coral reef ecosystem (krishna)

1 | College of Fisheries, (JAU), Veraval

AN ASSIGNMENTON

Coral Reef Ecosystem

Course Name: Library and Information Services (PGS 501)

Submitted to,Sh. C. H ShahSenior Librarian TechnicianJunagadh Agricultural University,Junagadh, (Gujrat)Submitted By,

Name: KrishnaReg. No. 2030316005M.F.Sc. 1stYearCollege of fisheries,(J.A.U.), Veraval

COLLEGE OF FISHERIESJunagadh Agricultural University

VERAVAL, GUJRAT 362265


CONTENT

Sn. No. Particular Page No.

01. Introduction 03

02. What is coral 03-04

03. The coral body 04

04. Types of corals 04

I. Hard corals 04

II. Soft corals 05

05. Where do reefs grow 05

06. Corals and their plant partners 06

07. Food sources 06

08. Reproduction and growth 06-08

09. Coral reef formation 08

10. Types of reefs 08

I. Fringing reefs 08

II. Barrier reefs 08-09

III. Atolls 09

11. Ecological role of coral reefs 09

12. Importance of the coral reefs 09-10

13. Threats 11

I. Natural threats 11-12

II. Human-caused threats 12-15

14. Conservation of coral reefs 16-19

15. References 20


INTRODUCTIONCoral reefs are one of the Earth’s most beautiful, ancient and complex ecosystems.

They play an essential role in sustaining life in the sea and serve as a source of food andprotection for human communities. But, coral reefs face an uncertain future. As a result ofgrowing human and environmental assaults, reefs are among the most threatened ecosystemson earth. Ecological research provides information fundamental to understanding andcombating this trend.

Coral reefs are important marine ecosystems that are found in clear, shallow, tropicalwaters around the world. They provide habitat for diverse communities of marine animalsand plants. Coral reefs consist of individual animals called coral polyps and their hardexoskeletons. These small animals have soft, cylindrical bodies and a ring of tentaclessurrounding a mouth. The coral polyp is a member of the phylum Cnidaria, which alsoincludes anemones, jellies, sea whips, sea fans and siphonophores. All members of thisphylum, including coral, have tentacles which they use to catch prey. The tentacles arecovered with stinging cells called nematocysts, which can stun or even kill small animalscalled zooplankton that drift too close to the coral. After the zooplankton have been stung, thetentacles direct them toward the central mouth where they are digested.

Since coral polyps are soft-bodied animals, the bulk of a coral reef ecosystem comesfrom the hard exoskeleton polyps create around themselves. The exoskeleton is composed ofcalcium carbonate (CaCO3) found in sea water, and provides protection for polyps. Sincepolyps occur in groups called colonies, coral reefs consist of a colony’s collective calciumcarbonate exoskeleton in addition to the living polyps.

All reef-building corals have algae called zooxanthellae living inside their tissues.Through the process of photosynthesis, the algae convert carbon dioxide and water intooxygen and carbohydrates. These carbohydrates provide nutrients for the coral polyp. Thepolyp, in return, uses oxygen for respiration and provides carbon dioxide and shelter to thezooxanthellae. Because these algae require light in order to perform photosynthesis, theircoral hosts are restricted to relatively shallow (30 meters), clear water. The algae account forabout half of the weight of the coral body, and algal pigments give the coral its color. Sincethe algae play such a crucial role in coral survival, without it, coral reproduction comes to ahalt.

WHAT IS CORALCoral is an invertebrate (animal without a backbone) marine organism of the class

Anthozoa (phylum Cnidaria). Members of this class are characterized by a body that onlyopens at one end, the mouth, and by skeletons, either internal or external, of a stone like,horny, or leathery consistency. Some cnidarians, such as jellyfish, float through the water.Others, such as sea anemones and corals, attach themselves to the reef. Basically, there aretwo groups of corals: hermatypes, or hard corals that build reefs; and ahermatypes, or corals(both soft and a few hard) that do not. The major difference between hard corals and softcorals is that hard corals contain zooxanthellae (microscopic algae) within their tissue and thesoft corals do not. The term coral is also used to describe the skeletal remains of these


animals, particularly those of the hard corals which form a limestone base that becomes thefoundation of the reef. The Great Barrier Reef is the largest structure built by livingorganisms on Earth, and it is the only living structure visible from outer space. Located alongthe northeast coast of Australia, it measures 1,240 miles (2,000km) in length.

