Natural and man-induced changes in a tidal channel mangrove system under tropical semiarid climate at the entrance of the Maracaibo lake (Western Venezuela)

Abstract

Cano Paijana is a tidal channel that connected, until recently, theUruba bay at the mouth of the Limon river, to the Gulf of Venezuelanorth of Maracaibo, Venezuela. It separated the Island of San Carlos fromthe mainland. In the last 50 years the channel has been drying out rapidly,to the extent that presently there is no water flow into or from the seathrough its mouth opening on the Gulf of Venezuela. This mouth wascovered by healthy mangroves (mainly Avicennia germinans) until atleast 1952. The two extremes of the Paijana water channel differ radicallytoday. At Uruba bay end the channel is fringed by dense mangrovevegetation dominated by Rhizophora mangle, while at the Gulf ofVenezuela mouth the vegetation cover is mostly constituted by scrubby,scattered trees of Avicennia germinans, xerophytic shrubs acting asdune fixers, and halophytic strand vegetation. The process is the result ofcomplex interaction between: a) high frequency of low-rainfall years; b)high dune activity during dry years c) dam construction on tributaries ofthe Limon river that reduced discharge of fresh water into Uruba bay.