Are Coral Reefs really the Rainforest of the Sea? A Comparison between Coral Reefs and Rainforest (Final)
This topic submitted by Abby Hils (
firstname.lastname@example.org) at 5:55 PM on 6/5/07.
Some of our happy group at Lighthouse Cave,
San Salvador, Bahamas.
Coral reefs are aragonite structures produced by living organisms, found in shallow, tropical marine waters, which have little to no nutrients in the water. These amazing underwater worlds have varied over millions of years in growth, diversity of species and their interactions, water quality, to locations. However, human contact and needs of food and money have caused a decline the biodiversity of reefs. Just as coral reefs have changed over time, so have rainforests. Rainforests are numerous trees of assorted heights containing high biodiversity, with minimal nutrients in the soil and high rainfall. Again, humans have caused the rainforest and its diversity to decrease immensely because of our need for land, food, medicine, etc. Now, some say coral reefs are “the rainforests of the sea”, but from reading the Enchanted Braid, Osha Gray Davidson suggests that rainforest are “the coral reefs of land.” (Davidson, 1998). Both of these habitats are disappearing because of human contact. By comparing these two habitats’ biodiversity, their resilience and ability to adapt, and the effects of human interaction, will reveal that coral reefs and rainforests are analogous and how humans need to care for them.
Rainforests are the Earth’s oldest living ecosystems. Picture trees with heights well beyond our eyesight and widths larger than four people holding hands in a circle, vines creeping up the trees, while the colors and sizes surrounding you makes you feel plain and minuscule. The music around you fills your eardrums with buzzes, bird cries, monkey warnings, snarling jaguars, branches shaking from jumping monkeys, frogs croaking to each other, and so on. Even the smells are surprising. The air is moist and humid because the rain is about to fall again, each flower you stop by has its own unique and wonderful smell, and the freshness of oxygen fills your lungs as you breathe out only a minute amount of carbon dioxide for the trees to breathe. However, this wonderful array of fauna and flora of this ecosystem has been taken for granted. Tropical rainforests are a world like none other; and their importance to the global ecosystem and human existence is paramount. Unparalleled in terms of their biological diversity, tropical rainforests are a natural reservoir of genetic diversity, offering a rich source of medicinal plants (birth control hormones, cocaine, stimulants, and tranquilizing drugs), high-yield foods (coffee, fruit, chocolate, and sugar cane), and a myriad of other useful forest products, such as lumber. Furthermore, they are an important habitat for migratory animals and sustain as much as 50 percent of the species on Earth, as well as a number of diverse and unique indigenous cultures (Butler, 2007). An estimation of hundreds of millions of new species of plants, insects, and microorganisms are still undiscovered and yet unnamed by science (Barkmann, 2007).
Despite their monumental role, tropical forests are restricted to the small land area between the latitudes 23.5° North and 23.5° South of the equator, or in other words between the Tropic of Capricorn and the Tropic of Cancer. In this region sunlight strikes Earth at roughly a 90-degree angle resulting in intense solar energy, as the latitude increases the intensity decreases. This intensity is due to the consistent day length on the equator: 12 hours a day, 365 days per year, while regions away from the equator have days of varying length. This consistent sunlight provides the essential energy necessary to power the forest via photosynthesis. The other important characteristic of rainforests is apparent in their name. Rainforests lie in the intertropical convergence zone (ITCZ) where intense solar energy produces a convection zone of rising air that loses its moisture through frequent rainstorms. Rainforests are subject to heavy rainfall, at least 80 inches (2,000 mm), and in some areas over 430 inches of rain each year (Butler, 2007). The moisture of the rainforest from rainfall, constant cloud cover, and transpiration, creates intense local humidity. Each canopy tree transpires some 200 gallons of water annually, translating to roughly 20,000 gallons of water transpired into the atmosphere for every acre of canopy trees (Butler, 2007). Large rainforests, and their humidity, contribute to the formation of rain clouds, and generate as much as 75 percent of their own rain. The Amazon rainforest is responsible for creating as much as 50 percent of its own precipitation (Butler, 2007). These large trees also are the huge “lungs of our planet,” providing the essential environmental world service of continuously recycling carbon dioxide into oxygen. More than 20 percent of the world’s oxygen comes from the Amazon Rainforest (Butler, 2007).
