Coral Growth Research Articles (Page 1)

Local and climatic drivers of coral growth in Southwestern Atlantic turbid-zone reefs

Corals grow annually at varying rates, influenced by environmental conditions. As key indicators of marine ecosystem health, studying coral growth is essential for predicting the impacts of environmental change. While previous research has explored coral growth extensively, most studies focus on existing conditions and the descriptive influence of environmental parameters. In fact, coral growth time-series data offer potential for deeper analysis, particularly in identifying dominant periodicities and enabling long-term projections. This study aims to develop an annual coral growth model using fuzzy logic approach. The Indian Ocean Dipole (IOD) is identified as a significant factor influencing the growth of Porites lutea in Tunda Island. Variations in sea surface temperature during IOD events notably affect coral growth, with positive IOD phases (IOD+) generally enhancing it. Analysis shows that the annual growth rings of Porites lutea in the northern station of Tunda Island, which borders open waters respond more slowly to SST fluctuations compared to the southern station, which is more sheltered. Fuzzy simulation results suggest that corals may be able to adapt to climate change. By the year 2085, coral growth is projected to recover from -0.75 cm to 0.1 cm by 2100. Based on SST projections from 1900 to 2100, SST anomalies are expected to continue increasing, reaching +0.45 °C.

Perforated thin-plate structures, which can effectively dissipate wave energy and also serve as base structures for growing corals in nature-based solutions to shore protection problems, can be promising alternatives to traditional rubble-mound breakwaters for shore protection. The growth of corals may be affected by the geometrical shapes of the base structures. This study investigates wave interaction with one or multiple submerged perforated thin-plate structures, emphasizing effects of structure's shapes on wave transmission and wave loading. Using a multi-domain boundary element method (BEM) and a parameterization of the pressure drop across a perforated thin plate, six cross-sectional shapes that belong to the following four types are considered for different ratios of structure height to water depth: rectangular, trapezoidal, triangular, and semi-circular shapes. For the purpose of verifying the BEM codes, an analytical solution was also developed for a single structure with a rectangular shape. The results show that for a given number of structures, the rectangular and trapezoidal shapes are more effective in reducing wave energy transmission, providing protection across a range of wave periods. The reduction of wave energy in the transmitted waves is controlled mainly by the energy dissipation into turbulence. Resonant reflection, found when multiple structures are used, can only slightly affect wave transmission in the frequency range of practical relevance. The wave loading on the structures for promising designs is studied. The results reported here are useful for marine biologists and coastal engineers to choose a suitable shape for the base structures for reducing wave energy and growing corals and geotechnical engineers to design foundations and anchoring schemes.

Millennial-scale episodic coral growth on the northern margin of the South China Sea

The role of macroalgae in modulating coral calcification: Mixed species responses in a changing reef environment.

Coral biomineralization drives the formation of reef structures, but ocean acidification (OA) threatens this process. Coral survival requires effective skeletogenesis in early life stages, through the formation of co-joined growth zones: rapid accretion deposits (RADs) and thickening deposits (TDs). Contrasting theories and lack of data on how these zones form hamper our understanding of normal coral growth and under future OA. This study describes growth patterns of RADs and TDs during the early stages of coral calcification under both normal and OA conditions. The work reveals geometric characteristics of RADs and TDs at micro- and sub-micrometer scales, as a basis for learning how OA impacts the early-formed skeletons. By combining material science approaches and Monte-Carlo simulations to model electron interactions that probe mineral phase composition, we show how TDs and RADs form simultaneously, challenging the classical "step-by-step" growth hypothesis. Unexpectedly, under normal pH, TDs comprise ≈65% amorphous calcium carbonate (ACC) and only 35% crystalline aragonite. Under OA, skeletons exhibit higher densities, with only 50% ACC. RADs are underdeveloped under OA, reducing skeletal bending resistance and increasing fracture risk. These findings reveal that the effect of OA on coral skeletogenesis is more complex than previously understood.

Thermally resistant coral Stylophora pistillata survives but does not thrive under chronic elevated baseline temperature.

Ecological quantitative criteria for reef site prioritisation to maximise survivorship and growth of outplanted corals.

Coral-reef degradation is disrupting the balance between reef accretion and erosion and threatening the persistence of essential coral-reef habitats. In south Florida, most reefs are already net eroding, and without intervention, valuable ecosystem services may be lost. Coral restoration holds the potential to reverse those trends; however, typical restoration monitoring does not adequately capture key geo-ecological functions. We addressed this knowledge gap using carbonate budgets and Structure-from-Motion models to evaluate the impact of coral restoration on reef-accretion potential and structural complexity at eight offshore and three inshore coral reefs in the Lower Florida Keys. Within 2-6 years following outplanting, restoration of rapidly growing A. cervicornis populations increased reef-accretion potential to 2.8mm y- 1 and drove significant increases in structural complexity. There was no measurable impact of restoring slower-growing, massive corals on reef-accretion potential inshore; however, whereas the severe 2023 coral-bleaching event immediately following our study caused near-complete mortality of A. cervicornis, 59% of massive corals survived, highlighting potential trade-offs between coral growth and survival on future restoration efficacy. We conclude that although restoration can produce rapid, small-scale increases in reef-accretion potential, there remain important uncertainties about how and whether ecosystem-scale benefits of restoration on important geo-ecological reef functions can persist long term.

