This proposal investigates how nearshore environmental variability is recorded in coral skeletal geochemistry, with the goal of developing a site-specific proxy framework for reconstructing past coastal ocean conditions. Focusing on reef-building corals (including microatoll-type growth forms) from the Balaoan, La Union area, the study treats corals as high-resolution environmental archives that can preserve signals related to sea-surface temperature and salinity, sea-level/relative sea-level behavior, and associated oceanographic–climatic forcing. By linking modern instrumental and reanalysis products (e.g., temperature, salinity, sea-surface height and related climate indices) with measured coral geochemical tracers, the work aims to quantify which environmental drivers are most strongly expressed in the local coral record and to establish a defensible baseline for future paleoclimate and coastal-hazard applications.
The approach combines (1) environmental data acquisition and preprocessing, (2) targeted field sampling, (3) laboratory preparation and geochemical measurement, and (4) statistical calibration and interpretation. Environmental datasets (e.g., SST, SSS, sea-surface height/sea level and relevant climate/ocean indices) are compiled for the study region and harmonized through resampling and time-alignment to match coral growth chronology and sampling resolution. Coral samples are collected through fieldwork at the target site(s), documented for context (setting, elevation/relative position, morphology), and prepared using standardized cutting/cleaning procedures to minimize contamination and to isolate growth bands suitable for analysis. Coral powders or micro-samples are then analyzed for elemental ratios and trace-element composition using appropriate analytical platforms (e.g., ICP-OES/ICP-MS) to generate time-series geochemical data. Finally, the study applies regression and related statistical models to evaluate relationships between coral geochemistry and environmental parameters, supported by visualization and sensitivity checks, to identify robust predictor–response pairs and quantify uncertainty (including potential confounders such as growth effects, seasonality, and local hydrodynamics).
The project delivers a calibrated, locality-relevant coral geochemical framework that can strengthen coastal paleoclimate reconstruction and environmental monitoring in northwestern Luzon. Scientifically, it clarifies which oceanographic variables (temperature, salinity, and/or sea-level-related changes) dominate the chemical signals preserved in corals from this setting, improving confidence in how coral archives are interpreted under complex nearshore conditions. Practically, the outputs support longer-term reconstruction of baseline variability and extremes, which is useful for understanding climate-driven coastal change, informing reef and coastal-resource management, and guiding future work on relative sea-level history and hazard context in the region. Methodologically, it also reinforces capacity for repeatable coral geochemistry workflows (from field collection through ICP-based analysis and calibration), creating a foundation for expanded proxy development and comparative studies across Philippine coastal sites.
This research addresses UN Sustainable Development Goals for Climate Action (SDG 13) and Life Below Water (SDG 14).
Cover photo: Sampling of a coral microatoll slab. A) Optimal sampling path for a coral microatoll slab along the fan's central axis (DeLong et al., 2013). B) X-ray of coral slab showing sampling path (Farley et al., 2024).
- DeLong, K. L., Quinn, .TM,. Taylor, F. W., Shen, C.-C., &Lin, K. (2013). Improving coral- base palcoclimate reconstructions by replicating 350years of coral St/Ca variations. Palacogeography, Palacoclimatology, Palacoecology, 373, 6-24.
- Farley, ,N. Antonioli, G,. Hallmann, N,. Camoin, G., Eisenhauer, A., Vella, C,. Milne, G. ,A. & Samankassou, E. (2024). Assessment of Porites microatolls for paleothermometry: Calibration for French Polynesia. Palaeogeography, Palacoclimatology, Palaeoecology, 642, 112146.
