Data from: Life stage and species identity affect whether habitat subsidies enhance or simply redistribute consumer biomass

1. Quantifying the response of mobile consumers to changes in habitat availability is essential for determining the degree to which population-level productivity is habitat limited rather than regulated by other, potentially density-independent factors. 2. Over landscape scales, this can be explored by monitoring changes in density and foraging as habitat availability varies. As habitat availability increases, densities may: (1) decrease (unit-area production decreases; weak habitat limitation); (2) remain stable (unit-area production remains stable; habitat limitation); or (3) increase (unit-area production increases; strong habitat limitation). 3. We tested the response of mobile estuarine consumers over five months to changes in habitat availability in situ by comparing densities and feeding rates on artificial reefs that were or were not adjacent to neighboring artificial reefs or nearby natural reefs). 4. Using either constructed or natural reefs to manipulate habitat availability, we documented three-fold density decreases among juvenile stone crabs as habitat increased (i.e. weak habitat imitation). However, for adult stone crabs, density remained stable across treatments, demonstrating that habitat limitation presents a bottleneck in this species’ later life history. Oyster toadfish densities also did not change with increasing habitat availability (i.e. habitat limitation), but densities of other cryptic fishes decreased as habitat availability increased (i.e. weak limitation). Feeding and abundance data suggested that some mobile fishes experience habitat limitation, or, potentially in one case, strong limitation across our habitat manipulations. 5. These findings of significant, community-level habitat limitation provide insight into how global declines in structurally complex estuarine habitats may have reduced the fishery production of coastal ecosystems.

1. 量化移动消费者对生境可利用性变化的响应，是明确种群水平生产力在多大程度上受生境限制，而非受其他潜在密度非依赖因子调控的核心前提。2. 在景观尺度下，可通过监测生境可利用性变化时种群密度与觅食行为的改变来探究该科学问题。伴随生境可利用性提升，种群密度可能出现三种响应模式：(1) 下降（单位面积生产力降低，生境限制作用较弱）；(2) 维持稳定（单位面积生产力不变，存在生境限制）；(3) 上升（单位面积生产力提升，生境限制作用较强）。3. 本研究通过对比相邻、非相邻人工鱼礁，以及邻近自然鱼礁周边的人工鱼礁上的种群密度与摄食率，开展了为期五个月的原位实验，以检测河口移动消费者对生境可利用性变化的响应。4. 本研究通过构建人工鱼礁或利用自然鱼礁操控生境可利用性，发现随着生境面积增加，幼年石蟹的种群密度下降至原来的三分之一，即生境限制作用较弱。然而成年石蟹的种群密度在各实验处理组间均未发生显著变化，表明生境限制是该物种后期生活史中的关键瓶颈。豹蟾鱼的种群密度同样未随生境可利用性提升而改变，即存在生境限制；但其他隐蔽性鱼类的种群密度则随生境可利用性增加而下降，即生境限制作用较弱。摄食与种群丰度数据显示，部分移动鱼类在本次生境操控实验中表现出生境限制，其中至少一个类群可能存在较强的生境限制。5. 本研究揭示了群落水平显著的生境限制现象，该发现为解析全球范围内结构复杂的河口生境衰退如何削弱海岸生态系统的渔业生产力提供了重要理论视角。