Maintenance of Biological Diversity
A coral is composed of tiny, fragile animals called coral polyps. When we say "coral" we are actually referring to the animals and the skeletons they leave behind after they die. Although there are hundreds of different species of corals, they are generally classified as either "hard coral" or "soft coral". Hard corals grow in colonies and are the architects of coral reefs. They include such species as brain coral and elkhorn coral. Their skeletons are made out of calcium carbonate (also known as limestone) which harden and eventually becomes rock. Hard corals are hermatypes or reef-building corals and need tiny algae called zooxanthellae (pronounced zo-zan-THEL-ee) to survive. Generally, when we talk about "coral" we are referring to hard corals.Soft corals such as sea fingers and sea whips, are soft and bendable and often resemble plants or trees. These corals do not have stony skeletons, but instead grow wood-like cores for support and fleshy rinds for protection. They are referred to as hermatypes or non-reef building corals and they do not always have zooxanthellae. Soft corals are found in both tropical seas and in cool, dark regions.
Coral reefs are massive structures made of limestone that is deposited by living things. Although thousands of species inhabit coral reefs, only a fraction produce the limestone that builds the reef. The most important reef building organisms are corals.Coral reefs support over twenty five percent of all known marine species. As one of the most complex ecosystems on the planet, coral reefs are home to over 4,000 different species of fish, 700 species of coral and thousands of other plants and animals.A good way to imagine a coral reef is to think of it as a bustling city or community, with buildings made of coral, and thousands of inhabitants coming and going, carrying out their business. In this sense, a coral reef is like a metropolis under the sea.
A coral polyp is a spineless coral animal.
Coral polyps can be the size of a pinhead while others are larger, sometimes
a foot in diameter. One coral branch or mound is covered by thousands
of these animals. They are invertebrates (spineless animals) and
are cousins of anemones and jellyfish. When thousands of these
animals are grouped together, they are referred to as coral colonies.
Each coral "tree" or "mound" is one colony of coral
polyps. A polyp has a sac-like body and an opening or mouth encircled
by stinging tentacles called cnidae. The polyp uses calcium carbonate
from seawater to build itself a hard, cup-shaped skeleton. This
limestone skeleton protects the soft, delicate body of the polyp.
Coral polyps are usually nocturnal, meaning that they stay inside their
skeletons during the day. At night polyps extend their tentacles
out to feed..
Where do Corals live?
Coral reefs are found in over 100 countries. Most reefs are located between the tropics of Cancer and Capricorn, in places such as the Pacific Ocean, the Indian Ocean, the Caribbean, the Read Sea and the Arabian Gulf. Corals are also found farther from the equator in places where warm currents flow out of the tropics, such as Florida and southern Japan. Worldwide, coral reefs cover an estimated 284,300 square kilometers (110,000 square miles).Coral reefs grow best in waters with a temperature of between 21 and 29 degrees Celsius (70 and 85 degrees Fahrenheit). It is possible for soft corals to grow in hotter and colder places, but growth rates under these conditions are very slow. Corals prefer clear and shallow waters, where lots of sunlight filters through to their symbiotic algae. It is possible to find corals at depths of up to 91 meters (300 feet), but reef-building corals grow poorly below 18-27 meters (60 to 90 feet). Corals also grow poorly near river openings or coastal areas with excessive run-off, because corals need salt water to survive.
How long does it take for coral to grow?
Corals grown at different rates, depending on water temperature, salinity, turbulence, and the availability of food. The massive corals are the slowest growing species, adding between 5 and 25 millimeters (.2 inches to an inch) per year to their length. Branching and Staghorn corals can grown much faster, adding as much as 20 centimeters (8 inches) to their branches each year.
How do corals get their shape?
