Publishing 12 times a year. ISSN 0006-3568.
A natural waterfall, such as this one on Río Lajas in the Grande de Añasco river basin in Puerto Rico, may limit diadromous fishes' dispersal and access to habitat. Dams and other artificial obstacles may do likewise, and in the article that begins on page 176, Thomas J. Kwak and Patrick B. Cooney describe their study of the critical influence of both natural and artificial barriers in structuring the fish assemblages of streams in Puerto Rico. Photograph: Patrick B. Cooney.
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