the main island. We raised the hypothesis that the decreases in fish fauna metrics could be attributed to several factors: (1) the recency of the NTR expansion, making it difficult to detect the benefits of protection in this short time frame (i.e., less than five years); (2) the type of habitat protected after the expansion, which included mostly sandy bottoms, possibly not promoting connectivity; and (3) the presence of recreational divers in the recently protected area hampering the detection of fish due to possible changes in fish behaviour (mainly for large species with commercial use). By studying one of the largest southwestern Atlantic no-take MPAs, we add evidence that area increment alone is not enough to optimize the protection of marine biodiversity within a short time scale and continuous ecological monitoring is essential for adaptive management, especially in the early stages of MPAs.

中文翻译：

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最近禁捕保护区的大规模扩张是否足以改变珊瑚礁鱼类的结构？西南大西洋阿尔卡特拉斯野生动物保护区的前后评估

建立海洋保护区（MPA）的目的是保护和恢复海洋环境以及管理渔业活动。海洋保护区的一些特征可以增强保护目标，例如完全禁止、执行良好、规模大、古老和孤立。西南大西洋阿尔卡特拉泽斯群岛的禁捕区最近从 1987 年建立的 4 个 3 公里（总计 12.5 公里）的独立小区域扩大到 8 月建立的 675 公里的大型连续禁捕保护区（NTR） 2016年，允许旅游活动。在这项研究中，目的是利用主岛周围特定地点的目视普查样本来检测 NTR 扩张后珊瑚礁鱼类群落的最新变化。这些调查是在 NTR 扩大之前（2015-2016 年；n = 230 次人口普查）和之后（2019-2020 年；n = 320 次人口普查）进行的。考虑深度、年份和特定地点等因素，拟合广义加性混合模型来预测鱼类丰富度、功能丰富度、丰度和生物量。平均丰富度、功能丰富度、丰度和生物量的最简约模型都包含与扩张后的保护呈负相关关系，但随着独特物种和独特功能实体的增加。扩张后地点之间的β多样性值下降，嵌套的贡献较小，这表明主岛周围的珊瑚礁区域之间的物种共享更大。我们提出假设，鱼类区系指标的下降可能归因于以下几个因素：(1) NTR 扩张的近期时间，使得在如此短的时间范围内（即不到五年）很难检测到保护的好处; (2) 扩张后保护的栖息地类型，其中大部分为沙底，可能不会促进连通性；(3) 最近保护区内休闲潜水员的存在妨碍了鱼类的检测，因为鱼类行为可能发生变化（主要是用于商业用途的大型物种）。通过研究西南大西洋最大的禁渔海洋保护区之一，我们补充了证据表明，仅靠面积增量不足以在短时间内优化海洋生物多样性的保护，持续的生态监测对于适应性管理至关重要，尤其是在早期阶段海洋保护区。