Coral Reefs: Delicate and Diverse, Degraded and Fast Disappearing

Francis Staub, International Year of the Reef

Steve Turek - Coral Reef Photobank

Introduction to Corals and Coral Reefs Coral reefs are often referred to as the rainforests of the sea. Given their immense biodiversity, confined to relatively little space, perhaps the reference should really be the other way around: rainforests are the coral reefs of the land! At the level of phyla�the broadest taxonomic organization in the kingdom of animals (kingdoms being the major groupings of animals, plants, fungi and protists)�coral reefs harbor 33 of the 38 known animal phyla�more than any other ecosystem on the planet. By contrast, tropical rainforests host only 8 phyla. Some rainforests may have more types of species, but coral reefs harbor a greater overall diversity of life. Estimates range from 100,000 to greater than one million species living on coral reefs. Much has been written on the beauty, color and splendor of coral reefs. They evoke a range of visual images and associations: from clear blue waters and lazy days under the sun�to excitement in exploring the unknown�unfamiliar animals and life forms, thoughts of adventure, shipwrecks and sunken treasure. Perhaps more importantly, they provide resources for millions of coastal people worldwide � the only readily available source of protein, and crucial livelihoods. Corals and related animals also provide a cornucopia of pharmaceutical compounds, with new cancer treatments and wonder drugs being discovered regularly. But unfortunately, the plight of coral reefs is now equally renowned. Over only the course of one human generation, most coral reefs have declined around the world. The causes include a range of insults occurring as a consequence of our ever-expanding population, especially along our coastal zones. For example, of the 17 mega-cities around the world (i.e. those cities containing more than 10 million people), 14 occur within the coastal zone. Not all of these cities are adjacent to coral reefs, but most between the tropics of Cancer and Capricorn are�especially in Asia�and they rely upon the ecosystem services of coral reefs to some important degree�either for products, shoreline protection or tourism revenue. The Millennium Ecosystem Assessment found that within the coastal zone, the vast majority of people live in close proximity to reefs.i

We are adding population to coastal lands, and many of these coastal people are taking more than our ecosystems can produce, and mismanaging their by-products and wastes. Threats of over-fishing, excessive sedimentation from deforestation and coastal land transformation, untreated sewage, unregulated agriculture and other forms of mismanagement all stress coral reefs and associated ecosystems such as mangrove and sea grass habitats. It is also increasingly apparent that impacts from climate change�in the form of higher sea surface temperatures, increased erosion from changed ocean chemistry, more powerful storms, and sea level rise� will bring repeated shocks to coral reefs in the coming years and decades ahead. A recently published paper in the journal Science suggests that levels of CO2 could become unsustainable for reefs within 50 years, dooming reefs worldwide.ii Thus the outlook for reefs is poor -- unless we can halt the degradation, and quickly. Coral Biology Corals are invertebrate animals belonging to the phylum Cnidaria (along with the jellyfishes and sea anemones), with stinging cells (or cnidocytes), as a distinguishing characteristic. Their basic body plan and shape are quite simple ― a vase-like sac (known as a polyp) with a hole in one end (the mouth), surrounded by stinging tentacles that can capture food. During feeding, a coral polyp will extend its tentacles out from its body and wave them in the water current, where they encounter small plankton or other food particles and capture prey with their tentacles� stinging cells.

Anatomy of a coral polyp

Source: NOAA

Coral polyps can extract abundant calcium from surrounding seawater and use this to create a hardened structure for protection and growth. Coral reefs are created by millions of tiny polyps forming large carbonate structures, and are the basis of a framework and home for hundreds of

thousands, if not millions, of other species. Coral reefs form the largest biological structures on earth; they are only ones distinctly visible from space.

Tureia Atoll from the air Earth Sciences and Image Analysis Laboratory - http://www.reefbase.org

The coral reefs as we know them today have evolved on earth over the past 200 to 300 million years. Over this history, corals have developed a highly evolved form of symbiosis, or a mutually-beneficial living arrangement between coral animals and tiny single-celled plants, known as zooxanthellae. Inside the tissues of each coral polyp live these microscopic, single-celled algae. These two groups ―animal and plant ― share space, gas exchange and nutrients to survive.

Image of Orange Cup Coral (Tubastraea coccinea) polyps with tentacles extended.