The variety of shapes and sizes of coral colonies largely depends on their location and species. Some species form hard, pointed shapes, while others form soft, rounded shapes. The shape of coral colonies also depends on the location of the coral. For example, where there are strong waves corals tend to grown into robust mounds or flattened shapes. In more sheltered areas the same species may grow in more intricate shapes such as delicate branching patterns.How do Coral Polyps eat? Coral polyps eat in two different ways, depending on their species. Many coral polyps are nourished in a unique way by a tiny algae called zooxanthellae (pronounced zo-zan-THEL-ee). The algae live within coral polyps, using sunlight to make sugar for energy, just like plants. Zooxanthellae process the polyp's wastes to retain important nutrients and in turn provide the polyp with oxygen. Meanwhile, the coral polyps provide the algae with carbon dioxide and a sage, protected home. Zooxanthellae living with the tissue of hard corals can supply them with up to 98 percent of their nutritional needs.Another way that corals eat is by catching tiny floating animals known as zooplankton. At night the polyps come out of their skeletons to feed, making the reef look like a "wall of mouths". The polyps stretch out their long, stinging tentacles to capture the zooplankton that are floating by. The captures plankton are then put into the polyp's mouths and digested in their stomachs.
How do corals get their colour?
Most coral polyps have clear bodies and their skeletons are white, like human bones. Most corals get their colour from the zooxanthellae inside them. Several million zooxanthellae live in just one square inch of coral and produce pigments. These pigments are visible through the clear body of the polyp and give the coral its beautiful colour.
How do Corals reproduce?
Coral reproductive methods vary, depending on the species. Some species such as brain and star corals are hermaphrodites, meaning they produce both sperm and eggs at the same time. Other corals, such as Elkhorn and boulder corals, are gonochoric, meaning that they produce single-sex colonies. In these species, all of the polyps in one colony produce only sperm and all of the polyps in another colony produce only eggs. Coral larvae are formed in two different ways. The larvae are either fertilized within the body of a polyp or outside the polyp's body in the water. Fertilization of an egg within the body of a coral polyp is achieved from sperm that is released through the mouth of another polyp. The sperm and egg merge and form a planula larvae, which matures inside the body of its mother. When the larva is ready, it is "spit" into the water through the mouth of its mother. Other species of coral reproduce by ejecting large quantities of eggs and sperm fertilize in the water. This process is called coral spawning. In some areas, mass coral spawning events occur on one night a year and scientists can predict exactly when this will happen. Trillions of eggs and sperm are simultaneously released into the water in one of the most astounding acts of synchronicity in the natural world. Once in the sea, larva are naturally attracted to light. They swim to the surface of the ocean, where they remain for days or even weeks. If predators do not eat the larva during this time, they fall back to the ocean floor and attach themselves to a hard surface. An attached planula metamorphasizes into a coral polyp and begins to grow and divide itself in half, making exact genetic copies of itself. As more and more polyps are added, a coral colony develops. Eventually the coral colony becomes mature, begins reproducing and the cycle of life continues!
What do Corals need to survive?
How old are coral reefs?
The geological record indicates that the ancestors
of modern coral reef ecosystems were formed at least 350 million years
ago. The coral reefs existing today began growing as early as
50 million years ago. Most established coral reefs are between
5,000 and 10,000 years old. Although size sometimes indicates
the age of a coral reef, this is not always true. Different species
of coral grow at different rates, depending on water temperature, oxygen
level, amount of turbulence, and availability of food.
How is a coral reef constructed?
Coral reefs are complex, multi-story structures with
holes and crevices shared by various creatures. If a coral reef
can be thought of as a metropolis of the sea, then a coral colony can
be thought of as an apartment building with many different rooms and
hallways that house different marine species. Not all coral species
build reefs. The actual architects of coral reefs are hard or
stony corals, which are referred to as hermatypic or reef-building corals.
As the polyps of stony corals grow, the produce limestone for their
skeletons. When they die, their skeletons are left behind and
are used as foundations for new polyps, which build new skeletons over
the old ones. An actual coral mound or tree is composed of layer
upon layer of skeletons covered by a thin layer of living polyps.Other
types of animals and plants also contribute to the structure of the
reef. Many types of algae, seaweed, sponge, sediment and even
mollusks like giant clams and oysters, add to the architecture of a
coral reef. When these organisms die, they also serve as foundation
for new corals.
What are the different types of reefs?
Scientists generally divide coral reefs into four classes:
fringing reefs, barrier reefs, atolls and patch reefs:
The geological record indicates that the ancestors of modern coral reef ecosystems were formed at least 350 million years ago. The coral reefs existing today began growing as early as 50 million years ago. Most established coral reefs are between 5,000 and 10,000 years old. Although size sometimes indicates the age of a coral reef, this is not always true. Different species of coral grow at different rates, depending on water temperature, oxygen level, amount of turbulence, and availability of food.
