Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USA.
J Anim Ecol. 2017 Oct;86(6):1394-1403. doi: 10.1111/1365-2656.12745. Epub 2017 Sep 28.
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. 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). We tested the response of mobile estuarine consumers over 5 months to changes in habitat availability in situ by comparing densities and feeding rates on artificial reefs that were or were not adjacent to neighbouring artificial reefs or nearby natural reefs. Using either constructed or natural reefs to manipulate habitat availability, we documented threefold 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. 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.
量化移动消费者对栖息地可利用性变化的响应对于确定种群水平生产力在多大程度上受到栖息地限制，而不是受到其他潜在的与密度无关的因素的调节至关重要。在景观尺度上，可以通过监测随着栖息地可利用性的变化，密度和觅食的变化来探索这一点。随着栖息地的增加，密度可能会：(1)减少（单位面积的产量减少；栖息地限制较弱）；(2)保持稳定（单位面积的产量保持稳定；栖息地限制）或(3)增加（单位面积的产量增加；栖息地限制较强）。我们通过比较人工礁石上的密度和摄食率来测试移动性河口消费者对栖息地可利用性变化的反应，这些人工礁石有的与相邻的人工礁石或附近的天然礁石相邻，有的则没有。我们使用人工或天然礁石来操纵栖息地的可利用性，记录到随着栖息地的增加，幼年石蟹的密度下降了三倍（即栖息地的模仿较弱）。然而，对于成年石蟹，密度在处理过程中保持稳定，这表明栖息地限制是该物种后期生活史中的一个瓶颈。牡蛎蟾鱼的密度也没有随着栖息地的增加而变化（即栖息地限制），但其他隐密鱼类的密度随着栖息地的增加而减少（即限制较弱）。摄食和丰度数据表明，一些移动鱼类经历了栖息地限制，或者在一种情况下，在我们的栖息地操作中经历了强烈的限制。这些关于重要的、群落水平的栖息地限制的发现为理解全球结构复杂的河口栖息地的减少如何可能降低沿海生态系统的渔业产量提供了线索。
