David Wollensak
Ms. Borowski
Scientific & Technical Writing
Literature Review
Importance of Coral Reefs
Coral reefs provide for more organisms per unit area than any other form of marine
ecosystems. Of these organisms, 800 species are corals, 4,000 species are fish, and much more
species are yet to be identified. The biodiversity of these super-ecosystems contributes to the
possibilities of cures for bacterial infections in humans, arthritis, viruses, and cancer. In addition
to advancements in health, another benefit provided by coral reefs is that these marine
environments produce trade goods and supplies that amount to $375 billion each year. Also,
coral reefs protect coasts from tidal damage and avert erosion. The reefs protect valuable
wetlands along the coast, and they also provide shelter to harbors and ports from storm waves.
Across the globe, approximately 500,000,000 people live within 100 kilometers from a coral reef
and are beneficiaries of the services provided by the reef (Importance of Coral Reefs, 2008).
Basics of Coral
Most corals maintain a symbiotic relationship with dinoflagellates, which are unicellular
protozoan, zooxanthellae. The coral provides shelter for the zooxanthellae and also the required
chemicals used by the dinoflagellates during photosynthesis. For the coral, the zooxanthellae
produces oxygen which assists the coral rid itself of waste. The zooxanthellae also provides the
coral with compounds produced through photosynthesis that contribute to the coral in structuring
its calcium carbonate skeleton. The symbiotic relationship between the zooxanthellae and the
coral is essential to the life of coral and sustainability of coral reefs (Symbiotic Algae, 2011).
Coral Bleaching
Coral bleaching is when the coral host excommunicates the zooxanthellae algae living in
its tissues. When this occurs, the coral will transform into a white ghost of its previous self (the
zooxanthellae algae provide the coral with its color). When this event occurs, the coral is not
dead. However, the coral is placed under extreme stress and becomes prone to mortality. In the
past, mass bleaching events have dotted the timeline, wiping out frightening amounts of coral
from the ocean. For example, the Caribbean lost 50% of its coral reefs due to a mass bleaching
phenomenon. Events similar to this one occur globally (What is Coral Bleaching, 2015).
Figure 1. Image of bleached coral next to a healthy coral in the Great Barrier Reef (Hoegh-Goldburg,
2015).
Basics of UV Light
Light’s frequency is provided by the amount of energy the light contains; light with high
energy has a high frequency and light with low energy has low frequency. Wavelengths of high
energy light fluctuate at high speeds and wavelengths of low energy light fluctuate at low speeds.
At the moment of contact between light and a material, the material does three things to the light:
scattering the light (bouncing the light off in various directions), allowing the light to pass
through, or absorbing the light (either completely or only in specific wavelengths).
Scattering
Transmission
Absorption
Figure 2. Depicted above are the reactions of light when it comes in contact with an object.
The electromagnetic spectrum is the array of types of light given off by the sun. In the spectrum,
ultraviolet light falls between visible light (while some ultraviolet light still being visible) and xray. The measurements of the wavelengths of ultraviolet light range from 100 to 10,000
angstroms. An angstrom is a measurement of length, which is equal to one tenth of one
nanometer (The Nature of Light, 2010).
Table 1. Ranges of angstroms associated with each type of light in the spectrum of light.
Gamma
0.01 – 10
angstroms
X-Ray
10 – 100
angstroms
Ultraviolet
100 –
10000
angstroms
Visible
3800 –
7500
angstroms
Infrared
Microwave Radiowave
10000 –
10000000 100000000
100000000 angstroms angstroms
angstroms
The variety of wavelengths within the ultraviolet light spectrum can be categorized as
either UVA, UVB, or UVC. UVA light has the longest wavelength (3200-4000 angstroms).
UVA can be further divided into two categories: UVA I (3400-4000 angstroms) and UVA II
(3200-3400 angstroms). Ninety-five percent of the ultraviolet light that the earth experiences on
the surface is UVA. UVB light has shorter wavelengths (2900-3200 angstroms) than UVA.
Because UVA light and UVB light both harm organisms, protection from both wavelengths is
necessary. UVC has the shortest wavelengths but most of the UVC radiation from the sun is
absorbed by the ozone (Epstien, Wang 2015). The light that reaches the surface of the earth is
comprised of 4% ultraviolet light, 52% infrared or weaker light, and 44% visible light (The
Nature of Light, 2010).
Table 2. Ranges of angstroms associated with different forms of ultraviolet light.
Ultraviolet Light
UVA
UVB
UVC
4000-3200 angstroms
3200-2800 angstroms
2800-100 angstroms
UVAI
UVAII
4000-3400 angstroms
3400-3200 angstroms
Photosynthetic organisms only use visible light for the process of synthesizing food.
