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The Great Morass

The Great Morass measures roughly 5660 acres (229 square kilometers), reaching depths of over 12m. It runs parallel to Negril's beaches, encompassing mangroves, swamps and marshlands dominated by sawgrass (Cladium jamaicense).


The Great Morass, Negril, highlighting its canalisation. Reprinted from Ambio (1991). Retrieved from Copyright 2016 by ITHAKA.

Since its canalization that transformed some parts into agricultural land, the Great Morass' peat wetlands drain into the sea. Nutrient and peat laden river water flows freely into the ocean while simultaneously, seawater incursion and seasonal drought impact the morass. Also, dykes all along the canals restrict mangrove growth. The Morass is fragmented on all sides: to the north by the North Control Canal, to the South by the South Control Canal, to the East by the North/South Canal and to the west by the Norman Manley Boulevard. Dykes all along the canals restrict mangrove growth. Impounding wetlands precludes their contribution to, among many things, fish habitat, water and sediment processes and wave control, from the barrier beach system. South Negril River was just a trickle of water before being canalized. The river’s mouth, when left alone, eventually forms a shoal.

The eroded soil of the morass hinders mangrove recolonization. Parts of the lowland and swamp area are overtaken by sawgrass (Cladium), cattails (Typha), beak-sedge (Rhynchospora) and ferns (Acrostichum). Restoring the wetland habitat of the Great Morass implies degrading canal banks and reinstating the wetlands’ natural drainage system. Tidal flow maintains not only the movement of detritus and input of dissolved oxygen in the barrier beach system, but also the entering flood tides and exiting ebb tides that allow organisms to alternate between habitats. Restoring hydraulics in respect of the tolerance of mangroves to tidal inundation enables natural recolonization and, if one method has to be chosen over the other, more successful than planting alone.

Satellite image of the coast and the wetlands of Negril, Jamaica. Reprinted from Google Earth, 2016. Retrieved from,-78.3319422,9699m/data=!3m1!1e3. Copyright (2016) by DigitalGloge, CNES/Astrium, Data SIO, NOAA, US Navy, NGA, GEBCO & Google.

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