Search Results (292)

This study introduces GAT-CAMDA, a novel framework for the structural health monitoring (SHM) of composite materials under temperature-induced variability, leveraging the powerful feature extraction capabilities of Graph Attention Networks (GATs) and advanced domain adaptation (DA) techniques. By combining Maximum Mean Discrepancy (MMD) and Correlation Alignment (CORAL) losses with a domain-discriminative adversarial model, the framework achieves scalable alignment of feature distributions across temperature domains, ensuring robust damage detection. A simple yet at the same time efficient data augmentation process extrapolates damage behaviour across unmeasured temperature conditions, addressing the scarcity of damaged-state observations. Hyperparameter optimisation via Optuna not only identifies the optimal settings to enhance model performance, achieving a classification accuracy of 95.83% on a benchmark dataset, but also illustrates hyperparameter significance for explainability. Additionally, the GAT architecture’s attention demonstrates the importance of various sensors, enhancing transparency and reliability in damage detection. The dual use of Optuna serves to refine model accuracy and elucidate parameter impacts, while GAT-CAMDA represents a significant advancement in SHM, enabling precise, interpretable, and scalable diagnostics across complex operational environments. Full article

This study introduces a hybrid Brain–Computer (BCI) system with a robust and secure activation mechanism between sessions, aiming to minimize the negative effects of visual stimulus-based BCI systems on user eye health. The system is based on the integration of Electroencephalography (EEG) signals and Electrooculography (EOG) artefacts, and includes an LED stimulus operating at a frequency of 7 Hz for safe activation and objects moving in different directions. While the LED functions as an activation switch that reduces visual fatigue caused by traditional visual stimuli, moving objects provide command generation depending on the user’s intention. In order to evaluate the stability of the system against physiological and psychological conditions, data were collected from 15 participants in two different sessions. The Correlation Alignment (CORAL) method was applied to the data to reduce the variance between sessions and to increase stability. A Bootstrap Aggregating algorithm was used in the classification processes, and with the CORAL method, the system accuracy rate was increased from 81.54% to 94.29%. Compared to similar BCI approaches, the proposed system offers a safe activation mechanism that effectively adapts to users’ changing cognitive states throughout the day by reducing visual fatigue, despite using a low number of EEG channels, and demonstrates its practicality and effectiveness by performing on par or superior to other systems in terms of high accuracy and robust stability. Full article

Black band disease (BBD), which overgrows and kills scleractinian coral, is known to have various phases. The initial phase is the cyanobacterial patches (CPs) phase, followed by the intermediate phase (IP), and finally the mature BBD phase. Here, we hypothesize, pending further evidence, that when coral fragments infected with mature BBD are placed under shaded conditions, the BBD band shifts into a CP-like condition, with the shading causing a complex shift in the microbial consortium. While these microbial changes are beyond the scope of this paper, the photographs within provide interesting potential insights into this transition. Full article

Increased seawater temperatures and nutrient loading are stressors that affect coral reefs and their microbiomes. In this study, filamentous algae were collected and exposed to different temperatures and nutrient concentrations through a laboratory experiment. Microbial DNA was extracted and analyzed using amplicon sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. In total, 1 domain, 51 phyla, 131 classes, 335 orders, 549 families, and 1905 species were identified. Proteobacteria and Bacteroidota were the dominant taxa reported. Elevated seawater temperatures and nutrient enrichment impacted microbial communities associated with turf algae under laboratory culture. Bacterial species diversity and abundance differed under different temperature and nutrient conditions. Proteobacteria and Actinobacteria were abundant in lower-temperature conditions, while Desulfobacterota, Spirochaetota, and Firmicutes were abundant in higher-temperature conditions. Ruegeria was abundant in low-temperature conditions, whereas Vibrio abundance was low. Regarding nutrient conditions, Proteobacteria and Cyanobacteria were abundant under high-nutrient conditions, while Firmicutes and Desulfobacterota were abundant under ambient-nutrient conditions. The higher nutrient concentration increased the abundance of pathogenic bacteria, such as Vibrio and Photobacterium, while Pseudoalteromonas, which is beneficial for reefs, was present under ambient nutrient conditions. This study demonstrates that temperature and nutrient enrichment can shape microbial communities under laboratory conditions, providing an experimental setting for further studies of bacterial functions and metabolic processes in natural conditions under thermal and nutrient stresses. Full article

