Reefs are rich ecosystems that are coming under an increasing amount of strain from human exploitation. Humans have developed a general attitude that most ecosystems exist to provide us with something. Reefs are no exception to this and are suffering directly and indirectly from the increasing pressure of mans' resource exploitation. Unfortunately strategies for managing the exploitation of reef ecosystems have too often been aimed at short term gain, ignoring the long-term consequences of human activities. In order to maintain a sustainable usable yield from the reef and associated ecosystems, it is important to realize that reefs are not an infinite resource. They require good long term management and protection from over exploitation and degradation. Without these measures we will surely see, too late, that reefs are in fact finite resources.
Fishing is one of our most important and valuable marine industries. However there are a number of growing concerns about problems with the management of fisheries resources and fishing methods which are placing excessive strain on the oceans ecosystems, including reefs, which are major fishery resources. Some of these concerns are: (1) The increased capacity to exploit fish stocks due to increased demand and effort (time at sea, number of boats) and improvements in fishing technology. (2) Significant declines in fish stocks seen globally. (3) The destruction or alteration of spawning and nursery grounds through fishing practices or coastal development. (4) The lack of field monitoring for some fisheries and lack of information on the status of many species fished. (5) The death of many non-commercial species or 'by-catch' in some fishing fleets, and the impacts on threatened species such as turtles and dugongs, some sharks and sea lions. (6) The removal of long lived, slow growing species such as Coral Trout and Blue Groper by spear fishing and recreational fishing. (7) Changes in the structure of fish populations by reduction in the numbers of grazing fish or predator species may adversely affect the ecology of marine habitats, and there is a need for more knowledge in this area. (8) The impacts of aquaculture on marine habitats and the exclusion of fishers and other users from areas where aquaculture is developed. (9) Unsound fishing methods - trawling is regarded as one of the most environmentally dubious fishing methods. It is estimated that 70% of the Great Barrier Reef lagoon is trawled at least once a year, impacting on the bottom living (benthic) communities. (10) The impacts of recreational fishing have been largely un-monitored, but studies suggest that the recreational catch for some species is substantially greater than the commercial catch, accounting for up to 90% of some estuarine fish and more than 50% of all fish caught. For example, on the east and south coast of Australia, it is estimated that the recreational catch for some species is as much, or more than the commercial catch. Existing fisheries management measures for recreational fishing appear to be quite inadequate for current levels of fishing activity.
Over fishing and Collecting
Reefs have complex food webs, and reef ecosystems may be affected both directly and indirectly. Fishing for a particular species obviously affects that species directly, but it also affects the animals and/or plants in both directions along the food chain - the predators and the prey of the fish will both be affected, and changes to them will also affect their predators and prey, and so on. For example, reductions in stocks of herbivorous fish on coral reefs from over fishing mean that less algae are being eaten, and this may mean that algae overgrow the normal reef animals and change the whole system. Reefs are also threatened indirectly by fishing which occurs in the open ocean around reefs as well. This can affect the numbers of animals on the reef that have a larval dispersal stage. For example, it is thought that over fishing may reduce predation on Crown of Thorns Starfish larvae, contributing to outbreaks of these coral-eating pests on coral reefs. Another threat to reef ecosystems is “bycatch“. Healthy seafloor communities are crucial to maintaining biodiversity in the ocean, yet unregulated trawlers drag huge heavy nets, chains and gear along the bottom of the ocean floor scraping away all life forms and habitat, and destroying vast ecosystems. Ocean bottom inhabitants and marine ecosystems are ripped up, crushed, exposed, and buried, leaving the seafloor looking like an underwater desert. What took centuries, and in some areas thousands of years, to develop is swept up and totally destroyed by one pass of a fishing trawler. Sea corals provide critical habitat for fish and other organisms in marine ecosystems. As much as 70 percent of sea life scraped up in the nets is not "usable" or sought by the trawlers. These dead and dying "non-target" fish and marine animals are tossed back into the ocean. This is referred to as "bycatch," and "trawler trash." Bottom trawling is believed to have caused the decline of major fisheries. Trawling the ocean bottom is like vacuuming up all life and the habitat which supports life under water. According to the Food and Agriculture Organization of the U.N., indiscriminate fishing practices kill and waste between 18 and 40 million metric tons of "unwanted" fish, seabirds, sea turtles, marine mammals, and other ocean life annually - fully one-third of the world catch. (1)
In many parts of the world, especially Asian and South-West Pacific reefs, destructive fishing methods, such as cyanide, are often used to try and obtain fish for western aquarium businesses and restaurants in Asia. Cyanide is often used to kill or stun fish that hide in caves when chased. The reef is often then torn apart to get to the dead or paralyzed fish in its hole. The monetary incentive to get every last fish is too hard for most poor fishermen to resist. Use of dynamite to stun fish is one of the most destructive activities of man on the reef, resulting in complete destruction of areas of the reef and the death of many other animals than the fish that is the target. In western countries, collecting by the general public has the potential to harm reef populations because people are often uneducated about the laws that limit the size and sex of species that may be collected. This is important because it is not good to take young animals that have not had a chance to grow and reproduce, or to take females which are important breeding stock for the species. On many coral reefs throughout the world, collection of tropical fish for aquariums has seriously depleted stocks of these fish on the reef.
