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Develop Testable Hypotheses About Response to Human Influence

 

Prepare list of attributes to be evaluated based on these hypotheses and define directional expectations for those attributes (e.g., taxa richness declines with increasing human influence). Then define how attributes will be quantified (e.g., count of taxa, % living tissue, etc.).

Many coral reef organisms rely on stony corals to provide shelter, food, and habitat. Dramatic, recent declines in coral reefs are a concern world wide. Coral reef condition can be evaluated by measuring the abundance and composition of coral colonies and species, the physical structure of the reef, and the biological condition of the coral colonies. Several candidate metrics have been proposed for assessing the biological health of stony coral assemblages. These attributes will be quantified and tested in the US Virgin Islands for their response to human disturbance.

Bleached coral colony in which the symbiotic zooxanthellae (single-celled algae) are lost from the host coral

Bleached coral colony in which the symbiotic zooxanthellae (single-celled algae) are lost from the host coral. Coral can survive without the zooxanthellae but benefit from their photosynthetic activity. Zooxanthellae may also recolonize the coral at a later time.

Massive coral

Massive coral with disease.

 
List of proposed metrics for coral reef condition, their predicted response to human influence, and how they are quantified.
Proposed metric (attribute) Predicted response How quantified
Abundance and Composition  
Coral abundance Decrease Number of coral colonies
Coral density Decrease Number of corals per m2
Species richness Decrease Number of species
Species frequency Depends on species Number occurrences
Unique species Decrease Number of taxa that are rare, unique or protected
Tolerant richness Increase Number of taxa
Intolerant richness Decrease Number of taxa
Physical Stature    
Reef surface area Decrease Total 3D surface area (m2) of corals
Reef volume Decrease Total volume (m3) of corals
Reef complexity Decrease Total 3D surface area (m2) of corals per m2
Reef structure Decrease Total volume (m3) of corals per m2
Population structure Depends on species Size-frequency distributions of a particular species relating the number of colonies, surface area, live surface area, or average percent live coral in a reef to colony size
Community structure Depends on species Size-frequency distributions applied to all coral colonies
Biological Condition    
Reef percent live coral Decrease Average percent live coral for all colonies
Reef live surface area Decrease Sum of live colony surface areas for all colonies
Reef dead surface area Decrease Sum of dead colony surface areas for all colonies
Reef live to dead surface area Decrease Ratio of live to dead coral surface area for all colonies

Biological Indicators | Aquatic Biodiversity | Statistical Primer

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