Coral Reefs Cycle B: Causal Chains of Event to Sphere interactions
By Jennifer Haren, Amy Parks, Stephanie Sarver-Lanham, David Sims, Todd Tayloe
Date: October 9, 2010
1)
B> B>H> E> L> B> H> A> E
Coral are animals that are symmetric; they look the same all the way around. They are built
like sacs with a hole in one end that is surrounded by stinging tentacles. During the mating season
the coral polyp will release eggs and sperm into the water. The baby coral will float in the water until it
can find a hard surface to attach itself to. At this time it will form a shell combining the carbon dioxide
and calcium, found in the water. When this forms it makes calcium carbonate or what we know as
limestone. The coral will then live inside of this shell. When the coral dies it leaves behind its shell
which will then attract a young coral to repeat the building process all over again. This repeated
building upon the older dead coral is what makes a coral reef. A coral reef will need to have warm
water, marine life, and ample sunlight. It also has to be at the right depth.
Global climate change and the buildup of greenhouse gases will affect the Coral Reefs. What
happens is carbon dioxide lets in almost all of the sun’s radiation, but blocks much of the outgoing
radiation from the Earth. This will cause an increase in the Earth’s atmosphere. Some scientists
believe that human actions are increasing these greenhouse gases. With this warming of the Earth
the ice is starting to melt and could cause the ocean levels to rise. This has happened in the past
when the glaciers melted. As the graph below indicates the sea level has changed in the past but
there has been a steady increase in the sea level for the past 15 years. What happens is that the
water level will increase faster than the coral can build. This increase in the greenhouse gases is
causing carbon dioxide to collect in the seawater. The increased levels of Carbon Dioxide are
expected to slow the ability of the coral to calcify and build their skeletal reefs of calcium carbonate.
Eventually the Coral Reefs cannot get enough sunlight to continue to thrive and will stop building.
These reefs become known as drowned reefs. Reefs serves an important job, they protect some
shorelines from storms and surge water. They will help to reduce the wave size and buffer the shore.
When a reef dies the bioeroders will take the calcium carbonate from the reef and make the reef
smaller. This will cause the waves to get larger. With the increase in wave size more erosion will
occur. Additionally humans are migrating to the coastal areas and are developing these areas
heavily. This construction has caused an increase in sediment that run into the oceans. Coral Reefs
and the sponges that live on them act as filter. They filter out the particles suspended in the water
column, which makes the water clearer. This allows sunlight to penetrate deeper in the ocean. If more
sediment and pollution is put into the oceans and there is less Coral to filter out these sediments the
water will become less clear and the sunlight could stop going as far down into the water. If the
sunlight does not reach the Coral then the Reef can die.
Picture of a drowned reef.
Picture of what has happen in the past.
B – the coral itself> B – humans > H – melting water, sea level increases > E – coral reefs dies > L –
shoreline affected > B – humans building, pollution > H – water getting cloudier > A – sunlight cannot
penetrate > E – Coral reefs dies.
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http://www.fao.org/focus/e/fisheries/icam.htm
http://oceanworld.tamu.edu/students/coral/coral1.htm
http://earthobservatory.nasa.gov/Features/Coral/
http://www.eoearth.org/article/Coral_reef?topic=49570
http://www.cotf.edu/ete/modules/coralreef/CRatmo.html
http://plaza.ufl.edu/amb1685/Coral_Bleaching1.html
http://fishingnj.org/artcoral4.html
http://reefrelief.org/the-importance-of-coral -reefs/
2)
E>L>B>L>H>B
Fringing reefs are initially created from an extinct volcano, which as the volcano begin to subside; the
shelves are covered by shallow, warm water. Coral reefs begin to form when free-swimming coral
larvae (planulae) attach to the submerged edges of volcanoes, islands or continents. The geographic
locations of coral reefs are restricted due to the algal-cnidarians symbiotic machinery needing a
narrow and consistent band of environmental conditions to produce the copious quantities of
limestone necessary for reef formation. Coral reefs support more than 25% of all marine life. This
marine life supports human populations economically, culturally, and aesthetically. Human depend on
coral reefs for their livelihood (fishing and tourism), a food source, and medicine. The increase in
tourism leads to the development of coastlines, which presents problems to the delicate ecosystems
of coral reefs. Development of hotels and resorts can cause erosion and sediment to run into the
water sources. Along with the sediment, comes chemicals, some from fertilizers, mixed into the
shallow seas that are home to the coral reefs by runoff. Plants that thrive on nitrogen, found in
fertilizers, can grow excessively and cause algal blooms. These algal blooms can block the sunlight
for the coral and the zooxanthellae in the coral cannot carry out photosynthesis and leave the coral
causing the bleaching effect and the coral to die. The invasion of humans into such a pristine
environment is currently a reason for the demise of coral reefs. Our only hope to preserve the current
reefs is to set limitations, not only on tourist, but on construction and fishing along the coastlines that
currently serve as home to such a majestic environment.
