Coleman Nicholas C, Burge Erin J
Department of Marine Science, Coastal Carolina University, Conway, SC, United States of America.
Chesapeake Biological Laboratory, University of Maryland Center for Environmental Sciences, Solomons, MD, United States of America.
PeerJ. 2021 Apr 8;9:e11164. doi: 10.7717/peerj.11164. eCollection 2021.
In marine systems, behaviorally-mediated indirect interactions between prey, mesopredators, and higher trophic-level, large predators are less commonly investigated than other ecologic interactions, likely because of inherent difficulties associated with making observations. Underwater videos ( = 216) from SharkCam, a camera installation sited beneath Frying Pan Tower, a decommissioned light house and platform, on a natural, hard bottom site approximately 50 km off Cape Fear, North Carolina, were used to investigate association behavior of round scad around sand tiger sharks . Videos containing sand tiger sharks were analyzed for the simultaneous presence of round scad, and six species of scad mesopredators, with scad-shark interactions assigned to one of three categories of association: no visible interaction, loosely associated, or tightly associated. The likelihood of scad being loosely or tightly associated with sharks was significantly higher in the presence of scad mesopredators, suggesting that sharks provide a predation refuge for scad. This behaviorally-mediated indirect interaction has important implications for trophic energy transfer and mesopredator control on hard bottoms, as scad are one of the most abundant planktivorous fish on hard bottoms in the western Atlantic Ocean. Although we were not able to provide statistical evidence that sand tiger sharks also benefit from this association behavior, we have clear video evidence that round scad association conceals and attracts mesopredators, enhancing predation opportunities for sand tiger sharks. These interactions potentially yield additional trophic consequences to this unique association and highlight the value of exploring behaviorally-mediated interactions in marine communities.
在海洋系统中，与其他生态相互作用相比，猎物、中层捕食者和更高营养级的大型捕食者之间由行为介导的间接相互作用较少被研究，这可能是因为进行观察存在内在困难。来自鲨鱼摄像机（SharkCam）的水下视频（n = 216）被用于研究圆鲹围绕沙虎鲨的关联行为。鲨鱼摄像机安装在北卡罗来纳州费耶特角约50公里外一个自然硬底地点的退役灯塔和平台“煎锅塔”下方。对包含沙虎鲨的视频分析其是否同时存在圆鲹和六种鲹科中层捕食者，并将鲹 - 鲨相互作用分为三类关联之一：无明显相互作用、松散关联或紧密关联。在存在鲹科中层捕食者的情况下，鲹与鲨鱼松散或紧密关联的可能性显著更高，这表明鲨鱼为鲹提供了捕食避难所。这种由行为介导的间接相互作用对硬底上的营养能量传递和中层捕食者控制具有重要意义，因为圆鲹是西大西洋硬底上最丰富的浮游生物食性鱼类之一。虽然我们无法提供统计证据表明沙虎鲨也从这种关联行为中受益，但我们有明确的视频证据表明圆鲹的关联会隐藏并吸引中层捕食者，增加了沙虎鲨的捕食机会。这些相互作用可能会给这种独特的关联带来额外的营养后果，并突出了探索海洋群落中由行为介导的相互作用的价值。
