Reef Organisms Research Articles

Marine mesocosm system: A reliable tool for testing bioaccumulation and effects of seawater enrichment with dissolved iron in reef organisms

In 2015, a marine mesocosm facility was designed and implemented by the Coral Vivo Project in its research station (Porto Seguro, Bahia State, Brazil) to initially study the effects of global impacts, especially ocean warming and acidification, on coral reefs. However, local impacts, including seawater contamination with metal(loid)s, are considered as a major threat to coral reefs. Also, in 2015, the largest disaster involving a mining dam occurred in Brazil. Iron (Fe) mining tailings originated from the dam failure affected not only freshwater ecosystems (rivers, lakes and lagoons), but also adjacent beaches, mangroves, restingas, reefs and other marine systems. Seawater, sediments and biota were contaminated with metal(loid)s, especially Fe, arsenic (As), mercury (Hg) and manganese (Mn). Therefore, we aimed to adapt the marine mesocosm facility of the Coral Vivo Project to evaluate the bioaccumulation and biological impacts of increasing concentrations of dissolved Fe on a diversity of reef organisms. Results obtained indicate a great versatility and reliability of the marine mesocosm system for application in biological and ecological studies on the isolated effect of seawater dissolved Fe on reef organisms of different functional groups simultaneously.•Studies involving seawater enrichment with dissolved Fe can be performed using a marine mesocosm system.•The marine mesocosm is a reliable tool to study the isolated effects of metal(loid)s on reef organisms.

Editorial preface to special issue: Paleoecology and evolution of Paleozoic corals and reef ecosystems

The Paleozoic Era was an interval of profound changes in metazoan reef ecosystems, which became magnificent in scale and diversity, owing to the evolution of various skeletal reef builders especially corals and sponges. This special issue comprises 16 papers that improve our understanding on the complex evolution and paleoecology of corals and metazoan reef ecosystems, and their response to environmental changes through the Cambrian to Permian. The case studies present detailed evidence that helps to reconstruct the complicated interactions among reef organisms, the succession of metazoan reefs, and their relations to paleoenvironments. Some key findings address (i) Cambrian reefs and microbe–metazoan reef transition to the Ordovician, (ii) reef component and paleoecological features of Siluro-Devonian coral-stromatoporoid reefs, and (iii) growth characteristics, paleogeography, and reef formation of Late Paleozoic corals and sponges. As such, this special issue will stimulate further work on reef studies and be of interest to a broad community of paleoecologists, to scholars in various fields of the geosciences as well as to reef biologists.

The hydrodynamics of Lizard Island lagoon, Great Barrier Reef

Hydrodynamic processes are a major driver for marine systems, linking marine organisms with their environment. However, a lack of hydrodynamic data at an ecologically relevant spatial resolution has stymied our understanding of reef function, as exemplified by Lizard Island on the Great Barrier Reef. To address this gap, 23 to 27 Marotte HS current meters were deployed over three periods, collecting 15 months of current velocity data. Combining these data with wind and tide datasets, we provide a preliminary description of the circulation in the Lizard Island lagoon, examining wind and tide influence, and flushing time. During south-easterly trade winds, flood tides flow through the Lagoon Entrance, while wind-induced waves cross the Bird-South crest, driving a north-westerly flow through Loomis Channel and across the western lagoon. Ebb tides flow east–south-east through the Lagoon Entrance and south-west through the Palfrey-South channel. Tides contribute a mean of 20.4% to the overall current speed, particularly in deeper sites with less reef interference, while shallow sites were more influenced by wind. Lizard Island lagoon flushing times ranged from a few hours to 10 days; longer during periods with low wind speeds. Hindcast flushing times during the 2016 coral bleaching event (following 8 Degree Heating Weeks) were approximately 22 h, suggesting that flushing time likely had minimal influence on bleaching. Our analyses provide initial insights into the circulation of the Lizard Island system and aid understanding of the potential relationships between reef organisms and their physical environment, bridging the gap between ecology and hydrodynamics.

Reefense: Design Of A Porous Modular Hybrid Reef For Coastal Protection

Hybrid artificial reef structures can be designed to promote the development of a self-sustaining habitat for reef organisms while simultaneously enhancing the extent to which they provide coastal protection. Such hybrid structures offer many additional ecosystem benefits over conventional engineering structures that are used to provide coastal protection. Here, we investigate the wave attenuation capacity of engineered oyster reef modules that have been designed through the DARPA initiative Reefense: A Mosaic Oyster Habitat for Coastal Defense. The modules are designed with significant porosity (through misaligned holes), shelves to facilitate oyster recruitment, and an interlocking mechanism to maximise reef stability.