Currently, tropical rainforests, like so many other natural places, are a scarce resource. The vast swaths of forest, swamp, desert, and savanna that carpeted Earth's land surface a mere five generations ago have been reduced to scattered fragments; today, more than two-thirds of the world's tropical rainforests exist as fragmented remnants (Butler, 2007). Just a few thousand years ago, tropical rainforests covered as much as 12 percent of the Earth’s land surface (about 6 million square miles), but today less than 5 percent of Earth's land is covered with these forests (about 2.41 million square miles). The largest unbroken stretch of rainforest is in the Amazon River Basin of South America. Over half of this forest lies in Brazil (The Amazon), which holds about one-third of the world's remaining tropical rainforests. Another 20 percent of the world's remaining rainforest exists in Indonesia and Congo Basin, while the balance of the world's rainforests are scattered around the globe in tropical regions (Richards, 1996).
As tourist walk through these magnificent trails, some of the vertical layers of the rainforests are present: the overstory, the canopy, the understory, the shrub layer, and the forest floor. Each layer has its own unique plant and animal species interacting with the ecosystem. The highest layer is the overstory. This layer refers to the crowns of emergent trees, which soar 20-100 feet above the rest of the canopy. Most of the animals present are arboreal and live off the fruits and leaves of the high emergent trees.
Below the overstory, the canopy stretches for vast distances, seemingly unbroken. Despite overlapping tree branches, canopy trees rarely interlock or even touch. Instead, there is some separation from one another by a few feet. Along with branches, the billions of leaves of the canopy act as miniature solar panels, providing the source of power for the forest by converting sunlight to energy through photosynthesis. Since the rate of photosynthesis of canopy trees is so high, these plants have a higher yield of fruits, seeds, flowers, and leaves, which attract and support a wide diversity of animal life which hop, glide, fly, and climb. Besides attracting a broad array of wildlife, the canopy plays an important role in regulating regional and global climate because it is the primary site of the interchange of heat, water vapor, and atmospheric gases (Butler, 2007). In addition to collecting solar energy and regulating the climate, the canopy shields the understory from harsh and intense sunlight, drying winds, and heavy rainfall, and retains the moisture of the forest below. Thus, these trees act as a shield to the interior region from the extremes of the canopy.
Now, the canopy is the dense ceiling of closely spaced trees and their branches, while the understory is the term for more widely spaced, smaller tree species and juvenile individuals that form a broken layer below the canopy. Underneath the understory is the shrub layer, which consists of shrubby species and juvenile trees that grow only 5-20 feet off the forest floor (Butler, 2007). Here, small berries grow, along with many species of animals that are camouflage dark, to hide from other prey or predators.
The last floor is the forest of ground floor. Despite its constant shade, the ground floor of the rainforest is the site for important interactions and complex relationships. The forest floor is one of the principal sites of decomposition, a process paramount for the continuance of the forest as a whole. Moreover, because decomposition is rapid, this creates fewer amounts of nutrients in the ground making it slightly acidic. It is also home to thousands of plants and animals, and provides support for trees responsible for the formation of the canopy. The forest floor is the ground layer of the forest made up of the trunks of trees, fungus, and low-growing vegetation. These layers are not always distinct and can vary from forest to forest, but serve as a good model of the vegetative and mechanical structures of the forest (Butler, 2007).
The sad fact is that rainforests around the world continue to fall. An estimate of 70-90 percent of life in the rainforest exists in the trees, above the shaded forest floor (Butler, 2007). However, the demand for more land for agricultural, medical, economical, and financial purposes has increased the reduction of trees. According to the United Nations Food and Agriculture Organization (FAO), during 1990-2000 the net forest loss was a staggering 8.9 million hectares per year. Since 2000, this annual rate has decreased only slightly to 7.3 million hectares per year, roughly the size of entire nations of Panama or Sierra Leone. According to the FAO, much of this deforestation occurred in developing countries, such as Brazil, Indonesia, Myanmar, and Sudan (Wish, 2006). Why should anyone care if some plants, animals, mushrooms, and microorganisms perish? Rainforests are often hot and humid, difficult to reach, insect infested, and have elusive wildlife. Nevertheless, the concern should not be about losing a few plants and animals; mankind stands to lose much more. By destroying tropical forests, we risk our own quality of life, gamble with the stability of climate and local weather, threaten the existence of other species, and undermine the valuable services provided by biological diversity (Butler, 2007). We are only one species in this world, so another species death will affect us eventually. Tropical rainforests have historically not supported dense human populations. Food resources within the forest are extremely dispersed due to the high biological diversity and what food does exist is largely restricted to the canopy and requires considerable energy to obtain (Bailey, 1989). In addition, rainforest soils are often thin and leached of many minerals and the heavy rainfall can quickly leach nutrients from rainforest plots cleared for cultivation. Nonetheless humans have and do exploit rainforests for food and shelter in several parts of the world: some farmers, some gathereres who like to trade products, others exploit the land that live nearby (Bailey, 1989).
