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Classify Coral Reef Systems
Define the number and types of unique reef environments based on physical features and describe or identify expected reference conditions.
Classification of coral reef systems is initially based on physical features. After testing for metric association with habitat type, classification will be restricted only to those physical features that influence biological indicators. Several approaches could be used to classify reef habitats including geomorphology (e.g., patch reef vs. continuous linear reef), water chemistry (e.g., salinity or temperature), or dominant coral specie (e.g. branching vs. massive corals).
In the US Virgin Islands, coral reefs will initially be classified according to reef type. Reef types include patch reefs, linear reefs, and colonized pavement.
Figure. St. Croix, USVI showing coral reef habitat types and 7 coastal management zones.
Within each coastal management zone, reef stations will be selected to contrast reef areas with minimal human influence with reef areas degraded by human activities. If coral metrics measured in different habitat types show similar responses to human influence, the habitats can be combined into a single category.
In the Florida Keys, measures of percent live coral were more variable for some reef types than for others. Whether differences in percent live coral were due to natural differences in the reef habitat or different levels of human influence could not be determined from the sampling design.
Figure. Percent live coral observed at reef stations in the Florida Keys.Values for percent live coral in transitional habitats were more consistent than values observed in fore and back reefs. Stations are arrayed along the x-axis from Key West north and east to the eastern coast of FL.
Why Classify? The primary reason for classifying a resource according to habitat type is to reduce variability when estimating regional condition. Reef habitat types may naturally have different coverages of living coral. If so, our expectations should reflect what is realistic for that habitat type. If not, similar habitat types should be combined and monitored as a single reef type with similar expectations for reference condition.