THE CORAL BODYThe body of a coral animal is called the polyp, a hollow sac-like structure that is

smaller than a common pencil eraser. At its free end is a mouth surrounded by tentacles, andinside the body is a stomach. The sticky tentacles contain harpoon-like stinging structures,called nematocysts that enable the polyp to gather food by paralyzing its passing prey. Thetentacles then deposit the food in the mouth where it passes down into the stomach. Nutrientsare absorbed from the food and any solid waste materials are passed back out through themouth. Within the stomach are long, tubular mesenterial filaments that the polyp extends todefend itself from attack by other encroaching coral. In addition, the polyps of the hard coralsextract calcium carbonate from the sea water and use it to build a hard external limestoneskeleton beneath and around their base which secures the fragile polyp to a surface and servesas its protection. Polyps have a mouth but they don’t have a head or any teeth for chewing(Fig. 1).

Fig. 1. Coral bodyTYPES OF CORALS

Hard CoralsReef-building corals, which secrete a hard external limestone skeleton, are commonly

known as hard(stony) corals. They characteristically have tentacles in multiples of six andcan be found either individually or in colonies. These hard coral colonies exhibit three basicgrowth forms: branching, massive, and plate.

Common types of hard corals are brain coral, mushroom coral, pillar coral, staghorncoral, and plate (or table) coral. Water movement influences the shape of the corals. Wherestrong waves hit the reef front, corals have thick branching, massive (boulder), or flattenedshapes. Where the water is calmer and deeper, the coral branches become more delicate andsome take on the shape of large thin plates to absorb a maximum amount of light for theirzooxanthellae. The mushroom coral is one of the few corals that does not grow in colonies.


Hard corals are the most widely distributed form of coral, occurring in all oceans from theshallow tidal zone to depths of 20,000 feet (6,000m) (Fig. 2).

Soft CoralsSome types of corals secrete a flexible or soft skeleton. These are called octocorals, so

named for their characteristic eight tentacles. Octocorals include the soft coral, sea fan, blackcoral, whip coral, and blue coral. Octocorals also grow in colonies on the reef, but do notbuild reefs. They have branching, ribbon-like shapes and their soft internal skeleton allowsthem to bend, wave, sway, and spread out in the water. Some of the soft corals produce toxiccompounds that make them unappetizing to predators. Soft corals thrive in strong currentswhere they have access to lots of plankton. They also grow well in areas where hard coralscannot grow, such as dark caves and overhangs.

Coral jewelry is made from harvesting soft coral, such as black coral and whip coral.Killing coral to make jewelry and ornaments harms the reef (Fig. 3).

Fig. 2. Hard Coral Fig. 3. Soft Coral

WHERE DO REEFS GROWReef-building corals have very specific requirements for growth that limit their

distribution. The water must be clear, shallow and warm, with an optimum temperature of 24degrees Celsius (75 degrees Farenheit). This temperature requirement limits coral growth totropical areas. Coral reefs are generally restricted to the eastern margins of continents wherewarm water from the equator arrives with the currents. Consequently, coral reefs form off thecoast of Florida, but not off the coast of California, where the water is much colder.

However, not all water along tropical coastlines is suitable for coral reefs. Otherenvironmental factors, such as the amount of salt in the water, or salinity, can limit coralgrowth. Corals require a salinity of at least 25 parts per thousand (ppt) and do best in full seawater (35 ppt). Areas with high freshwater runoff, like the mouth of the Amazon River, lackcoral reefs because the salinity is too low.

Coral reefs exist where all the environmental factors necessary for coral growthcoincide. The major areas of reef development are in the Caribbean and the Indo-Pacific


regions. The largest reef in the world, the Great Barrier Reef, is located off the east coast ofAustralia and spans 1,200 miles.

CORALS AND THEIR PLANT PARTNERSWithin the tissue of the polyp live many microscopic algae or plant cells called

zooxanthellae (also called endosymbionts). These algal cells have a symbiotic (mutuallybeneficial) relationship with the coral. The algae provide the polyp with food through theprocess of photosynthesis in which the plant cells use sunlight coming through the water toconvert the carbon dioxide and water in the polyp tissue into oxygen and carbohydrates. Theoxygen is used by the polyp for respiration and the carbohydrates are used for energy to buildits limestone skeleton. In return, the polyp provides the zooxanthellae with nutrients,protection, a place to live, and carbon dioxide, a byproduct of respiration which is vital forphotosynthesis.

The color of the coral comes from the color of the zooxanthellae living in the polyp’stissue. This color can vary from white, yellow, brown, and olive to red, green, blue, andpurple. The color of the coral’s limestone skeleton without the zooxanthellae is white (Fig. 4).

Fig. 4. Corals and their plant partners

FOOD SOURCESIn addition to getting food internally from the zooxanthellae, some corals eat plankton.

