The mangrove ecosystem of the Cienaga Grande de Santa Marta (Colombia): Observations on regeneration and trace metals in sediment

Alteration of water flows and consequent hypersalinization caused the death of nearly 70% of mangroves at the Cienaga Grande de Santa Marta, Colombia. Efforts to rehabilitate the ecosystem have been made through the construct ion of freshwater channels. Mangrove recovery was observed along a freshwat er channel and at a small lagoon behind the beach ridge. Factors identified in this study influencing mangrove regeneration are: salinity of surface w ater, duration and height of flooding, leaching property of soils, dispersa l of propagules and presence of fertile trees. Besides mangrove regeneratio n, a notable extension of freshwater plants was observed in the channel. Tr ace metal concentrations in sediments from the Magdalena River and its area of influence were investigated before the complete opening of the first ch annel. A relative comparison indicated that the highest concentrations of C d, Cu, Ni and Zn were above international recommended limits. However, meta l concentrations found in sediments at Clarin Channel did not affect the ma ngrove recovery. (C) 1999 Elsevier Science Ltd. All rights reserved.