Coral Bleaching

1) What is bleaching?

a) Corals and symbiotic relationship

i) What are zooxanthellae? - Dinoflagellates that live in coral tissues ii) What they do/importance? – photosynthesis, CO2 removal

b) Expulsion of zooxanthellae – give corals color, they now appear white

2) Causes

a) SST i) Stress on corals ii) Affects on symbiotic relationship iii) Past, present, and future predictions/ frequency of bleaching events

b) Acidification i) What is acidification? – CO2 dissolves in ocean and increases acidity which dissolves CaCO3 ii) Impact of acidification on bleaching – increases bleaching events iii) Synergy with SST – higher SST amplifies acidification effects and bleaching

c) Stress

i) Types

(1) Elevated temperature (2) High solar irradiance (3) Disease (4) Hostile/changing environment

ii) Disruption of symbiotic relationship

iii) Why expel zooxanthellae?

3) Effects

a) Disease – frequency increases

b) Ecosystem/reef effects i) Corals – productivity, recruitment, survivability/adaptation ii) Fish/Other organisms – habitat, recruitment, abundance

4) Special Case Study

a) US Virgin Islands following bleaching in 2005 b) Sunscreen and reefs

5) What we are currently doing to sustain coral ecosystems

a) USGS “Science Based Strategies” example

Sources:

Hoegh-Guldberg, Ove (1999) . Climate change, coral bleaching and the future of the world's coral reefs. Marine and Freshwater Research 50 , 839–866.

H. van Oppen, M. J., & Lough, J. M. (2009). Coral bleaching: Patterns, processes, causes and consequences. (Vol. 205). Springer Berlin Heidelberg. Retrieved from http://link.springer.com/book/10.1007/978-3-540-69775-6/page/1

USGS. (2008, June). Coral diseases following massive bleaching in 2005 cause 60 percent decline in coral cover and mortality of the threatened species, acropora palmata, on reefs in the u.s. virgin islands. Retrieved from http://pubs.usgs.gov/fs/2008/3058/pdf/fs2008-3058.pdf

USGS. (2008, September). Science-based strategies for sustaining coral ecosystems. Retrieved from http://pubs.usgs.gov/fs/2009/3089/pdf/brewercoralfs3.pdf

T. Tyrrell (2007). Calcium Carbonate Cycling in Future Oceans and its Influence on Future Climates.

K. R. N. Anthony, et al. (2008). Ocean acidification causes bleaching loss in coral reef builders. PNAS vol. 105 no. 45

O. Hoegh-Guldberg, et al. (2007). Coral Reefs Under Rapid Climate Change and Ocean Acidification. Science 318, 1737