Threats to the Coast
The entire Bahamas is considered a coastal zone. The health of our marine and coastal environment has direct impacts on the environmental, social and economic well-being of every Bahamian. In April of 2008 we are focusing our attention on how humans impact our coastal environment (threats to the coastal zone), how the impact of coastal degradation affects all Bahamians and visitors to The Bahamas, and what we can do to combat these threats.
Our coastal zone is made up of several different habitats. These include:
- Coral reefs
- Mangroves and wetlands
- Sandy beaches, rocks, low cliffs, bays
- Dune systems
- Sea grass beds
Marine Pollution is caused by anything that we throw into or allow to seep into the sea which can result in harm to the marine environment, marine life or both. In many instances marine pollution also can cause harm to people through either their use of the water such as swimming in contaminated water or by eating the meat of contaminated marine life such as fish and conch.
Sources of marine pollution include the carrying of nutrients such as fertilizers, sewerage, oil and other chemicals by rain water or rivers into the sea, the seepage of sewerage from sewer lines and septic tanks near the coasts into the sea, the throwing of garbage such as cans, plastics, bottles and other items into the sea and the escape of foreign plants and animals transported by visiting vessels and cargo ships into local waters. Excess fertilizers and pesticides from agriculture and golf courses etc, causes serious damage in the marine environment. Fertilizers cause algae, and seaweed to grow over the coral reefs, and block the light that the coral needs to grow. Sediments running into the ocean from coastal developments can smother the coral reefs, killing the coral polyps that build the reefs.
Algal and bacterial blooms from excess nutrients in the water many lead to fish kills, health problems associated by man eating the meat of infected fish and conch (conch poisoning) and health risks for persons swimming in contaminated waters.
Fish, birds and turtles can die when they eat or get entangled in plastic products. Many marine creatures can die when they come into contact with oil in the marine environment.
Climate change has been called the most pervasive and truly global of all issues affecting humanity. The world is now concerned with increasing belief and apprehension that the pattern of global climate is being altered by man’s own actions.
Studies have found that small island developing states such as The Bahamas are the most vulnerable to climate change. The major sector that will be impacted is the coastal area, an area that is crucial to the social and economic well-being of our people. The entire Bahamas is a coastal zone; climate change is an issue that will affect us all.
Our coastal and marine resources help shape our nations character and its distinctive personality, and are among the world’s most treasured but least understood wealth.
Changes in weather patterns such as more severe droughts and floods, higher rainfall intensity, more frequent and intense tropical cyclones and accelerated sea level rise could result in the increased erosion of shores and associated habitat and put some ecosystems at risk, including saltwater marshes, coastal wetlands and coral reefs. Other critical coastal resources, such as mangroves and sea-grass beds are also at risk from climate change impacts but are more threatened by human activities.
A rise in sea level or changes in storms or storm surges will increase salinity of freshwater aquifers, alter tidal ranges in bays and produce chemical contamination in coastal areas.
Changes in these ecosystems will have major negative effects on tourism, freshwater supplies, fisheries, and biodiversity that could make coastal impacts an important economic concern.
The Bahamas is fortunate in that it has extensive clear and pristine shallow water banks near to and in the tropics. This makes the Bahamas an ideal place for a variety of fishable resources to thrive. In addition to The Bahamas having tremendously productive waters it has a relatively small population which has to travel a great distance to access much of the fishable resources. All of these factors combined have allowed The Bahamas to enjoy relatively consistent large landings year after year.
However, The Bahamas is not immune to overfishing. Any longtime fisher would say that one now has to travel much further and fish longer to obtain commercial quantities of many fished resources. Indeed localized depletion of fished resources is quite evident near large population centers. There are also indications that The Bahamas is headed for trouble on a larger scale with regards to some of its major fisheries such as crawfish, conch and Nassau grouper.
With regards to crawfish, the last study that is believed to accurately assess lobster stocks was completed in 2002 and was based on historic data up to the 2000-2001 season. This study showed that the lobster fishery was approaching full exploitation. In 2004 a study was completed that showed that fishing mortality has risen since the 2000-2001 season. The 2004 study was unable to verify whether the fishery is overfished, however, based on the 2002 findings one can deduce that the fishery is even nearer to full exploitation or overexploited.
With regards to the conch fishery a study completed in 2000 and based on data from 1996-1999 showed that on major conch fishing grounds there was relatively good overall biomass of conchs. However the study cited the rampant harvesting of juveniles as a cause for concern but was unable to quantify the effect of these illegal harvests. In some parts of The Bahamas 75% of the conch that are harvested are juveniles. Harvesting of juveniles continues to take place and basic fisheries science tells us that the consistent harvesting of too many juveniles from any fishery is fatal to that fishery.
The Bahamas is one of very few places to enjoy a commercially viable Nassau Grouper fishery. The exact status of the Nassau grouper fishery is unknown but a precautionary approach is needed here. If The Bahamas continues to allow fishing of Nassau Grouper at its spawning aggregation sites the commercial fishery will disappear just like what has been observed in all other countries that allowed this practice to proceed unchecked.
As mentioned earlier, The Bahamas is blessed in terms of the extensiveness and productivity of its fishing grounds. However, the vastness and interspersed nature of these fishing grounds make them that much harder to monitor, assess and control. These factors combined with a lack of resources have left the status of Bahamian fisheries largely unknown from a scientific point of view.
