Feeding in Daphnia galeata on Oscillatoria limnetica and on Detritus Derived from It
Feeding in Daphnia galeata on Oscillatoria limnetica and on Detritus Derived from It
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帽状水蚤以湖边颤藻及其碎屑为食
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
E. Donk
中科院分区：
文献类型：
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作者：
R. D. Gulati;M. Bronkhorst;E. Donk
这些细丝。将两种食物以不同比例混合，测量水蚤的食物摄入量和食物掺入率。这项研究的主要发现是，较短的颤藻丝上的水蚤的特定清除率显着高于较长的丝，换句话说，较短的颤藻丝上的特定重量摄入率高于分批培养的较长的丝上的重量特定摄入率。颤藻丝越长，越容易结块，因此在食物收集和摄入过程中更容易被水蚤排斥。相比之下，较短的细丝显然不易结块，因此，与较长的细丝相比，水蚤的清除率更高。用双标记（ 14 C 和 32 P）较短的丝喂养水蚤表明，较短的颤藻丝的同化效率通常对 P 高于对 C，这可能是因为颤藻的 C/P 比率较高。水蚤（大小为 0.75-1.85 毫米）以死（碎屑）颤藻丝为食，明显优于以活颤藻丝为食，即使食物中碎屑的相对比例仅为活颤藻丝的四分之一左右。正如切森选择性系数 a 所示，这种对碎屑而非活颤藻的偏好，显然是一个被动过程，而不是主动食物选择的情况。这种以碎屑为食的“选择性”显然是由于对活丝的排斥力比对碎屑丝的排斥力相对更大而促进的。在非常高的食物浓度（15-25 mg C l ‐1）下，活颤藻丝的比例比碎屑大 2 至 2.5 倍，随着水蚤体型的增加，摄入率的增加比例低于根据这些动物的长度和体重之间的异速生长关系所预期的比例。这意味着体型较大的动物的振荡丝对食物收集和摄入过程的干扰作用更大。
these filaments. The two food types were mixed in different proportions, and both the food ingestion and food incorporation rates by daphnids were measured. The main findings of this study were that specific clearance rates of Daphnia on shorter Oscillatoria filaments were significantly higher than on the longer filaments, in other words the weight-specific ingestion rates were higher on the shorter Oscillatoria filaments than on the longer filaments from the batch cultures. The longer Oscillatoria filaments are more likely to clump and, therefore, are more liable to be rejected by Daphnia during the food collection and ingestion processes. The shorter filaments, in comparison, are apparently less prone to clumping and, therefore, are cleared by the daphnids at higher rates than the longer filaments. Feeding the daphnids on double-labelled ( 14 C and 32 P) shorter filaments revealed that the assimilation efficiency of shorter Oscillatoria filaments was generally higher for P than for C, probably because of a high C/P ratio of Oscillatoria. Daphnia (0.75‐1.85 mm in size) fed significantly better on dead (detritus) Oscillatoria filaments than on live Oscillatoria filaments, even if the relative proportion of detritus in the food was only about one-quarter that of the live filaments. This preference for detritus over live Oscillatoria, as indicated by Chesson’s selectivity coefficient a, was apparently a passive process, rather than a case of active food selection. This ‘selective’ feeding on detritus was apparently facilitated by the relatively greater rejection of the live filaments than the detrital filaments. At very high food concentrations (15‐25 mg C l ‐1 ), with the share of the live Oscillatoria filaments 2 to 2.5 times greater than that of the detritus, the ingestion rates increased proportionally less with increase in daphnid size than was expected on the basis of the allometric relationship between the length and weight of these animals. This implies that the larger animals had greater interfering effects of the Oscillatoria filaments on the food collection and ingestion processes.