Photographer: Chuck Savall Therefore, while corals are indeed animals, they functionally act like plants in many respects, explaining why reef-building corals are confined to living so near the surface of the water where they are easily reached by sunlight. The symbiosis between plant and animal also underlies the colors of corals, so appealing to divers on a reef. Light is important in driving corals to compete for space on the sea floor, and so constantly pushes the limits of their physiological tolerances in a competitive environment among so many different species. However, it also makes corals highly susceptible to environmental stress.

Damlesfish (Dascyllus aruanus) near branching coral (Acropora.). Andrew Cornish (http://www.reefbase.org)

(Chaetodon lunilatus) and other

fishes over brain coral. Yusri Yusuf (http://www.reefbase.org)

Many coral species reproduce once or twice each year. Most of coral species spawn by releasing eggs and sperm into the water, but the period of spawning varies from one species to another. Other coral species, with limited distribution, are brooders. A dertilized egg forms a larva known as a planula. This baby coral looks like a little tiny jellyfish and floats around near the surface at first, and then lower in the water column until it finds a suitable space to call home � usually a hard surface to which it can attach.

Mountainous star coral spawning at the Flower Gardens, 1993

Copyright © Greg Bunch / gbundersea In general, massive corals tend to grow slowly, increasing in size from 0.5 cm to 2 cm per year. However, under favorable conditions (high light exposure, consistent temperature, moderate wave action), some species can grow as much as 4.5 cm per year. In contrast to the massive species, branching colonies tend to grow much faster, and under favorable conditions, these colonies can grow vertically by as much as 10 cm per year.

Coral Life Cycle

Distribution of Coral Reefs Based on current estimates, shallow water coral reefs occupy somewhere between 284,000 and 512,000 km2 of the planet (add cold-water deep corals, and it comes to even more area). If all the world�s shallow water coral reefs were crammed together, the space would equal somewhere between an area of land ranging from the country of Ecuador (the low estimate) to Spain (the higher estimate). This area represents less than 0.015 percent of the ocean -- yet coral reefs harbor more than one quarter of the ocean�s biodiversity. That�s an amazing statistic when you think about it: no other world ecosystem occupies such a limited area with so many life forms.

Global Distribution of Coral Reefs

Source: NOAA's National Ocean Service, Education Division: http://oceanservice.noaa.gov/education Coral reefs are found both in tropical and subtropical waters, in a zone extending from 30°N to 30°S of the equator. Reef-building corals do not grow at depths of over 30 m (100 ft) or where the water temperature falls below 16 °C (72 °F). iii It was Charles Darwin who originally classified coral reefs as to their structure and morphology, and described them as follows: ! Fringing reefs lie near emergent land. They are fairly

narrow and recently formed. They can be separated form the coast by a navigable channel (which is sometimes incorrectly termed a �lagoon ").

! Barrier reefs are broader and lie farther away from

the coast. They are separated from the coast by a stretch of water which can be up to several miles wide and several tens of meters deep. Sandy islands covered with a characteristic pattern of vegetation have sometimes formed on top of a barrier reef. The coastline of these islands is broken by passes, which have occupied the beds of former rivers.

! Atolls are large, ring-shaped reefs lying off the coast,

with a lagoon in their middle. The emergent part of the reef is often covered with accumulated sediments and the most characteristic vegetation growing on these reefs consists of coconut trees.

Darwin�s three stages of atoll formation (source: NOAA)

The Value of Coral Reefs Coral reefs support an extraordinary biodiversity. They are home to a variety of tropical fishes, such as the colorful parrot fishes, angelfishes, damselfishes and butterfly fishes. Other fish groups found on coral reefs include groupers, snappers, grunts and wrasses. Over 4,000 species of fishes inhabit coral reefs. Reefs also provide spawning, nursery, refuge and feeding areas for a large variety of other organisms, including sponges, sea anemones, worms, crustaceans (including shrimp, spiny lobsters and crabs), mollusks (including cephalopods), echinoderms (including starfish, sea urchins and sea cucumbers), sea squirts, sea turtles and sea snakes.

Reef structures play also an important role as natural breakwaters, which minimize the wave impacts from storms such as cyclones, hurricanes or typhoons. Some reports state that the extent of the damage cause by the Asian Tsunami in 2004 was far less in areas in close proximity to healthy reefs areas than those close to degraded ones.

