On most understandings of what an ecosystem is, it is a kind of thing that can be literally, not just metaphorically, healthy or unhealthy. Health is best understood as a kind of well-being; a thing’s health is a matter of retaining those structures and functions that are good for it. While it is true both that what’s good for an ecosystem depends on how we define the system and that how we define the system depends on our interests, these facts do not force us to the conclusion that an ecosystem has no good of its own. Ecosystems and persons can have goods of their own in spite of the fact that the schemes we use to categorize them are matters that we decide upon.

18.3 Key Ingredients to Good Decision-making . . . . . . . . . . . . . . . . . . . . 531 18.3.1 Using the Best Available Information on the Sociopolitical Context 18.3.2 Using the Best Available Ecosystem Biophysical Information 18.3.3 Pursuing Efficiency and Effectiveness 18.3.4 Using the Best Available Information on Values 18.3.5 Considering Equity Concerns and Implications 18.3.6 Assigning Clear Accountability and Providing for Monitoring and Evaluation 18.3.7 Considering Vulnerabilities and Risks 18.3.8 Dealing with Uncertainties 18.3.9 Considering Cross-scale Effects

An ecosystem is a community of living organisms in conjunction with the non-living components of their environment, interacting as a system.These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can come in any size but usually encompass specific, limited spaces although some scientists say that the entire planet is an ecosystem.Energy, water, nitrogen and soil minerals are other essential abiotic components of an ecosystem. The energy that flows through ecosystems is obtained primarily from the sun. It generally enters the system through photosynthesis. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system.By breaking down dead organic matter,decomposers release carbon in to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form readily used by plantsand other microbes. Ecosystems are controlled both by external factors such as climate and some internal factors. They control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem.Other external factors include time and potential biota. Ecosystems are subject to disturbances and are in the process of recovering from past disturbances.Ecosystems in similar environments that are located in different parts of the world can have very different characteristics simply because they contain different species. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops.While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Biodiversity affects ecosystem function. Ecosystems provide a variety of goods and services upon which people depend. Classifying ecosystems into ecologicallyhomogeneous units is an important step towards effective ecosystem management, but there is no single, agreed-upon way to do this. AQUATIC ECOSYTEM An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems.

Ecosystem health is a desired endpoint of environmental management and should be a primary design goal for ecological engineering. This paper describes ecosystem health as a comprehensive, multiscale, measure of system vigor, organization and resilience. Ecosystem health is thus closely linked to the idea of sustainability, which implies the ability of the system to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience).