Context

Species interactions generating consistent landscape or seascape patterns are important to ecosystem health and function. One widely-documented pattern in shallow, tropical reefscapes is sand “halos” that separate coral patches from surrounding vegetation. Multiple hypotheses for this pattern have been proposed, but individual explanations are rarely integrated to reflect the complexity of systems where halos occur.

Objectives

To evaluate and synthesize multiple hypotheses of halo formation and maintenance into a single model, connect the halo pattern with similar terrestrial phenomena, and identify targets to guide future research and conservation.

Methods

We reviewed halo accounts from over fifty years in the scientific literature and combined them with related research on marine nutrients, bioturbation, analogous terrestrial processes, and new field measurements to create a conceptual model of halo formation and maintenance.

Results

Though halos are widely attributed to herbivory, grazing alone cannot explain patterns at all locations. Nutrients have large effects on tropical reefscapes but remain understudied for halos. Coupling nutrients and grazing explains a variety of observed halo patterns. Fish and invertebrate bioturbators also appear important. We combine these factors to explain pattern variability and present a framework for more comprehensive halo research.

Conclusions

Explanations for halos to date have been overly simplistic. Halos are common patterns with complex underlying causes, including foraging behavior and nutrient cycling. Not all halo-like patterns may be created or maintained by the same mechanism(s). Our integrated model provides a more complete understanding of factors contributing to these patterns, a framework for ecological interpretations, and a guide for conservation.

中文翻译：

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浅热带礁中的底栖模式形成：放牧解释了放牧的光环吗？

语境

物种相互作用产生一致的景观或海景模式对于生态系统的健康和功能很重要。在浅海热带礁中广泛记录的一种模式是“晕轮”，将珊瑚斑块与周围的植被区分开。已经提出了针对该模式的多种假设，但是很少集成个别的解释以反映出现光晕的系统的复杂性。

目标

要将光晕形成和维持的多种假设评估和综合为一个模型，将光晕模式与类似的地球现象联系起来，并确定目标以指导未来的研究和保护。

方法

我们回顾了超过五十年来科学文献中的晕轮账，并将其与有关海洋养分，生物扰动，类似的陆地过程和新的野外测量的相关研究相结合，以创建晕轮形成和维持的概念模型。

结果

尽管光环广泛地归因于草食性，但仅放牧并不能解释所有地点的模式。营养物质对热带珊瑚礁的影响很大，但晕轮作用仍未得到充分研究。营养物质和放牧的耦合解释了各种观察到的光环模式。鱼和无脊椎动物生物扰动器也显得很重要。我们结合这些因素来解释模式的可变性，并提出了更全面的光环研究的框架。

结论

迄今为止，对光环的解释过于简单。光环是具有复杂潜在原因的常见模式，包括觅食行为和养分循环。并非所有类似晕轮的图案都可以通过相同的机制创建或维护。我们的综合模型提供了对导致这些模式的因素的更完整的理解，生态学解释的框架以及保护的指南。