Coastal engineering and large-scale mangrove destruction in Guyana, South America: Averting an environmental catastrophe in the making

This short communication highlights potential destabilisation of the muddy coast of Guyana, South America, caused by large-scale mangrove destruction. The stability of the coast of Guyana, which is part of one of the world’s most extensive mangrove coasts, depends on large mud banks migrating alongshore from the mouth of the Amazon River and on mangrove colonisation of these banks. Under the pressures of economic development, the coastal zone of Guyana is progressively being transformed into agricultural land and aquaculture estates, protected by coastal dikes. These hard coastal defence structures, constructed in recent years, are less effective in dissipating wave energy than mud banks. They also hinder the various processes involved in the consolidation and subsequent mangrove colonisation of these banks, notably by enclosing mature mangrove forests and preventing propagule transport from these forests to mud banks. If unchecked, the progressive breakdown in the mud-bank and associated mangrove system that has led to progradation of the coastal plain of Guyana over the last 5000 years will result in large-scale coastal erosion that can only be countered by further engineering structures at prohibitive costs. The only coastal defence strategy, sound and viable over the long term, with regards to both environmental conservation and cost, consists in restoring a dynamic mud-bank and mangrove system on this wave-exposed coast.