The availability and stoichiometry of dissolved nutrients are known to have a significant effect on coral growth, biomineralisation, and stress tolerance. However, previous mechanistic studies have focused primarily on the photosynthetic symbionts. Here we studied the physiological and transcriptomic responses of the coral Stylophora pistillata exposed to four different concentration combinations of dissolved inorganic nitrogen (N) and phosphorus (P) over a period of eight weeks. Despite no significant effects on coral growth or calcification, corals from low P conditions bleached and had significantly fewer symbionts than those from high-phosphate treatments. Low P concentrations induced upregulation of ion transmembrane transporter activity, and downregulation of transcripts involved in phospholipid biosynthesis, protein processing, and protein maturation. Further, all enriched biological processes were related to phosphate metabolism. Our results suggest that S. pistillata controls a variety of molecular pathways to counteract the negative effects of insufficient nutrient supply.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-12130-3.

Benthic foraminifera as bioindicators of coral condition near mangrove environments.

Exploring bacterial diversity in Acropora pharaonis: Implications for coral health and growth anomalies.

The reefcube, a modular structure, serves as a primary habitat for fish and aids in the recruitment of new coral. The reefcube is predominantly made from fly ash and nickel slag, by-products of pyrometallurgy process that contain high content of CaO, MgO, dan SiO2. These compounds aid in the calcification process of newly recruited corals. This project has been conducted since 2021, which includes deployment processes, monitoring, and data collection. The data collection methods involve randomly sampling natural coral recruits that have grown on the modular structures and measured periodicaly. So far, the coral growth ranged from 2.41 cm to 12.90 cm over the course of two years. The observed genera include Acropora, Isopora, Pocillopora, Millepora, Porites, and all of which have shown significant growth on the Reefcube. There were 24 fish families recorded during the monitoring period, with the Pomacentridae family accounting for 53% of all sightings. The most commonly observed size range was between 0-5 cm and 16-20 cm, which represented 29% and 28% of the total observations. Within this size range from Pomacentridae and Acanturidae family. Several individuals of the species Abudefduf vaigiensis from the Pomacentridae family were notably present.Keywords:Coral reef ecosystemFish shelterGrowthNickle slagReefcube

Remote reefs offer insights into natural coral dynamics, influenced by regional environmental factors and climate change fluctuations. Clipperton Atoll is the eastern tropical Pacific’s most isolated reef, where coral reef growth and life strategies have been poorly studied so far. Recognizing the coral species’ growth response might help understand ecological dynamics and the impacts of anthropogenic stressors on coastal reefs. The present study evaluates annual coral growth parameters of the most abundant coral reef-building species, Porites australiensis, Porites arnaudi, Porites lutea, and Porites lobata. The results showed that during 2015–2019, corals exhibited the lowest annual linear extension (0.65 ± 0.29 cm yr−1), skeletal density (1.14 ± 0.32 g cm−3), and calcification rates (0.78 ± 0.44 g cm−2 yr−1) for the genera along the Pacific. Differences in growth patterns among species were observed, with Porites lutea and Porites lobata showing a higher radial extension, developing massive-hemispherical morphologies, and acting as structural stabilizers; meanwhile, P. arnaudi and P. australiensis exhibited more skeletal compaction but also with a high plasticity on their morphologies, contributing to benthic heterogeneity. These differences are particularly important as each species fulfills different ecological functions within the reef, contributing to the ecosystem balance and enhancing the relevance of the massive species in the physical structure of remote reef systems, such as Clipperton Atoll.

Abstract Coral reefs are in decline and face mounting stressors such as increasing sea temperatures, making it crucial to understand natural mechanisms that support coral health. Planktivorous damselfishes share tight associations with live corals and excrete inorganic forms of nitrogen and phosphorus that are typically limited in oligotrophic coral reef systems. Although these nutrient types are often beneficial to coral growth and overall physiological performance under both natural and controlled heat-stress conditions, the effects that fish-derived nutrients have on coral colony ecophysiology are poorly understood in terms of mechanisms, nutrient pathways, and performance. In this review, we discuss the nutrient requirements of corals and synthesize current knowledge on the potential for planktivorous coral-dwelling damselfishes to improve coral physiology under normal and elevated temperatures. This is particularly important for branching corals, which are the preferred homes of many species of damselfishes and are more susceptible to bleaching impacts. The biotic and abiotic factors that may influence nutrient transfer from damselfishes to corals are also critically evaluated to identify key knowledge gaps and provide direction for future research. Our findings indicate a number of potential pathways by which nutrients from damselfishes may enhance coral performance and heat tolerance; however, more research is warranted to investigate a range of physiological metrics in corals to quantify actual effects on coral physiology, in laboratory and especially field settings. Future research would also benefit from a method that enables nutrient flow to be directly traced and quantified from fishes to home corals.

