Watersheds indicators

Hall Jr., L.W., R.D. Anderson, J. Kilian, and D.P. Tierney (1999). Concurrent exposure assessments of atrazine and metolachlor in the mainstem, major tributaries and small streams of the Chesapeake Bay watershed Indicators of ecological risk. Environ. Monit. Assess., 59 155-190. 

Watersheds integrate the signal of atmospheric deposition and define the interface between the atmosphere and many aquatic ecosystems. The primary indicators... 

This book has identified the most useful indicators of environmental changes in mercury contamination in 4 compartments of the environment 1) airsheds and watersheds, 2) water and sediment, 3) aquatic organisms (with emphasis on freshwater ecosystems), and 4) wildlife that live in freshwater, terrestrial, and/or coastal ecosystems. The indicators identified in this book are wide-ranging and involve measurements made at several different scales of time and space. The authors believe that these indicators will provide the best information to policymakers, as well as other stakeholders, as to whether environmental concentrations are changing (A indicators) and what the reasons for those changes might be (B indicators). 

Fig. 1 Map of the Ebro River watershed showing the main cities and tributaries. The position of the Ebro with respect to the Iberian Peninsula is also indicated...

The Ebro watershed has a large surface area (85,000 km2) and a complex drainage network (a total of 347 streams). The Ebro is a relatively well known river from the point of view of the biological communities composition. Studies exist on the aquatic fauna and flora [3]. However, the functional activity of the river is largely unknown, mostly because of its complexity and associated technical difficulties. This chapter provides a state-of-the art of the who is who in the biological communities in the river, as well as considerations about the threats imposed by habitat deterioration, eutrophication, pollution and species invasions, and indicates the current gaps that still exist in the knowledge of the river. 

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