Issue Guide: Aquaculture and Mangrove Destruction
By Regan Norris & Mandy Cargile 
What is a mangrove?
   Mangroves are one of the rarer of the forest types in the world.  Along tropical and subtropical sheltered coasts, the  mangrove is the most common ecosystem encountered.  Found below the high tide level, mangroves are wetland ecosystems, consisting of plants and animals that are able to survive when the ground is submerged.  Mangroves are classified into two types:      Mangrove forests remain waterlogged throughout the year.  The soils consist of organic ooze with a high sulfur content.  Because of the waterlogged conditions, the soil is also anaerobic, without access to oxygen.  Plants must adapt in special ways to survive this environment.  Prop roots are a common sight among mangroves.  The main body of the tree is suspended above the water, supported by the prop roots.  Small roots known as pneumatophores branch off of the submerged roots and rise to the surface, creating a source of oxygen for the plants in the anaerobic environment.  Fringe mangrove vegetation species have also developed methods to remove salt from their tissues.
     One of the most productive ecosystems in the world, mangrove forests provide many services beyond their intrinsic beauty.  They serve many functions to fisheries, creating shelters for spawning, hatching, and feeding.  Many other wildlife species also call the mangrove forests home.  The shoreline is protected by mangroves, which stabilize the coast and absorb incoming waves.  Water is filtered through the submerged roots as it passes through the mangrove.  Timber has been harvested for many years from the forests.

What is Aquaculture?
     Aquaculture is essentially the farming of aquatic species.  For thousands of years, aquaculture has been used in Asia to provide a food source for many people.  Today aquaculture is an expanding industry, providing an increasing percentage of the annual fish production.  The industry is booming across the world, with particular success in southeast Asian countries, Costa Rica, and the United States.  Shrimp, salmon, tilapia, and several other species are common products of aquaculture.
      Several factors explain the current upward trend aquaculture has experienced:

What is the Problem?
        The problem is that in many areas, mangroves are being converted to fish and shrimp ponds for aquaculture.  This practice has led to the destruction of an enormous amount of the world's mangrove forests in nations such as India, Thailand, Costa Rica, and Ecuador.  Environmentalists argue that the mangroves should be protected, especially considering that mangroves were not abundant to begin with.  When the mangroves are destroyed for aquaculture, the many various services these ecosystems provide are traded for a single service.  Besides killing the mangroves, if not properly sustained, aquaculture can create many more problems for the surrounding environment, including:      Proponents of aquaculture in mangroves maintain that the benefits outweigh the costs.  They argue that the practice creates a vital food source that will become more and more necessary as the catch fisheries continue to be over exploited.  Also noted is that since it often occurs in low-income areas, aquaculture brings much-needed income to the people of the area.
     In rebuttal, defenders of the mangroves point out that in many cases, the owners of the aquaculture farms are foreigners to the country.  The profits made by the farm are subsequently shipped out of the country rather than into the economy of the producing country.  The food produced, like the revenue, is also often shipped out to other countries, leaving the workers and their families struggling to put food on their own tables.  The process of replacing mangrove forests with aquaculture ponds thus presents both environmental and socio-economic difficulties.

What is Being Done?
     Many countries have recognized that their mangrove forests are valuable when kept intact.  In 1971, the Ramsar Convention on Wetlands was held in Ramsar, Iran, where mangroves were included in protection actions agreed upon by several countries.  Several non-government organizations (NGO's) have reached agreements to urge governments to improve their practices to protect mangroves, such as the Choluteca Declaration on Unsustainable Shrimp Aquaculture, signed by 21 NGO's and community organizations from North America, Europe, Asia, and Latin America in October of 1996.  So far, a number of international environmental pacts have been made, but enforcement of these policies is weak, as with any international agreement.
     Some aquaculture companies have recognized the problems the industry creates for mangroves.   ZB Industries argues that mangroves are not even suitable for shrimp farming, due to the high sulfur content of the soils.  As increased knowledge of the situation spreads, more governments and other groups will join in the fight, and hopefully action will be taken.

Who to Contact:
     In order to express your opinion on the subject of the battle between mangroves and aquaculture, please contact:

For More Information:  
The authors are students in H90 "The Science of Biodiversity and Conservation", part of the Campuswide Honors Program at the University of California, Irvine. The instructor is Dr. Peter J. Bryant (, Director of the Interdisciplinary Minor in Global Sustainability 

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