Forward Richard B
Biol Bull. 1989 Jun;176(3):229-238. doi: 10.2307/1541981.
The ontogeny of behavioral responses of larvae of the crabs Rhithropanopeus harrisii and Neopanope sayi to rates of change in salinity were analyzed with a video system. A salinity increase evoked an ascent in both species. For R. harrisii the threshold rate of increase was 1.1 x 10 ppt s for the first and last zoeal stages and changed little with acclimation salinity. N. sayi larvae were more sensitive, as thresholds were 2.8 x 10 ppt s for Stage I zoeae and 7.0 x 10 ppt s for Stage IV. This difference in sensitivity may relate to the magnitude of salinity gradients in the estuarine/coastal areas inhabited by the larvae. At threshold rates of salinity increase the absolute amount of change before a response was lower for Stage I zoeae (0.09-0.11 ppt) than Stage IV zoeae (0.21-0.29 ppt) for both species. Decreases in salinity did not induce the expected descent response in either species at rates up to 4.7 x 10 ppt s. The different responses in a salinity gradient may have resulted because the rate threshold and absolute amount of change before a response to a salinity increase were below those for a salinity decrease. Considering larval sinking rates and normal environmental salinity gradients, larvae of both species can respond to rates and amounts of salinity increase in their environment. The ascent response may be important for keeping larvae up in the water column and reducing the likelihood that they will encounter the bottom.
利用视频系统分析了哈氏豆蟹（Rhithropanopeus harrisii）和赛氏新豆蟹（Neopanope sayi）幼体行为反应的个体发生与盐度变化率之间的关系。盐度升高会引起这两个物种的幼体上浮。对于哈氏豆蟹来说，在第一和最后一期溞状幼体阶段，盐度升高的阈值速率为1.1×10 ppt/s，并且随驯化盐度变化不大。赛氏新豆蟹幼体更敏感，第一期溞状幼体的阈值为2.8×10 ppt/s，第四期为7.0×10 ppt/s。这种敏感性差异可能与幼体栖息的河口/沿海地区盐度梯度的大小有关。在盐度升高的阈值速率下，两个物种的第一期溞状幼体在做出反应前的绝对变化量（0.09 - 0.11 ppt）低于第四期溞状幼体（0.21 - 0.29 ppt）。在盐度降低速率高达4.7×10 ppt/s时，两个物种均未出现预期的下沉反应。在盐度梯度中的不同反应可能是因为对盐度升高做出反应前的速率阈值和绝对变化量低于盐度降低时的情况。考虑到幼体的下沉速率和正常环境盐度梯度，两个物种的幼体都能对环境中盐度升高的速率和幅度做出反应。上浮反应对于使幼体保持在水柱中并降低它们接触底部的可能性可能很重要。