Overfishing does not just affect the fish populations on the reef; the health of the entire coral reef depends on the delicate balance between all the creatures that live make up the reef. Removing the fish from a reef can disrupt the balance and cause reef health to decline.
The Bahamas has embarked on an initiative to establish a network of marine reserves. These reserves will act as replenishment zones for our commercially important species, and they will provide numerous other benefits also. Big fish that are protected within marine reserves are able to produce many more offspring that can benefit fishermen outside the borders of the marine reserves. Marine Reserves function as an insurance policy for our oceans, that will help ensure that we have fish now and for generations to come.
Invasive plants out-compete local vegetation and contribute to coastal erosion. Invasive animals such as feral cats, rats, possums, hogs, goats, damage native plant and animal populations by eating birds and bird eggs.
Degraded ecosystems are prime habitat for colonization by invasive plant species. These plants, which are not native to The Bahamas, thrive in areas that have sustained damage, where soils have been eroded. A prime example of an invasive plant species which takes over damaged areas and is found in coastal environments is the Casuarina equisetifolia or Australian pine.
The Casuarina is thought by many to be native to The Bahamas, but it is not. It was imported into this country in the 1920s to be used as a hedge tree. When hedges were not maintained, the trees grew out of control and have taken over many landscapes. Casuarinas are invasive because they create monocultures or areas where only Casuarina trees exist. The Casuarina releases toxins into the soil which prevent other tree species from growing next to them. If you look around this country and see these trees, they usually exist in large patches that spread year by year. Their spread means that native plants and trees are lost as well as any native animals and birds that depend on these plants and trees for food and shelter.
Casuarinas are also invasive because they are not suited to the Bahamian environment. They have very shallow root systems and are one of the first trees to topple in hurricane force winds. This can cause damage to power lines, homes and roads. In coastal areas, they destroy beaches. Again, because of their shallow root systems, they fail to trap the sand on the beach. The sand is instead blown off the beaches. One only needs to drive past Saunders Beach in New Providence to see how that beach has been eroded by the Casuarina trees that line it. If this beach were planted with native coastal species such as Seagrape, Cocoplum and Sea Oats, the beach would be stabilized and sand would not be constantly blown into the road.
Studies have shown that islands, like those of The Bahamas, are especially vulnerable to invasions. Island species often have small populations and are unique when compared to continental species due to the isolation of islands throughout prehistoric times. This isolation has been provided by the natural barriers of oceans, mountains, rivers and deserts that have enabled these unique species and ecosystems to evolve. Most island species are ill-equipped to defend against aggressive invading species, like the Casuarina, and fare poorly in the face of competitors, predators, pathogens and parasites from other areas.
Human decisions and human activities affect the introduction and spread of invasive species. Our decision and activities also affect the resilience of ecosystems and the possibility of timely policy responses to deal with invasions. If policy responses are slow, the risk of invasive species becoming established is increased and the success of preventive or control measures is negatively affected. Bahamian biodiversity and ecosystems will not survive if decision-makers fail to address this issue and if Bahamians fail to act.
Any meaningful prevention and control strategy has a cost. Given budget constraints, any decision-making on what measures to apply will inevitably involve setting priorities and accepting trade-offs. In consequence, the determination of costs and benefits of invasive alien species control and the related options for prevention, control and management becomes vital.
Habitat Destruction is a major issue affecting our coastal zone in The Bahamas. Many plant and animal life depend on coastal habitats for their nutrition and shelter. Coastal habitats may include wetlands, seagrass, coral reefs, and sand dunes. The destruction of such habitats is a major cause leading to the decline of coastal species.
Habitat destruction is usually attributed to habitat modification due to urbanization, erosion and coastal degradation, caused by human activities and natural disasters. One of the major factors contributing to habitat destruction is coastal development.
Development activities such as the non-observance of setbacks and building on sand dunes, filling in wetlands, clearing existing vegetation, cutting and dredging mangroves for port facilities, resort developments, landfills, agriculture and housing for a growing population, cause significant damage and loss to ecosystems and its species, which it supports. In addition to the destruction of the habitats of the many animal species that depend on these environs, the economic impact is also significant.
Casuarinas are also invasive because they are not suited to the Bahamian environment. They have very shallow root systems and are one of the first trees to topple in hurricane force winds. This can cause damage to power lines, homes and roads. In coastal areas, they destroy beaches. Again, because of their shallow root systems, they fail to trap the sand on the beach. The sand is instead blown off the beaches. One only needs to drive past Saunders Beach in New Providence to see how that beach has been eroded by the Casuarina trees that line it. If this beach were planted with native coastal species such as Seagrape, Cocoplum and Sea Oats, the beach would be stabilized and sand would not be constantly blown into the road.
Coastal habitats such as wetlands, mangroves and coral reefs are economically important to commercial fishermen, and recreational tourism as it provides economies like The Bahamas with millions of dollars annually. Mangroves provide protected nursery areas for fish, lobsters, crabs and many other marine organisms of commercial and ecological importance. The trees also provide a food web to support snapper, bonefish, jack as well as other commercial fisheries. Similarly coral reefs provide habitat for rare and diverse fish and plant species. Annually, thousands of people visit The Bahamas to dive on the reefs and surrounding environments. These coastal habitats are very important to be preserved and not destroyed.