Plankton are creatures, both plant and animal, that move passively through the water at themercy of wind and ocean currents. Most plankton are too small for you to see unaided. Theplant plankton are called phytoplankton and the animal plankton are called zooplankton.They acquire their nutrients and energy from a different, distant ecosystem. It is estimatedthat as much as 60% of the plankton on the reef are eaten by the coral polyps as they drift by.

Most corals feed only at night, extending their tentacles when they are less likely to bepreyed upon. During the day, the tentacles are withdrawn into the skeleton for protection.Since corals are animals, those that eat only plants (phytoplankton) are called herbivores, andthose that eat only animals (zooplankton and small fishes) are called carnivores.

REPRODUCTION AND GROWTH


Coral polyps reproduce both sexually (with a partner) and asexually (by themselves).Sexual reproduction occurs when the corals spawn, releasing eggs and sperm into the water.The sperm then fertilizes the egg, creating a new individual called a planula or coral larva.Spawning usually occurs in mass in order to give the eggs and sperm a better chance offertilizing themselves and surviving predators. Although most hard corals are hermaphroditic,containing both male and female sex cells, they sometimes fertilize the sex cells of othercolonies thereby ensuring the coral’s ability to maintain genetic diversity and adapt to newconditions.

Once produced, the planula, which already contains zooxanthellae from the parent,floats up towards the light and drifts with the plankton from several hours up to several weeks.Those that survive then swim back down, settle on a solid, rocky surface, and develop intopolyps. This is the only way in which the stationary hard corals can move to a new location.This is also how corals develop on concrete blocks, shipwrecks, and oil drilling platforms.

Once a year in Australia, for a few nights following the full moon in spring (Octoberinthe southern hemisphere), more than 130 species of corals along the Great Barrier Reefrelease millions and millions of eggs and sperm into the water at the same time. Reeforganisms, like anemones, sea cucumbers, and the crown-of-thorns starfish, also spawn atthis time. Asexual reproduction occurs by budding. The parent polyp clones itself by dividingto form a new polyp which remains attached to the parent polyp’s tissue. A coral colonydevelops by the constant addition of new buds (Fig. 5).

As the new polyps grow, the old polyps beneath them die, adding their limestoneskeletons to the foundation of the reef. In optimum conditions in nature, massive corals maygrow up to .8 inches (2cm) a year and branching corals up to 4 inches (10cm) a year. Becauseof the corals’ slow growth, the creation of a reef can take hundreds of years. Coral coloniesmay also be attached to others of the same or different species, forming large and complexreef structures. Some of these colonies fight one another for more space and light byextending their long arms or mesenterial filaments that the polyp uses to attack and kill theother encroaching polyps. In the right conditions, new colonies can also grow from broken-off fragments of the original colony. In this way, reefs are able to regrow themselves afterdamage from storms, hurricanes, and cyclones.


Fig. 5. Reproduction of corals

In the 1970’s, it was discovered that the age of a coral could be determined in thesame way as a tree. By passing an X-ray through the coral, annual growth rings becomevisible and can be counted. Some of the corals along the Great Barrier Reef are estimated tobe more than 800-1000 years old. This means that they first began growing around the timethat the Battle of Hastings was fought in England (1066AD) and the first Crusade left Francefor Jerusalem (1096AD).

CORAL REEF FORMATIONToday’s coral reefs have accumulated during the last 10,000 years since the last

glacial periods of the Pleistocene epoch. As glacial ice melted and sea levels andtemperatures rose, present-day reefs began to form. Hard corals provide the main structuralframework. Other organisms, such as coralline algae and protozoans, bind and cementeverything together with sheet like growth that stabilizes the reef. Sand and sediments arecreated by boring organisms, such as sponges and bivalves (i.e. clams, oysters); greencalcified algae (Halmedia) which has calcium carbonate plates that drop off; and, grazers,such as parrotfish and sea urchins, which attack the coral for food, extracting nutrition fromthe polyps, breaking down their limestone bases, and excreting the waste as sand. Thecalcium carbonate from the sand, shells, and coral maintains the pH balance in the oceanwhich in turn maintains life as we know it.

TYPES OF REEFSJust as there are different types of corals, there are different types of coral reefs. The

three main types of reefs are fringing reefs, barrier reefs and atolls.

Fringing reefs


Fringing reefs are coral reefs that grow in shallow waters. They closely border thecoastline or are separated from it by a narrow stretch of water. Many of the reefs round SriLanka and Thailand are fringing reefs (Fig. 6).

Fig. 6. Fringing reef

Barrier reefsBarrier reefs grow parallel to the coast, but are separated from land by a lagoon.

Theyare found sometimes many kilometresfrom shore (10–100km). Barrier reefs cangrow infairly deep water, because, often,the living coral builds upon remains ofcorals that grew inthe same area whensea level was lower, during the last iceage. The Great Barrier Reef ofAustraliaextends about 2,010km parallel to theeast coast (Fig. 7).

