Herbivory in omnivorous fishes: effect of plant secondary metabolites and prey stoichiometry
Herbivory in omnivorous fishes: effect of plant secondary metabolites and prey stoichiometry
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DOI：
10.1111/j.1365-2427.2011.02618.x
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发表时间：
2011-09-01
影响因子：
2.7
通讯作者：
Bakker, Elisabeth S.
中科院分区：
文献类型：
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作者：
Dorenbosch, Martijn;Bakker, Elisabeth S.
1.许多食用淡水水生植物的动物是杂食性的（即，他们的饮食中包括植物和动物）。对于无脊椎杂食性消费者来说，选择水生植物物种部分取决于植物中次级代谢产物的存在、植物碳/营养平衡和/或植物的物理结构。然而，关于水生脊椎动物对水生植物摄食的影响机制还知之甚少.通过3个选择性试验，对杂食性红眼鲷和草食性草鱼的摄食偏好进行了测定。我们测试了（i）是否存在的次生代谢产物和水生植物的化学计量影响水生植物物种选择的鱼类，（ii）的重要性，水生植物的化学计量通过操纵实验和（iii）草食率时，最可口的水生植物是同时提供一个共同的动物猎物。在对5种沉水植物（Callitriche sp.，球形轮藻、伊乐藻、穗花狐尾藻和梳状眼子菜）中，狐尾藻明显被两种鱼消耗最少，这与该水生植物的最高酚浓度密切相关。五种水生植物的摄食量与碳氮比呈显著负相关。消耗量最大的两种水生植物的干物质浓度（DMC）也最低.在第二个选择实验中，C：N比的最少（狐尾藻）和最（眼子菜）可口的植物进行了操作，通过生长的大型植物在施肥和未施肥的条件下，随后喂他们陆克文。降低C：N比可部分缓解陆克文对化学防御狐尾藻的回避作用.第三个选择实验表明，这两种鱼更喜欢动物猎物（片足类钩虾）在最可口的水生植物（眼子菜）同时提供。端足类的C：N比约为水生植物中测得的最低C：N比的一半。在任何实验中，鱼类的摄食量都不能与猎物的C：P或N：P比例明确相关。我们的结论是，杂食性鱼类避免水生植物的化学防御。然而，当这些防御只是轻微的，化学计量（C：N比）结合DMC可能是一个决定因素的脊椎动物兼性食草动物的消费。
1. Many animals that consume freshwater macrophytes are omnivorous (i.e., they include both plant and animal matter in their diet). For invertebrate omnivorous consumers, selection of macrophyte species depends partly on the presence of secondary metabolites in plants, plant carbon/nutrient balances and/or physical structure of plants. However, little is known about the mechanisms influencing consumption of macrophytes in aquatic vertebrates.2. For two fish species, the omnivorous rudd (Scardinius erythrophthalmus) and herbivorous grass carp (Ctenopharyngodon idella), feeding preferences were determined in three choice experiments. We tested (i) whether the presence of secondary metabolites and macrophyte stoichiometry affects macrophyte species selection by fish, (ii) the importance of macrophyte stoichiometry by manipulating the macrophytes experimentally and (iii) the rate of herbivory when the most palatable macrophyte is offered simultaneously with a common animal prey.3. In a choice experiment with five species of submerged macrophytes (Callitriche sp., Chara globularis, Elodea nuttallii, Myriophyllum spicatum and Potamogeton pectinatus), Myriophyllum was clearly consumed least by both fishes, which strongly correlated with the highest phenolic concentration of this macrophyte. Additionally, a significant negative relationship was found between consumption and C : N ratio of the five macrophytes. The two most consumed macrophytes also had the lowest dry matter concentration (DMC).4. In a second choice experiment, the C : N ratio of the least (Myriophyllum) and most (Potamogeton) palatable plants was manipulated by growing the macrophytes under fertilised and unfertilised conditions and subsequently feeding them to rudd. The avoidance of consumption of the chemically defended Myriophyllum by rudd was partly alleviated by the lowered C : N ratio.5. The third choice experiment showed that both fishes preferred animal prey (the amphipod Gammarus pulex) over the most palatable macrophyte (Potamogeton) when offered simultaneously. The C : N ratio of the amphipods was about half that of the lowest C : N ratio measured in the macrophytes. Consumption by the fishes could not clearly be related to C : P or N : P ratios of prey items in any of the experiments.6. We conclude that omnivorous fish avoid macrophytes that are chemically defended. However, when these defences are only minor, stoichiometry (C : N ratio) in combination with DMC may be a determining factor for consumption by vertebrate facultative herbivores.