Download Due to warming waters, natural bleaching of corral reefs have taken

Bailey Heick
Neil Paz
Adrian Gonzales
Candace Aragon
The term "coral reef" generally refers to a marine ecosystem in which the main
organisms are corals that house algal symbionts within their tissues(Encyclopedia of
Earth).Coral reefs are the greatest expression of ocean life, and the most biodiverse
ecosystem on Earth with 30 of 34 known animal phyla present (PCRF, 2004). Coral
reefs form natural barriers that protect nearby shorelines from the eroding forces of the
sea, thereby protecting coastal dwellings, agricultural land and beaches (Nature
Conservancy, 2007). Coral reefs are created from calcium carbonate secretions made by
corals which are “soft-bodied polyps” (Lewis, 2004, p.471). The polyps attach
themselves to already existing coral in order to feed and take in sunlight. As Lewis
(2004) states, “A coral reef is at the same time an immense graveyard” (p.893). As layers
of coral add onto more layers, you get an enormous growth which creates an ecosystem
for other living species. Coral reefs are the only animal known to have an ecosystem
named after them. Kleypas (2007) states, “These ecosystems require fully marine waters,
warm temperatures, and ample sunlight.” Because of this, coral reefs are limited to
“shallow waters of tropical and subtropical regions” (Kleypas, 2007). Corals can live in
deeper, darker, colder waters, also known as cold-water corals, hardly develop reefs are
not well studied by scientists.
Coral reefs are usually classified into three categories:
1. Fringing reefs are simply reefs that grow attached to the shoreline (of
either continents or islands). Fringing reefs begin growth in shallow water
close to shore and tend to accumulate outward. Many reefs of the Florida
Keys are fringing reefs.
2. Barrier reefs typically grow along the outer edges of continental shelves,
separated from the mainland by open water, and are actually discontinuous
composites of many smaller reefs separated by channels. These often grow
on top of one or more ancient reef structures that had grown during the
previous “interglacial” but then dried out during the following glacial
periods (the Great Barrier Reef is an example of this type of reef).
3. Atolls are circular reefs enclosing lagoons, such as Bikini Atoll. Atolls
begin by colonizing a seamount or volcano, and then grow upward as the
seamount sinks and/or as sea level rises. Eventually, the seamount sinks
below the sea surface, while the coral reef continues to grow upward
resulting in the characteristic donut-shaped reef enclosing a central lagoon.
(Encyclopedia of the Earth).
Coral reefs have existed on Earth for many millions of years, but they are in a
crisis of dying at an alarming rate worldwide. In fact, an estimated 25% of coral reefs
have already disappeared and an estimated two-thirds of all coral reefs are at risk today
(PCRF, 2004). Coral reefs are subject to threats by nature and man.
In recent years, hurricanes have destroyed parts of the coral reefs. Infectious
diseases have led to overgrowth in algal food which clogged and killed many coral reefs.
Ocean acidification, which is a lowering of the pH in ocean water caused by an “uptake
of atmospheric carbon dioxide has been shown to decrease the rate at which corals and
coralline algae secrete their calcium carbonate skeletons” (Kleypas, 2007). Lastly,
cyanide and dynamite fishing have created destruction and poisonous waters for coral
reefs to survive. The loss of coral reefs has a domino effect that is killing millions of
species.
Due to warming waters, natural bleaching of corral reefs has taken place.
The alkalinity of the water has an effect on the pH. Acidic values are considered to be
below a pH of 5. If there are acidic conditions, it will affect the life cycle of corral reefs.
The best salinity value is between 34 and 37 parts per 1,000. Optimal temperatures
should also be between 25 and 31 degrees. Due to the fluctuations of the alkalinity of the
water, there is a threat of a 70 percent loss.
The threat of disease is also more prevalent with these altering temperatures
and pH values. A perfect condition would require adequate values of phosphorus and
nitrogen as well as a salt content with optimal temperatures. The values of pH could be
adjusted on a microscale for example by small additions of bicarbonate (HCO3).
However on a grand scale such as the ocean, there is a harder variable to control and that
is the overall size and volume. The parameters of the ocean are so large, and largely
affected by the climate of the earth, being able to manually adjust desired variables would
be a difficult task.
Furthermore, the conditions required are needed for photosynthesis which is the
energy cycle of ATP which allows a plant or organism to obtain food from carbon
dioxide. Natural contaminants from urban runoff chemical spills, and fishermen using
cyanide could directly affect the natural cycle of coral reefs. This can be accomplished if
a mechanism of photosynthesis is altered by an inhibitor. Cyanide is a natural
neurotransmitter inhibitor which would directly destroy any photosynthesis in a corral
reef. There is a role of human involvement with some of the destruction of these animals.
