Publicação
Using reflectance to measure chlorophyll a in corals: calibration and implications of skeletal optical properties
| datacite.subject.sdg | 14:Proteger a Vida Marinha | |
| datacite.subject.sdg | 13:Ação Climática | |
| datacite.subject.sdg | 09:Indústria, Inovação e Infraestruturas | |
| dc.contributor.author | Watty, Kay | |
| dc.contributor.author | Schoepf, Verena | |
| dc.contributor.author | Johnson, Kelly W. | |
| dc.contributor.author | Littke, Sophie | |
| dc.contributor.author | Zande, Rene M. van der | |
| dc.date.accessioned | 2026-03-06T09:53:00Z | |
| dc.date.available | 2026-03-06T09:53:00Z | |
| dc.date.issued | 2026-02-17 | |
| dc.description.abstract | Climate change-driven coral bleaching and associated chlorophyll (Chl) loss increasingly threaten coral reefs, highlighting the need for non-invasive, cost-effective tools to assess corals’ physiological condition. Researchers have explored the reflectance-based Normalized Difference Vegetation Index (NDVI) as a proxy for Chl a. However, almost no calibration curves exist to date; thus it remains unknown if the relationship between Chl a and NDVI differs among coral species, and whether it is influenced by skeletal optical properties. Here, we correlated Chl a content to NDVI in three coral species with different skeletal morphologies and reflectance modes across a range of health states (i.e., bleaching states). We found a strong positive relationship between Chl a and NDVI in all species, validating NDVI as a proxy for Chl a in corals. However, this relationship is non-linear, showing deviations at the highest and lowest ends of the pigmentation spectrum. We propose that in healthy states, this non-linearity is due to pigment self-shading, whereas in bleaching states, it is caused by backscattering of light by the increasingly exposed coral skeleton, because pigment loss enhances absorption by the remaining Chl a pigments and lowers, rather than increases, reflectance. To avoid Chl a under- or overestimation, we recommend to log-transform Chl a and create species-specific calibration curves. Overall, the non-invasive, repeatable, and scalable nature of reflectance measurements and NDVI make them valuable tools for assessing coral health both ex- and in situ. They provide a comprehensive view of the holobiont’s physiological condition and hold potential for broader applications in reef-scale monitoring, remote sensing, coral restoration, and conservation. | eng |
| dc.identifier.doi | 10.1007/s00338-026-02831-0 | |
| dc.identifier.eissn | 1432-0975 | |
| dc.identifier.issn | 0722-4028 | |
| dc.identifier.uri | http://hdl.handle.net/10400.1/28347 | |
| dc.language.iso | eng | |
| dc.peerreviewed | yes | |
| dc.publisher | Springer | |
| dc.relation.ispartof | Coral Reefs | |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | |
| dc.subject | Coral bleaching | |
| dc.subject | NDVI | |
| dc.subject | Reflectance | |
| dc.subject | Chlorophyll a | |
| dc.subject | Light scattering | |
| dc.subject | Symbiodiniaceae | |
| dc.title | Using reflectance to measure chlorophyll a in corals: calibration and implications of skeletal optical properties | eng |
| dc.type | journal article | |
| dspace.entity.type | Publication | |
| oaire.citation.title | Coral Reefs | |
| oaire.version | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |
| person.familyName | Littke | |
| person.givenName | Sophie | |
| person.identifier.orcid | 0009-0000-7587-6865 | |
| relation.isAuthorOfPublication | 4667cb75-18f1-4e88-b361-095e2b8feec3 | |
| relation.isAuthorOfPublication.latestForDiscovery | 4667cb75-18f1-4e88-b361-095e2b8feec3 |