The next best way to quantify the amount of protoplasm in each trophic level is to weigh it.

确定每一个营养阶层原生质总量的第二个好办法是称重。

Producers are often referred to as being in the first trophic level and are called autotrophs by the heterotrophs.

生产者通常被称为第一营养级，被异养称为自养。

The average trophic level of what is being caught is rising — and this in principle should indicate improving ecosystem health.

食物链等级体系中的高等级物种平均捕获率(而捕获正在并将持续进行)处于持续上升态势之中——按照所谓食物链等级理论，这应当意味着海洋生态系统的健康平衡发生了变化。

In chapter 3, in this paper, we investigated a three trophic level food chain system with periodic constant impulsive perturbations for top predator.

第三章将在对顶级捕食者进行脉冲干扰，即周期性的向食物链中投放定量的顶级捕食者的前提下，研究三种群食物链系统的稳定性。

According to the comprehensive trophic level index (TLI), the values of Tangxi reservoir were between 30 and 50. It showed that the reservoir was mesotrophic.

结果表明，汤溪水库综合营养状态指数(TLI)在30 ~ 50之间，属中营养水平。