Agriculture has long been a part of the Caribbean islands and its effects on the reefs are far reaching. Increased runoff from agricultural lands, particularly from cultivated soils and fertilizers, leads to increased levels of nitrogen and phosphorous in the ecosystem. These nutrients resulted in the overgrowth of macroalgae which outcompetes native plants and essentially causes an imbalance in the coral reefs. This leads to die-off of previously thriving coral colonies, reducing the overall diversity of the coral system.
The agricultural runoff also impacts the water quality, leading to higher levels of silt and turbidity in the ocean. Cloudy waters restrict the amount of sun reaching the corals, limiting the amount of photosynthesis that can be conducted by the photosynthetic organisms. This lack of sunlight places coral reefs under immense stress, eventually leading to the death of these fragile organisms.
In addition to the direct effects on the coral reefs, agricultural runoff could lead to an increase in temperature in the surrounding waters. This can result in bleaching events, where coral colonies start to lose color and eventually die as a result of the temporary increase in temperature. With no coral, the underwater ecosystem of the Caribbean islands will be greatly depleted.
Another effect of agricultural activity on Caribbean reefs is the introduction of invasive species into the system. The agricultural runoff helps to introduce and circulate non-native species that often have no natural predators to keep them in check. These species can then take over the reef and compete with other, native species for food, resources and space.
Agricultural pollution isn’t the only source of sediment that can damage coral reefs in the Caribbean. The sedimentation that occurs from beach construction and other human activities, including yacht mooring, can be just as damaging as agricultural runoff. These sediments not only smother coral resource, but also provide a food source for sponges, which are often seen as enemies of coral reefs.
Sewage Pollution
Sewage pollution is one of the greatest contributors to the degradation of Caribbean corals. Sewage pollution releases a combination of nitrates, sulfates, and phosphates that can cause major disruption in coral reef ecology. Algal blooms are likely to occur, leading to a decrease in biodiversity, as well as diminished water clarity. Not only can these pollutants kill off the coral, it can also affect the humans who rely on healthy coral reef ecosystems. Fecal matter from sewage pollution can contain harmful bacteria, heavy metals, and viruses that can lead to the spread of infectious diseases.
Destructive Fishing Practices
Destructive fishing practices have had a major impact on Caribbean coral reef systems. Many fishing practices, such as the use of dynamite and other explosives, can lead to damage through crushing coral colonies and formation of dead zones. In addition, the harvesting of large predatory fish can lead to an increase in the abundance of smaller, more resilient fish species that can out-compete the coral, leading to further degradation. Sedimentation from dredging can also cause considerable damage to coral reefs.
Over-Tourism
Due to their beauty and interesting wildlife, Caribbean reefs are a popular destination for tourists. The presence of these individuals can lead to unintentional damage that can be extremely detrimental to the coral reefs. Activities such as careless snorkelling and diving can have drastic impacts, as touching and standing on the coral can damage them beyond repair. The waste produced by the tourists can also be detrimental, as the accumulation of non-biodegradable materials can lead to decreased water clarity. Pollution from motor boats can also cause disruption, sometimes leading to the death of coral.
Over-Harvesting
The harvesting of coral species can lead to a number of negative effects on Caribbean coral reefs. Over-harvesting of reef fish and invertebrates for the commercial and aquarium trade can lead to a decrease in biodiversity, as well as a decrease in the ability to effectively control populations of species that can have a large impact on coral health and longevity. Additionally, the harvesting of coral itself for the use of jewelry, artifacts, and other consumer goods can lead to a dramatic decrease in the overall health of the coral reef system.
Ocean Acidification
As carbon dioxide accumulates in our atmosphere, it is then picked up and transported to the ocean, leading to a decrease in pH and increased acidification. This can lead to adverse effects, as ocean acidification reduces the ability of corals to build and maintain their structures. As the coral colonies become increasingly more fragile, they become more vulnerable to the other disturbances that may impact their ecosystems, leading to an overall decrease in the overall health of Caribbean coral reefs.
