Reciprocal transplant experiment:
In February 2022, 32 colonies (subclone/ramet) of the Caribbean thin finger coral, Porites divaricata (Taxonomy ID: 262287) were identified. 3 to 9 branch fragments were collected from every subclone (colony/ramet). 1 to 3 fragments from each ramet were moved to three designated sites: M1 (mangrove site 1), M2 (mangrove site 2), and R (reef site). 7 to 9 adjacent ropes were deployed at each site (seven ropes at M1 and R, and nine ropes at M2). Following a six-month period (February 2022 - July 2022), two traits were measured for each fragment: length change and red channel intensity, which serves as an inverse indicator of chlorophyll pigment density (Winters, Holzman, Blekhman, Beer, & Loya, 2009).

Trait Measurements:
To measure fragment growth, all fragments were photographed against a scale before and after transplantation, and their lengths were measured from base to apex using ImageJ software. The change in fragment length was determined by dividing the difference between the final and initial lengths by the initial length of the fragment. To measure red channel intensity, all fragments were collected at the end of the experiment and photographed against a laminated DKK color standard (DGK Color Tools) featuring an eleven-step gray scale with true white. Employing the methodology outlined by Winters et al. (2009), these photographs were used to estimate the chlorophyll density of each fragment. Initially, all images were standardized using the gray scale and the MATLAB macro CalibrateImageA. Subsequently, the MATLAB macro AnalyzeIntensity was employed to compute the mean red channel intensity for 20 swatches measuring 25 × 25 pixels for each fragment. Higher values of red channel intensity indicate lower levels of algal photosynthetic pigments (and hence, lower chlorophyll density) (Winters et al., 2009). The MATLAB scripts CalibrateImageA and AnalyzeIntensity are provided in the supplementary files in Winters et al., 2009.

See 'Related Datasets' for the environmental data from the coral transplant sites.