'Novel ecosystem' is a concept which was introduced in the 21st Century to describe ecosystems heavily modified by humans, about 15 years after 'ecohydrology' had been introduced as concept within UNESCO IHP, to facilitate the sustainable management of aquatic ecosystems by humans and about 5 years after the concept of IHP 'Demonstration Sites' had been introduced to promote ecohydrological principles globally. The tropical African Lake Naivasha became a DS initially to demonstrate the importance of papyrus-dominated wetland edges for nutrient and climate control in an aquatic ecosystem driven by regional hydrological instability, but it already represented a ‘novel’ ecosystem.

This paper critically examines the consequences of the aquatic food web restructuring by the major alien species, common carp (Cyprinus carpio L.) – whose arrival is directly an ecological consequence of hydrological instability. Carp were first recorded in Lake Naivasha in 2001 and reached dominance in the commercial fishery by 2003. The costs and benefits of its dominance are shown by comparing aspects of the ecosystem state before and after arrival. These were hypothesized and tested by comparing data in 2012-4 with data gathered in the 1990s using the same methodologies. Carp have filled a previously vacant benthivorous niche. The species achieved moderate density but has not caused ecological disruption. Overall, carp has been a positive contributor to the local community. More intensive management strategies, better post-harvest processing and new marketing techniques need to be developed to enhance financial gain.

“新型生态系统”是 21 世纪引入的一个概念，用于描述被人类严重改变的生态系统，大约在“生态水文学”作为概念被引入联合国教科文组织国际水文计划之后 15 年，以促进人类对水生生态系统的可持续管理，以及在国际水文计划“示范点”概念被引入以在全球推广生态水文原则之后 5 年。热带非洲奈瓦沙湖最初成为 DS，以证明纸莎草占主导地位的湿地边缘在区域水文不稳定驱动的水生生态系统中对养分和气候控制的重要性，但它已经代表了一个“新的”生态系统。

本文批判性地研究了主要外来物种鲤鱼 ( Cyprinus carpioL.) – 其到达直接是水文不稳定的生态后果。鲤鱼于 2001 年在奈瓦沙湖首次被记录，到 2003 年在商业渔业中占据主导地位。通过比较到达前后生态系统状态的各个方面来显示其主导地位的成本和收益。通过将 2012-4 年的数据与 1990 年代使用相同方法收集的数据进行比较，对这些进行了假设和检验。鲤鱼填补了以前空置的底栖生态位。该物种达到了中等密度，但没有造成生态破坏。总体而言，鲤鱼一直为当地社区做出积极贡献。需要开发更密集的管理策略、更好的收获后处理和新的营销技术，以提高财务收益。