AtollsAtolls grow surrounding (or partly surrounding) an island which then sinks relative to

sea level (usually because volcanic activity forming the island stops), or was flooded as sealevel rose after the last ice age. Atolls surround (or partly surround) a central lagoon. TheMaldives consists of 26 atolls. Although these are the three main types of reefs, there aremany reefs that do not fit these models (Fig. 8).

Fig. 7. Barrier reef Fig. 8. Atolls

ECOLOGICAL ROLE OF CORAL REEFS


In addition to their high diversity, coral reefs are very productive marine communities.They play a critical role as habitat and nursery grounds for 10% to 20% of the world’sfisheries. They are intimately connected to other marine communities such as mangroveforests, sea grass beds, and the open seas as water currents transport larvae, plants, animals,nutrients, and organic materials. Coral reefs play a significant role in the development ofother ecosystems such as mangroves and wetlands and protect coastlines from wave andstorm damage and erosion. Life-saving medicines, such as anticoagulants, and anticanceragents, such as prostaglandins, come from coral reefs.

The rocky framework of coral reefs is formed from the calcium carbonate depositedmainly by calcareous algae and the stony corals, most of which are colonial animalsresembling tiny, interconnected sea anemones. Reef building corals contain symbiotic algaein their tissues, enabling them to develop the large, massive, branching, or encrustingcarbonate skeletons that provide habitat and food resources for support of other reeforganisms, such as fish, lobsters, giant clams, and sea urchins to name but a few. Reefsmaintain a network of intimate ecological relationships and delicate food webs. Disruption ofcoral reef communities can break up these ecological bonds. Under natural conditions, ahealthy coral reef can recover from natural disturbance such as hurricanes, within 10 to 20years. But when subjected to chronic human-induced stress, recovery from even naturaldisturbance may be impossible.

IMPORTANCE OF THE CORAL REEFSCoral reefs are extremely productive ecosystems and provide humans with many services.

Provisioning ServicesCoral reefs support human life and livelihoods and are important economically.

Nearly 500 million people depend - directly and indirectly – on coral reefs for theirlivelihoods, food and other resources. Further, it is estimated that nearly 30 million of thepoorest human populations in the world depend entirely on coral reefs for their food. A km2of well-managed coral reef can yield an average of 15 tonnes of fish and other seafood everyyear.

Regulating ServicesVery importantly, coral reefs protect the shoreline, providing a physical barrier – a

wall against tidal surges, extreme weather events, ocean currents, tides and winds. In doing so,they prevent coastal erosion, flooding and loss of infrastructure. Because of this, they serve toreduce huge costs involved with destruction and displacement due to extreme weather events.The value of this protective service of coral reefs is estimated at 314 million USD inIndonesia.

Supporting ServicesThe natural action of waves breaks pieces of calcified coral and these are washed up

onto beaches. Through the process of natural physical breakdown, these larger pieces are


broken into smaller and smaller pieces and eventually become part of the rubble, buildingthese beaches. Corals, therefore, contribute, in part, to the process of accretion - which is theopposite of erosion.

Coral reefs are very diverseCorals do not even cover 1% of the Earth’s surface, but they are extremely diverse. In

fact they are dubbed the rain forests of the sea because of this immense diversity. The nooksand crannies formed within reefs by constant beating of waves provide shelter to manyspecies.

They are the home (they provide shelter and nursery grounds) of 25% of marine fish. Thirty two out of the 34 described groups of organisms are found in coral reefs. (As a

comparison, only nine groups are found in tropical rain forests.). Coral reefs support a complex and interdependent community of photosynthesizing

organisms and animals. There is an incredible diversity of life on coral reefs such asalgae, corals (there may be as many as 750 species on one coral reef), sponges, marineworms, echinoderms (sea stars and their relatives), molluscs (snails, mussels and theirrelatives), crustaceans (crabs, shrimps and their relatives) and fish.

Coral reefs have high primary productivityZooxanthellae photosynthesize and produce their own food (like green plants do on

land) and corals benefit from this association. Because of the immense diversity of coral reefs,there is a great deal of exchange of nutrients and primary productivity (food production) isvery high. Primary productivity of coral reefs is estimated at 5-10g C/m2/day. Thisproductivity is derived mainly from algae.

Cultural servicesThe beauty of coral reefs and their diversity are essential parts of many cultures in

different parts of the world. Because of their easy access, visiting coral reefs is an importantrecreation for snorkelers, scuba divers, recreational fishermen and beach lovers.

In Seychelles, tourism was estimated to have generated one fifth of GDP and over60% of foreign exchange earnings in 1995.

