Seagrasses are productive habitats that support diverse communities of economically and ecologically important fishes and macroinvertebrates. However, most seagrass faunal assessments are conducted only during daylight hours. Here, we documented diel patterns in seagrass-associated fish and macroinvertebrate community structure in seagrass near Seahorse Key, Florida (USA). Artificial light is prevalent in many coastal areas and may influence day/night assemblages; therefore, we added lights to the natural environment to get a better understanding of its effect on community composition. Seagrass inhabitants were quantified using 25-m seine transects during different diel periods (day or night) and in areas where light was manipulated to mimic light pollution (artificial + natural light or natural light). Results suggest that the magnitude of diel effects exceeded that of light addition. While total abundance was similar between day and night, communities did change, with Lagodon rhomboides (Pinfish) dominating day samples and Farfantepenaeus duorarum (pink shrimp) most abundant at night. Other fishes such as Orthopristis chrysoptera (Pigfish) and Strongylura notata (Needlefish) had higher catches during the day, while invertebrates such as Callinectes sapidus (blue crab) and Palaeomonetes spp. (grass shrimp) were more prominent at night. In addition to the differences in abundance and community structure, we also identified diel differences in sizes for some species. No clear patterns were observed with the short-term addition of artificial light. This research highlights the role of diel variability in seagrass communities and suggests that diel movement of organisms may represent an important conduit for the transfer of energy to adjacent habitats.

海草是高产的栖息地，为经济和生态上重要的鱼类和无脊椎动物的多样化社区提供了支持。但是，大多数海草动物区系评估仅在白天进行。在这里，我们记录了美国佛罗里达州海马斯基附近海草相关鱼类的迪尔模式和海草中的大型无脊椎动物群落结构。人造光在许多沿海地区都很普遍，并且可能会影响白天/晚上的聚会。因此，我们在自然环境中增加了灯光，以更好地了解其对社区构成的影响。在不同diel期间（白天或夜晚）以及在操纵光以模仿光污染（人工+自然光或自然光）的区域中，使用25米围网样带对海草居民进行定量。结果表明，狄尔效应的强度超过了光添加的强度。尽管白天和夜晚的总丰度相似，但社区确实发生了变化，白天采样的菱形泻湖（Pinfish）和晚上最多的粉红色虾（Farfantepenaeus duorarum）（粉虾）占主导地位。其他鱼类，例如Orthopristis chrysoptera（猪）和Strongylura notata（Needlefish）在白天的捕获量较高，而无脊椎动物如Callinectes sapidus（蓝蟹）和Palaeomonetesspp。（草虾）在夜间更为突出。除了丰度和群落结构的差异外，我们还发现了某些物种大小上的diel差异。短期添加人造光未观察到清晰的图案。这项研究突出了迪尔变异性在海草群落中的作用，并表明生物的迪尔运动可能代表了能量向邻近生境转移的重要渠道。