Rainforests need a conservation movement because they are constantly harvested for their resources and land. Deforestation of the world’s rainforests not only removes a carbon sink, it also releases carbon dioxide into the atmosphere. The Amazon rainforest has been referred to as the “lungs of the world" however there is no scientific basis for such a claim as tropical rain forests are known to be essentially oxygen neutral, with little or no net oxygen production (Barkmann, 2007). Yet, deforestation continues. Supporters of deforestation argue that some tree farms act as alternative habitats to old-growth forests because “stable” populations of animals can exist there. Research has not proven the long term survivability of the populations in these farms because breeding has not been observed on any of the farms. Another problem with farming arises because the soil is does not have much nutrients. The top-soil is so fertile because of the constant litter of organic material from the trees above, but once those trees are removed the soil quickly becomes unfertile. Farm animals also graze the land unsustainably so pastures must keep on expanding, cutting down more old-growth forest (Wish, 2006).
People have started to notice the importance of conserving rainforests, but it is a slow awakening. There are a couple ways to go about conserving a rainforest; one is to ensure that conservation will provide economic incentives for the farmers, and the other is to work with the indigenous people to understand a more sustainable way of living (Barkmann, 2007). Speaking with the local people living in, and around the rainforest, conservationists can learn information that would allow them to best focus their conservation efforts. The most economically and ecologically feasible option is to convert forests to agro forestry, meaning shade-grown coffee is cultivated (Barkmann, 2007). This allows for the forest to remain somewhat functional and the farmer can still make some money. Another way conservation has become the most economically beneficial option is through carbon credits. Carbon credits are a tradeable permit scheme. They provide a way to reduce greenhouse gas emissions by giving them a monetary value to carbon. By way of example, assume a factory produces 100,000 tonnes of greenhouse emissions in a year. The government then enacts a law that limits the maximum emissions a business can have. So the factory is given a quota of say 80,000 tonnes. The factory either reduces its emissions to 80,000 tonnes or is required to purchase carbon credits to offset the excess. So, a credit gives the owner the right to emit one tonne of carbon dioxide. Under the Kyoto Protocol, countries must reduce their emissions of carbon dioxide by 5% below the 1990 levels before 2012 (Barkmann, 2007). Through conservation or reforestation of the rainforest, countries can receive carbon credits. Recycling is a great way of slowing deforestation. We use aluminum for popcans and other storage items, but bauxite creates aluminum which comes from the rainforest. So, recycling cans can slow the cutting of wood down.Without the rainforest, human life will slowly fade. As Davidson stated, “We really are ‘just one species among many’—and sooner or later we must act the part” (Davidson, 1998).
If humans cannot save the rainforest on land, which we see plants, birds, and land animals everyday, how are we suppose to protect habitats that we do not encounter as often such as the oceans, coral, and marine creatures? Now imagine floating in clear, warm, shallow waters on a beautiful sunny day, gazing at the plethora of color and life underneath. What an incredible view! This world beneath has mesmerized mankind for many years and may never be completely revealed to us. Coral reefs are located in the warm, tropical waters worldwide. They are among the most diverse and productive communities on Earth. Located roughly between the Tropics of Cancer and Capricorn, about 20° N and 20° S of the equator. Reefs estimate to cover 284,300 square kilometers, with the Indo-Pacific region (including the Red Sea, Indian Ocean, Southeast Asia and the Pacific) accounting for 91.9% of the total. Southeast Asia accounts for 32.3% of that figure, while the Pacific including Australia accounts for 40.8%. Atlantic and Caribbean coral reefs only account for 7.6% of the world total (Green, 2001). There are several famous coral reefs are, the largest is the Great Barrier Reef off the coast of Australia, the second largest is the Belize Barrier Reef off the coast of Central America, and the deepest photosynthetic coral reef is the Pulley Ridge which is 250 miles west of Cape Sable, Florida.
