id.41 “An 6oosyetem is commonly defined as a spatial unit of Nature in which living organisms and the non-living environment interact adaptively.” (ENVWA/WP.3/R,7/Rev.l), p. 3, pera. 9. The Expert Group on Environmental Law of the World Commission on Environment and Development, in the comment to Article 3 of it6 Legal principles and recommendations, defines “ecosystems” as “8 ys terns of plants, animals and micro-organisms together with the non-living components of their environment”. m Proationluat-&@& muaLnpmant_LecralP~~8.and.. e.c;QllN@ndatiQnS (1987), pe 45. 1w “Ecosystems approach to water management” (ENVWA/WP. 3/R.7/Rev. l), p. 3, pera, 9. ku/ IRM., para. 11. m/ ufi., para. 9. - 148 -nIntoractions between freshwater ecosystems on the one hand and human activities on the other sre becoming more comples and incompatible as socio-economic development proceeds. Water basin development activities can have nel,lative impacts too, leading to unsustainable development, particularly where these water resources are shared by two or more States .I’ AI.81 The obligation to protect and preserve the ecosystems of intornationel watercourss(s] [tiystems] addresses this problem, which is already acute in some parts of the world end which will become SO in others as increasing human populations place ever greater domends on finite water resources. A&V (3) The obligation to “protect” the ecosystems of international watercourse[s] [systems] is a specific application of the requirement contained in article 6 that watsrcourse States are to use and develop an international watercourse [syotern) in a manner that is consistent with adequate protection thereof, LtQ/ In essence, it requires that watercourse States shield the ecosystems of international watercourse[s] [eysteme] from harm or damage. It thus includes the duty to protect those ecosystems from a signif icant threat of harm. ;L5.1/ The obligation to “preserve” the ecosystems of international watercourse[s] [syo\.ems], while similar to that of protection, applies in pertlicular to freshwater ecosystems that are in a
**Analysis**
The text discusses the concept of ecosystems and the obligation to protect and preserve them, specifically in the context of international watercourses. The text highlights the increasing complexity and incompatibility of human activities with freshwater ecosystems, and the need for watercourse States to use and develop these watercourses in a manner that is consistent with adequate protection of the ecosystems. The focus is on the environmental impact of human activities and the need for conservation and protection of ecosystems.

**Category**
Natural resources and environment, International trade