A healthy
coral (or sea anemone) is colored by the zooxanthellae (single-celled algae)
that live cooperatively in it. This type of relationship is called
symbiosis. In a healthy coral/algal symbiotic association both the
algae and its coral host benefit. The algae use photosynthesis to
provide quick energy to their coral host while the coral offers protection,
nutrients, and carbon dioxide to the algae. The symbiosis persists
until warmer temperatures and higher than normal ultraviolet light, both
associated with global environmental change, cause the organisms to part
ways. This situation causes the coral to lose color allowing the
white coral skeleton to show through the clear animal tissue (a process
called bleaching). This is not just a loss of color but also the
loss of an energy source.
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Anemone
A solitary soft-bodied marine animal
belonging to Phylum Cnidaria.
Attenuation
The overall reduction in irradiance
due to absorption and scattering of light as it passes through a medium
such as water.
Benthic Spectrofluorometer
(BSF)
A portable diver-operated instrument
that measures the reflectance and fluorescence of marine organisms.
Biological Action Spectrum
Shorter wavelengths cause more damage
per unit dose than longer wavelengths, a biological action spectra weights
the intensity of each wavelength by its effectiveness in causing biological
damage.
Bleaching
A phenomenon occurring when corals
under stress expel their mutualistic zooxanthellae or when the concentration
of photosynthetic pigments is decreased. As a result, the corals'
white skeletons show through their tissues, and they appear bleached.
Coral
A marine animal (yes it's an animal)
from the same group of organisms as the sea anemone. It is colonial
and secretes a hard calcium carbonate skeleton.
Global Warming
The warming of the lower atmosphere
due to the increased emission of greenhouse gases.
Greenhouse Gasses
Molecules such as water vapor, carbon
dioxide, and methane which absorb, or trap, energy that is radiating from
the Earth's surface.
High Performance
Liquid Chromatography (HPLC)
A technique for separating and quantifying
specific pigments.
Irradiance
The amount of light energy that
falls on unit area (m2) per unit time (sec).
Optical Spectra
The amount of light energy at each
wavelength. The energy may be reflected solar energy from a surface
(e.g. coral) or emitted through fluorescence in response to excitation
of a chemical or pigment such as chlorophyll.
Photosynthesis
The process by which plants and
algae use energy from the sun to convert water and carbon dioxide to usable
sugars.
Photosyntheticaly Active Radiation
(PAR)
Energy from the sun consists of
many wavelengths of light. Wavelengths from 400-700 nm are used in photosynthesis
and together constitute photosynthetically active radiation.
Remote Sensing
The science of deriving information
about the earth's land and water features from images acquired from a distance.
Spectroradiometer
An instrument which measures the
amount of light at each wavelength.
Symbiosis
The close relationship of
two organisms in proximity, with one benefiting and the other either benefiting
(mutualism), not being significantly affected (commensalism), or being
harmed (parasitism) by the relationship.
Zooxanthellae
Photosynthetic dinoflagellate algae
that live in the tissue of certain marine invertebrates, including reef
building corals and sea anemones.
The following
sites provide further information about coral reefs and marine conservation:
Coral
Health and Monitoring Programs
Marine
Conversation Biology Institute
National
Science Foundation
Oceanic
Research and Applications Division (ORAD)
Reefnet
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