Further complicating this issue is the need to maintain healthy aquatic ecosystems. 更为复杂的问题在于保持健康的水生生态系统的需要。
The result showed that the pollution of the waterbody exerted agreat disadvantageous effect to the Haihe River ecosystem. 结果表明，水体污染已经对海河水生生态系统产生了明显的有害影响。
