Foraging efficiency and prey selectivity in a visual predator: differential effects of turbid and humic water
Foraging efficiency and prey selectivity in a visual predator: differential effects of turbid and humic water
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DOI：
10.1139/cjfas-2013-0150
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发表时间：
2013-07
影响因子：
2.4
通讯作者：
M. Jönsson;L. Ranåker;P. Nilsson;C. Brönmark
中科院分区：
文献类型：
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作者：
M. Jönsson;L. Ranåker;P. Nilsson;C. Brönmark
捕食者通过捕食对较低的营养水平施加强大的调节力。由于大多数鱼是视觉觅食者，水中的视觉条件可能会改变这一规定的力度。研究了浑浊度和腐殖质水对北方狗鱼(Esox Lucius)对蟑螂(Rutilus Rutilus)摄食效率和猎物选择性的影响。在浑浊和腐殖质的水中，相遇的几率都有所下降，但搜索活动的增加并没有抵消这一点。捕获成功率不受浑浊度的影响，但受到腐殖质水的非线性影响，即在清澈和高度腐殖质的水中捕获成功率较高，而在腐殖质较少的水中捕获成功率较低。在高腐殖度的水中，视线接近梭鱼的打击距离，加上其神秘的颜色，梭鱼可能在猎物发现它之前就发起了攻击，限制了猎物躲避的可能性。清水中猎物对小型猎物的选择性在浑浊水中消失，但在腐殖质水中保持不变。由于其光学性质，浊度通过散射比腐殖质水通过吸收更多地降低视觉信息的质量。我们发现，视觉退化对觅食的影响取决于视觉退化的原因，这在以前的视觉觅食文献中还没有得到承认。(更少)
Predators exert strong regulating forces on lower trophic levels through predation. As most fish are visual foragers, visual conditions in the water may alter the strength of this regulation. We evaluated effects of turbidity and humic water on foraging efficiency and prey-size selectivity in Northern pike (Esox lucius) feeding on roach (Rutilus rutilus). Encounter rates decreased in both turbid and humic water but were not counteracted by increased searching activity. Capture success was unaffected by turbidity but was nonlinearly affected by humic water by being high in clear and highly humic water but low in less humic water. In highly humic water, the visual range approached pike's strike distance and, together with its cryptic colours, pike may have initiated its attack before the prey detected it, limiting the possibility for prey evasive manoeuvres. Prey-size selectivity towards small prey in clear water disappeared in turbid water but was maintained in humic water. Owing to its optical properties, turbidity degrades the quality of the visual information more through scattering than humic water does through absorption. We show that the effect of visual degradation on foraging depends on the cause of visual degradation, which has not previously been acknowledged in the visual foraging literature. (Less)