To understand the composition of reefs, scientists have classified here are three types of reefs: fringing reefs, barrier reefs, and atolls. Each range in diverse flora and fauna. Fringing reefs occur along shorelines of continents and islands and commonly found in Hawaii and the Caribbean. Barrier reefs located farther offshore than fringing reefs, occur most often in the Indo-Pacific and Caribbean. Atolls are a series of low coral islands surrounding a central lagoon, frequently found in the Indo-Pacific. The largest reef in the world, the Great Barrier Reef in Australia is longer than 1200 miles—that is longer than the distance between Seattle, Washington and Los Angeles, California!
Snorkeling and scuba diving are major tourist activities, which demonstrate the underwater world that many love. Although coral reefs have been around for millions of years, the reefs we see today as we snorkel and dive occurred over the past 5,000 to 10,000 years (Kreger, 2005). Coral reefs cover only a tiny fraction, less than .2 percent of the ocean's bottom, yet they contain more than 25 percent of all marine life (Kreger, 2005).
The main attraction of scuba divers and snorkels are the bright colors that rest beneath them in the water. Most of these bright colors are sessile animals found in the animal phylum Cnidaria, which feed upon zooplankton and small crustaceans. Many think that coral is just a plant, but in reality, they are carnivorous animals. There are two types of corals: hard and soft. Hard corals are considered the reef builders, while soft do not build reefs but just subsist on or near reefs. Some common examples of hard corals found in the Bahamas are elkhorn and staghorn, boulders, brains, pillars, and star and flower corals (Castro, 2000). Some of the common soft corals are sea whips, sea rods and sea fans. However, coral make up only a small part of the life found on the reefs. These reefs provide habitat for numerous other species. Countless colorful fish inhabit the reef. Damselfish, gobies, parrotfish, sergeant majors, black durgons, angelfish, tangs, snappers, chubs, fairy basslets, and hundreds of other beautiful fish call the reef home (Castro, 2000). These fish are brightly decorated to attract fish of the opposite sex in order to reproduce. In addition to these rainbow fish, mollusks and gastropods, like the awesome flamingo tongue, sea slugs, snails and clams live around the reef too. Often, these critters eat coral polyps or algae that may be growing on the corals and reef substrate (Castro, 2000). There are also many other species of fungi, sponges, sea worms, crustaceans and mollusks that bore into coral skeletons for protection and cause bioerosion. This creates the fine white sand that surrounds many tropical islands. Octopi, squid, rays and skates, shrimps, lobsters, and even nurse or reef shark enjoy the protection and food provided by the coral reef. Other organisms that inhabit the coral reefs include sea urchins, jellyfish, oysters, turtles, and sea anemones (Cousteau, 1985). Another major feature of reefs is the algae. Algae comes in all sorts colors, which are from the major groups green, red, brown, blue-green, that grow on coral reefs too. Algae are popular food item for many fish and other reef critters. Sometimes algae reefs are mistaken for coral reefs. However, most of the reefs in the Caribbean are coral reefs. The corals are the composers of the reefs, calcium carbonate structures built up upon hundreds of years of coral polyp life and death.
This beautiful array of color and life disregards threats that are destroying this magnificent universe underwater. Human activity continues to represent the single greatest threat to coral reefs. In particular, pollution and over-fishing are the most serious threats to these ecosystems. Dragging weighted nets across the floor breaks the coral and scoops loads of the wildlife out of the ecosystem creating turmoil in the environment. Extensive and poorly managed land development threatens the survival of coral reefs because of the large amounts of sediment that flow into the ocean. 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 because the demand for shrimp throughout the world has amplified (Murtough, 2007). Even sea-grass, which also helps absorb the sediments and nutrients traveling towards the reefs, are being destroyed because the grass hides the fish and other organisms that we want for food such as fish, urchins, and clams. If the water becomes too rich in nutrients because there are no mangroves or sea-grass beds to absorb them, fleshy algae and phytoplankton will thrive. These algal blooms suffocate everything underneath it because it takes up the sunlight for energy. 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 significant factors affecting water quality on inshore reefs (Murtough, 2007).
