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