Size and structure of 'footprints' produced by Daphnia:: impact of animal size and density gradients
Size and structure of 'footprints' produced by Daphnia:: impact of animal size and density gradients
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DOI：
10.1093/plankt/21.3.509
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发表时间：
1999-03-01
影响因子：
2.1
通讯作者：
Strickler, JR
中科院分区：
文献类型：
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作者：
Gries, T;Jöhnk, K;Strickler, JR
密度比周围水体高的水蚤必须将水向下推，以保持它们在水柱中的位置。该游动电流主要是第二天线的运动的结果，并且仅在很小程度上是由于滤波器电流。水蚤下的水结构是非常多变的，这取决于游泳行为。我们集中在跳跃和下沉的行为，其中向下推动的水团形成的尾流，可以被描述为一个蘑菇形的漩涡。该结构的体积随时间线性增加。尾流体积比浮游动物本身大得多，这对于机械感知食肉掠食者的可感知性很重要。在密度梯度为10 kg m（-4）的水中，尾流长度W-L可以用W-L = 1.64（+/- 0.096）x L-1.58（（+/- 0.14））来描述，水蚤L的长度以毫米为单位。5 s后测得的尾流长度在梯度达1 kg m（-4）时保持不变。高于该值时，尾流长度下降，与理论预期值W-L = 10.66（+/- 0.21）x（d rho/dz）（-0.265（+/- 0.010））非常一致。由于内部和种间的“通信”（例如，配偶寻求，浮游植物和细菌之间的营养分区，捕食者回避）可以预期将绑定到尾流的流体动力学特性，不同的尾流形式和大小最有可能有一个重要的影响发出的信息。
Daphnids with higher density than the surrounding water body have to push water downwards to hold their position in the water column. This swimming current is mainly the result of the movement of the second antennae and only to a small extent due to the filter current. The water structures under the Daphnia are very variable depending on the swimming behavior. We focused an the hop and sink behavior, where the downward-pushed water masses form a wake which can be described as a mushroom-shaped vortex. The volume of this structure increases linearly with time. The wake volume is much larger than the zooplankton itself which can be important for the perceptibility by mechanically sensing carnivorous predators. In water with a density gradient of 10 kg m(-4) the wake length W-L can be described by W-L = 1.64 (+/- 0.096) x L-1.58 ((+/- 0.14)) With the length of the Daphnia L in millimeters. The wake length, measured after 5 s, remained constant for gradients up to 1 kg m(-4). Above this value, the wake length declines in good agreement with the value expected from theory with W-L = 10.66 (+/- 0.21) x (d rho/dz)(-0.265 (+/- 0.010)). Since the intra- and inter-specific 'communication' (e.g. mate seeking, nutrient partition between phytoplankton and bacteria, predator avoidance) can be expected to be bound to the hydrodynamic properties of the wakes, different wake forms and sizes most likely have an important impact on the information sent out.