Collaborative Research: Habitat fragmentation effects on seagrass fish diversity at landscape scales: experimental tests of multiple mechanisms

生境的数量和质量被认为对维持沿海海洋生态系统至关重要。这项研究将使用大规模的实地实验来帮助了解鱼类种群如何以及为什么对海草栖息地的破碎做出反应。这个问题很复杂，因为海草床破碎的增加减少了数量，也减少了栖息地的结构（一个斑块分裂成许多块，斑块变得更远，边缘的数量增加，等等）。研究人员先前在天然海草草甸的工作提供了证据，表明破碎化与栖息地数量相互作用，影响沿海海洋景观中鱼类的群落动态。其中，破碎化在生境较大时没有影响，而在生境较小时则有负作用。在本研究中，研究者将建立人工海草栖息地，并在一系列大规模的操作现场实验中使用。这些结果将提供新的、更具体的信息，说明沿海鱼类群落动态如何受到海草栖息地总量和破碎化变化的影响，以及干扰、幼虫扩散和波浪能等因素的影响。该项目将支持两名早期职业调查人员，为海岸管理提供栖息地保护战略信息，并为研究生和本科生提供培训机会。调查人员计划从代表性不足的群体中寻找研究机会。在以往海草环境研究的基础上，本研究将在新的相关尺度上进行一系列实地实验，以测试栖息地面积和破碎化如何影响鱼类多样性和生产力。具体来说，将使用人工海草单元（ASUs）创建15 × 15米的海草床，该单元可以控制斑块内（~1-10 m2）的因素，如芽密度和长度。研究人员将使用ASUs来控制北卡罗莱纳州温带河口海草床的总栖息地面积和破碎程度。在第一年，在这些景观中定居的鱼类的反应将被测量为丰度，生物量，群落结构，以及分类和功能多样性。然后将有针对性地清除ASU，以确定物种对栖息地干扰的特定反应。在第二年，景观阵列和采样制度将增加一倍，一半的景观将播种低扩散能力的幼虫后鱼，以测试招募前或招募后的过程是否驱动景观尺度模式。在第三年，波浪暴露（海草破碎的自然驱动因素）在调节鱼类群落对景观配置的响应中的作用将通过在低能量和高能量环境中部署亚利桑那州立大学草甸来测试。

Amount and quality of habitat is thought to be of fundamental importance to maintaining coastal marine ecosystems. This research will use large-scale field experiments to help understand how and why fish populations respond to fragmentation of seagrass habitats. The question is complex because increased fragmentation in seagrass beds decreases the amount and also the configuration of the habitat (one patch splits into many, patches become further apart, the amount of edge increases, etc). Previous work by the investigators in natural seagrass meadows provided evidence that fragmentation interacts with amount of habitat to influence the community dynamics of fishes in coastal marine landscapes. Specifically, fragmentation had no effect when the habitat was large, but had a negative effect when habitat was smaller. In this study, the investigators will build artificial seagrass habitat to use in a series of manipulative field experiments at an ambitious scale. The results will provide new, more specific information about how coastal fish community dynamics are affected by changes in overall amount and fragmentation of seagrass habitat, in concert with factors such as disturbance, larval dispersal, and wave energy. The project will support two early-career investigators, inform habitat conservation strategies for coastal management, and provide training opportunities for graduate and undergraduate students. The investigators plan to target students from underrepresented groups for the research opportunities. Building on previous research in seagrass environments, this research will conduct a series of field experiments approach at novel, yet relevant scales, to test how habitat area and fragmentation affect fish diversity and productivity. Specifically, 15 by 15-m seagrass beds will be created using artificial seagrass units (ASUs) that control for within-patch-level (~1-10 m2) factors such as shoot density and length. The investigators will employ ASUs to manipulate total habitat area and the degree of fragmentation within seagrass beds in a temperate estuary in North Carolina. In year one, response of the fishes that colonize these landscapes will be measured as abundance, biomass, community structure, as well as taxonomic and functional diversity. Targeted ASU removals will then follow to determine species-specific responses to habitat disturbance. In year two, the landscape array and sampling regime will be doubled, and half of the landscapes will be seeded with post-larval fish of low dispersal ability to test whether pre- or post-recruitment processes drive landscape-scale patterns. In year three, the role of wave exposure (a natural driver of seagrass fragmentation) in mediating fish community response to landscape configuration will be tested by deploying ASU meadows across low and high energy environments.