The effect of multiple stressors on the Florida Keys coral reef ecosystem: A landscape hypothesis and a physiological t

1. The effect of multiple stressors on the Florida Keys coral reef ecosystem: A landscape hypothesis and a physiological test.

2. Perspectives on Coral reef Biology • Coral reefs thrive in shallow, coastal tropical marine environments • Environment is low in nutrient content • Coral reefs are amongst the most species diverse and productive ecosystems • High productivity enabled by symbiosis between photosynthetic zooxanthallae and coral

3. Stress and the Coral Reef • Coral reefs are very intolerant of environmental changes • Stress refers to any physiological change resulting from adverse environmental factors • Stress can be measured by decreased growth rates, metabolic differences, and biochemical changes

4. Stressors-Sedimentation • Sedimentation from land activity makes the water turbid, interfering with photosynthesis • Runoff of elevated nutrient levels are a contribution of sedimentation, promoting algal blooms • Coral expends energy fighting off sediment instead of its usual functions

5. Temperature and Salinity as Stressors • Increases in temperature lead to “bleaching,” the expulsion of zooxanthallae • Coral reefs grow best in temperatures that do not go below or beyond 68oFand 83oF • Droughts contribute to hypersaline conditions

6. Methods • Coral from the species Montastreaannularis were collected and put in aquaria • Four experiments were set up 1. A control with water at 30oC and 35% salinity 2. Single stress of temperature at 33oF, and salinity at 35% 3. Single stress of salinity at 40%, and temperature at 30oC 4. Combined stress of 35oC temperature and 40% salinity

7. Results

8. Results

9. Conclusion • Corals exposed to higher than normal temperatures are affected more severely • Corals exposed to hypersaline water survived • Increased salinity extended coraline life 18 hrs. in higher temperature