In the Maldives, ‘tourism contributes more than 60% of foreign exchange receipts,over 90% of government tax revenue comes from import duties and tourism-related taxes, and almost 40% of the workforce is employed in the industry’.

THREATSCorals are highly sensitive to environmental conditions. They grow best in shallow,

clear water between 68˚F and 84˚F (20˚C and 29˚C) with normal oceanic salinity. Bothnatural and human-caused (anthropogenic) disasters threaten coral reefs worldwide. In 1997,the International Year of the Reef, it was recognized that corals around the world arethreatened:


In the Philippines, about 70% of the coral reefs have been degraded seriously andonly about 5% are thought to be in good condition;

In Jakarta Bay, Indonesia, human activities have caused the average coralcoverage to diminish from 30% to 5% between 1985 and 1995;

In Jamaica, where the coral coverage was 50% to 70%, overfishing has accountedfor a decline of coral coverage to just 5%;

In the Florida Keys, coral diseases, massive algal blooms, and a precipitous dropin water visibility on the world’s 3rd largest barrier reef reflects the damage fromagricultural runoff from Florida Bay and inadequate sewage treatment throughoutthe Keys.

Conservative estimates indicate that up to 10% of the Earth’s coral reefs arealready seriously degraded and a much larger percentage is threatened by theimpact of human activities;

At the current rate of destruction, estimates indicate that 40% of the world’s reefscould be destroyed by the year 2020.

While natural impacts such as hurricanes and population fluctuations of predatorsplay a role in the degradation of coral reefs, it is becoming increasingly clear that humanactivities are having the most catastrophic effects on these fragile marine ecosystems. We allknow that human population growth is the single greatest threat to global environmentalhealth, but the problem has pointed significance for coastal regions. In 2025 three quarters ofthe world’s population will be living within 50 miles of the world’s oceans, seas and lakes.

Natural ThreatsNatural threats to coral reefs include sea level changes, hurricanes, cyclones,

abnormal weather patterns, fluctuations in seawater temperatures, heavy rains that dilutesalinity, extreme low tides that expose coral, disease, and predator population explosions,such as crown-of-thorns sea stars. Reef scan sometimes recover from these seeminglydisastrous attacks if human-caused stresses do not impede their recuperation process.

Human-Caused ThreatsThe human impact on the world’s coral reefs are widespread and reaching

catastrophic proportions. Some scientists believe that the effect of coral reef destruction onglobal biodiversity is of the same magnitude as that of the destruction of rainforests. Indeed,coral reefs are often referred to as the “rainforests of the sea” because they are the mostbiologically diverse marine ecosystem. The most destructive human impacts on coral reefsinclude overharvesting of fish; destructive fishing practices (cyanide and dynamite fishing);nutrients and pesticides draining onto the reefs from agricultural areas upstream; tourists whounwittingly damage reefs, boat anchors dropped onto fragile corals; raw sewage from coastalareas with insufficient treatment capacity; coral mining for construction materials;sedimentation from deforestation, road construction and dams; and oil pollution fromshipping.

Overexploitation (Over-fishing)


For foodA recent report states that ‘centuries of over-fishing by man have emptied the world’s

oceans of giant fish, whales and other large sea creatures, destroying coastal environments’.

In Seychelles, tourism was estimated to have generated one fifth of GDP andover 60% of foreign exchange earnings in 1995.

In the Maldives, ‘tourism contributes more than 60% of foreign exchangereceipts, over 90% of government tax revenue comes from import duties andtourism-related taxes, and almost 40% of the workforce is employed in theindustry’.

In South Asia, 45% of 19,210 km2 of coral reefs have been destroyed, another10% are critically threatened and 25% are threatened. Only 20% are at lowrisk from human activities.

In Southeast Asia, 38% of 91,700 km2 of coral reefs have been destroyed,another 28% are critically threatened and 29% are threatened. Only 5% are atlow risk from human activities.

The human global population is expected to double in the next 50 years, and with it,an ever increasing demand for life essentials such as food. Fish is the primary source ofprotein for one fifth of the world’s population. The demand for fish has doubled in the last 50years, and fish production would have to double again in the next 25 years to keep up withthe demand and population growth. Because coral reefs are within the reach of small boats,they are especially vulnerable to over-fishing. Particular groups of coral reef fish such asgroupers, snappers and large wrasses have been overexploited. In Southeast Asia, the live fishtrade (both as food fish and as ornamentals) is estimated to be over a billion USD per year in(mostly) illegal trade.

Irresponsible tourismTourism is essential for the economic development of many countries in the region.

