January 27, 2004
Dams and Fish Life

The most recent public statements by the CFE about plans for Boca del Cerro dam emphasize that the water levels will never rise above the normal high water mark. That is supposed to calm fears of widespread flooding and loss of land. But this unnatural constant high level has its own consequences.

The following article mentions the work of Peter Bayley, who is just finishing a term as visiting Fulbright Scholar in Villahermosa, Mexico. I am looking forward to his findings regarding the centlas of the Usumacinta.

World Conservation 2/99 - Barriers to Diversity (pdf)

Nothing alters a river as much as a dam, and nothing is more destructive of riverine and riparian species.

...What ecologist Peter Bayley terms the "flood pulse advantage" is the main reason for the astonishing diversity and productivity of rivers and floodplains...Annual floods on tropical rivers are estimated to produce fish yields a hundred times that of rivers without floodplains.

...Dams are therefore the main reason why fully one-fifth of the world's 9000 recognized freshwater fish species have become extinct, threatened or endangered in recent years. The percentage rises in countries which have been most heavily dammed.

More on the "flood pulse" can be found in these studies:

Sustaining Freshwater Ecosystems

The Flood Pulse Concept in Wetland Restoration (pdf)

Mekong River Commission - Floods are vital for fisheries - Catch and Culture

The flood pulse also affects plant and tree growth:

International Conference "Tree Rings and People"

And here is an abstract of the paper in which Peter Bailey and others first defined the flood pulse concept:

The flood pulse concept in river-floodplain systems - Abstract (pdf)"

Posted by Dave at January 27, 2004 10:45 PM