Data from: Protection promotes energetically efficient structures in marine communities

The sustainability of marine communities is critical for supporting many biophysical processes that provide ecosystem services that promote human well-being. It is expected that anthropogenic disturbances such as climate change and human activities will tend to create less energetically-efficient ecosystems that support less biomass per unit energy flow. It is debated, however, whether this expected development should translate into bottom-heavy (with small basal species being the most abundant) or top-heavy communities (where more biomass is supported at higher trophic levels with species having larger body sizes). Here, we combine ecological theory and empirical data to demonstrate that full marine protection promotes shifts towards top-heavy energetically-efficient structures in marine communities. First, we use metabolic scaling theory to show that protected communities are expected to display stronger top-heavy structures than disturbed communities. Similarly, we show theoretically that communities with high energy transfer efficiency display stronger top-heavy structures than communities with low transfer efficiency. Next, we use empirical structures observed within fully protected marine areas compared to disturbed areas that vary in stress from thermal events and adjacent human activity. Using a nonparametric causal-inference analysis, we find a strong, positive, causal effect between full marine protection and stronger top-heavy structures. Our work corroborates ecological theory on community development and provides a quantitative framework to study the potential restorative effects of different candidate strategies on protected areas.海洋群落（marine communities）的可持续性对于支撑诸多生物物理过程至关重要，这些过程能够提供促进人类福祉的生态系统服务（ecosystem services）。已有研究预测，气候变化、人类活动等人为干扰（anthropogenic disturbances）会倾向于形成能量利用效率更低的生态系统，即单位能量流所能支撑的生物量（biomass）更少。不过，目前仍存在争议：这种预期的群落变化，究竟会导向底重型群落（即小型基底物种丰度最高），还是顶重型群落（即更高营养级（trophic levels）、体型更大的物种支撑了更多生物量）？本研究结合生态学理论与实证数据，证明全海洋保护（full marine protection）能够推动海洋群落向顶重型、能量高效的结构转变。首先，我们借助代谢缩放理论（metabolic scaling theory）证明，受保护群落相较于受干扰群落，理论上会呈现更显著的顶重结构。同理，理论分析表明，能量传递效率较高的群落，其顶重结构也会比低传递效率的群落更为突出。随后，我们对比了全保护海洋区域（fully protected marine areas）与受不同程度热事件、邻近人类活动干扰的区域中观测到的群落结构，并通过非参数因果推断分析（nonparametric causal-inference analysis）发现，全海洋保护与更强的顶重结构之间存在显著的正向因果效应。本研究验证了群落发展的生态学理论，并为探究不同候选保护策略对保护区的潜在修复效果提供了量化框架。