Infrared light is not used for photosynthesis because the energy levels are too low. In addition,
ultraviolet light is not used because the energy levels are too high, and UV light impacts plants
negatively, it causes the creation of free radicals which are known to break essential chemical
bonds. In summary, visible light has perfect energy levels used for photosynthesis (July, 2010
The Nature of Light).
Ultraviolet Light in the Ocean
The ocean is divided into three different zones which are categorized by their relation to light.
The epipelagic zone of the ocean spans from the surface down to two-hundred meters deep. This
zone is defined by the amount of light available that is sufficient enough for the process of
photosynthesis. The next layer down, the mesopelagic zone, contains only enough light for
vision, not photosynthesis. The next region down is known as the aphotic zone, where no
sunlight is present (Sosik, 2004).
Figure 3. A map of the different zones of the ocean along with their depths in meters and feet (Layers of
the Ocean, 2015).
The water in the ocean absorbs light much more efficiently than air in the atmosphere.
Visible light is comprised of an array of different wavelengths; and each wavelength is seen as a
different color of the rainbow. Ocean water absorbs the colors yellow, red, and orange; and this
leaves blue wavelengths penetrating deep into the ocean, which gives the sea its blue appearance.
Because the ocean does not absorb lights with shorter wavelengths, along with the blue light,
ultraviolet light also penetrates deep into the ocean. If a scuba diver were to wear glasses that
could view ultraviolet wavelengths, about 50% of the light he would see looking vertically and
sideways would be ultraviolet light (Sosik, 2004).
The small fraction of the ocean where sufficient amounts of sunlight penetrate is the only
area where marine photosynthesis can occur. This part of the ocean is only the upper two
hundred meters. Ultraviolet radiation is capable of causing harm to both terrestrial and marine
life. The presence of high energy ultraviolet light in this location of the ocean may cause
disastrous effects. Scientists have recently found out that UV radiation harms life deeper down in
the ocean than previously thought. The death of phytoplankton, the retardation of the growth of
phytoplankton, and the disruption of the relations between marine organisms are all caused by
growing amounts of UV light penetrating the ocean (Sosik, 2004).
Ocean species have adapted to the increased amounts of ultraviolet light present in their
environment by developing pigments that absorb UV wavelengths, containing the skill the heal
DNA harmed by UV, and formulating the behavior of escaping UV light by retreating deeper
into the ocean. Unfortunately, fluctuations in the ozone are occurring too quickly in order for the
evolution of marine species to keep up with. The entirety of the spectrum of life may be affected
by this change due to the identity of phytoplankton as a base for many of Earth’s ecosystems and
chemical processes (Sosik, 2004).
Impacts of Ultraviolet Light on Coral
The limpid qualities of open ocean water allow ultraviolet radiation to penetrate down to
twenty meters in depth. Alarming amounts of UV-B have been measured as deep as ten meters,
and furthermore, the effects of UV-B on life in the marine environment extend down to thirty
meters in depth. High photon flux densities, which are the numbers of photons in specific areas
for set amounts of time (cm-2 s-1), occur frequently during the advent of blooms of dinoflagellates
in shallow waters. These high photon flux densities could cause photochemical damage that is
induced by ultraviolet radiation. At the cause of these new environmental conditions, the
dinoflagellates could adapt in order to survive, but these adaptations could result in a dearth of
biological diversity (Banaszak, 2015).
Processes that determine biological impact, that approximate the impact of specific
wavelengths on biological functions, such as photosynthesis, suggest that UV-A suppresses
photosynthesis while the impacts of UV-B on photosynthesis are more drastic. Where there are
high levels of ozone disintegration, the repair functions of organisms that are meant to counteract
the damage done by exposure to harmful ultraviolet wavelengths are not fast enough to keep up
with the rates of damage induced. If the UV penetration in the ozone increases, then the UV
penetration in the ocean also increases proportionally at all depths. Hence, ultraviolet radiation
will be a growing significant factor affecting surface level blooming dinoflagellates. This will
specifically target the dinoflagellates in symbiotic relationships with coral (Banaszak, 2015).
Ultraviolet radiation (UVR) is capable of causing numerous harmful effects on marine
organisms, specifically dinoflagellates. UVR is capable of deactivating RNA, DNA, proteins,
and the synthesis of these biological structures inside of the dinoflagellates. These damages can
lead to the prevention of cell division and growth, which can lead to the death of the cells.
Increased exposure to UV-B has significant impacts on organism growth and awareness of freeliving dinoflagellates as well as dinoflagellates involved in symbiotic relationships with coral.
Finally, exposure to ultraviolet radiation induces the demolition of photosynthetic pigments in
dinoflagellates (Banaszak, 2015).
