Sub-surface hotspots in shallow seas: fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll
Sub-surface hotspots in shallow seas: fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll
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DOI：
10.3354/meps08552
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发表时间：
2010-06
影响因子：
2.5
通讯作者：
B. Scott;J. Sharples;Oliver N. Ross;Jianjun Wang;G. Pierce;C. J. Camphuysen
中科院分区：
文献类型：
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作者：
B. Scott;J. Sharples;Oliver N. Ross;Jianjun Wang;G. Pierce;C. J. Camphuysen
在浅海同时观察了7种海洋顶端捕食者的觅食生境，并通过连续测量详细的生物物理水柱特征来确定生境偏好。我们发现了小规模的“热点”，其中50%的动物在不到5%的1000 km的调查断面中积极觅食。通过调查各种食鱼海鸟和海洋哺乳动物的觅食策略的对比范围，我们确定了哪些栖息地特征在不同物种之间始终是重要的。一个静态的栖息地变量，潮汐分层，log 10（h/U 3）（h =水深，U =潮流振幅），被认为是最好的指标的概率存在和丰富的个别物种。所有7个移动的顶端捕食者优先觅食的栖息地内的小规模（2至10公里）补丁有（1）高浓度的叶绿素在次表层叶绿素最大值（CHLmax）和（2）高的差异，在底部地形，不同的物种更喜欢在这些栖息地内的不同位置觅食。CHLmax的斑块性与强水平温度梯度（锋）或高表面叶绿素值的位置无关，但可能与局部垂直混合增加导致的高次表层初级生产力区域有关。这些小规模区域代表了新确定的一类空间上重要的位置，可能在浅海的营养耦合中发挥关键作用。这种次表层热点可能代表了大多数捕食者-猎物相互作用发生的有限位置，尽管只占海洋环境的一小部分。
The foraging habitats of 7 species of marine apex predators were observed simultane- ously in a shallow sea, with continuous measurements taken of the detailed bio-physical water column characteristics to determine habitat preferences. We found the occurrence of small-scale 'hotspots', where 50% of all animals were actively foraging in less than 5% of the 1000 km of tran- sects surveyed. By investigating a contrasting range of foraging strategies across a variety of fish- eating seabirds and marine mammals, we determined which habitat characteristics were consistently important across species. A static habitat variable, tidal stratification, log10(h/U 3 ) (h = water depth, U = tidal current amplitude), was found to be the best indicator of the probability of presence and abundance of individual species. All 7 mobile top-predators preferentially foraged within habitats with small-scale (2 to 10 km) patches having (1) high concentrations of chlorophyll in the sub-surface chlorophyll maximum (CHLmax) and (2) high variance in bottom topography, with different species preferring to forage in different locations within these habitats. Patchiness of CHLmax was not associ- ated with the locations of strong horizontal temperature gradients (fronts) or high surface chlorophyll values, but instead may be related to areas of high sub-surface primary production due to locally increased vertical mixing. These small-scale areas represent a newly identified class of spatially important location that may play a critical role within the trophic coupling of shallow seas. Such sub- surface hotspots may represent the limited locations where the majority of predator-prey interactions occur, despite making up only a small percentage of the marine environment.