The stunning beauty of coral reefs makes them a powerful magnet for tourists, and well managed tourism provides a sustainable means of earning foreign currency and employment for people around the world � even in remote areas of developing countries. Several attempts have been made to estimate the values of coral reefs in terms of dollars. Benefits from coral reefs can be categorized into 2 types: �direct use values� (fisheries and tourism industries, for instance), and �indirect use values� (benefits from coastline protection, for example). According to a United Nations estimate, the total economic value of coral reefs range from US$ 100,000 to 600,000 per square kilometer per yeariv.

Coral Reef Status and Threats The latest estimates (2004) of The Global Coral Reef Monitoring Network (GCRMN), globally states that 20% of the coral reefs are regarded as effectively lost globally (which means damaged beyond repair). Another 24% of the remaining reefs are at critical status (high to very high threat of destruction, if we do nothing), and only 50% are currently classified as low riskv. The majority of reef loss or damage is not deliberate. Coral reefs are being degraded by an accumulation of stresses arising from human activities. In simple terms, stresses can be grouped by the actions of people extracting material from, and placing materials upon, coral reefs. Over-fishing, pollution and coastal development top the list of chronic stressors. However, long term changes in the oceans and atmosphere (rising sea temperatures and rising levels of CO2 that will reduce coral calcification), and acute stresses from highly variable seasons, severe storms, earthquakes and volcanic eruptions also affect reefs.

Uplifted Dead Coral in Simeulue, Indonesia from theDecember 26, 2004 Earthquake.

(Craig Shuman, Reef Check/Marine Photobank)

In many situations chronic stresses are overwhelming the resilience (or the capacity for self-repair) of reef communities. Some coral reefs are covered with sand, rock and concrete to make cheap land and stimulate economic development. Others are dredged or blasted for their limestone or to improve navigational access and safety. Currently, the stresses of greatest concern are: Over-fishing and destructive fishing methods Aggressive intensity and fishing methods hurt coral reefs, especially in south and southeast Asia, where fishermen commonly dynamite reefs and inject cyanide into the water. Both these methods stun the fish, making them easier to catch. The fishermen say they have no other option if they are to compete with trawlers and overcome a smaller supply of fish because of previous over-fishing. Some estimates indicate that 90 percent of the coral reefs in the Philippines have been harmed so much that they probably can't recover.

Dynamiting and poisoning reefs are blatant approaches. Less obvious is the damage caused by over-fishing. This is a problem in many parts of the world. Many people know the problems that cod and salmon fishermen have faced with a smaller supply of fish. However, over-fishing of certain species near coral reefs can easily affect the reef's ecological balance and biodiversity. For example, over-fishing of herbivorous fish can also lead to high levels of algal growth. Blast fishing impacts (c) Wolcott Henry 2005/Marine Photobank.

Bottle found near one of the Capone islands, still shows a slightly burned fuse and explosive sediment inside used for destructive "dynamite" or "blast" fishing. (Jeffrey Jeffords/ http://www.reefbase.org)

Young boys with net, catch bag, and squirt bottle with cyanide, used for immobilizing fish in about 70 feet of water, breathing from a tube held in the corner of his mouth. Photo: Jeffrey Jefford (http://www.reefbase.org)

One method to reduce over-fishing and destructive fishing methods is the implementation of Marine Protected Areas (MPAs)vi , in order to promote responsible fishery management and habitat protection. Much like the designation of national parks and wildlife refuges, potentially damaging extraction activities are prohibited. The objectives of MPAs are both social and biological, including restoration of coral reefs, aesthetic maintenance, increased and protected biodiversity, and economic benefits.vii Coral Bleaching Coral bleaching occurs when the symbiosis between corals and their symbiotic zooxanthellae breaks down. This results in the loss of the brown symbionts and a rapid whitening of the coral host (thus the term "bleaching")viii. This is a stress response by the coral host. If the temperature decreases, the stressed coral can recover; if it persists, the affected colony can die. The impacts from coral bleaching are becoming global in scale, and are increasing in frequency and intensity. Mass coral bleaching generally happens when temperatures around coral reefs exceed 1oC above the an area's historical norm for 4 or more weeks. Sea surface temperature increases have been strongly associated with El Niño weather patterns. However, light intensity (during doldrum (i.e. flat calm) conditions) also plays a critical role in trigger the bleaching response. If temperatures climb to more than 2o C for similar or longer periods, coral mortalities following bleaching increase.

