Coastal resources in the Wider Caribbean are under increasing impact from human activity. Some of the causes of this pressure are increasing population growth, development of coastal resources, agriculture, industrialization, and tourism. The overexploitation of fisheries stocks and degradation of critical habitats is also a major concern in many areas. The following section provides a summary of some of the main activities and sources of impact in the coastal areas of the Wider Caribbean.

Residence in the coastal zone

The majority of the population in the Wider Caribbean and worldwide lives on the coasts. The number and location of humans living in the coastal zone have profound effects upon marine and coastal ecosystems. Problems range from sewage and waste disposal to the clearance of mangroves and littoral forest for human habitation. There is also increased pressure on local fisheries and wildlife resources, increased erosion and siltation of coastal habitats, and increased susceptibility to floods, storms, and sea level rise. Ideally, integrated coastal zone management will meet the needs of the human population without damage to the environment.

Tourism

Tourism is considered one of the world’s fastest growing industries. Most of the tourism in the Caribbean is concentrated in coastal areas. Tourism related development impacts on the coastal and marine environments by contributing to the problem of pollution and human sewage and waste disposal. Other detrimental effects include the destruction of mangroves for development, which in turn causes siltation of coastal waters. Oil leaks from boat engines, and physical damage to the reef and seagrass bottoms caused by divers, snorkellers, and boat anchors also have a negative effect. However, tourism is often a major contributor to the local economy, and is based on natural and cultural attractions and resources, where the use of those resources is renewable. Coastal tourism, and especially ecotourism, have the potential of becoming economic incentives to facilitate sustainable development and effective resource management in coastal areas of the Caribbean and elsewhere. A new but integral component to the subprogramme of the Caribbean Environment Programme (CEP) on Specially Protected Areas and Wild Fauna and Flora (SPAW) is the on-going USAID/UNEP Caribbean Environment Network (CEN) Project on promotion of environmentally sound tourism in the Wider Caribbean Region.

Fisheries

The state of the fisheries is intimately linked to the health of the coastal ecosystems. A coral reef showing signs of degradation due to pollution will not support a healthy fishery. The clearance of mangroves removes important nursery areas of many commercially valuable species, which may consequently not survive to see adulthood. The main fisheries products throughout the Wider Caribbean are conch, lobster, reef and pelagic fishes, and invertebrates. There are more than 30 species of commercially important reef fishes throughout the Wider Caribbean. Sportfishing and recreational fishing are becoming important in many areas, often in connection with tourism. Unfortunately, the status of the major commercial fish stocks are, in many cases, not known with certainty because of a lack of historical, systematically collected data on catch and effort. The comprehensiveness of current data collection programs also varies from country to country. Because of this, definitive assessments of numbers and sustainable yields for the various Wider Caribbean fishery resources are not available, although stocks in general are thought to be seriously declining. Management techniques include closed seasons, size and catch limits, and area closures, all of which can have dramatic responses within a fishery. Enforcement of such practices remains a problem in traditionally unmanaged and essentially artisanal fisheries. Management plans and practices need to take into account local customs and traditional conservation methods.

Waste disposal, pollution and oil spills

Pollution is generally considered to include solid and liquid waste, garbage, sewage, industrial and domestic runoff, sediment, chemicals including fertilizers, pesticides and oil. The coastal zone is the ultimate depository of most pollutants, whether they originate from the land or from the sea. Of the land-based sources of pollution, eutrophication from human sewage disposal is a growing problem in the Wider Caribbean, particularly in the vicinity of large coastal cities and harbors. Increased nutrient loading from sewage stimulates algal growth and degrades coral reefs and seagrasses. Fisheries production may also decline, and bacteria in the sewage may pose a threat to human health. Other effects include loss of recreational swimming areas and damage to drinking water supplies. Activities outside of the coastal zone may also have a direct impact on the health of the coastal areas, for example when sedimentation and pollution from forestry and agriculture enter coastal areas via rivers and other waterways. Agricultural pesticides and fertilizers result in changes in the reef and seagrass communities, and may, in high concentrations, cause fish kills in areas of poor water circulation. Sedimentation from land clearance results in increased water turbidity, which in turn decreases the productivity of coral reefs and seagrasses. With high levels of sedimentation, physical smothering of corals, and benthic organisms by sediments and fine silt may take place. Shipping can also be a source of pollution. The transport of potentially hazardous substances, such as oil, fertilizers and insecticides is always a hazardous activity, and there have been several oil spills within the Wider Caribbean region. While the local impact is immediate and obvious, there is little information and few quantified studies on the long-term effects of oil in the coastal zone. Corals do not die from oil remaining on the surface of the water. However, gas exchange between the water and the atmosphere is decreased, with the possible result of oxygen depletion in enclosed bays where surface wave action is minimal. Coral death does result from smothering when submerged oil directly adheres to coral surfaces, and oil slicks affect sea birds and other marine animals. Tar accumulation on beaches reduces tourism potential of coastal areas. With increased shipping activity in the Wider Caribbean, the dumping of garbage and washing of bilges at sea have become serious problems. Garbage dumped in international waters are driven by wind and currents to the shorelines of the Caribbean, causing persistent pollution, which threatens both the tourism and fishing industries, as well as the health of coastal communities. The AMEP (Marine Pollution and Integrated Environmental Management) Subprogramme of the Caribbean Environment Programme deals with the assessment and management of environmental pollution. Read in more detail about land based sources of marine pollution in our Environmental Issues in the Caribbean Section.