How is a coral reef constructed?
Coral reefs are complex, multi-story structures with holes and crevices shared by various creatures. If a coral reef can be thought of as a metropolis of the sea, then a coral colony can be thought of as an apartment building with many different rooms and hallways that house different marine species. Not all coral species build reefs. The actual architects of coral reefs are hard or stony corals, which are referred to as hermatypic or reef-building corals. As the polyps of stony corals grow, the produce limestone for their skeletons. When they die, their skeletons are left behind and are used as foundations for new polyps, which build new skeletons over the old ones. An actual coral mound or tree is composed of layer upon layer of skeletons covered by a thin layer of living polyps.Other types of animals and plants also contribute to the structure of the reef. Many types of algae, seaweed, sponge, sediment and even mollusks like giant clams and oysters, add to the architecture of a coral reef. When these organisms die, they also serve as foundation for new corals.
What are the different types of reefs?
Scientists generally divide coral reefs into four classes: fringing reefs, barrier reefs, atolls and patch reefs:
What is coral bleaching?
Coral normally gets most of its oxygen
and nutrients from tiny algae that live within it, called zooxanthellae
(zoo-zan-THEL-ee) and without this algae, corals would die. Zooxanthellae
also contains pigments, which give coral colonies their beautiful colours.
Sometimes, when coral is under extreme stress, it expels the zooxanthellae,
causing the coral to turn white. Coral bleaching is a term used
to describe this process.
How serious is the coral bleaching process?
Incidences of localized bleaching, from factors such as chemical spills and sedimentation, have been recorded since 1870. Since 1983, however, a new phenomenon has appeared, called mass coral bleaching. In such instances, elevated water temperature and increased amounts of UV light cause coral reefs in unrelated areas around the world to bleach during the warm season. Many mass bleaching are correlated with El Niņo/La Niņa events, which create unusual warm water currents. Many scientists are also concerned that global warming is leading to elevated water temperatures and consequently causing mass bleaching events.
What can I do about coral bleaching?
The best thing you can do to prevent mass coral bleaching is use "precautionary methods" when thinking about how you use energy. For instance, try using less energy (because most energy comes from burning fossil fuels) and support alternative energy sources, such as wind and solar power. You can also walk or ride a bike, instead of driving, buy energy-efficient appliances, recycle paper products, and plant trees. Ask your policy makers to support sustainable energy sources and efficient energy use. In addition, you can support conservation organizations that are working to prevent climate change and/or support coral reef conservation groups too. If you scuba dive or snorkel, keep a lookout for bleached colonies. You can play an important role in alerting scientists as soon as coral bleaching begins, so that they can study the phenomenon and try to determine its causes. If you think you've found a section of bleached coral, report it to your dive operator and ask them to notify the nearest marine research station.
Much remains unknown about the diversity of life on Earth. Promoting biodiversity research is an important component of its preservation. Up-to-date quantitative and qualitative data lay a foundation to all types of activities involved in the conservation of biodiversity. Biodiversity inventories should be a priority for all countries. Similarly, long-term, site-specific, multidisciplinary research on the links among biodiversity, sustainable economic development and conservation is important. Rapid ecological assessments are a fast way to gather information about the biodiversity of an area. Research should include a balance between basic and applied research. Included in all this should be improving skills and institutional capacity, and an awareness of the rights of the local people and the responsibilities of researchers.
Studying biodiversity means documenting its composition, distribution, structure, and function. Integral to this is understanding the roles and functions of genes, species, and ecosystems, and the complex links between modified and natural systems. Systematics, the description and classification of species, is fundamental for our understanding of biological diversity. Identification of a particular species provides the basis into further research and for management of that species. Systematics collections are maintained by many countries, and are used to support a variety of pure and applied studies. Systematics collections can aid in identifying a species and determining if a specimen is actually a new species, as well as providing an inventory of biodiversity.
Some of the key biodiversity research topics include
Data gathering is a tool for decision making. Data gathering and research provide the basis for developing national, regional and international strategies, plans and programs for the conservation and sustainable use of biological diversity. Long-term studies are needed in order to develop a full understanding regionally of the composition, structure and functioning of ecosystems. Long term studies also lend themselves to monitoring ecosystems and tracking changes in the health, species composition, and functioning of those ecosystems.