Preserving coral reefs is crucial for safeguarding marine biodiversity, global ecosystems, and coastal communities. Coral restoration focuses on farming and transplanting corals back onto reefs. However, traditional attachment methods, such as petroleum‐based epoxy, pose environmental risks or provide inefficient affixation. Moreover, maximizing coral growth while farming boosts the restoration rate of the reefs. Hence, an environmentally friendly, conductive hardening bicomponent paste is developed to transplant and anchor corals, provide them with a solid growing substrate, and enable mineral accretion technology (MAT), a strategy to accelerate coral farming. The bicomponent paste consists of bio‐based and biodegradable acrylate soybean oil matrix and graphene nanoplatelets fillers. The paste hardens through mixing, transitioning from a Young's modulus of ≃0.1 to ≃60 MPa and reaching a strength of ≃5 MPa. Rheological tests demonstrate the tunability of the crosslinking dynamics of the paste. The paste exhibits a resistivity of 0.1 Ω∙m, with stable electrical properties for over 40 days in seawater. MAT tests show significant enhancement of coral growth rates within two weeks, doubling those of the control group. This paste offers versatility for application in aquaria and nurseries, does not require prone‐to‐oxidation metallic structures underwater, and can be employed on reefs.

Survivorship and growth of corals in Hawaiʻi two years post-bleaching: signs of resilience

Empirical observations of the rate of sea-level rise (SLR) and the timing of its recent acceleration are critical for validating ensemble methods used to determine global mean sea level trends. Such records are critically important at far-field locations where instrumental datasets are scarce. Here we construct a continuous 90-year sea level record (1930–2019) from the central tropical Indian Ocean derived from the incremental growth of a coral microatoll, which is demonstrated to reflect changes in sea level at annual timescales. Our record, which overlaps with tide gauge observations, extends the instrumental record by six decades and reveals climatic variability and marked changes in sea level behaviour across the twentieth century characterised by: (1) an increase in sea level of 0.30 m between 1930 and 2019; (2) low rates of SLR in the early twentieth century (1.42 ± 0.42 mm.yr−1); (3) a marked acceleration in SLR to ~3.44 ± 0.68 mm.y−1 in the late 1950’s; and (4) a further increase to 4.39 ± 0.48 mm.y−1 over the past three decades. Our results provide empirical evidence for a mid-century SLR acceleration in the central Indian Ocean, which is earlier than instrumental records indicate for coastal sites at the continental margins.

Abstract Carbonate clumped isotopes are a powerful tool for paleoclimate reconstruction due to the ability to reconstruct past changes in both temperature and precipitation‐evaporation balance. Here we test the utility of this method on last millennium carbonate lagoonal sediments from Kiritimati, a coral atoll where modern climate variability is driven by interannual changes in the El Niño‐Southern Oscillation. We find last millennium lagoonal temperatures from clumped isotopes are cooler than anticipated compared to modern measurements and other paleoclimate reconstructions. This discrepancy is probably due to sediments containing a mixture of high‐magnesium calcite derived from primary precipitates and benthic foraminifera and aragonite derived from warm water corals. We employed an inverse mixing model to minimise the impact of vital effects related to coral growth on clumped isotope compositions and found an increasing difference between modelled and measured T(Δ47) values through time. This potentially indicates that the composition of lagoon water became increasingly unique from the coral carbonate formation waters through the last millennium. This study highlights the necessity of detailed understanding of carbonate mineralogy, sedimentology and provenance in interpreting clumped isotope temperature reconstructions.

Climate change and human activities threaten coral reefs, requiring effective restoration. This study assessed the growth and calcification rates of transplanted corals by examining skeletal characteristics, conducted in the Coral Fragmentation (CF), Natural Reef (NA), Coral Nursery (CN), and Coral Restoration (CR) areas on Wuzhizhou Island, Hainan. Samples of Acropora hyacinthus and A. microphthalma were collected from each area in April 2024, with CR samples including corals transplanted for 1, 2, and 3 years using the Framed Reef Module. Results indicated that while Fv/Fm values remained consistent among samples, significant differences in symbiont density and biomass suggest variations in symbiont adaptation. Extended transplantation significantly influenced both the ecological volume (EV) and calcification rates of transplanted corals. Specifically, A. hyacinthus and A. microphthalma demonstrated significant increases in EV of 267.78 and 271.70%, respectively, when comparing corals transplanted for 3 years to those transplanted for only 1 year. Additionally, the calcification rates of these species showed a marked increase over time, with A. hyacinthus achieving a rate of (9.24 ± 2.70 g CaCO3 cm−2 yr−1) in the 3‐year transplants, compared to (5.02 ± 1.86 g CaCO3 cm−2 yr−1) for the 1‐year transplants. Similarly, A. microphthalma exhibited a calcification rate of (9.06 ± 2.62 g CaCO3 cm−2 yr−1) for 3‐year transplants, compared to (4.24 ± 2.18 g CaCO3 cm−2 yr−1) for 1‐year transplants. Survival rates for both species fell below 70% due to 2023 thermal stress, highlighting their vulnerability. Although extended transplantation boosts coral growth, challenges like thermal stress hinder restoration success. This study provides insights to improve coral resilience in the face of climate change.