Furthermore reefs are important in the carbon cycle and can be used as medicine in some
treatments.
Another sphere which can affect coral reefs is the lithosphere. The lithosphere is
the outermost part of the solid earth. It includes Earth's surface. "The lithosphere is made
up of plates. These plates move against each other, causing some regions of Earth's
surface to rise and others to fall. Coral reefs are also part of the lithosphere because once
the calcium carbonate from the skeletons of the deceased animals hardens it begins to
form limestone which in turn forms metamorphic rocks.
The rise and fall of Earth's surface under the oceans can have major effects on
coral reefs. Volcanoes can affect coral reefs in a different way. Although volcanoes have
their sources deep in Earth's interior, they penetrate through the lithosphere" (Exploring
the Environment).Some islands are capped with coral reef at nearly 1000 feet above sea
level. This is possible due to the earth's plates shifting (Exploring the Environment).One
way the lithosphere affects coral reefs is by volcanic eruptions.
In the winter of 1992 after the eruption of Mount Pinatubo located in the
Philippines, parts of coral reefs were seen dying in the Gulf of Aqaba. This area is part of
the Red Sea between Africa and the Arabian Peninsula. 1992 was the coldest winter in
the 46 years since weather reports had been made for that area. "Mount Pinatubo had
injected large amounts of sulfuric acid aerosol high into the stratosphere. This aerosol
reflected sunlight, resulting in the cooler than average weather. When the Red Sea coral
began to die, scientists looked for possible reasons—volcanic dust's smothering the coral,
presence of hydrogen sulfide (H2S), disease, or some combination of causes. When
scientists measured water temperatures, though, they found cold water mixed very
thoroughly too great depths. (Cold water is usually found very deep with warmer water
near the surface. Here's what had happened: The unusually cold surface water had sunk,
helping to mix the water column. This helped to also mix nutrients (like phosphorous)
that normally stay deep in the cold water to near the water's surface. This resulted in the
growth of thick, red algal blooms. They are thought to have smothered the coral, blocking
out the sunlight. When temperatures returned to normal, the algal blooms died because
they no longer had the nutrients they needed. The reefs were soon healthy
again"(Exploring the Environment).The eruption of the volcano (the lithosphere) caused
the atmosphere to block the needed sunlight for the coral to grow (the biosphere).
In addition to natural events, humans often influence events in the biosphere.
When fertilizer on the mainland runs off, it increases nutrients in the sea. Plants that
thrive on nitrogen in the form of nitrates (contain the NO3- ion) from the fertilizer then
grow to the point that they can choke out other plants. This eutrophication (increased
nutrients) can lead to a decrease in biological diversity (Exploring the Environment,
2004).
As a major marine ecosystem, coral reefs are very important to the lives of
millions of plant and animal species, a variety of microorganisms, and humans. They
play other roles to the environment such as “serving as barriers between powerful ocean
currents and beaches, control nutrient flow to the oceans, and their inhabitants feed
millions of people” (Lewis, 2004, p. 909) it is estimated that coral reefs provide $375
billion per year around the world in goods and services. 500 million people rely on coral
reefs for their food and livelihoods. If the present rate of destruction continues, 70% of
the world's coral reefs will be destroyed by the year 2050 (Nature Conservancy, 2007).
References:
Earth Observatory
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.p
hp3?img_id=4335
Encyclopedia of Earth
http://www.eoearth.org/article/Coral_reef
Exploring the Environment
http://www.cotf.edu/ete/modules/coralreef/CRlitho.html
http://www.nature.org/joinanddonate/rescuereef/explore/facts.html
http://www.pcrf.org/reeffacts.html
http://www.kmuska.com/ocean/whatiscoral.html
http://www.cotf.edu/ete/modules/coralreef/CRbio.html
http://life.bio.sunysb.edu/marinebio/coralreef.html
Kleypas, Joanie (Lead Author); Jean-Pierre Gattuso (Topic Editor). 2007. "Coral reef."
In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental
Information Coalition, National Council for Science and the Environment). [First
published in the Encyclopedia of Earth October 18, 2006; Last revised August 15, 2007;
Retrieved November 10, 2007]. http://www.eoearth.org/article/Coral_reef
Lewis, R; Gaffin, D; Hoefnagels, M; Parker, B. 2004. In Life 5th edition. McGraw-Hill:
New York, NY. NOAA’s Coral Reef Information System 2007. In “What are corals and
coral reefs.” Revised January 23, 2007 and Retrieved on November 10, 2007 from
http://www.coris.noaa.gov/about/what_are/