Many reports have showed that the transgenic plants have some disadvantages and potential influences on the non-target species, even the higher trophic level organisms, e. g. predators and parasites.

现有一些资料表明：转基因植物对有益生物如天敌尤其是寄生性天敌将产生一些潜在的不利影响。

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。

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沖干扰，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。

The fractions and distribution of bioavailable phosphorus in river sediments were studied in order to identify the trophic level of inflow rivers to the west of Taihu Lake.

为了解太湖入湖河道的营养状况，研究了太湖西部河流沉积物生物利用磷的组成与分布。

The ecosystem appears to be a young weak one caused by overfishing, with small and low-valued fishes dominated and low ecotrophic efficiency for trophic level I.

系统受过度捕捞渔业影响很大，并存在营养级I利用效率低和渔业资源小型化、低值化等不稳定的幼态特征。

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。

The main characteristic of trophic level of each watershed is: The degree of eutrophication is more serious in flood season than in dry reason, in upstream than in downstream along the watershed.

各流域富营养化主要特征是：丰水期比枯水期严重，从上游到下游逐渐加重。

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。

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。