Goodbody-Gringley, G. | Search bioRxiv

bioRxiv2026

Asymmetric depth acclimation and plasticity limit the refugial potential of mesophotic Porites astreoides

Mesophotic coral ecosystems have been proposed as climate refugia for shallow reefs, yet the capacity of mesophotic corals to persist across depth gradients remains unresolved. We conducted a 7-month reciprocal transplantation of the Caribbean coral Porites astreoides between shallow (10 m) and mesophotic (40 m) reefs to assess physiological, skeletal, and transcriptomic plasticity. Shallow colonies exhibited higher metabolic activity and skeletal extension, whereas mesophotic colonies showed reduced protein content, slower extension, and elevated expression of skeletal organic matrix genes. Transplant responses were asymmetric: shallow-to-deep corals acclimated through coordinated physiological and transcriptional adjustments, while deep-to-shallow transplants experienced elevated mortality and limited plasticity. SNP-based analyses suggest incomplete isolation across depth, while reciprocal transplant responses reflect greater phenotypic plasticity in shallow corals and indications of depth-specific specialization in mesophotic corals. Our findings indicate that shallow populations harbor greater acclimatory capacity, whereas mesophotic corals show constrained upward resilience, challenging the generality of deep reefs as refugia under rapid environmental change.

ecology↗

bioRxiv2019

Comparative thermal performance of Orbicella franksi at its latitudinal range limits

Temperature drives biological responses that scale from the cellular to ecosystem levels and thermal sensitivity will shape organismal functions and population dynamics as the world warms. Reef building corals are sensitive to temperature due to their endosymbiotic relationship with single celled dinoflagellates, with mass mortality events increasing in frequency and magnitude. The purpose of this study was to quantify the thermal sensitivity of important physiological functions of a Caribbean reef-building coral, Orbicella franksi through the measurement of thermal performance curves (TPCs). We compared TPC metrics (thermal optimum, critical maximum, activation energy, deactivation energy, and rate at a standardized temperature) between two populations at the northern and southern extent of the geographic range of this species. We further compared essential coral organismal processes (gross photosynthesis, respiration, and calcification) within a site to determine which function is most sensitive to thermal stress using a hierarchical Bayesian modeling approach. We found evidence for differences in thermal performance, which could be due to thermal adaptation or acclimatization, with higher TPC metrics (thermal optimum and critical maximum) in warmer Panama, compared to cooler Bermuda. We also documented the hierarchy in thermal sensitivity of essential organismal functions within a population, with respiration less sensitive than photosynthesis, which was less sensitive than calcification. Understanding thermal performance of corals is essential for projecting coral reef futures, given that key biological functions necessary to sustain coral reef ecosystems are thermally-mediated.\n\nSummary statementWe apply a thermal performance curve approach to a variety of fitness related parameters in a reef building coral across its geographic range and various functions to improve our understanding of the inherent variability in thermal tolerance.

physiology↗