For example, marine and coastal tourism is the largest industry in the Maldives and accountsdirectly for 20% of GDP and its wider effects help produce 74% of national income; almost40% of the workforce is employed in the industry. When carried out in a controlled andsustainable manner, tourism can be a positive economic earner and should be an incentive forcountries to invest in managing coral reef ecosystems to continue attracting tourist revenue.

However, when managed poorly, tourism has both direct and indirect negative effectson coral reefs. Snorkeling, diving and boating can cause direct physical damage to reefs,while overexploitation of reef species as food, for aquaria and as curios for tourist marketscan threaten the survival of species. In some cases, bad tourism practices are not prevented.For example, tourists are allowed to walk on reefs, causing physical damage to the reefstructure and stirring up sediment. Sometimes they even directly collect species off reefs.Boats carrying tourists can damage reefs by dropping anchors directly onto reefs, disturbingspecies and also causing marine pollution through excessive traffic.


Indirectly, careless and irresponsible building of infrastructure directly onto reefs ortoo close to beaches, river mouths and lagoons, results in increased sedimentation and leavesthe infrastructure vulnerable to damage from extreme weather events. Another indirect effectof tourism is often the irresponsible disposal of sewage and solid waste. Two decades ago,sewage and solid waste were mostly disposed directly into the sea but the current situationhas improved greatly.

Global Warming and the Greenhouse EffectGreenhouse gases (carbon dioxide, methane, nitrous oxide and chlorofluoro-carbons)

are accumulating in the atmosphere, trapping the heat from the sun and causing the Earth’satmosphere to become abnormally warm. These gases are increasing as people burn morefossil fuels for energy and cut down carbon-dioxide absorbing forests. The resulting increasein sea temperatures, sea levels, and violent storms negatively affect corals. The weakenedcoral then becomes more susceptible to disease. One of these effects, coral bleaching, resultswhen the coral is stressed, as when the water temperature becomes too warm for the coralpolyps to survive. When the polyps die, the coral loses its color and becomes white.

Harmful Fishing PracticesCoral reefs provide habitat for marine life, such as fish, turtles, octopus, bivalves

(mussels, clams), gastropods (snails, conchs), spiny lobster, shrimp, echinoderms (seacucumbers, urchins). These are sources of food and income for many coastal people, as wellas large commercial fishing operators. Around the world, more and more fisheries arecollapsing (species of fish are disappearing from many areas) due to damaging fishingtechniques and overfishing (more fish being harvested than the area can reproduce). In manyplaces, traditional fishing methods have been replaced with super-efficient moderntechnologies, often with damaging long term effects. The introduction of motorized boats andSCUBA gear, such as masks and fins, has increased the catch, often to unsustainable levels.Biodegradable traps and nets woven from vegetable fiber or coconut fronds have beenreplaced with non-biodegradable nylon, metal and wire. When lost they often becomedangerous: entangling and injuring or killing marine life (Figure 3-4), breaking corals, orcontinuing to catch fish that will never be collected.

Cyanide PoisoningCyanide poison is used by fishers in Indonesia, the Philippines, and other island

nations to stun fish, making them easier to catch. Chlorine bleach and quinaldine are used inthe United States. Hunting for food or aquarium fish, the fishers shoot the chemical solutionsat reef fish or into coral enclaves where they live. The poisonous residue kills coral,invertebrates, and other fish. Fishers in the Pacific and Southeast Asia often blast reefs withdynamite or other explosives that rupture fishes’ air bladders so they can scoop them up asthey float to the surface. The explosions destroy reef formations, kill non-target fish (by-catch), and often kill or maim the fishers themselves. Some fishers also use ‘Muro-Ami’,which is the name of the net that fish are driven into when hundreds of boys pound on thecoral and wave white plastic streamers. Again, this technique damages the coral and results inhuge quantities of by-catch.


MaricultureMariculture, the farming of marine plants and animals, is becoming more popular in

the tropics, often in response to the loss of wild stocks. Giant clams, fish, conch, seaweed andshrimp are among the many farmed species. Unfortunately, while mariculture provides ameans of employment and reduces pressure on overexploited stocks, it can have a negativeimpact on the reef. In many areas, entire mangrove forests have been bulldozed to makeshallow ponds for these farms, eliminating juvenile fish nurseries and habitat for marine birdsand animals. In addition, these farms siphon already short fresh water supplies, poison thewater with chemicals and antibiotics, and cause a decrease in wild fish populations.Ultimately, the coastal people are left with little protein source since they are unable to affordthe mariculture product.