Architecture and exploration target areas of the Senegal Basin, West Africa

The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention. Despite this, several exploration wells in this area fail, which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation conditions. This study examines these characteristics utilizing gravity, seismic and drilling data, and finally makes a comparison with the Cote d’Ivoire Basin, a typical transform margin basin in the South Atlantic. The results suggest that the Senegal Basin, influenced by multiple transform faults and a weak Paleozoic basement, experienced three evolutionary stages: rifting, transitional, and drifting. Each stage contributed to the development of distinct depositional sequences - syn-rift sequences, sag sequences, and continental margin sequences, respectively. The Triassic - Early Jurassic rifting stage predominantly formed continental deposits, like fluvial, lacustrine, and deltaic deposits, in the syn-rift sequences. The Middle-Late Jurassic transitional stage, influenced by transform faults, witnessed the formation of marginal ridges or submarine uplift zones. These zones, in conjunction with landward high terrains, formed a restricted environment promoting the development of source rocks in the sag sequences. During the drifting stage, three types of reservoirs, namely platform carbonate rocks, deltas, and slope-floor fans were formed. Notably, large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire Basin. The Upper Jurassic - Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges, suggesting substantial potential for hydrocarbon exploration in the Senegal Basin.

Linking Transpiration to Reef Nitrogen Supply on a Tropical Coral Island

AbstractCoral reef islands are biodiversity hotspots with high conservation value, but we have a poor understanding of how island vegetation, through transpiration, influences groundwater nutrient supply to adjacent reef systems. Here we combine stable isotope tracing, geophysical surveys, and satellite analysis to unravel the links between transpiration and the discharge of groundwater nitrate to the waters surrounding a coral reef island (Lady Elliot Island in the Great Barrier Reef). Over a 2‐year study period (2020–2021) there was a net loss of freshwater from the island, that is, evapotranspiration (ET) exceeded rainfall, largely caused by high rates of transpiration (73% of ET). Transpiration was higher in forested areas, and groundwater salinity appeared to be higher there. By tracing the nitrogen stable isotope signature of groundwater nitrate into reef organism tissue we were able to map groundwater nitrogen discharge spatially and temporally. Groundwater nitrogen discharge was focussed on one side of the island and did not vary seasonally as expected, despite reduced rainfall and seabird guano inputs over the austral winter/spring. Based on our results, we propose that transpiration by island vegetation slows groundwater flow and concentrates nitrate in the groundwater being released to the surrounding reef system. High concentrations of nitrate in groundwater (up to 27 mmol L−) were observed on Lady Elliot Island and these seem to have increased since 2014, but further work is required to understand if this is a normal scenario for tropical coral islands or the result of the islands' revegetation program.

Reef fish identification through image records using artificial intelligence and convolutional neural network system

Coral reef environments show great diversity and abundance of species that represent important biological resources for obtaining food and medicines, in addition to acting as bioindicators of the quality of reef environments, serving as a parameter to diagnose environmental impacts and, simultaneously, to evaluate the availability and use of fishing stocks and biological resources in such environments. Monitoring such ecosystems arises from the urgent need to better understand the natural geographic and environmental variability of these systems, as well as their main drivers of change, to inform and promote more effective management of such environments. With the growing need to monitor communities of reef organisms, particularly fish, the creation of a digital analysis method would make a great contribution to the studies of reef fish. To fill this knowledge gap, our work evaluates the possibility of using an artificial intelligence mechanism using convolutional neural networks (CNN) to identify and count reef fish in image records, to optimize digital analysis of videos and/or photos in reef environments for fish ecology studies. The accuracy of the CNN identification method was effective, although it still has challenges to improve, such as: the need for a preliminary survey of reef fish species existing in the target area to be monitored, with the capture of good resolution images in different positions space for each species; production of an image bank with a large number of diverse images for each species (minimum of 200 images per species) and; To detect fish in videos, fast computers with a dedicated GPU card are needed, especially if the videos are high or ultra-resolution and have a large number of fps.

The First Evidence of the Water Bioremediation Potential of Ficopomatus enigmaticus (Fauvel 1923): From Threat to Resource?