Tourism
The incredible diversity of life in the ocean means that they are very attractive to scuba divers, snorkellers and reef walkers. This creates a physical threat to the actual reef structure as 'reef walking' breaks the Calcium skeletons of the coral and decreases the amount of areas that are good for the animals and plants to live on. The same thing happens with careless scuba divers and snorkellers who break or squash fragile corals and other marine life because they are not careful. Indirectly tourism affects reef ecosystems through the building of resort and holiday areas close to reefs to allow people to enjoy the areas. This brings problems with sewage disposal and increased runoff causing sedimentation and eutrophication. Careful management of the tourist industry on reefs can minimize the harmful effects of tourism, and allow the development of a strong economic incentive to keep reefs in a healthy state to maintain the income from tourism.
Mining on the reef
Drilling for oil and gas pose a threat to reef life through physical structural damage, pollution, due to waste disposal and spills from the rigs, and problems with shipping associated with transporting the oil or other commodities through the reef waters. Oil causes great damage to ecosystems when it comes into contact with plants and animals, and it is possible that oil can harm invertebrate larvae in the ocean - affecting colonization on reefs long distances away. Often trying to clean up oil spills with chemicals or hot water does more damage than the spill itself.
Shipping and the Marine Environment
Shipping poses a number of threats to reef ecosystems. Pollution, such as oil and noise, from the huge number of boats and ships on the sea engines is constantly increasing. Unfortunately it's becoming all to common that accidents occur with ships transporting cargo very dangerous to a reef ecosystem. Oil spills from ships kills reef life that come into contact with the oil, on all levels from birds, fish and mammals to the tiny coral polyps. Oil spills can have long-lasting consequences on the marine ecosystem, including long-term inhibition of settlement by larvae, which means that areas of the reef may remain bare for long periods. Again, if any one part of the ecosystem is affected, then the repercussions may be felt all the way throughout it, in ways that we cannot yet foresee. Shipping all over the world has also brought another problem with it. Sometimes animals, plants and protists from one part of the world grow on outer parts of ships (fouling organisms) or get sucked into the ballast water taken onboard when replacing cargo weight. This ballast water is sometimes then expelled in the harbor where new cargo is taken on (Many countries now require ships to exchange ballast water in the open sea). This means animals and plants can be taken across the world and left in a place where they don't naturally occur. If this new environment is good for them then they'll flourish and compete with the native residents. Often when this happens they can do better than the native species and the original occupants of the area find they cannot keep up with the new ones and are crowded out or smothered through exclusion. The northern Pacific Sea star is an example of an introduced animal around Tasmania that is doing enormous damage to temperate reefs, it is a voracious predator and scavenger, it can dig up buried prey, and has a special liking for mussels, scallops and clams - threatening industries like the scallop fishery in Tasmania.
Solutions
There are a number of things can be done to fix the problem of resource exploitation and the reef. Firstly on a government level, regulations about fishing (both commercial and recreational), mining and tourism need to be formulated and policed. Some examples include: placing and enforcing size limitations on fishing quotas, conducting thorough and unbiased environmental impact statements on potential mining and tourist sites, and conducting ongoing monitoring of established tourist or mined areas as well as pristine areas, to monitor and assess change in reef ecosystems. Scientific research in these areas provides the answers to some of the mysteries and problems on the reefs, but there is a need to forge stronger links between science, industry and government management authorities so that research is done where it is needed, and that information used in a constructive way to minimize the impacts of resource exploitation on the reef. On a community level, general education is needed about marine life and the reef ecosystem. If people understood more about how interconnected life on the reef is then they would possibly think more about everything that will be affected when they snorkel and take abalone or fish from a rocky platform. It is possible to use the reef with minimal impact. This comes with increased awareness about the animals, the reef and the ecosystem as a whole living thing that relies on every part of itself to function to the best of it's ability. Everyone can help achieve this and help save the reefs by learning about the animals that live there and exactly how they all rely on each other. Your interest can make all the difference to the reef.
Five outlandish ways to save the ocean
Deploying buoyant shade cloth (it's been tried on the Great Barrier Reef) to protect corals from heat stress that leads to bleaching and death
Using electrical current to stimulate coral growth and mitigate bleaching
Trying selective breeding or genetic engineering to help species develop biological resistance and adaptation
Maintaining or managing ocean chemistry by adding base minerals such as carbonates and silicates to neutralize acidity and help marine creatures make their shells/skeletons
Convert CO2 from land-based waste into dissolved bicarbonates to add to the ocean for carbon sequestration and reduced ocean acidity
