• 50% of the world's wetlands have been lost since 1900.
• 60% of the world's 227 largest rivers are severely fragmented by dams, diversions and canals, leading to the degradation of ecosystems.
• Between 34 and 80 fish species have become extinct since the late 19th century, 6 since 1970.
• In the United States, 120 of 822 freshwater fish species are considered threatened, representing 15% of total fish species.
• At a global level, around 24% of mammals and 12% of birds are classified as threatened.
• 60% of the world's 227 largest rivers are severely fragmented by dams, diversions and canals, leading to the degradation of ecosystems.
• 5 out of 55 rivers in Europe are considered pristine, and only the upper sections of the 14 largest rivers retain 'good ecological status'.
• In Asia, all rivers running through cities are badly polluted.

World Water Assessment Program. 13 March, 2010. http://www.unesco.org/water/wwap/facts_figures/protecting_ecosystems.shtml

Wetlands are areas that are permanently or periodically covered by water. They are very important ecosystems that serve as filters to contaminants and are home to many endangered and threatened plants and animals. Agriculture and urbanization have made wetlands scarce in Illinois and other parts of the world.

There are many differing types of wetlands, and various words are used to describe wetlands including bogs, fens, kettle holes, marshes, muskegs, peatlands, riparian areas and swamps. There exists a plethora of information about wetlands, so narrowing your search to a particular type of wetland or geographical region is more likely to help you find useful information.

There are many Library of Congress subject headings which you may want to use to look for books and journals in the online catalog. You can divide many of these subject headings further by geography and/or a more specific subject