Making the connection
Coral reefs are one of the world’s most productive ecosystems, providing valuable resources including fisheries, coastal protection and tourism income. In order to survive, coral reefs need specific environmental conditions, such as low nutrient and sediment levels. These conditions can easily be altered by the content and quantity of water that flows through watersheds and into coral reef waters. Human activities, including deforestation, agriculture, coastal development and dam construction have altered the natural flow of watersheds, putting coral reefs at risk. In addition, pollutants, such as sewage and chemical fertilizers, make their way to reefs through watersheds, endangering not only coral reefs, but also human health. By effectively managing watersheds, we can protect both the health of coral reefs and the people who depend on them.
Land development alters natural water flows leading to erosion and greater amounts of fresh water, nutrients, and sediments reaching coral reefs. The three largest impacts on reefs from watersheds are agricultural industry inputs, sewage, and sedimentation:
• Ineffective management of agriculture, sewage, and land-use has created excessive loads of sediment and nutrients in the watershed.
• Land alterations, such as deforestation and large-scale agriculture have increased the overall amount of runoff received from the watershed and increased sediment and nutrients levels.
• Dam construction and extraction of water for agriculture have altered river and stream water flows to the ocean and changed levels of sedimentation.
Recovery of coral reefs from pollution is dependent upon many factors such as the nature, intensity, and frequency of the disturbance, as well as the composition of reef species, the availability of species to reproduce, and other environmental variables needed for coral reproduction. Once the watershed is managed properly, it can take years to decades for a reef to recover.
Local Solutions Include:
1. Dispose of sewage and storm water properly. Build and maintain waste water treatment plants and ensure plants are not are overloaded, malfunctioning, or have outfalls that are incorrectly positioned.
2. Establish Marine Protected Areas (MPAs). Coral reef communities that are protected from multiple stresses are more likely to recover faster from any single disturbance.
3. Promote more sustainable land-use practices. Support the implementation of Integrated Coastal Zone Management (ICZM). ICZM is an approach to develop and implement environmentally, culturally, and economically sustainable uses of the coastal zone. For more information see ICRAN Issue Brief: Coral Reefs, Coastal Development, and Coastal Zone Management.
International Policies & Agreements Supporting Management of Watersheds and Reefs:
Policies listed below support the implementation of ICZM and watershed management.
• The Montreal Declaration on the Protection of Marine Environment from Land-based Activities
• The Convention on Biological Diversity
• Agenda 21, United Nations Conference on Environment and Development (UNCED): Earth Summit
• The Convention on Wetlands, otherwise known as the Ramsar Convention
International Policies and Agreements Supporting Management of Watersheds and Reefs:
• Cartagena Convention for the Protection and Development of the Marine Environment
• Jakarta mandate on the “Conservation and Sustainable Use of Marine and Coastal Biological Diversity”
• Barbados Programme of Action from the Global Conference on the Sustainable Development of
Small Island Developing States
• The Protocol for Specially Protected Areas and Wildlife (SPAW)
|Inputs from watersheds into coral reef waters||Benefits to the reef by reducing input||Benefits to humans by reducing input|
|Agricultural Industry Inputs
Water discharged from agricultural sites
contains herbicides, fungicides, pesticides,
and nutrient fertilizers. Nutrient levels and
pesticide concentrations in watersheds
can be greatly elevated from unmanaged
agricultural wastewater. Nitrogen and
phosphorus from fertilizers are the main
nutrients deposited in waterways.
| 1. Reduces excess nutrients and
prevents algae from growing over
corals and blocking sunlight.
2. Decreases risk of toxic algal
3. Reduces threats from pesticides,
herbicides, and fungicides that
accumulate and weaken immune
systems in corals and other reef
animals and plants.
4. Protects biodiversity
| 1. Reduces cancer risk from
nitrates and pesticides,
herbicides, and fungicides in
contaminated drinking water.
2. Increases availability of other
such as fresh water
Sewage is made up from solid and liquid
human waste, which contains nutrients,
bacteria and viruses. Sewage enters reef
systems from rivers and outfall pipes (point
source) as well as runoff and ground water
(non-point source). Sewage discharged
into waterways is often minimally or not
| 1. Decreases diseases
associated with contamination
of marine life from synthetic
2. Decreases coral disease caused
by fecal bacteria, such as White
3. Protects biodiversity.
4. Reduces water cloudiness,
which improves coral feeding,
reproduction, and overall health.
| 1. Decreases infectious diseases
related to bathing and
swimming in coastal waters
contaminated with sewage
2. Decreases infectious
diseases associated with
the consumption of seafood
harvested from coastal waters.
3. Improves quality of drinking
water by reducing the presence
of fecal coliform bacteria.