Impacts of Sunblock on the Ocean
The residue from cosmetic and personal-care products such as sunscreen or makeup
create environmental issues as they leak into ecosystems. UV filters (as those used in sunscreen)
are considered particularly harmful to marine environments. While ultraviolet filters do take
away from the UV light that directly harms marine organisms, they are also known to degenerate
the symbiotic relationship between coral and its photosynthesis partner zooxanthellae. The harm
to coral is detrimental to the entirety of the ecosystem (Blitz, 2008). Once the main components
of sunscreen arrive in marine ecosystems, different ingredients of the sunscreen settle in varying
parts of the environment. The components may be bioconcentrated (the process of accumulation
of water-borne chemicals by fish and other aquatic animals through non-dietary routes) and/or
bioaccumulated (the accumulation of chemicals or pesticides in an organism) into the food web.
The varying inorganic and organic components can be photo-excited by sunlight creating higher
concentrations of reactive oxygen compounds that have detrimental effects on phytoplankton or
be photodegraded by-products. Additional ingredients of sunscreen dissolve in water and induce
algal growth (Sanchez-Quiles, Tovar-Sanchez, 2015).
Figure 4. Depicted above is a graphic that shows the different things that sunscreen can do once exposed
to a marine environment (Sosik, H. M., 2004).
Basics of Sunscreen
The essential factors of sunblock are the UV filters, which are materials that are capable
of absorbing light in the UVA and the UVB ranges (4000-3200 angstroms and 3200-2800
angstroms respectively) and close to no absorption of visible light (Sanchez-Quiles, TovarSanchez, 2015).
The UV filters can be categorized into two sections: inorganic and organic filters.
Organic filters include substances such as cinnamates, camphor products, p-aminobenzoic acid
and its products, salicylates, and benzophenone products. Inorganic filters are limited to only two
compounds: titanium-dioxide and zinc-oxide. The inorganic components of sunscreen are
nanoparticles (TiO2) and nanorods (ZnO) in order to continue their protection from UV
wavelengths as well as not whiten the skin. Different benefits are provided by the two UV filters.
Organic filters are capable of absorbing definite wavelengths while the inorganic filters provide a
wide variety of protection because they reflect, absorb, and scatter UV-light. Sunblock is
typically made up of one or more or a mixture of these components; and combinations of
inorganic and organic filters provide favorable UV protection (Sanchez-Quiles, Tovar-Sanchez
2015).
In order to prevent the introduction of alien chemicals into marine environments, divers
are cautioned not to wear sunblock in the vicinity of coral reefs. A recent experiment supports
this idea that sunblock is harmful to sea life (Brown, 2008).
This issue was first recognized by Mexican resort managers when small pools of water
(also known as cenotes) along the Yucatan coast became frequently used as swimming holes for
tourists by Mexican resort managers. Roberto Danovaro from the Polytechnic University of
Marche in Ancona, Italy states that the death count of organisms living in the cenotes spiked
during this time. Sunblock was looked to as the suspect, so many resorts prohibited the
beachgoers/divers from applying sunblock while swimming in areas near coral reefs or in
cenotes (Brown, 2008).
Benzophenone-3
Benzophenone-3 is becoming more and more of a threat to the stability of marine
environments. Benzophenone-3 can be found in various everyday products used worldwide.
Oxybenzone is an ingredient in shampoos and conditioners, lip balms and other cosmetics, a
variety of facial products, dish soaps, and sunscreens. This chemical is introduced to marine
ecosystems via waders and boats. Oxybenzone is a photo-toxicant, which means that in order for
the toxic effects of oxybenzone to be activated, light is required. The toxic effects of
benzophenone-3 are worsened with more light exposure. Oxybenzone is hazardous to coral reefs
because it debilitates the corals durability to climate change (Downs, 2015).
Coral reef areas worldwide are exposed to between 6,000 and 14,000 tons of
benzophenone-3 based sunscreens each year. About 10% of the globe’s reefs are at risk of being
exposed to this detrimental chemical, and about 40% of the coastal reef areas experience this
same risk. At Okinawa Island, Japan, the reefs that range from 300-600 meters away from the
shore experience approximately 0.4 to 3.8 parts per trillion of oxybenzone. In South America,
coastal reefs experience levels of an average of 54 to 578 parts per trillion of oxybenzone.
Benzophenone-3 is especially alarming because despite its half-life in seawater being only many
months, there is a constant income of oxybenzone into the oceans. This creates a seemingly
constant exposure to oxybenzone by the corals (Downs, 2015).
Interestingly, in an experiment testing the effects of benzophenone-3 on coral planulae,
this chemical still deformed the planulae into a debilitated, immobile state in both darkened and
lightened conditions. Also, the coral planulae exhibited alarming rates of coral bleaching in both
conditions. When the coral planulae was exposed to higher concentrations of benzophenone-3,
the rate of coral bleaching increased. Oxybenzone is identified as a genotoxicant to corals,
meaning that this chemical destructively impacts the DNA of coral. As the concentrations of
benzophenone-3 were increased during the experiment, higher rates of DNA-AP lesions were
observed. In addition to that, oxybenzone is a skeletal endocrine disruptor, which means that it
induces the process that changes the cartilage of the planulae into bone. When exposed to
benzophenone-3, the coral planulae become enveloped inside of their own skeleton (Downs,
2015).
