Sanitation and Wastewater Atlas of Africa

3.2 The Concept of Ecosystems Health

among the components of these systems are. A healthy ecosystem is one that remains organized and autonomous over time – one that is stable, sustainable, active, free from ‘distress syndrome’ and resilient to stress (Costanza 2012). In a healthy ecosystem, there is balanced interaction among the various components and the whole natural system functions together to provide the many life- sustaining benefits we receive from nature which contribute to environmental and human health and well-being (Myers et al. 2013). Furthermore, a healthy ecosystem is stable and sustainable in its provision of goods and services used by human societies (Bukhard et al. 2008). It maintains its organizational structure, its vigour of function and resilience under stress and continuously provides quality ecosystem services for present and future generations in perpetuity (Lu et al. 2015). Healthy aquatic ecosystems are characterized by high species diversity and good water and habitat quality, among other aspects. Ecosystem health is usually defined in terms of the non-appearance of pathological signs in a particular natural system. For example, lakes, ponds and rivers are healthy if they show no signs of diseased conditions such as contamination, loss of aquatic species or algal blooms (Rapport et al. 2001). High contamination, low aquatic species diversity, algal blooms due to eutrophication as a consequence of high nutrient input are indications of unhealthy freshwater ecosystems.

A healthy ecosystem is stable and sustainable, and resilient to stress

An ecosystem consists of living organisms (biotic components), including humans interacting with their physical environment (abiotic components), which includes elements such as soil, water, climate and atmosphere (Van Jaarsveld et al. 2005). These biotic and abiotic components interact to form stable systems and are regarded as linked

together through nutrient cycles and energy flows. Such ecosystems include agroecosystems, forest ecosystems, grassland ecosystems and aquatic ecosystems.

The productivity of an ecosystem depends on how organized and coordinated interactions

In a healthy ecosystem the whole natural system functions together to provide the many life sustaining benefits

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SANITATION AND WASTEWATER ATLAS OF AFRICA