Coral Dysfunction: Local Threats

Question 1

List of Local Threats (7)

In order of importance

Answer 1

Overfishing 
Algal Overgrowth 
Nutrient pollution
Mass mortality events 
Other land-based runoff pollution 
Sedimentation from development
Physical disturbance

Question 2

Overfishing

Answer 2

Worldwide fishing extractions are at least 2-3x more than replacement
Tropical reef ecosystems provide food for about a 500million people worldwide
Overfishing changes community structure
90% decline in the size of large trophy fish

Question 3

Overfishing of Herbivores

Answer 3

Causes phase shift as algae takes over the reef

Can form alternative stable states

Question 4

Overfishing of Predators

Answer 4

Functional groups matter – predator biomass has been dramatically reduced

Healthy reefs should have higher biomass of predators than lower trophic levels (inverted pyramid)

Question 5

Destructive Fishing

Answer 5

Dynamite Fishing
Bleach Fishing
Muro ami Fishing

Question 6

Algal overgrowth

Answer 6

Caused by nutrient pollution (eutrophication)

Can result in semi-permanent phase shift to algal dominated reef

Question 7

Acropora Die-Off

Answer 7

This altered the composition of Carribean reefs

Occurred before major bleaching events, likely due to overfishing

Question 8

Diadema urchin die-off`

Answer 8

Loss of these urchins further contributed to reef loss and phase shift
Loss of these is a part of the loss of functional redundancy

Question 9

Other forms of waterborne pollution

Answer 9

Sedimentation
Pharmaceuticals
Suntan Lotion