Damage from BoatsIn areas that are popular with recreational, diving or fishing boats, the reef is subject

to damage from accidents and carelessness. Anchors tossed on coral break the fragile animals(Figure 3-5), and the chains drag a swath of destruction around them. Boats and ships that runaground on the reef can destroy hundreds of corals in an instant. Propellers churn upsediments that smother the reef. Boat bilges and toilets are discharged, dumping an overloadof algae-causing nutrients into the water. Some cruise ships and recreational boats have beendocumented dumping their trash overboard, despite laws against ocean dumping.

Damage from DiversAlthough recreational divers are often the greatest advocates for protection of coral

reefs, careless diving can present a hazard to the ecosystem. Popular dive spots often attractmore visitors than is healthy for the area. Lack of mooring buoys can result in damage fromanchors. Unscrupulous dive charters may use food to lure fish toward their customers,disrupting their normal feeding and behavior patterns. Divers and snorkelers who takesouvenirs, touch coral, let their fins and other equipment bash into it, or even kick up excesssediments contribute to the demise of the very reef they came to enjoy.

Coral MiningCoral mining is a problem in countries with few resources for construction. Iron bars

are used to dismantle entire sections of reef to build roads, walls, homes and office buildings.

PollutionAfter it rains, storm water runoff carries trash, oils, chemicals, and other undesirables

from the land into the sea. Fertilizer, pesticides, and herbicides from agriculture also wash outof fields into streams and into the ocean. Chemicals, such as chlorine-based cleaningsolutions, PCB’s and DDT, heavy metals, and minerals from mining and other industrialpollution are known to be poisonous to marine animals.

Deforestation and development


Deforestation and development can damage coral reefs offshore, smothered byloosened soils washed by rain into rivers and out to sea. Insufficiently treated or raw sewageintroduces excess nutrients on the reef, covering corals with algae. Warm water dischargesfrom power plants cause corals to bleach. Large sections of reef off Guam and Taiwan havebeen destroyed by this thermal pollution. Corals are vulnerable to oil pollution caused byspills, leaks in tanks or pipelines, ships flushing their tanks and bilges, offshore oilexploration and land-based sources, such as refineries and gas stations. Trash from fishingvessels, cruise ships, recreational boaters, ocean dumping and beach visitors inflicts damageon beaches, reefs, and marine animals. Some turtles and seabirds often make the deadlymistake of eating plastic bags and debris because it resembles one of their favorite foods,jellyfish. Every year many marine animals and fish are entangled in nylon fishing nets, six-pack rings and other garbage.

Radioactive pollutionRadioactive pollution, including nuclear bombs, accidents and leaks at nuclear power

plants, and nuclear testing, whether atmospheric, underground or underwater, all are knownto kill a wide range of reef life.

DredgingDredging to clear channels for shipping, marinas, and ports, or to mine coral rock or

sand causes excess silt to contaminate the water. Corals can be damaged by artificiallycreated channels, as they trigger changes in water circulation, tidal flow, and water levels.

Coral HarvestingCoral is also harvested to make jewelry, gift store curios (Figure 3-7), coffee table

knick-knacks, and aquarium habitat. Under optimum conditions, many corals take 37 years toregenerate.


CONSERVATION OF CORAL REEFSGiven that 20% of the world’s coral reefs have already been destroyed much has to be

done in the future for the conservation of coral reefs.

Establishment of marine protected areasOne of the key mechanisms of protecting coral reefs is the establishment of Marine

Protected Areas (MPAs). Although there are many types of MPAs, in all MPAs, marine areasare set aside from unrestricted human activities. Where restriction is highest, MPAs are setaside as ‘no-take’ areas where extraction of all marine life is prohibited; even research,education and recreation is restricted. Some MPAs are established and managed specificallyfor a purpose (for example, for recreation, for the preservation of a historical site or as arefuge for a particular species to breed). Multiple-use MPAs are zoned to allow for completerestriction of harvest in some areas, restricted use in others and managed use in yet others.

Although more and more MPAs are being established now worldwide, the ratiobetween MPA and terrestrial protected areas still remains low at 1:7. Less than 1% of theworld’s oceans are protected.

However, a major problem with MPAs is that they are often only parks on paper and amajority of MPAs fail to meet their management objectives: in 1995, only 31% (1306) MPAswere found to have met their management objectives. Even though MPAs may be gazettedlegally, enforcement of relevant laws (zoning, prohibiting certain activities) is often poor.

Prevention of over-harvesting through legislationMany species are protected under general species protection laws across the region.

Most of this protection is afforded to marine vertebrates, but some countries - such as Indiaand Sri Lanka - have laws protecting several species of coral, molluscs and echinoderms.

MonitoringMonitoring of coral reefs is essential for the development of effective management

strategies. It is only through monitoring that trends and patterns of use and the health of reefscan be assessed.

