A common life cycle pattern in benthic-dwelling taxa in the ocean is an obligate pre-competent dispersal period of microscopic propagules followed by their entry into a competent period, during which they are capable of transitioning back to the sea floor at settlement. The behavior of larvae during their competent periods varies: some taxa are characterized by discriminating larvae that will only accept high quality habitat in which to settle, whereas larvae from other taxa may initially be discriminating, but will become increasingly ‘desperate’ to settle as they age. Larvae in this latter class, if they fail to encounter optimal settlement habitat, are observed to accept increasingly sub-optimal habitat as their competent period progresses. Here we show that a brief exposure of competent sand dollar larvae (Dendraster excentricus) to a high intensity of turbulent shear shifts larvae into less discriminating settlement behavior. Specifically, turbulence-exposed larvae will settle in response to a wider variety of settlement cues, and will do so more rapidly than will their unexposed siblings. We also report that turbulence causes larvae to sink to the bottom in greater numbers, presumably increasing their exposure to cues on the substrate. We conclude that fundamental aspects of larval life history and habitat selection are sensitive to short term environmental exposure. We discuss these findings in the context of how larvae might more generally utilize transient features of their environment to make key life history decisions. Such a perspective has implications for issues as diverse as aquaculture, population recovery following disturbance, and the sensitivity and response of marine organisms to climate change.

中文翻译：

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湍流暴露再现了后期沙钱幼虫的绝望行为

海洋底栖生物分类单元中常见的生命周期模式是微型繁殖体的专职先扩散期，然后进入繁殖期，在此期间它们能够在定居时过渡回海床。幼虫在其活动时期的行为各不相同：某些类群的特征是，仅能接受定居高质量栖息地的幼虫，而其他类群的幼虫最初可能会受到歧视，但随着它们的成群，它们会变得越来越“绝望”年龄。后一类中的幼虫，如果不能遇到最佳的栖息地，则随着其适应期的发展，它们会接受越来越次优的栖息地。在这里，我们表明，将能干的沙钱幼虫（Dendraster excentricus）短暂暴露于高强度的湍流剪切作用下，会使幼虫变成较不易分辨的沉降行为。具体来说，湍流暴露的幼虫会响应各种各样的沉降线索而沉降，并且比未暴露的同胞更快地沉降。我们还报告说，湍流会导致幼虫大量下沉到底部，大概是增加它们对底物线索的暴露。我们得出结论，幼虫生活史和栖息地选择的基本方面对短期环境暴露敏感。我们在幼虫如何更普遍地利用其环境的瞬时特征来做出重要的生命史决策的背景下讨论这些发现。