SEEING THE REEF FOR THE CORALS: A QUANTITATIVE CASE FOR REMOTE SENSING
Coral reefs provide very valuable ecosystem goods and services, but they are severely threatened. An estimated 33-50% of reefs worldwide have already been severely degraded, and the rest are threatened with destruction by mid-century. Despite the severity of the problem, state of the art coral reef assessment remains firmly diver-centric. For a concept study exercise, I downloaded all publicly available data for three well-surveyed coral reef regions: the Great Barrier Reef, Hawaii, and Florida/Puerto Rico/U.S. Virgin Islands. Data were compiled to geolocated values of coral cover, then binned to 1×1 km grid cells to approximate the reef ecosystem scale. Observations were very sparse, both within reefs and across regions. The binned data do not exhibit any trends with large-scale physical parameters (PAR, thermal history, wave history) except for possibly a negative relationship with aragonite saturation state. Coral cover does appear to increase with coral species richness, but also appears to increase with increasing human threats, except overfishing. Overall, the observed patterns contradict the prevailing understanding of how reefs relate to their environment. In truth, because they are so sparse, the available benthic cover data are not actually representative of the ecosystem scale. Thus, the comparison with reef-scale biogeophysical forcing parameters is not sound. Remote sensing is the only feasible means to gather uniform, high-density, ecosystem-scale data across vast coral reef regions.
Hochberg, E. J., Bermuda Institute of Ocean Sciences, Bermuda, email@example.com
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