Editing Coral reef live cover fraction

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{| class="wikitable" style="float:right; clear:right; margin:0 0 1em 1em; width:320px;"
|+ SIGNAL Earth Structured Data
|-
! Object type
| Damage Signal
|-
! SIGNAL Earth ID
| DS-00101
|-
! Observable type
| Coral reef live cover fraction
|-
! Unit
| % (%)
|-
! Temporal structure
| Annual
|-
! Monitoring backbone
| —
|}
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{{SignalTerm|type=DS|id=DS-00101|label=Coral reef live cover fraction}} is a key environmental indicator representing the proportion of a coral reef area covered by living coral organisms. This measure reflects the health and vitality of coral reef ecosystems, which are critical habitats supporting diverse marine life and providing ecosystem services such as coastal protection and fisheries support. Changes in live coral cover can signal impacts from environmental stressors including climate change, ocean acidification, pollution, and physical disturbances.

Monitoring coral reef live cover fraction is essential for understanding reef condition trends over time and assessing the effects of natural and anthropogenic pressures. This indicator is widely used in marine ecology and conservation to evaluate reef resilience and degradation. It provides a quantifiable metric for comparing reef status across geographic regions and temporal scales.

Within the broader context of ocean biogeochemistry and ecosystem monitoring, coral reef live cover fraction serves as a receptor condition reflecting the biological response of reefs to environmental changes. Its assessment supports scientific research and management efforts aimed at sustaining coral reef ecosystems globally.

== Geographic / System Context ==
Coral reefs occur primarily in tropical and subtropical ocean regions, typically between 30°N and 30°S latitude. These ecosystems are distributed globally across major ocean basins including the Caribbean Sea, the Indo-Pacific region, the Red Sea, and parts of the Western Atlantic and Indian Oceans. Coral reefs develop in shallow, warm, and clear waters where sunlight penetration supports photosynthetic symbiotic algae within coral tissues.

The geographic scope of coral reef live cover fraction monitoring is global, encompassing diverse reef types such as fringing reefs, barrier reefs, atolls, and patch reefs. Variability in reef structure, species composition, and environmental conditions influences live coral cover patterns. Regional oceanographic factors, such as [https://en.wikipedia.org/wiki/Sea_surface_temperature sea surface temperature], aragonite saturation state, and water quality, interact to affect coral growth and survival.

== Monitoring and Measurement ==
Scientists monitor coral reef live cover fraction using a combination of in situ field surveys and remote sensing techniques. Field methods include transect line surveys, photo-quadrat analysis, and diver-based visual assessments to estimate the percentage of reef substrate occupied by live coral. These approaches provide detailed, site-specific data on coral abundance and community composition.

Remote sensing technologies, including satellite imagery and aerial photography, enable broader spatial coverage and temporal monitoring of reef conditions. Advances in high-resolution imaging and spectral analysis support the detection of live coral cover changes over time. Monitoring programs are often coordinated by marine research institutions, governmental agencies, and international collaborations, although a standardized global monitoring backbone for this signal is still under development.

Within the SIGNAL system, this phenomenon is treated as a defined environmental signal whose boundaries and measurement conventions are described below.

== Signal Definition ==
The coral reef live cover fraction signal quantifies the proportion of a defined coral reef area covered by living coral tissue, expressed as a percentage. It represents a receptor condition within the Ocean-Biogeochem domain, capturing the biological state of coral reef ecosystems as an outcome impacted by environmental stressors.

== Boundary Conditions ==
Boundary inclusions encompass all living coral organisms present on the reef substrate within the spatial unit of measurement, including hard corals forming the reef framework. Boundary exclusions include non-living coral skeletons, algal cover, other benthic organisms, and abiotic substrate. Measurements are confined to the benthic zone of coral reef habitats and exclude adjacent seagrass beds, mangroves, or open water areas.

== Aggregation Semantics ==
Geographic aggregation involves summarizing live coral cover percentages across spatial units such as reef patches, reef systems, or regional reef complexes to assess broader ecosystem condition. Temporal aggregation is typically annual, reflecting the seasonal and interannual variability in coral cover. Cross-signal aggregation may integrate coral live cover data with related environmental signals such as sea surface temperature, ocean acidity, and coral bleaching severity to provide a comprehensive assessment of reef health and stressor impacts.

== Observational Status ==
Current monitoring of coral reef live cover fraction relies on a combination of localized field surveys and emerging remote sensing datasets. While global-scale systematic monitoring frameworks are evolving, data coverage remains uneven across regions. Future SIGNAL releases aim to incorporate standardized datasets and improved spatial-temporal resolution to enhance the assessment of coral reef condition worldwide. Continued integration with related environmental signals will support more robust interpretations of reef ecosystem dynamics.

== Related Signals ==
* Aragonite saturation state (Ωar)
* Coastal litter accumulation density
* Coral bleaching severity index
* Marine fish biomass stock (declared species group)
* Marine plastic concentration
* Ocean surface acidity (pH)
* Sea surface temperature (global mean)

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== Key Associated People ==
* '''Terry Hughes''' — Steward-candidate (James Cook University) [Domain expert]
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== Sources ==
* [https://www.nature.com/articles/nature21707 Global warming and recurrent mass bleaching of corals — 2017 — Nature]
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