http://img.geocaching.com/cache/1f63f1a6-29ab-4911-8046-07985381126f.jpg
http://www.ncdc.noaa.gov/paleo/outreach/coral/sor/sor_global.html
Dr. Eric Wolanski of the Australian Institute of Marine Science, explains the process of fringing reefs
as a development of a coral system found in tropical climates around volcanic islands. Studies
recently performed by NOAA affiliates in Japan indicate that the coral formation occurs in
environments temperatures that do not fall below 18°C for extended periods of time, require very salty
(saline) water ranging from 32 to 42 parts per thousand, and water must also be clear to permit high
light penetration. According to the National Parks Conservation Association, USGS, and Sea and
Sky; marine life in the coral reefs is comparable to the abundance of life in the rainforest. David
Adams published a conglomeration of articles, using reputable sources, all of which state human
impact decreasing coral reefs throughout the world and not just in localized areas for several different
reasons, one of which is the influx of hotels and resorts to tropical coastlines. The “Theme section on
the Aspects of interactions between humans and coral reefs” by R. B. Pollnac compiles studies of the
impact of humans specifically the contamination of coastal waters by toxic runoff and its impact on
coral reefs, all of the studies link this aspect of human interference to the decline of coral reefs.
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A map of sedimentation problems combines effects of increased runoff from deforestation, the
dumping of mine tailings, and sediment from a variety of construction projects. Sediment in low
amounts reduces coral growth and resilience to stress. In large amounts, particularly during
storms, sediment can bury corals or whole coral communities.
http://www.ncdc.noaa.gov/paleo/outreach/coral/sor/sor_global.html
http://scrippsnews.ucsd.edu/Releases/?releaseID=666
http://coris.noaa.gov/about/what_are/
Exploring the Environment site: “Coral Reefs: Anthrosphere”;
http://www.cotf.edu/ete/modules/coralreef/CRanthro.html
http://books.google.com/books?hl=en&lr=&id=NvcuL7pU7EC&oi=fnd&pg=PA1&dq=creation+of+fringing+reefs&ots=LtvfOwOadV&sig=phmaefY
UgAMTV-iWb5vIwgvoqK8#v=onepage&q&f=false The Physical Oceanic Environment by Eric
Wolanski
http://www.globalissues.org/article/173/coral-reefs
http://resources.metapress.com/pdf-preview.axd?code=330t647388552537&size=largest
http://www.eoearth.org/article/Coral_reef?topic=49570
http://www.ncdc.noaa.gov/paleo/outreach/coral/sor/sor_global.html
3)
H>L>A>B>E
Warmer global temperatures are expected to cause an intensification of the hydrologic cycle, with
increased evaporation over both land and water. The higher evaporation rates will lead to greater
drying of soils and vegetation, especially during the warm seasons. If global warming continues to
persist, more windblown dust will be carried and deposited in areas of coral reefs in the Caribbean
due to droughts in Africa. When a drought occurs in Western Africa, some coral in the Caribbean will
die. West African dust, which is thickest during drought years, is carried by winds to the Caribbean.
The transfer of African dust is a double whammy for coral reefs in the Caribbean, not only does the
dust reduce sunlight, but it contaminates the water with deadly fungi. This dust contains the fungus
aspergillus, which thrives on sea fans, a type of coral, in addition to the toxic pesticides used in
agricultural processes of Africa. The pathogenic particles are a concern for both human and marine
life; an increase in toxic chemicals will reduce not only the coral, but also all marine life that inhabits
the coral reef. The thick dust will also block out the sun’s rays, resulting in reduced photosynthesis by
the symbiotic algae. A decrease in symbiotic algae will diminish the coral’s food source, leading to
the death of the coral.
The Union of Concerned Scientists has published an article based on several studies using climate
projection models. These models indicate projected changes in the distribution and timing of rainfall in
combination with a decrease in summer rainfall and increased evaporation will lead to more severe
and longer-lasting droughts in some areas. This suggests that increasing drought frequency has the
potential to affect land-based natural and managed ecosystems, coastal systems, and both
freshwater quality and quantity. According to the USGS, mineral dust from Africa’s Sahara desert can
be transported thousands of miles through the atmosphere to the Caribbean every year. Scientists
are currently studying the African dust found in air of Tobago and St Croix (Caribbean locations).
http://www.wri.org/publication/content/7851
http://media3.washingtonpost.com/wpdyn/content/graphic/2007/08/20/GR2007082000
075.gif
These two diagrams show what humans to increase greenhouse gasses and how that affect the growth of
phytoplankton and the ability to absorb oxygen.