Each year, a staggering 700,000 tons of synthetic dyes are manufactured globally, leading to the release of dye-laden wastewater into aquatic systems. These synthetic dyes resist biodegradation, endangering human and environmental health. Since traditional wastewater treatments are basically unable to remove dyes, exploring the potential of alternative solutions, such as bioremediation, is crucial to reduce dye contamination in aquatic ecosystems. Ficopomatus enigmaticus (Fauvel 1923), listed as one of the 100 worst invasive species in Europe, is considered an invasive ecosystem engineer capable of causing economic and ecological losses. Despite this negative status, the literature suggests its positive contributions to aquatic ecosystems as habitat former and water bioremediator. However, existing evidence on the potential of F. enigmaticus to improve water quality is fragmented and lacks experimental data from laboratory tests. This study examined the potential of Ficopomatus reefs, both living and dead, to enhance water quality by removing contaminants, focusing on methylene blue (MB), one of the most common synthetic dyes. Bioaccumulation and bioadsorption were identified as key mechanisms for dye removal, supported by ATR-FTIR and microscopic analyses. Ficopomatus efficiently removed up to 80% of MB within 24 h. Bioaccumulation in the soft body accounted for 18% of the total removal, while complex adsorption phenomena involving carbonaceous, microalgal, and organic reef components accounted for 82%. Surprisingly, bioremediated solutions exhibited significant effects in ecotoxicological tests on bacteria, indicating the potential of F. enigmaticus to disrupt bacterial quorum sensing related to biofilm formation, and suggesting a possible antifouling action. This study underscores the intricate interplay between F. enigmaticus, water quality improvement, and potential ecological consequences, stressing the need for further investigation into its multifaceted role in aquatic ecosystems.

The reproductive system of the cryptogenic alga Chondria tumulosa (Florideophyceae) at Manawai, Papahānaumokuākea Marine National Monument

ABSTRACT Determining the relative importance of sexual and asexual reproduction is critical for determining how genetic diversity is partitioned within and among populations. Macroalgae exhibit reproductive system variability, with many species capable of both sexual and asexual reproduction. Thus, rates of fragmentation (asexual) versus sporic recruitment (sexual) must be quantified. This is critical during range expansions when shifts to uniparental reproduction are common. Chondria tumulosa is a cryptogenic red alga that was discovered forming thick mats at Manawai, in the Northwestern Hawaiian Islands, during opportunistic sampling in 2019. It reduced the biodiversity and abundance of associated coral reef organisms. To characterize the reproductive system of C. tumulosa in this atoll, we visually assessed 124 thallus clumps for reproductive structures and used five microsatellite loci to genotype 41 thalli. All thalli bearing reproductive structures (20%) and all thalli that were genotyped were tetrasporophytes. No gametophytic thalli were observed using microscopy or microsatellite genotyping, though 80% of thalli observed under the microscope were vegetative. We observed in situ thallus fragmentation supported by the presence of 17 repeated genotypes and other genetic signatures, suggesting high rates of asexual reproduction. These results suggest that C. tumulosa is partially clonal in this atoll and has the potential for spreading to other nearby atolls. Rapid establishment, thallus fragmentation and tetrasporophytic dominance are consistent with other red macroalgal invasions studied to date. Understanding the reproductive system is an important component of developing management strategies for this alga and expanding our understanding of the population genetics of partially clonal taxa.

Geographic range size and species morphology determines the organization of sponge host-guest interaction networks across tropical coral reefs.

Sponges are widely spread organisms in the tropical reefs of the American Northwest-Atlantic Ocean, they structure ecosystems and provide services such as shelter, protection from predators, and food sources to a wide diversity of both vertebrates and invertebrates species. The high diversity of sponge-associated fauna can generate complex networks of species interactions over small and large spatial-temporal gradients. One way to start uncovering the organization of the sponge host-guest complex networks is to understand how the accumulated geographic area, the sponge morphology and, sponge taxonomy contributes to the connectivity of sponge species within such networks. This study is a meta-analysis based on previous sponge host-guest literature obtained in 65 scientific publications, yielding a total of 745 host-guest interactions between sponges and their associated fauna across the Caribbean Sea and the Gulf of Mexico. We analyzed the sponge species contribution to network organization in the Northwest Tropical Atlantic coral reefs by using the combination of seven complementary species-level descriptors and related this importance with three main traits, sponge-accumulated geographic area, functional sponge morphology, and sponges' taxonomy bias. In general, we observed that sponges with a widespread distribution and a higher accumulated geographic area had a greater network structural contribution. Similarly, we also found that Cup-like and Massive functional morphologies trend to be shapes with a greater contribution to the interaction network organization compared to the Erect and Crust-like morphos. Lastly, we did not detect a taxonomy bias between interaction network organization and sponges' orders. These results highlight the importance of a specific combination of sponge traits to promote the diversity of association between reef sponges and their guest species.

