Department of Biological Sciences, Florida International University, North Miami, Florida, USA.
PLoS One. 2013 Apr 12;8(4):e61907. doi: 10.1371/journal.pone.0061907. Print 2013.
Habitat selection decisions by consumers has the potential to shape ecosystems. Understanding the factors that influence habitat selection is therefore critical to understanding ecosystem function. This is especially true of mesoconsumers because they provide the link between upper and lower tropic levels. We examined the factors influencing microhabitat selection of marine mesoconsumers - juvenile giant shovelnose rays (Glaucostegus typus), reticulate whiprays (Himantura uarnak), and pink whiprays (H. fai) - in a coastal ecosystem with intact predator and prey populations and marked spatial and temporal thermal heterogeneity. Using a combination of belt transects and data on water temperature, tidal height, prey abundance, predator abundance and ray behavior, we found that giant shovelnose rays and reticulate whiprays were most often found resting in nearshore microhabitats, especially at low tidal heights during the warm season. Microhabitat selection did not match predictions derived from distributions of prey. Although at a course scale, ray distributions appeared to match predictions of behavioral thermoregulation theory, fine-scale examination revealed a mismatch. The selection of the shallow nearshore microhabitat at low tidal heights during periods of high predator abundance (warm season) suggests that this microhabitat may serve as a refuge, although it may come with metabolic costs due to higher temperatures. The results of this study highlight the importance of predators in the habitat selection decisions of mesoconsumers and that within thermal gradients, factors, such as predation risk, must be considered in addition to behavioral thermoregulation to explain habitat selection decisions. Furthermore, increasing water temperatures predicted by climate change may result in complex trade-offs that might have important implications for ecosystem dynamics.
消费者的栖息地选择决策有可能塑造生态系统。因此，了解影响栖息地选择的因素对于理解生态系统功能至关重要。对于中型消费者来说尤其如此，因为它们在上层和下层营养级之间提供了联系。我们研究了影响海洋中型消费者（幼年巨型铲吻鲟、网状长尾鲨和粉长尾鲨）微生境选择的因素，这些消费者生活在一个具有完整捕食者和猎物种群以及明显时空热异质性的沿海生态系统中。我们使用带式横断法和水温、潮高、猎物丰度、捕食者丰度和射线行为的数据相结合，发现巨型铲吻鲟和网状长尾鲨最常在近岸微生境中休息，尤其是在温暖季节的低潮时。微生境选择与猎物分布的预测不符。尽管在大尺度上，射线的分布似乎符合行为体温调节理论的预测，但细尺度的研究表明存在不匹配。在高捕食者丰度（温暖季节）期间选择低潮时的浅近岸微生境表明，这种微生境可能是一种避难所，尽管由于温度较高，可能会带来代谢成本。这项研究的结果强调了捕食者在中型消费者栖息地选择决策中的重要性，并且在热梯度内，除了行为体温调节外，还必须考虑捕食风险等因素来解释栖息地选择决策。此外，气候变化预测的水温升高可能会导致复杂的权衡，这可能对生态系统动态产生重要影响。
