Long‐Term Impacts of the 1997–1998 Bleaching Event on the Growth and Resilience of Massive Porites Corals From the Central Red Sea

Abstract

This study investigates the impact of extreme heat wave events on long‐lived massive corals (Porites spp.) from the central Saudi Arabian Red Sea using trace element (Sr/Ca, Li/Mg, Mg/Ca, U/Ca, B/Ca, and Li/Ca) records preserved in the coral skeleton for the period between 1992 and 2012. Prior to 1998, the trace element records show strong correlations with sea surface temperature. However, during the prolonged high temperature phase associated with the 1998 El Niño event, the seasonal trace element signals were disrupted, which also coincided with a reduction in extension rates. This disruption in normally highly correlated seasonal trace element ratios‐sea surface temperature relationships was unusually long, lasting for approximately 2 years in the inner‐shelf reef site and nearly 4 years in the outer‐shelf reef site. Although the seasonal signal of trace element ratios in both cores eventually stabilized, for the inner‐shelf core the amplitude and absolute values in most trace element ratios remained significantly different compared to pre‐1998 levels. This suggests that prolonged thermal stress can induce subtle but potentially long‐lasting physiological changes that affect the elemental composition of the coral's calcifying fluid. The lack of indication of stress in the core records during later bleaching events (2003, 2005, and 2010) suggests that some of these physiological changes could have induced increased thermal tolerance, particularly for inner‐shelf corals, lending support to the capacity for corals to acclimatize.

Coral Records of Variable Stress Impacts and Possible Acclimatization to Recent Marine Heat Wave Events on the Northwest Shelf of Australia

“…While this evidence for thermal acclimatization is limited by the absence of intrasite reproducibility of these TE signatures, as well as supporting environmental data (water quality, light, etc. ), we do note its consistency with previous research that has shown increased thermal resilience in corals following their repeated exposure to marine heat waves (DeCarlo et al, ; D'Olivo et al, ; Guest et al, ; Maynard et al, ). For example, DeCarlo et al () recently showed a reduced proportion of stress bands in Porites spp.…”

The past century of coral bleaching in the Saudi Arabian central Red Sea

“…Corals themselves can shed light on past SST variability, though, since the trace-element geochemistry of their skeletons is sensitive to temperature ( Corrège, 2006 ; Nurhati, Cobb & Di Lorenzo, 2011 ). Previous analyses of temperature proxies in coral skeletal cores from Abu Shosha and Shi’b Nazar showed some of the highest summer temperature peaks in the early 2000s ( D’Olivo et al, 2019 ; see also Murty et al, 2018 ), broadly consistent with the satellite data, especially OI-SSTv2.…”

“…I can conclude with 95% confidence that no prior event reached this severity since 1934. Skeletal geochemistry of Abu Shosha Porites was also perturbed during this event, indicative of disruptions to the normal calcification process ( D’Olivo et al, 2019 ). The complete absence of stress bands in cores outside of Abu Shosha suggests this event may have been restricted to nearshore environments.…”

Reproducibility of Coral Mn/Ca‐Based Wind Reconstructions at Kiritimati Island and Butaritari Atoll

“…Given the high concentrations of Mn present in the coral tissue layer, which often covers ∼1 year of skeletal growth, it is possible that the incorporation of Mn into the coral skeleton occurs over the course of several months, whether during thickening, formation of tissue inclusions, or adsorption onto the skeleton following tissue decay. Such biosmoothing may be exacerbated during the El Niño‐related warming that follows WWEs, given sufficient stress to impact calcification rates (D'Olivo et al., 2019). However, another possibility is that the morphology of Tarawa's lagoon is very different from that of either Kiritimati or Butaritari.…”