Reproductive consequences of thermal stress-induced bleaching in the giant clam Tridacna crocea

Reproduction is a fundamental process necessary for maintaining a population. However, reproductive processes are sensitive to thermal stress which can cause bleaching in reef organisms such as corals and giant clams. Here we examined the phototrophic and physiological performances, particularly the reproductive processes, in Tridacna crocea during bleaching and recovery periods. Giant clam individuals were induced to bleach at heated treatment (32-33 °C) for 16 days and allowed to recover at 28-29 °C for 35 days. The control giant clams were kept at 28-29 °C. Heated giant clams showed lower phototrophic performances (Fv/Fm and photosynthesis), but their respiration and survival were similar to control giant clams. The gonadosomatic index (GSI) was lower, and the proportion of regressive eggs (i.e., eggs that are no longer viable) was higher in heated than in control giant clams. However, heated giant clams were able to maintain their egg size. In addition, T. crocea showed recovery of phototrophic potential and color of mantle but not of their reproductive output after a month of recovery. Our results indicate that bleaching reduces the reproductive output in giant clams by disrupting their gametogenesis, such as through egg resorption, but giant clams showed potential reproductive strategy, through maintenance of their egg size, to ensure the quality of their offspring. Furthermore, one month of recovery is not sufficient to restore the normal reproductive processes in T. crocea, which may delay their population recovery after a bleaching disturbance.

The impacts of artificial light at night on the ecology of temperate and tropical reefs.

Despite 22% of the world's coastal regions experiencing some degree of light pollution, and biologically important artificial light at night (ALAN) reaching large portions of the seafloor (greater than 75%) near coastal developments, the impacts of ALAN on temperate and tropical reefs are still relatively unknown. Because many reef species have evolved in response to low-light nocturnal environments, consistent daily, lunar, and seasonal light cycles, and distinct light spectra, these impacts are likely to be profound. Recent studies have found ALAN can decrease reproductive success of fishes, alter predation rates of invertebrates and fishes, and impact the physiology and biochemistry of reef-building corals. In this paper, we integrate knowledge of the role of natural light in temperate and tropical reefs with a synthesis of the current literature on the impacts of ALAN on reef organisms to explore potential changes at the system level in reef communities exposed to ALAN. Specifically, we identify the direct impacts of ALAN on individual organisms and flow on effects for reef communities, and present potential scenarios where ALAN could significantly alter system-level dynamics, possibly even creating novel ecosystems. Lastly, we highlight large knowledge gaps in our understanding of the overall impact of ALAN on reef systems. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Contact-free impacts of sessile reef organisms on stony coral productivity

Coral reefs are biodiversity and productivity hotspots where space limitation makes interactions between organisms inevitable. Biodiversity loss alters these interactions, however downstream effects on the productivity of individual species remain unexplored. Here, we quantified immediate and long-term changes in stony coral productivity in response to contact-free interactions with various benthic organisms (stony corals, soft corals, macroalgae, sponges). We show that corals sense the presence of other organisms and subsequently modulate their productivity. Each stony coral species had a characteristic reaction to contact-free stimuli, while the identity of the interaction partner was of subordinate importance. Our data highlight downstream effects that biodiversity loss and shifting coral reef communities may have through indirect modulation of productivity, resulting in uneven effects among species. The productivity response is probably mediated by secondary metabolites released into the water. The underlying communication pathways that mediate these interactions remain to be investigated.

