The Limits to Copepod Growth: Resolving the Malthusian Dilemma

浮游动物是碳转移到更高营养水平、更深层次的水和沉积物的主要途径。对浮游动物生产量的估计对于理解初级生产量的短期和长期变化如何影响这些碳转移速率至关重要。兰德里、亨特利和洛佩兹博士假设，仅从栖息地的温度就可以很好地预测桡足类的生长。如果这种关系被证明是可靠的，我们将有一个强大的工具来估计浮游动物的产量。然而，这一关系的明显简单性引发了有关浮游生物动力学的重大问题，因为它否认了浮游动物受到食物限制的常见假设。这些来自加州大学和夏威夷大学的研究人员将调查这一论点，即在种群水平上，桡足类的食物限制主要通过死亡率的变化来发挥作用。他们提出，在密度依赖于早期生命阶段死亡率的鱼类种群中，有强有力的证据表明这一点。因此，对于海洋种群来说，马尔萨斯困境的一般解决方案是英年早逝，而不是稍后挨饿。他们将通过以下方式解决这些关键问题：-(1)直接测量各种暖水桡足类物种的世代时间，以填补数据库中的一个关键空白；-(2)对特定大小的捕食压力可以通过提高种群水平的表观发育速度来补偿食物限制增长率的影响这一假设进行了实验测试。

Zooplankton are the major pathway for carbon transfer to higher trophic levels, and to deeper water and the sediments. Estimates of zooplankton production are critical in understanding how short and long term variations in primary production affect these rates of carbon transfer. Drs. Landry, Huntley and Lopez have hypothesized that copepod growth is predictable with first-orderprecision from habitat temperature alone. If this relationship proves to be robust, we will have a powerful tool for estimating zooplankton production. However, the apparent simplicity of this relation raises major issues about plankton dynamics since it denies the usual assumption that zooplankton are food-limited. These investigators from the Universities of California and Hawaii will investigate the thesis that, at the population level, food limitation of copepods operates mainly through changes in mortality rate. They suggest that there is strong evidence for this in fish populations where density dependence operates on the mortality of the early life stages. Thus, the general solution of the Malthusian dilemma for marine populations is to die young rather than starve later. They will address these key questions in the following ways: - (1) Direct measurements of the generation times of a variety of warm-water copepod species, to fill a critical gap in the database; - (2) Experimental testing of the hypothesis that size-specific predation pressure can compensate for the effects of food-limited growth rate by increasing apparent development rate at the population level.