Coprophagy and coprorhexy in the copepods Acartia tonsa and Temora longicornis: clearance rates and feeding behaviour
Coprophagy and coprorhexy in the copepods Acartia tonsa and Temora longicornis: clearance rates and feeding behaviour
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DOI：
10.3354/meps299217
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发表时间：
2005-09
影响因子：
2.5
通讯作者：
L. Poulsen;T. Kiørboe
中科院分区：
文献类型：
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作者：
L. Poulsen;T. Kiørboe
数十年的沉积物捕集器研究表明，浮游动物粪便颗粒在沉积通量中所占的比例远低于从桡足动物的丰度及其预期的粪便颗粒产量中所预期的比例。对此的解释被认为是桡足类动物吞食（摄入）粪便颗粒。我们检测了tonsa和longicora的粪便颗粒清除率和tonsa的摄食行为。tonsa和T. longicors雌性的颗粒清除率相似，但自己的颗粒清除率较低（雌性-1 d -1 11 ~ 22 ml）。我们自己的数据和从文献中编译的观察结果表明，桡足类粪便颗粒清除率随着相对颗粒大小的增加而降低，并且所有物种都可以用一个共同的关系来描述。在tonsa中，替代浮游植物食物的存在增加了颗粒清除率。直接观察表明，这是通过浮游植物对摄食行为的调节作用来实现的。在没有浮游植物的情况下，tonsa是不能动的，但在远处感知到下沉的粪便颗粒。然而，只有一小部分进入探测距离的弹丸引起了攻击。在有浮游植物食物存在的情况下，tonsa切换到悬浮摄食，并遇到所有被摄食流夹带的粪便颗粒。与饲喂方式无关，粪便颗粒在排斥反应中主要通过破碎降解，只有一小部分被实际摄入（5%）。因此，tonsa对粪便颗粒垂直通量的主要影响是通过共降解（破碎）将粪便颗粒变成更小、下沉速度更慢的颗粒。
Decades of sediment trap studies have revealed that zooplankton fecal pellets constitute a much smaller fraction of the sedimentary flux than expected from the abundance of copepods and their anticipated production rates of fecal pellets. The explanation for this is thought to be coprophagy (ingestion) of fecal pellets by copepods. We examined fecal pellet clearance rate of Acar- tia tonsa and Temora longicornis and feeding behaviour of A. tonsa. Pellet clearance rates in A. tonsa and T. longicornis females were similar but low on their own pellets (11 to 22 ml female -1 d -1 ). Our own data together with observations compiled from the literature revealed that copepod fecal pellet clearance rates decrease with increasing relative pellet size and that all species can be described by a common relationship. In A. tonsa, the presence of alternative phytoplankton food increased pellet clearance rate. Direct observations revealed that this was accomplished through the modulating effect of phytoplankton on the feeding behaviour. In the absence of phytoplankton, A. tonsa is non- motile but perceives sinking fecal pellets at distance. However, only a small fraction of the pellets that came within detection distance elicited an attack. In the presence of phytoplankton food, A. tonsa switched to suspension feeding, and all fecal pellets entrained in the feeding current were encoun- tered. Independent of the feeding mode, fecal pellets were mainly degraded by fragmentation dur- ing rejection and only a small fraction was actually ingested (5%). The main impact of A. tonsa on the vertical flux of fecal pellets is therefore through coprorhexy (fragmentation) turning fecal pellets into smaller, slower-sinking particles.