1. Coral Bleaching due to UV Radiation
Group # 3
Rodolfo Barros, Santas Rosario, Alexandra Mayard, Jose Ruiz,
Yanka Diaz

2. Background Coral bleaching:
Coral expels some or all its zooxanthellae in response to stress.
Coral appears white/ transparent, but isn’t dead.
Algae expelled to prevent death by over production of oxygen/ free radicals.
Healthy Coral
Bleached Coral

3. Stressed Out by UV?
Corals can’t tolerate prolonged exposure to stress.
Increased UV light causes bleaching under calm, clear water conditions.
Zooxanthellae very sensitive to UV light even if adaptable to quick changes in photosynthetically active radiation (PAR)

4. Details
UV radiation in the environment is subdivided into long waves (400–315 nm), medium waves (315–280 nm) and short waves (< 280 nm).

5. Mycosporine-like Amino Acids (MAAs)
Protects zooxanthellae in corals.
Greatest UV absorbance from nm (broad band filter)
maximal absorption: nm.
Used in combination to absorb, reflect or fluorescence UV light.

6. Project Question
Does prolonged exposure to UV radiation cause Aiptasia to bleach?

7. Hypothesis Aiptasia will bleach completely after two weeks.
Stress will initially cause production of MAAs for protection, but will not be enough to sustain zooxanthellae.
Normal Aiptasia
Bleached Aiptasia

8. Methods
Obtain cell density, chlorophyll a concentration and protein concentration for Aiptasia once a week for two weeks.
Set a black light to a timer to alternate between 12 hrs of UV radiation (during daylight) and 12 hrs of darkness.
Place UV light on rack (~ 4 inches from tank) so that light is positioned towards the tank’s middle.
For the next 4 weeks obtain: cell density, protein and chlorophyll a concentration to evaluate the effect of time of UV light exposure vs. Zooxanthellae concentration.

9. Experimental data (previous to UV exposure)
10/18/06: Week 1
Zooxanthellea density (cells/g) = 386x10^6
10/25/06: Week 2
Zooxanthellea density (cells/g) = 96.8x10^6
Protein conc./ g wet wt. (mg/g) = 15.49
Chlorophyll a per cell (ng/cell) = 15.20
11/0106: Week 3
Zooxanthellea density (cells/g) = 184x10^6
Protein conc./ g wet wt. (mg/g) =
Chlorophyll a per cell (ng/cell) = 4.693

10. More… Coming Soon