Ecological indicators for coastal and estuarine environmental assessment

Ecological indicators address ecosystems structure and/or function and are commonly used to provide synoptic information about their state. Through quantitative representations of either the forces that steer ecosystems, responses to forcing functions, or of previous, current, or future states of an ecosystem, indicators are expected to reveal conditions and trends that will help in development planning and decision making processes. Ecological indicators combine numerous environmental factors in a single value, which may be useful in terms of management and in the development of ecological concepts, compliant with the general public's understanding. Nevertheless, their application is not exempt of criticisms, the first of which is that aggregation results in an oversimplification of the ecosystem under observation. Ecological indicators must therefore be handled following the right criteria and in situations that are consistent with its intended use and scope, otherwise they may drive to confusing interpretations of data. Despite the evident convergence of ideas between different authors, it is clear that what a good indicator should be does not gather unanimity of opinions. The present book provides an updated revision and examples of application of indicators available to assess the status of coastal and transitional ecosystems. Moreover, a decision tree to be used as guidance in selecting which indicators should be applied in any particular case involving benthic fauna is proposed. Finally, differences in performance of various indicators are illustrated through a series of case studies on marine and estuarine ecosystems.