Thompson R J
Marine Sciences Research Laboratory, Memorial University of Newfoundland, A1C 5S7, St. John's, Nfld., Canada.
Oecologia. 1983 Jan;56(1):50-57. doi: 10.1007/BF00378216.
Gamete production, somatic growth and reproductive effort were measured in sea urchins maintained on a mixture of kelp and mussel flesh at three ration levels. Urchins on low ration were able to maintain an output of gametes half that of urchins fed ad libitum. This was achieved at the expense of somatic production, which was negative in the low ration groups. Despite the reduction in the output of gametes, reproductive effort was greater in the low ration urchins than in the well fed ones. The lipid content and the energy content were greater in eggs released by urchins fed ad libitum than in eggs produced by urchins at low ration.Several indices of reproductive effort were derived from the data and their advantages and disadvantages evaluated. All showed the same trend towards an increase in reproductive effort as the food supply was depleted. In order to obtain some of these indices, it was necessary to measure oxygen uptake, ammonia excretion, ingestion rate and absorption rate, but a direct partitioning of energy between growth and reproduction was found to be the most ecologically meaningful approach to the problem, and does not require measurement of physiological variates. In situations where growth cannot be measured, however, reproductive effort may be expressed as the production of gametes divided by the energy ingested or absorbed.A shift in the allocation of resources from growth to reproduction is seen as an appropriate response to a depletion of the food supply in an environment in which the duration of adverse conditions cannot be predicted. Under these circumstances, investment in growth may be unprofitable, yet the urchin may retain the capacity to restore the normal energy balance should conditions improve.
在三种投喂水平下，对以海带和贻贝肉混合物饲养的海胆的配子产量、体细胞生长和繁殖投入进行了测量。低投喂水平的海胆能够维持的配子产量是自由摄食海胆的一半。这是以体细胞生长为代价实现的，低投喂水平组的体细胞生长为负。尽管配子产量有所下降，但低投喂水平海胆的繁殖投入高于喂食良好的海胆。自由摄食海胆释放的卵子中的脂质含量和能量含量高于低投喂水平海胆产生的卵子。从数据中得出了几个繁殖投入指标，并对其优缺点进行了评估。所有指标都显示出随着食物供应减少，繁殖投入增加的相同趋势。为了获得其中一些指标，有必要测量氧气摄取量、氨排泄量、摄食率和吸收率，但发现能量在生长和繁殖之间的直接分配是解决该问题最具生态意义的方法，并且不需要测量生理变量。然而，在无法测量生长的情况下，繁殖投入可以表示为配子产量除以摄入或吸收的能量。资源分配从生长向繁殖的转变被视为对食物供应减少的一种适当反应，在这种环境中，不利条件的持续时间无法预测。在这种情况下，对生长的投资可能无利可图，但海胆可能保留在条件改善时恢复正常能量平衡的能力。