Sea‐weeding: Manual removal of macroalgae facilitates rapid coral recovery

Abstract Coral reef ecosystems globally are under threat, leading to declining coral cover and macroalgal proliferation. Manually removing macroalgae (i.e. ‘sea‐weeding’) may promote local‐scale coral recovery by reducing a biological barrier, though the impact of removal on community composition of benthic reef organisms has not been quantified. In this three‐year study (2018–2021), fleshy macroalgae (predominantly Sargassum spp.) were periodically removed from 25 m2 experimental plots on two inshore fringing reefs of Yunbenun (Magnetic Island) in the central Great Barrier Reef. By the end of the study, coral cover in removal plots (n = 12 plots) assessed through in‐field transects increased by at least 47% (2019 mean: 25.5%, 2021 mean: 37.4%), and macroalgal cover decreased by more than half. In contrast, in control plots (n = 12 plots), there was no change in macroalgal cover while coral cover remained stable (2019 mean: 16.4%, 2021 mean: 13.6%). Changes in benthic cover were supported by photoquadrat data, with Bayesian probability modelling indicating a 100% likelihood that coral cover more than doubled in removal plots over the study period, compared to only a 29% chance of increased coral cover in control plots. Synthesis and applications. Manual macroalgal removal can provide rapid benefits and enhance inshore coral reef recovery. Through involvement of community groups and citizen scientists, larger scale removal of macroalgae is a low‐tech, high‐impact, and achievable method for local reef management.

Microorganisms and dissolved metabolites distinguish Florida's Coral Reef habitats.

As coral reef ecosystems experience unprecedented change, effective monitoring of reef features supports management, conservation, and intervention efforts. Omic techniques show promise in quantifying key components of reef ecosystems including dissolved metabolites and microorganisms that may serve as invisible sensors for reef ecosystem dynamics. Dissolved metabolites are released by reef organisms and transferred among microorganisms, acting as chemical currencies and contributing to nutrient cycling and signaling on reefs. Here, we applied four omic techniques (taxonomic microbiome via amplicon sequencing, functional microbiome via shotgun metagenomics, targeted metabolomics, and untargeted metabolomics) to waters overlying Florida's Coral Reef, as well as microbiome profiling on individual coral colonies from these reefs to understand how microbes and dissolved metabolites reflect biogeographical, benthic, and nutrient properties of this 500-km barrier reef. We show that the microbial and metabolite omic approaches each differentiated reef habitats based on geographic zone. Further, seawater microbiome profiling and targeted metabolomics were significantly related to more reef habitat characteristics, such as amount of hard and soft coral, compared to metagenomic sequencing and untargeted metabolomics. Across five coral species, microbiomes were also significantly related to reef zone, followed by species and disease status, suggesting that the geographic water circulation patterns in Florida also impact the microbiomes of reef builders. A combination of differential abundance and indicator species analyses revealed metabolite and microbial signatures of specific reef zones, which demonstrates the utility of these techniques to provide new insights into reef microbial and metabolite features that reflect broader ecosystem processes.

DECADAL EVOLUTION OF CORAL ISLANDS IN A CHANGING OCEAN AND CLIMATE

Coral reef islands are under threat from warming and rising seas, ocean acidification and increased storminess. Coral islands are low-lying accumulations of sediment derived from the shells and skeletons of calcifying reef organisms. IPCC predications and COP26 highlight that the future of coral islands is not certain as islands are morphologically active. It is unclear what tipping points are causing negative impacts on some coral reef islands and not others. A better understanding of island stability and vulnerability is urgently needed. This has direct implications for over 200 million people that rely on reefs and their islands for their livelihoods (Ferrario et al., 2014). Further, coastal States such as Australia, USA, the Philippines and Small Island Developing States (SIDS) use coral reef islands as legal baselines to support their maritime jurisdictions (UNCLOS, 1982). We focus on 31 of Australia’s offshore coral reef islands on 10 reefs across the Coral Sea and NW Shelf. These islands are environmentally and geo-politically important as they support and extend Australia’s maritime jurisdiction. Island morphology (e.g., shoreline positions, areas, shapes) in historical aerial and satellite imagery (1977-now) were compared to ocean and climate data (e.g., storm tracks, NOAA Coral Watch). We used this data to identity tipping points that drive decadal changes in coral reef island stability.

Novel Interaction between a Rabbitfish and Black Corals

Herbivorous fishes play important functional roles in coral reef ecosystems, and their influence on mediating competitive dynamics between corals and macroalgae is well studied. Nonetheless, direct interactions between herbivorous fishes and corals may also be relevant, although these are less studied. Here, we describe a series of observations of schools of the herbivorous streaked rabbitfish (Siganus javus) nibbling on black corals (order Antipatharia) at the SS Yongala wreck, within the Great Barrier Reef Marine Park. We provide a hypothesis that may explain this behaviour, which, if confirmed, would represent a mechanism influencing the health of the corals. Moreover, this interaction extends the typical coral–algae competition for space paradigm and furthers knowledge of complex relationships between coral reef organisms.