Mass coral bleaching was not documented in the scientific literature before 1979; however, significant mass bleaching events have since been reported in 1982ix, 1987, 1992 and the strongest sea surface warming event ever recorded occurred in 1998, where an estimated 46% of corals in the western Indian Ocean were heavily impacted or died. In 2005, sea surface temperatures in the Caribbean were the highest reported in more than 100 years, and there was also significant coral bleaching following this warming. And in 2007, coral bleaching is being reported in several locations around the world. The onset of coral disease has been shown to spread following coral bleaching events, so the evidence of a connection between warmer-than-normal water and coral disease is growing stronger. If sea surface temperatures continue to rise, then the frequency and severity of coral bleaching will also increase, likely affecting the ability of coral reefs, as we have known them, to adapt and to provide many of the services (such as shoreline protection, and fisheries) that people rely upon.

Coral Bleaching (Bahamas)

(c) Wolcott Henry 2005/Marine Photobank Global warming has other impacts on reefs as well, and some of these may be even more damaging to reefs than bleaching. Ocean acidification results from global warming, and when the pH of seawater drops, corals and other calcareous organisms are impeded in their ability to lay down calcium carbonate skeletons (see Ocean Acidification, W2O Ocean Observer archives). Land development and pollution Extensive and poorly managed land development can threaten coral reefs. Within the last 20 years, once prolific mangrove forests, which absorb massive amounts of nutrients and sediment from runoff caused by farming and construction of roads, buildings, ports, channels, and harbors, are being destroyed. Nutrient-rich water causes fleshy algae and phytoplankton to thrive in coastal areas in suffocating amounts known as algal blooms. Coral reefs are biological assemblages adapted to waters with low nutrient content, and the addition of nutrients favors species that disrupt the balance of the reef communities. Both the loss of wetlands and mangrove habitats are considered to be significant factors affecting water quality on inshore reefs. Poor water quality is suspected (and is currently being investigated) as a facilitator in the spread of infectious diseases among corals. x

Coastal Development in Cancun (Mexico) (c) Wolcott Henry 2005/Marine Photobank

Black band disease advancing from right to

left in coral Diploria strigosa Sven Zea, Universidad Nacional de Colombia/Marine Photobank

And, as if this were not enough, coral reefs are suffering from the paradoxical situation that we are loving reefs to death. Visitors to reefs add stresses, in some cases tipping the balance such that immune-suppressed corals become suspectible to further disease spread and die. In addition, the marine souvenir and curio trade is responsible for the denuding of reefs all around the world � corals are taken for jewelry and as live rock for aquaria, and reef fishes and other organisms are sold in preserved form in trinket shops and alive in pet shops. According to the U.S. Coral Reef Action Plan, the U.S. is the world�s largest importer of ornamental coral reef species, and as such has a critical responsibility to address degradation of coral reef ecosystems that may arise from destructive collection practices and unsustainable trade. The U.S. has banned the use of most destructive fishing practices, and collection of stony corals and live rock are prohibited in most federal, state and territorial watersxi. However, unenlightened U.S. tourists join tourists from many other parts of the globe to buy reef souvenirs, unwittingly contributing to the dramatic decline of reefs around the world.

Coral trees and jewelry items for sale Tony Montgomery/Marine Photobank How can coral reefs be protected? It is now time to learn to use coral reefs in ways that preserve coral reef species for our children without compromising the services that reefs provide. In order to effectively protect coral reefs and other marine environments, it is imperative to manage our uses and impacts so that they do not exceed the self-repair capacity. The biological and physical processes influencing coral reefs are generally much larger than the management ability of governments and communities. However, most of the human actions that damage coral reefs can be managed locally. A variety of activities, including education, establishment of international conventions and treaties, research projects, and the establishment of marine protected areas are under way to protect coral reefs.

One of the most important things that can be done is to spread awareness about the value and services that coral reefs (and their related ecosystems, such as mangroves and sea grasses) provide to people, and to encourage communities, companies and governments

to take steps to protect them. In that in mind, the International Coral Reef Initiative (ICRI) has designated 2008 as the International Year of the Reef (IYOR 2008 � www.iyor.org)�a year-long campaign of events and initiatives hosted by governments, individuals, corporations, and schools around the world�to promote awareness, conservation action and strengthen long-term support for coral reef conservation. The primary objectives are to communicate to a broad range of interests, including people who live far away from coral reefs, their value and services, and to facilitate public involvement in coral reef conservation in all countries. Since 1994 the International Coral Reef Initiative (ICRI), has served as an informal partnership of governments, international organizations, non-governmental organizations and scientists and was established out of concern for the degradation of coral reefs. ICRI is one of the fourteen multilateral environmental agreements, programs, partnerships and networks relevant to the protection and conservation of coral reefsxii.

