ABSTRACT: Plankton is an important component of the food web in coastal reef ecosystems. Ocean currents subsidise local production by supplying plankton to resident and reef-associated planktivorous fishes. Measuring the fine-scale distribution of these schooling fishes provides insight into their habitat use and how they balance risk and reward while foraging for plankton. Maintaining their proximity to benthic structure can provide refuge from predation but may also limit foraging opportunities. We used a portable multibeam echosounder to survey schooling fish at 5 natural and 3 artificial reefs, during day and night and under different current conditions. We isolated midwater acoustic targets and used generalised linear models to explain the distribution of schools as a function of current exposure, distance from structure and seafloor complexity. We also isolated individual schools and used generalised least squares to model how school characteristics differed between night and day, using spatial metrics of school area, perimeter length and height above the seafloor. Modelling revealed that the occurrence of schools was almost twice as likely upstream versus downstream of artificial reefs, although distance to reef structure was the main influence. School occurrence was also more likely on artificial versus natural reefs. Schools at artificial reefs exhibited greater volume and areal coverage at night, and during the day they rose higher in the water column while aggregating more closely around the reef. These findings suggest that artificial and natural reefs featuring enhanced vertical relief and direct exposure to the prevailing current are preferred habitats for planktivorous fish.

中文翻译：

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温带岩石和人工鱼礁上浮游动物鱼类的精细空间和饮食动态

摘要：浮游生物是沿海珊瑚礁生态系统食物链的重要组成部分。洋流通过向居民和与珊瑚礁相关的浮游鱼类提供浮游生物来补贴当地生产。测量这些群居鱼类的精细分布可以深入了解它们的栖息地利用以及它们在觅食浮游生物时如何平衡风险和回报。保持它们靠近底栖结构可以提供躲避捕食的避难所，但也可能限制觅食机会。我们使用便携式多波束测深仪在白天和黑夜以及不同的水流条件下对 5 个天然鱼礁和 3 个人工鱼礁中的群鱼进行了调查。我们隔离了中水声学目标并使用广义线性模型来解释学校分布作为当前暴露的函数，与结构和海底复杂性的距离。我们还隔离了个别学校，并使用广义最小二乘法来模拟学校特征在白天和黑夜之间的差异，使用学校面积、周长和海底高度的空间度量。建模显示，尽管与珊瑚礁结构的距离是主要影响因素，但在人工鱼礁上游和下游出现群落的可能性几乎是下游的两倍。在人造珊瑚礁和天然珊瑚礁上也更有可能发生群落。人工鱼礁群在夜间表现出更大的体积和面积覆盖，白天它们在水柱中上升得更高，同时更紧密地聚集在珊瑚礁周围。