Source: http://www.cotf.edu/ete/modules/coralreef/CRatmo.html and
http://www.cotf.edu/ete/modules/coralreef/CRatmo.html
Citations:
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http://coastal.er.usgs.gov/african_dust/ and
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http://www.cotf.edu/ete/modules/coralreef/CRlitho.html
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http://www.star.nesdis.noaa.gov/star/Eakin_M.php
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http://ezinearticles.com/?Drought-Affects-Coral-Reefs---Small-Hotel-Industry-and-TourismThreatened&id=4099682
4)
B> A > H > E
The increase in carbon dioxide into the Earth’s atmosphere is currently being linked to the increased
burning of fossil fuels (human impact) Fossil fuels have been considered the main source of fuel for
countries throughout the world. Often industrialization is a step in which as developing nations
progress through, unfortunately until recently the backbone of industrialization has been fossil fuels,
the main contributor to atmospheric carbon dioxide. Carbon dioxide from the Earth’s atmosphere is
rapidly accumulating in the ocean waters because it is a soluble gas. The high levels of CO2 in the
seawater will cause a rise in the acidity level, which will then reduce the amount of carbonate that
coral animals need to construct reefs. Ocean acidification will dramatically reduce the ability of corals
and other organisms to produce their calcium carbonate skeletons and shells. What this means is
that coral reefs are slowing dissolving.
“Recent experimental studies conducted both here in Bermuda, by Dr. Alexandra Amat and BIOS
Senior Research Scientist Dr. Nick Bates, and elsewhere show a decrease in the ability of some coral
species to produce calcium carbonate under lower dissolved carbonate conditions and higher ocean
acidity.
http://environmental.lilithezine.com/images/Climate-Change-Chart-01.jpg
According to Ecology.com people from developed nations throughout the world would agree that it
was coal that fueled the Industrial Revolution, forever changing the way people would live. Half the
carbon dioxide released into the atmosphere by the burning of fossil fuels is actually winding up the
oceans, says new research published in the journal Science. The studies so far reveal a potentially
dire outlook for coral reefs due to ocean acidification. But all is perhaps not bleak for the future of our
coral reefs. BIOS's preliminary studies suggest that some coral species are adaptable to changing
ocean chemistry and potentially capable of calcifying at healthy rates in the future. Other researchers
have recently demonstrated that very low voltage electricity passing through wire cages can help
corals to produce calcium carbonate. Nonetheless, the potential impact of increased ocean
acidification on coral reefs and other species that secrete hard calcium carbonate skeletons is an
important, emerging question in marine science.”
Source: http://www.bios.edu/Labs/co2lab/research/Coral.html
http://www.naturalnews.com/001398.html
http://ecology.com/features/industrial_revolution/
http://www.sustainabletable.org/issues/energy/
http://environmental.lilithezine.com/Climate-Change.html
5)
L>A>H>B>E>A>H>B
A volcanic eruption can spew dust and sulfuric acid aerosols high into the stratosphere. Any coral
reefs in the area are sure to be impacted by this event. The gray clouds of dust prevent sunlight from
penetrating and reaching the Earth’s surface. The lack of sunlight cools the atmospheric temperature.
Cool surface water begins to sink and mix with deeper nutrient rich water. This nutrient rich water
results in overgrowth of red algae, called algal blooms. Algal blooms smother the coral by blocking
out the sunlight. In addition, the sulfuric acid aerosol that is released by the volcano, mixes with water
vapor in the atmosphere to create acid rains which fall onto the Earth’s surface. Acid rain will alter the
pH of the shallow seas, eliminating coral that is sensitive to the acidic change. The dust will smother
the coral preventing photosynthesis for the algae that feeds the coral. Coral bleaching will occurs due
to the diminished amount of sunlight. Once the dust and ash settle from the volcanic eruption, the
atmosphere will no longer carry a thick cloud of dust. When the atmosphere returns to normal, the
hydrosphere will begin to warm. The warming of the shallow seas will prevent surface waters from
mixing with deep, nutrient rich water. As the nutrients decrease the red algae will begin to die. The
death of the algal blooms, in turn will allow the symbiotic algae of the coral to begin to thrive. The
return of warm, clear waters and a nutritional base will encourage the regrowth of coral in the area.
http://rst.gsfc.nasa.gov/Sect16/originals/Fig16_3.jpg
http://terra.nasa.gov/FactSheets/Aerosols/volcano.jpg
Sediments covered the coral reefs of the Gulf of Aqaba, coral bleaching occurs.
http://article.wn.com/view/2010/09/05/RP_scientists_note_massive_bleaching_of_coral_reefs/
http://www.indiana.edu/~sierra/papers/2006/Robison_files/image002.jpg
This cycle occurred when Mount Pinatubo erupted in 1992. Following the eruption, the coldest winter
that the Philippines had every experienced proceeded. Scientist found that the coral in the Gulf of
Aqaba were dying due to this cycle of events. Additionally, scientist have found that after an eruption
of the Montserrat Volcano in the Caribbean, Garibaldi Reef experienced coral bleaching due to a
change in pH and a layer of ash sediment that covered the reef.
Citations
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http://www.cotf.edu/ete/modules/coralreef/CRlitho.html
http://www.sei.org/impacts.html
http://www.unescap.org/mced2000/pacific/background/disasters.htm
http://www.nature.com/nature/journal/v377/n6549/abs/377507a0.html
http://www.statemaster.com/encyclopedia/Mount-Pinatubo