Several Non-Governmental Organizations (NGOs) have also included coral reefs protection within the priorities of their marine programs, including WWF, TNC, CI and many others. What Prognosis for Reefs? The global situation regarding these diverse and valuable marine ecosystems is dire, but hope is not lost. With 2008 being the International Year of the Reef, we can expect greater public attention to the problems, greater support for conservation, and greater political will to tackle the many stressors that coral reefs face. Let�s hope it�s not too late to stem the tide of reef degradation, for the world will be a significantly poorer place if coral reefs continue to disappear from the world�s ocean waters. Useful on-line resources: The International Year of the Reef (IYOR) 2008 web site: www.iyor.org The ICRI Electronic Partnership Forum (ICRIForum) serves as a central gateway to information related to the International Coral Reef Initiative (ICRI) and sustainable coral reef management, conservation, science, information and awareness, and to strengthen communication among the partners supporting the ICRI mission. www.icriforum.org The Coral Reef Targeted Research & Capacity Building for Management Program (CRTR) is a leading international coral reef research initiative that provides a coordinated approach to credible, factual and scientifically-proven knowledge for improved coral reef management. www.gefcoral.org ReefBase mission is to improve sharing and use of data, information, and knowledge in support of research and management of coral reef resources . www.reefbase.org CORAL Reef Alliance is a non-profit organization, dedicated to protecting the health of coral reefs by integrating ecosystem management, sustainable tourism, and community partnerships. www.coral.org The Global Coral Reef Monitoring Network (GCRMN) works hard to improve management and conservation of coral reefs by providing manuals, equipment, databases, training, problem solving, and helps with finding funds for reef monitoring - all coordinated in a global network. www.gcrmn.org The Coral Reef Initiatives for the South Pacific (CRISP): www.crisponline.net The Mesoamerican Barrier Reef System Project purpose is to enhance protection of the unique and vulnerable marine ecosystems comprising the MBRS, and to assist the countries of Mexico, Belize, Guatemala and Honduras to strengthen and coordinate regional policies, regulations, and institutional arrangements for the conservation and sustainable use of this global public good. http://www.mbrs.org.bz/english/en_index.htm The Reef Check Foundation is an international non-profit organization dedicated to conservation of two ecosystems: tropical coral reefs and California rocky reefs.

www.reefcheck.org Endnotes i www.maweb.org ii Hoegh-Guldberg, O. et al., (2007) Coral Reefs under Rapid Climate Change and Ocean Acidification, Science Magazine, AAAS. iii Spalding MD, Ravilious C, Green EP (2001) World Atlas of Coral Reefs. University of California Press, Berkeley, USA. iv UNEP-WCMC (2006) In the front line: shoreline protection and other ecosystem services from mangroves and coral reefs. UNEP-WCMC, Cambridge UK. 33pp (available online at http://www.unep-wcmc.org/resources/publications/UNEP_WCMC_bio_series/24.cfm) v Status of coral reefs of the world: 2004, Edited by Clive Wilkinson vi UNEP: People and reefs: successes and challenges in the management of coral reef marine protected areas. UNEP Regional Seas Reports and Studies No. 176. UNEP 2004. vii Coral Reef Protected Areas in International Instruments. Bernard Salvat, Jessica Haapkylä and Muriel Schrimm viii Barnes and Hughes. 1999. An Introduction to Marine Ecology; Third edition. Oxford, UK: Blackwell Science Ltd. pp. 117-141. ix Glynn PW (1984) Widespread coral mortality and the 1982-83 El Nino warming event. Environmental Conservation 11(2): 133-146. x Bryant, D., L. Burke, J. McManus, and M. Spalding. 1998. Reefs at Risk: A Map-based Indicator of Threats to the World�s Coral Reefs. World Resources Institute. 56 pp. http://www.wri.org/wri/reefsatrisk/. xi www.coris.noaa.gov/activities/actionstrategy/04_goal_12.pdf xii Conventions and Coral Reefs. Fourteen Multilateral Environmental Agreements, Programmes, Partnerships and Networks Relevant to the Protection and Conservation of Coral Reefs and the World Summit on Sustainable Development Plan of Implementation. Produced by the UNEP Coral Reef Unit in collaboration with the WWF Coral Reefs Advocacy Initiative