Aquatic Ecosystems

Here is some information you might find useful to do your homework. This is a link that you can explore for some information:
http://environment.nationalgeographic.com/environment/freshwater/aquatic-ecosystems/

This video may give you good ideas:
http://www.youtube.com/watch?v=p6udw-6sIOw

Some more information at:
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/Freshwater.html

One more, it has information about marshlands and swamps:
http://www.personal.ceu.hu/students/03/nature_conservation/wwddetail/Types_classif.html

Finally, a video about wetlands:
http://www.youtube.com/watch?v=1lLtfbde16A