World's lakes are in crisis.

 

In fact, the occurrence and management oflake problems is influenced by three characteristics of lentic water systems – • integrating nature • long water retention time and • complex response dynamic.

Integrating Nature 

 Lakes receive pollutant inputs from diverse sources in various forms from their drainage basins and beyond. The inputs to a lake can exist in the form of 

 • precipitation; flows from rivers and other inflowing channels; heat- and wind-induced energies that cause waves; 

• Thermal energies that affect mixing properties; and 

• Land-based and airborne pollutants and contaminants, nutrients, and organic substances, both living and nonliving matter. 

The integrating nature refers nature refers to the mixing of these in o the mixing of these inputs within a lake so that both resource both resources and problems are disseminated throughout the volume of a lake.

Management Implications Integrating nature

 The integrating nature of a lake means that many lake resources, as well as lake problems, are shared throughout the lake. As a result, it is not sensible to subject different parts of a lake to different management regimes. This is particularly relevant to transboundary lake basins. A related consequence of their integrating nature is that It is difficult to exclude users from accessing a lake’s resources. These properties require lakes and their basins to be subjected to adaptive management, utilizing wide ranging policy instruments.

Long retention time 

• Although Although Lake ecosystems are resilient whenfaced with stress that have existed over evolutionary time scales, they can be extremely extremely vulnerable to “new” stresses, such as the introduction of exotic species. 

• The long water retention time also means that once a lake is degraded, it can aded, it can take a very long time – if ever–for it to recover or be restored. It also leads to lags in ecosystem response hat are poorly  matched to the human management time-scale..

• The relatively long retention time of mostlakes compared to rivers, means that the ”lake time scale” is not equal to the political time scale. There is usually a significant delay between an action (positive and negative) and the change in a lake.

Management Implications long retention time.

 Because the problems can build up  and become noticed slowly, and take  equally as long to be managed, institutions involved in lake basin  management need to be prepared to engage in sustained actions, with long funding commitments. 

Management with a precautionary approach.

Complex response dynamics 

• Means that connections are often indirect and not easy to determine. Changes are often irreversible and dependent on path. This behavioural characteristics apply not only to natural lakes but also to man – made lakes all essential c85omponents to .river basin systems.

Management Implications complex response dynamics

 Complex response dynamics, particularly  in relation to long water retention times, imply that the problems need to be anticipated as far in advance as possible through monitoring, development of indicators and analytical studies, while carrying out scientific explorations to unravel the complex processes  and their implications. • Scientific studies studies may also help develop novel solutions to these problems,

Why lakes? 

Lakes and their surrounding watersheds are unique and valuable ecosystems for both people and nature. Lakes both people and nature. Lakes are critical "storage tanks" for freshwater. More than 90% of all available liquid surfacefreshwater is contained in lakes and reservoirs. Despite their importance, many of the world's lakes are in crisis.