A less obvious threat to reefs is over-fishing. People think that there is an overabundance of fish in the sea. Over-fishing is a problem in many parts of the world. People know the problems cod and salmon fishermen have faced with a smaller supply of fish. Money is an issue, but it takes more than ten years for the population to rebound (Davidson, 1998). Over-fishing of certain species near coral reefs can easily affect the reef's ecological balance and biodiversity. One example where over-fishing has caused problems is with groupers. Grouper is a very popular fish to eat. With less grouper, the number of damselfish increased. Damselfish are one of the grouper’s preys. Without the grouper eating it, the increased amounts of damselfish created pockets in coral because they feed upon the algae growths in these pockets. In time, algae could take over a reef, essentially smothering it, again suffocating everything. All of these events are due to a reduction in top predator fish.
Another problem is the physical destruction of reefs due to boat and shipping traffic is also a problem. Many boats and huge ships accidentally beach themselves over coral reefs, which in turn breaks off many of the coral and kills many too. Another problem is the live food fish trade, which is a driver of decline due to the use of cyanide and other chemicals in the capture of small fishes. These fish become either pets or eventually a dinner. The chemicals used, break down the coral or kill it to make the opening of the coral easier. These chemicals affect many surrounding corals too. Finally, the boats and cars of humans, have increased the carbon dioxide in the air, which is causing the last greatest threat to many coral reefs, global warming. Above normal water temperatures due to climate phenomena such as El NiĖo and global warming, can cause coral bleaching. According to The Nature Conservancy, if destruction increases at the current rate, 70% of the world’s coral reefs will have disappeared within 50 years (Hughes, 2003). This loss would be an economic disaster for people living in the tropics. With increased human population and improved storage and transport systems, the scale of human impacts on reefs has grown exponentially (Hughes, 2003). However, most people do not realize this because there seem to be plenty of reefs still around, but they are shrinking at a rapid rate.
Currently researchers are working to determine the degree various factors affecting the reef systems. The list of factors is long but includes the oceans acting as a carbon dioxide sink, changes in Earth's atmosphere, ultraviolet light, ocean acidification, biological virus, impacts of dust storms carrying agents to far-flung reef systems, various pollutants, impacts of algal blooms and others. Reefs are threatened well beyond coastal areas and so the problem is broader than factors from land development and pollution. These do cause considerable damage, but they are simply a part of the problem. According to the U.S. Environmental Protection Agency’s Coral Reef Initiatives, an estimated 10 percent of Earth's coral reefs have already been seriously harmed, and a much higher percentage is threatened (Kreger, 2005). Coral reefs vast biodiversity has influenced many governments worldwide to take measures to protect these features. In Australia, the Great Barrier Reef Marine Park Authority protects the Great Barrier Reef and this reef is the subject of many plans and pieces of legislation, including a Biodiversity Action Plan. In the Florida Keys, the no-take protection from the Florida Keys National Marine Sanctuary protects the keys and their areas by monitoring the reefs day to day. There is also the Committee on Reef Area Loss (CORAL), which has been looking into ways to prevent such a loss of biodiversity possibly by building artificial reefs where natural reefs are being destroyed (Kreger, 2005). Nonetheless, humans need to help protect and allow these beautiful creations to continue to redevelop.
From all the information gathered, both rainforests and coral reefs are unique and probably worthy of the sound-bite analogy. Both concentrate diversity, have complex habitat architecture and are highly productive habitats. Species richness and canopy heights are greater in rainforests, while gross productivity is greater on reefs. Taxonomic composition differs significantly too. In rainforests, most species are insects, angiosperms and birds. Reefs have no marine insects, hardly any angiosperms and some birds that do use the reef. These birds do affect the water quality and productivity of coral due to their feces. Coral reefs, though, have much greater higher-order diversity (e.g., number of phyla). While there is a wider phyletic range of primary producers (endosymbionts, plankton, and multiple phyla of benthic algae), within group diversity for each it is relatively low. For example, species richness in algae is much lower than that for angiosperms and reef fish are less diverse than rainforest birds. There are low diversity reefs that have many of the same zones, groups and ecosystem function of high diversity reefs. However, because the rainforest covers about ten times the land that coral reefs do (2 percent compared to .2 percent), the coral reefs could outnumber rainforests if they both had equal territory. Overall, each of these habitats has amazing characteristics of which, us, humans should take extreme care.
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