UV Absorption and Potential of Chicken Eggshell Cuticle
It was demonstrated that the absence of the external coats of bird eggshells with cuticles
increases UV reflectance. This proposes that the cuticle regulates the reflectance of UV light in
white eggshells. It is assumed that this regulation of UV light is attained by the absorption of
UV-wavelengths by substances in the organic portion of the eggshell (cuticle). The chicken
eggshell is intriguing due to the fact that the absorption of UV light significantly decreased after
the removal of the cuticle. This proposes that a trait of the chicken eggshell raises the intrinsic
reflectance of UV light of calcite potentially via nanostructuring (no known pigment is capable
of absorbing light across the entirety of the spectrum of wavelengths), but it is not accurately
discerned what this function is. The data of the experiment offer the idea that cuticle absorbs
UV-light. The eggshells of birds are exceptional candidates for biomimetic projects (clothing,
paints, sunscreen, etc.) because it decreases the harmful impacts of exposure to the sun. Chicken
eggshells in particular are favorable candidates for biomimetic research because the UVreflectance traits exceed being of solely calcite (Fecheyr-Lippens, 2015).
Figure 5. This diagram shows the effects of the EDTA treatment on the UV-Chroma of the avian
eggshells over time (Fecheyr-Lippens, 2015).
Composition of Chicken Eggshell
The results of the study suggest that the cuticles of avian eggshells absorb UV-light
because of their high concentrations of organic compounds (calcium phosphates in the cuticle in
opposition to the mainly calcite eggshell). Two known components of the eggshell that
specifically absorb UV-light are the tetrapyrrole pigments- biliverdin and protoporphyrin IX, yet
it is assumed that other components of the eggshell also absorb UV-light and advance the
efficiency of absorption of the tetrapyrrole pigments. The cuticle is composed of lipids,
polysaccharides, calcium carbonate, proteins, and calcium phosphates. The components of the
proteins (amino acids) and the calcium phosphates have a noticeably larger pool of light waves
that they are capable of absorbing than biliverdin and protoporphyrin IX. Both families of
compounds capitalize their UV-light absorption potential and are main ingredients of the avian
eggshell. Specifically, the cuticle of the chicken eggshell is composed of 85-90% proteins, 2.53.5% lipids, and 4-5% polysaccharides. These carbon based factors absorb UV-light. It is also
possible for the inorganic factors also absorb UV-light (Fecheyr-Lippens, 2015).
Figure 6. These graphs show the dispersed reflectance of UV-light over a time duration of EDTA
treatment. The gray area represents the UV wavelength range (Fecheyr-Lippens, 2015).
Eggshells as a Waste Product
The disposal of eggshells is a daunting topic for the waste management industry.
Organizations are paying up to $100,000 annually to manage the waste of eggshells in landfills.
In addition to that, the quantity of eggshells being disposed of each year is huge and requires
ample amounts of space in landfills. Also, the protein-based membrane on the inside of the
eggshell rots in the landfills and attracts rodents, which contaminate the disposal systems
(Sonenklar, 1999).
Literature Cited
Sosik, H. M., Johnsen, S. (2004, October, 15). Shedding Light on Light in the Ocean. Oceanus
Magazine, 43.
“Layers of the Ocean.” – Deep Sea Creatures on Sea and Sky. N.p., n.d. Web. 22 Nov. 2015
Downs, C., Kramarsky-Winter, E., Segal, R., Fauth, J., Knutson, S., Bronstein, O., . . . Loya, Y.
(2015). Toxicological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination
in Hawaii and the U.S. Virgin Islands. Springer Science. doi:10.1007/s00244-015-0227-7
Importance of Coral Reefs. (2008, March 25). Retrieved November 24, 2015.
Symbiotic Algae. (2011, May 13). Retrieved November 24, 2015.
What is Coral Bleaching? (2015, October 8). Retrieved November 26, 2015.
Hoegh-Goldburg, O. (n.d.). Coral Bleaching. Retrieved Novomber 26, 2015.
Brown, S. (2008). Sunscreen wipes out corals. Nature: International weekly journal of science.
doi: 10.1038/news.2008.537
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Sanchez-Quiles, D. Tovar-Sanchez, A. (2015). Are sunscreens a new environmental risk
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Trench, R, K. Banaszak, A, T. (2001). Ultraviolet Sunscreens in Dinoflagellates. Protist, Volume
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