Land use practices

The major impact of development on land is excessive sedimentation. Shoreline construction, including harbors, groins, channels, and the removal of beach sand that often goes along with these activities, interferes with natural coastal sediment transport processes. An interruption in this "river of sand" can lead to serious beach erosion, the impacts of which are often seen on beaches downstream of the construction. Sedimentation may lead to the loss of benthic habitats, including coral reefs and seagrasses, and to the consequent decline of commercially important fisheries species. Mangrove clearance for housing and tourism development is a serious problem in many areas of the Caribbean. The clearance of mangroves results in the loss of nursery grounds for many important fisheries species, the destabilization and erosion of the shoreline, and the loss of a natural filtering system for land-based runoff. Beach sand mining is a destructive activity. Although no pollutants are introduced into the marine environment, the results are severe beach erosion and the adding sediment to the water column. The effects can be more widespread when the natural drift of sand along a shoreline is interfered with, and the beaches downstream of this drift will receive a reduced supply of sand.

Global warming and sea level rise

Based on available evidence, the global mean sea levels are thought to have risen by approximately 10-20cm during the last hundred years. The rise in sea level has not been uniform, and large variations exist between localities. Estimates of sea level rise due to current levels of greenhouse gas emissions (WMO-UNEP Intergovernmental Panel on Climate Change) predict an increase of 6 cm/decade (from a low estimate of 3 cm to a high estimate of 10 cm). This would mean an increase in sea level on the order of 20 cm by the year 2030, and approximately 65 cm by the year 2100. There is a lack of long term data on sea levels for the Wider Caribbean region, complicating estimates of future sea level rise. However, the UNEP Task Team of Experts for the Wider Caribbean concludes that a mean sea level rise of 10 cm by the year 2025 might be realistic, although this value should be accepted with some caution. In conjunction with existing shoreline erosion in low-lying areas and island nations, potential effects of sea level rise can include

• More severe and frequent storm damage and flooding
• Inundation, erosion, and recession of barrier beaches and shoreline
• Destruction and drowning of coral reefs and atolls
• Disappearance or redistribution of wetlands and lowlands
• Increased salinity of rivers, bays, and aquifers
• Reduction in biological diversity and possible wildlife extinctions
• Loss of beaches, low islands, and spits
• Loss of coastal structures, both natural and man-made
• Changes in the biophysical and biochemical properties of the coastal zone
• Greater populations at risk from natural disasters in low lying areas and island nations

The extent to which any particular location may be vulnerable to sea level rise depends on such factors as the geological and geomorphological history and character of the area, elevation, ecology, level of human presence, and the value of resources likely to be impacted.

Aquaculture

Aquaculture is a general term referring to the farming of any animal or plant that lives in the water. These organisms can range from unicellular algae to shrimp, clams, lobster, fish and crocodiles to name a few. Mariculture refers specifically to the culture of marine organisms. Aquaculture has generated worldwide interest recently. To some extent the reason for this may be the overexploitation of wild stocks combined with a growing international demand for fish and seafood products. There is a lot of potential for aquaculture in the Caribbean region, with its abundance of long coastlines with protected bays, relatively fertile brackish water estuaries, mangrove swamps, and other wetlands. The tropical climate favors year-round growth. The presence of edible or commercially valuable species of crustaceans, mollusks, fishes, seaweeds, etc. also favors the development of coastal aquaculture. However, aquaculture can cause potentially serious environmental impacts. These include the clearance of mangroves and other coastal vegetation for ponds, declining water quality caused by nutrient enrichment and oxygen depletion of outflowing water, and the introduction of non-native species, which may escape the aquacultural ponds and disrupt natural ecosystem functioning. While aquaculture has great potential for alleviating the pressure on wild stocks, some caution is necessary. Sites and species used in aquaculture should be selected for their suitability in order to minimize impact on the environment.