DOI: 10.5061/dryad.vq83bk3z5
title: Data from: Local environment and coral composition affect recovery and determine long-term coral responses to recurrent mass mortalities in the Lakshadweep Archipelago

description: A quarter century after the first global coral bleaching event in 1998,
 reports differ on the relative importance of anthropogenic influences,
 local environment and bleaching recurrence in determining the resilience
 of coral reefs. While life history traits largely determine how corals
 respond to temperature anomalies, it is unclear if these traits also
 determine how corals fare over time.  From 1998 to 2022, we
 tracked compositional changes in reefs across the Lakshadweep Archipelago
 to explore how global El Niño events, and local environment (wave climate
 and depth) influenced coral responses to repeated mass bleaching. From the
 1998 to the 2016 bleaching event, the magnitude of coral mortality reduced
 overall, particularly at deeper reefs (shallow: -38% to -3%; deep: -18% to
 -0.45%). Post-bleaching recovery correlated positively with higher wave
 exposure, linked to the creation of stable structures for coral settlement
 and survival. Across bleaching phases, recovery was initially slow (6-7
 years post-mortality), but, given time, showed a much steeper increase,
 led by space-occupying genera like Acropora. However, recurring mass
 bleaching maintained coral cover low (~15% across all sites). These broad
 trends mask dynamic compositional patterns. Genera such as Porites,
 Pocillopora, and Favia declined less through time compared to
 Acanthastrea, Turbinaria, Psammocora and Plesiastrea among others. We
 identified six community clusters that describe contrasting long-term
 responses to local and global factors, mediated by depth and wave
 exposure. Interestingly, genera with different functional traits cluster
 together indicating that bleaching susceptibility interacts with depth and
 exposure, creating a spatial mosaic of coral assemblages. These clusters
 serve as a predictive, site-specific framework to understand the
 dynamically shifting but declining assemblage of Lakshadweep reefs. While
 local management could help maintain this changing composition, urgent
 global action is needed to secure the long-term ecological integrity of
 tropical reefs.
description: We sampled each site at deep (~16 m) and shallow (~8 m) depth
 classes, where we estimated coral cover in 1x1 m quadrats, placed at a
 minimum of 10-15 m of distance from one another. NAs pertaining to the
 depth column are for years when the depth measurement was not noted and
 instead characterised by deep/shallow. Each depth class therefore had, on
 an average, 18 quadrats, corresponding to 18 m<sup>2</sup> of
 area. Each quadrat is assumed to be independent of one another and from
 our unit of sampling. Data were recorded either directly
 <em>in-situ</em> (1998-2003) or with digital photographs (2007
 onwards). Photoquadrats were analysed with ImageJ (Schneider et al.,
 2012), where the percent cover of broad benthic categories were estimated
 in overlaid 10 x 10 cm grids. NAs in the 'Photo_ID' column
 indicate inwater surveys where photography was not possible. This is
 largely restricted to the years 1998 & 1999. Live coral was
 identified to the genus, based on Veron’s (2000) classification
 (Supplementary Table 1 for new classification; surveys in 1998 and 1999
 did not record genus-level information). All samples were collected within
 the months of January – March, before the peak summer season in the Indian
 subcontinent. We analyse changes in coral composition from 1998 to 2022
 and present data for 13 years across this 24-year period (Supplementary
 Table 2 for details on sampling period).
description: # Data from: Local environment and coral composition affect recovery and
 determine long-term coral responses to recurrent mass mortalities in the
 Lakshadweep Archipelago --- Information of coral cover and genera are
 provided in the spreadsheets. These are information from photoquadrats
 that have been analysed and entered in spreadsheets. ## Description of the
 Data and file structure Files: AGT_corals_dryad; KDT_corals_dryad and
 KVT_corals_dryad All values of interest are given as percentage values.
 Each row corresponds to a particular genera of coral. Year corresponds to
 the years in which data was collected; Atoll mentions the larger atoll
 within which different sites are located. Each site further has a category
 of Aspect, which is largely East and West There's a corresponding
 depth associated with each transect, followed by a categorical
 representation of the depth. Transect represents the transect ID whereas
 quadrat refers to the number of quadrats in a 50m transect.
 'Photo_ID' corresponds to the photograph from which data was
 extracted. Genera refers to the genera of coral found in the quadrats
 along with their morphology or lifeform shape. Percent denotes the
 percentage cover of corals. NAs pertaining to the depth column are for
 years when the depth measurement was not noted and instead characterised
 by deep/shallow.