Worldwide, there are several organisations that monitor the status of coral reefs. TheGlobal Coral Reef Monitoring Network (GCRMN) coordinates efforts to improve themanagement of coral reefs through knowledge sharing and capacity building, and worksclosely with Reef Check and Reef Base. The latter is a global database of coral reef relatedinformation. After the 1998 coral bleaching event, and with the ongoing threat of coraldegradation as a consequence of other human activities, Coastal Ocean Research andDevelopment in the Indian Ocean (CORDIO) was commenced in 1999. CORDIO funds andsupports scientists and institutions in the Indian Ocean Region, to ensure that the status ofcoral reefs in the region is monitored, focussing both on the ecological and socio-economiceffects of coral reef degradation. Many other organisations partner these major players toprovide an annual status report of coral reefs across the world.

Building awarenessBuilding awareness about coral reefs, their diversity and the services they provide,

helps greatly in mitigating the threats to these fragile ecosystems. Awareness at the


community level is most effective as it can help to encourage users of coral reefs to changetheir behavior to sustainable use of these ecosystems. Awareness at national level - throughthe media and conservation education - is essential to ensure that policy makers integratecoral reef conservation into all stages of development. It is also critical to ensure that landbased environmental issues – such as unplanned or badly planned inland development andpollution-are prevented to safeguard coastal ecosystems such as coral reefs.

In response to the growing threats to coral reefs around the world, 1997 wasdesignated the International Year of the Reef (IYOR) worldwide. Year 2008 was alsodesignated an International Year of the Reef.

Reef ResilienceAdapting to climate change is, perhaps, the biggest challenge that coastal managers facetoday in respect to coral reef conservation and management. Understanding why some reefsdo not succumb to bleaching while others nearby do (i.e., why they are resistant) and whysome ‘bounce’ back quickly while others do not (i.e., why they are resilient) has becomeextremely important. The Nature Conservancy and its partners have developed an R2-ReefResilience Toolkit that is designed to help managers prepare for and respond to coralbleaching events.

Supporting participation and sustainable livelihoods in reef dependent communities:The connection between poverty and coral reef ecosystems is significant: two thirds of allcountries with reef areas are developing countries, and a quarter of these are least Developedcountries.

Coral reefs provide important resources for the poor, and contribute to nationaleconomies. The current trend of increasing threats to reef resources is likely to affect poorcommunities, who are dependent on coral reefs. To make things worse, management of coralreefs for conservation purposes often restricts community access to these resources, leavingthem even fewer livelihood options. Often, these restrictions are not followed bycommunities, who have little understanding of or involvement in the management process.

It is now well recognized that such communities need to be offered alternatives fortheir livelihoods in order to ensure that coral reefs are not further damaged, as well as toalleviate poverty in coastal areas. Therefore, coastal managers are shifting towards moreintegrated and participatory approaches to reef management and conservation. Suchapproaches include identifying and supporting alternative livelihoods to reduce dependenceon coral reefs, as well as enhancing current livelihood activities to make them more cost andresource efficient. Limited and controlled local use of coral reefs is now advocated in certaincircumstances, instead of blanket restrictions on use. Rights to reef access and resolution ofconflicts over resource use, community involvement and collaborative management are nowbeing incorporated in to reef management.

New management initiativeIt is now understood that ‘standard’ methods of coastal zone management have not

been successful in achieving sustainable development and conservation goals and that a shiftin approaches is needed.


Shifting from small, isolated management efforts to large-scale networks using collaborativemanagement is now the trend. Increasing the area of reefs under high protection is a majorthrust of this shift and 33% of the Great Barrier Reef has now been declared as highprotection zones or no-take areas - where harvesting is not permitted. Collaborating to createlarger networks of MPAs is yet another approach that has been favored by major NGOs suchas Conservation International, The Nature Conservancy and the World Wildlife Fund who aredeveloping training modules to identify and develop a network of MPAs in Asia based onareas of highest biodiversity. Others are assisting managers to cope with climate changeimpacts. Another change is the effort to focus research on real-life problems that resourcemanagers face (Wilkinson, 2004). There is also a definite trend towards integratedmanagement which understands that unsuitable land use inland poses serious threats to thecoastal zone. Therefore, it emphasizes inland land use and watershed management. Anecosystem approach - integrating ecological, economical and social principles in a holisticmanner, involving all stakeholders, is now the favoured approach.


REFERENCES1. Miththapala Sriyanie. 2008. Coral Reefs. Coastal Ecosystems Series (Volume 1).

Ecosystems and Livelihoods Group Asia, IUCN. Pp 01- 20.2. Weir Wendy et. Al. 2004. Corals Reef Teachers guide.3. Holing, Dwight. 1990. Coral Reefs. San Luis Obispo. California: Blake Publishing.

coral reef ecosystem (krishna)

Education