A new reef classification model with insights into Phanerozoic evolution of reef ecosystems

AbstractOrganic reefs are largely calcareous build‐ups of sessile organisms, commonly in shallow marine ecosystems, with a long Precambrian to Modern history. Despite a long history of study, the reef classification is still open to development due to reefs encompassing diverse organic and inorganic components with various imprecise and synonymous terms. In this study, a new classification model for organic reefs is expressed in two hierarchical levels.Level 1: Reef outline geometry has two major forms: bioherms (prominent relief and laterally constrained) and biostromes (low relief and large lateral extension interbedded with non‐reef sediments), within which constructional components highly vary.Level 2: Four reef constructor groups form end‐members in a pyramid diagram: macroskeleton (S), microbia (Mi), matrix (Ma) and cement (C). Thus five reef types are recognized depending on the composition and structure of these constructors: (i) S‐supported reef; (ii) Mi‐supported reef (calcimicrobial and agglutinated microbial); (iii) Ma‐supported reef (cluster and carbonate mud mound); (iv) C‐supported reef; and (v) hybrid component‐supported reef (comprising two or more major types of reef components). This arrangement makes a more streamlined and accessible reef classification than prior schemes. Two associated non‐reef habitats that may grade into reefs are relevant: debris biostromes/banks and level‐bottom communities containing taxa found in adjacent reefs. Based on this ‘SMiMaC’ model, the structural evolution of reef ecosystems is demonstrated for the Phanerozoic, characterized by S‐supported and hybrid‐supported, and Mi‐supported and Ma‐supported structures under cooling and intense warming climates, respectively.

SCUBA noise alters community structure and cooperation at Pederson’s cleaner shrimp cleaning stations

Recreational SCUBA diving is widespread and increasing on coral reefs worldwide. Standard open-circuit SCUBA equipment is inherently noisy and, by seeking out areas of high biodiversity, divers inadvertently expose reef communities to an intrusive source of anthropogenic noise. Currently, little is known about SCUBA noise as an acoustic stressor, and there is a general lack of empirical evidence on community-level impacts of anthropogenic noise on coral reefs. Here, we conducted a playback experiment on Caribbean reefs to investigate impacts of SCUBA noise on fish communities and interspecific cooperation at ecologically important cleaning stations of the Pederson’s cleaner shrimp Ancylomenes pedersoni. When exposed to SCUBA-noise playback, the total occurrence of fishes at the cleaning stations decreased by 7%, and the community and cleaning clientele compositions were significantly altered, with 27% and 25% of monitored species being affected, respectively. Compared with ambient-sound playback, SCUBA-noise playback resulted in clients having to wait 29% longer for cleaning initiation and receiving 43% less cleaning; however, cheating, signalling, posing and time spent cleaning were not affected by SCUBA-noise playback. Our study is the first to demonstrate experimentally that SCUBA noise can have at least some negative impacts on reef organisms, confirming it as an ecologically relevant pollutant. Moreover, by establishing acoustic disturbance as a likely mechanism for known impacts of diver presence on reef animals, we also identify a potential avenue for mitigation in these valuable ecosystems.

Constant shell density of hyaline large benthic foraminifers under thermal stress

Recently, increased concentrations of anthropogenic atmospheric CO2 have caused ocean warming and acidification, leading to swift environmental alterations. In coral reef regions, bleaching and death of symbiotic calcifying organisms have been distressing. Generally, large benthic foraminifers (LBF), a principal symbiotic calcifying organisms in coral reefs, have gained popularity because thermal stress impedes their growth and ecological functions. Nevertheless, due to the complex nature of the shell structure, it is unclear whether indicators (shell volume, density, and size) influence the calcification rate. Micro X-ray computed tomography (MicroCT) has been efficiently used to study these parameters on porcelaneous LBF; however, hyaline LBF remained largely unexplored. In this research, reproducing populations of LBF Calcarina gaudichaudii were grown asexually under six varying temperatures (19 °C–29 °C). They were then determined using MicroCT. Shell weight and volume is reduced under high and low thermal stress with an optimal water temperature of 26 °C. However, the density of the shell was sustained at a continual level. These outcomes indicate that C. gaudichaudii can sustain a continual shell density given circumstances of growth inhibition due to thermal stress.