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. 量化移动消费者生物对生境可用性变化的响应，是确定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无关因素调控的关键前提。2. 在景观尺度下，可通过监测生境可用性变化时种群密度与觅食行为的改变开展此类研究。随着生境可用性提升，种群密度可能出现三种变化模式：(1) 下降（单位面积生产力降低，即弱生境限制）；(2) 保持稳定（单位面积生产力不变，即典型生境限制）；(3) 上升（单位面积生产力提升，即强生境限制）。3. 本研究针对河口移动消费者生物开展了为期5个月的原位生境可用性变化响应实验，通过对比毗邻或不毗邻周边人工鱼礁、亦或邻近自然鱼礁的人工鱼礁上的种群密度与摄食率，完成了相关测试。4. 本研究通过构建鱼礁或自然鱼礁操控生境可用性，结果显示：随着生境面积扩张，幼年石蟹的种群密度下降至原来的三分之一，表现为弱生境限制。而成年石蟹的种群密度在各处理组间均保持稳定，表明生境限制是该物种后期生活史中的瓶颈因素。食牡蛎蟾鱼的种群密度亦未随生境可用性提升发生改变，符合典型生境限制特征；但其他隐蔽性鱼类的种群密度则随生境可用性增加而下降，表现为弱生境限制。摄食与种群丰度数据表明，部分移动鱼类存在生境限制现象，在本次生境操控实验中甚至有一例疑似强生境限制的情况。5. 本次研究发现群落水平存在显著生境限制，这一结果为解析全球结构复杂的河口生境退化如何削弱沿海生态系统的渔业生产力提供了重要科学参考。