Coral Bleaching
Post on 24-Feb-2016
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Coral BleachingRebecca Cebulka
What are Corals?Marine invertebrates that live in colonies
Similar to anemonesSome can catch small fish and plankton
Typically live in deep oceanMost obtain nutrients from symbiotic algae
which live in the coral’s tissuesGrow in clear, shallow waterForm coral reefs
Coral Reefs
What is coral bleaching?Corals get their color from symbiotic algaeChanges in surrounding water cause stress
Warmer or colder temperaturesMore or less light
Stress causes coral to expel algae, leading to bleaching and a lack of food for the coral
CHANGES IN WATER
CORAL BECOMES STRESSED
COLOR-PRODUCING ALGAE EXPELLED
Healthy Coral & Bleached Coral
What Causes Bleaching?Temperature changes of 1-2°C over several
weeksIncrease in T more likely to cause bleaching
What Causes Bleaching?Solar Radiation
Increased UV radiation(280-400nm) and photosynthetically active radiation (400-700nm)
Corals in shallow waters are more prone to bleaching – coral reefs especially!
Effects of Coral BleachingAlgae provide necessary nutrients for corals –
prolonged bleaching will result in coral death due to lack of food
Destroy ecosystems which are the only home to many species used for both food and medicine
Effects of Coral BleachingDestroy reefs that protect shores from the
impact of waves and stormsCut back on economic benefits to local
communities from tourismBecoming more and more prevalent
Other DangersIncreased carbon dioxide
Raises ocean acidity, preventing coral from building its calcium carbonate skeleton
Won’t kill coral directly, but makes it more difficult to recover from things such as bleaching
Other DangersOverfishing
Kills off a main part of the reef’s ecosystem
Some types of fishing involves scraping the ocean floor, ripping up coral
In SummaryCoral bleaching occurs when corals expel
symbiotic algae due to changes in the surrounding water
Causes of coral bleaching include increasing water temperature and solar radiation
Increased CO2 in the air is making it difficult for coral to recover from bleaching events.Death of coral reefs is becoming more and
more common and is expected to continue.
Referenceshttp://ocean.si.edu/corals-and-coral-reefshttp://www.marinebiology.org/
coralbleaching.htmhttp://oceanservice.noaa.gov/facts/
coral_bleach.htmlhttp://www.onr.navy.mil/focus/ocean/
habitats/coral2.htmhttp://www.globalissues.org/article/173/coral-
reefs
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