The specification and design of databases required to store and process biodiversity data will have to be considered according to each countrys needs, priorities and existing information management capabilities. The most effective way to handle spatial and spatially-related data is in a relational database linked to a Geographic Information System (GIS), capable of producing maps incorporating layers of data from the databases. A GIS is a powerful tool with extensive spatial data analysis capabilities that can reinforce the process of national and regional biodiversity conservation and policy-making, and long-term integrated resource management.
The world's tropical coastal zone contains coral reefs, one of the most productive and biologically rich ecosystems on the planet. Almost half a billion people live within 100 km (60 miles) of coral reefs and this population continues to grow along with expanding coastal development. The growth of cities, the building of roads and airports, dredging of harbours and shipping channels, and other construction projects are threatening coral reefs primarily from the deposition of sediment and poorly treated sewage. Damage tot he coral reef community as a result of unplanned coastal development leads to long-term socio-economic loss. By using Intercoastal Zone Management (ICZM) practices, a country can create sustainable coastal development projects that also serve to protect their coral reefs.The ProblemUnplanned coastal development projects not only damage coral reefs, but also local economies that are supported by tourism. Eighty-five percent of all tourism worldwide is in coastal areas, fueling a $385 billion dollar industry. The sustainability of reef ecosystems, a significant driver of this industry and the communities that it supports, are compromised by unplanned, high-impact development.Ecological Impacts of Unplanned Coastal Development:
Tourism Impacts on Coral Reefs : Increasing Awareness in the Tourism Sector by Tom van't Hof (2001) looks at the impact of tourism on the coral reefs of the Caribbean.
The International Coral Reef Initiative (ICRI) is one of the leading authorities in the fight for coral reef presevation. This organisation operates through regional bodies around the globe and is well recognised by governments and NGO's alike for experise in this regard. For more information ...
What is cyanide fishing?
Cyanide fishing is a popular method of
capturing live reef fish for the seafood and aquarium markets.
It is widely practiced in Southeast Asia and South Pacific and is starting
to spread to other parts of the world. Cyanide fishers squirt
cyanide into coral holes and crevices, where reef fish seek refuge.
The cyanide stuns the fish, making it easy for cyanide fishers to capture
their dazed prey. The cyanide poisons reefs and is extremely harmful
to coral polyps and other reef organisms. Furthermore, less than
half the fish caught with cyanide survive long enough to be sold to
aquariums or restaurants.
In the South Pacific and the Southeast Asia market demand for live reef fish has created incentives for local fishers to turn to modern fishing techniques, such as cyanide fishing, to support themselves and their families. The profits from live fish, such as grouper, wrasse, rock cod and snapper are many times higher than that of dead fish. Exporters demand much more money for live fish than dead fish at luxury fish markets in Asia. While most nations have decided that the profits from cyanide fishing are not worth its destructive cost, many governments do not have the resources to monitor and enforce laws against cyanide use.
What can you do to stop cyanide fishing?
The concept of sustaining biodiversity means conserving biological resources so that they last indefinately. According to the manual on Global Biodiversity Strategy (produced by World Resources Institute (WRI), The World Conservation Union (IUCN) and United Nations Environment Programme (UNEP) in 1992) the development of national and international policy frameworks that foster the sustainable use of biological resources and maintenance of biodiversity are important conservation objectives.
Conditions and incentives for effective conservation by local communities need to be created. Biodiversity conservation cannot be successful unless local communities receive their fair share of benefits from and assume a greater role in managing local biological resources.
The tools for conserving biological diversity must also be strengthened and applied more broadly. These tools include protected areas, seed banks, botanic gardens etc. The conservation tools cannot serve their purpose if they are underfunded and understaffed. The human capacity for conserving and using biodiversity sustainably must be greatly strengthened, particularly in developing countries. Conservation can only succeed if people understand the distribution and value of biodiversity, understand how it influences their own lives and aspirations, and learn to manage areas to meet human needs without diminishing biological diversity. Finally, conservation action must be catalyzed through international cooperation and national planning.
For futher information on coral reefs, threats and preservation visit the ICRIN website
Environment Programme, Regional Coordinating Unit