This study develops a geomorphological identification methodology for wall reefs in the microcontinental environment of Wangiwangi Island, Indonesia, using medium-resolution Landsat 8 satellite imagery and morphological analysis based on Maxwell’s geomorphological framework. The uniqueness of the wall reef landform lies in the fact that the lagoon elongates on limestone, resulting in a habitat and ecosystem that develops differently from those of other shelf reefs, namely, platform reefs and plug reefs. Using Optimum Index Factor (OIF) optimization and RGB image composites, four reef types were successfully identified: cuspate reefs, open ring reefs, closed ring reefs, and resorbed reefs. A field check was conducted at fifteen observation sites, which included measurements of depth, turbidity, and water quality parameters, as well as an in situ benthic habitat inventory. The analysis results showed a strong correlation between image composites, geomorphological reef classes, and ecological conditions, confirming the successful adaptation of Maxwell’s classification to the Indonesian reef system. This hybrid integrated approach successfully maps the distribution of reefs on a complex continental shelf, providing an essential database for shallow-water spatial planning, ecosystem-based conservation, and sustainable management in the Coral Triangle region. Policy recommendations include zoning schemes for protected areas based on reef landform morphology, strengthening integrative monitoring systems, and utilizing high-resolution imagery and machine learning algorithms in further research. Full article

Stony corals are long-lived, calcifying cnidarians that can be preserved within archaeological strata, offering insights into past seawater conditions, anthropogenic influences, and harbor dynamics. This study analyzes sub-fossil Cladocora sp. colonies from ancient Akko, Israel, dated to the Hellenistic period (~335–94 BCE), alongside modern Cladocora caespitosa from Haifa Bay, Israel. We employed micromorphology, stable isotope analysis, and DNA sequencing to assess species identity, colony growth form, and environmental conditions experienced by the corals. Comparisons suggest that Hellenistic Akko corals grew in high-light, cooler-water, high-energy environments, potentially with exposure to terrestrial waste. The exceptional preservation of these colonies indicates rapid burial, possibly linked to ancient harbor activities or extreme sedimentation. Our results demonstrate the utility of scleractinian corals as valuable paleoenvironmental archives, capable of integrating both biological and geochemical proxies to reconstruct past marine conditions. By linking archaeological and ecological records, this multidisciplinary approach provides a comprehensive understanding of historical coastal dynamics, including ancient harbor use, climate variability, and anthropogenic impacts. Full article

Coral reefs exposed to chronically turbid conditions challenge conventional assumptions about the optical environments required for reef persistence and productivity. This study investigates the utility of light absorption coefficients as indicators of optical water quality in Varadero Reef, an extreme coral ecosystem located in Cartagena Bay, Colombia. Field campaigns were conducted across three seasons (rainy, dry, and transitional) along a transect from fluvial to marine influence. Absorption coefficients at 440 nm were derived for particulate (a_p(440)) and chromophoric dissolved organic matter (a_CDOM(440)) to assess their contribution to underwater light attenuation. Average values across seasons show that a_p(440) reached 0.466 m⁻¹ in the rainy season (September 2021), 0.285 m⁻¹ in the dry season (February 2022), and 0.944 m⁻¹ in the transitional rainy season (June 2022). Meanwhile, mean a_CDOM(440) values were 0.368, 0.111, and 0.552 m⁻¹, respectively. These coefficients reflect the dominant influence of particulate absorption under turbid conditions and increasing a_CDOM(440) relevance during lower turbidity periods. Mean Secchi Disk Depth (ZSD) ranged from 0.6 m in the rainy season to 3.0 m in the dry season, aligning with variations in Kd PAR, which averaged 2.63 m⁻¹, 1.13 m⁻¹, and 1.08 m⁻¹ for the three campaigns. Chlorophyll-a concentrations at 1 m depth also varied significantly, with average values of 2.3, 2.7, and 6.2 μg L⁻¹, indicating phytoplankton biomass peaks associated with seasonal freshwater inputs. While particulate absorption limits light penetration, CDOM plays a potentially photoprotective role by attenuating UV radiation. The observed variability in these optical constituents reflects complex hydrodynamic and environmental gradients, providing insight into the mechanisms that sustain coral functionality under suboptimal light conditions. The absorption-based approach applied here, using standardized spectrophotometric methods, proved to be a reliable and reproducible tool for characterizing the spatial and temporal variability of IOPs. We propose integrating these indicators into monitoring frameworks as cost-effective, component-resolving tool for evaluating light regimes and ecological resilience in optically dynamic coastal systems. Full article

To tackle the difficulties in cross-domain fault diagnosis for rolling bearings, researchers have devised numerous domain adaptation strategies to align feature distributions across varied domains. Nevertheless, current approaches tend to be vulnerable to noise disruptions and often neglect the distinctions between marginal and conditional distributions during feature transfer. To resolve these shortcomings, this study presents an innovative fault diagnosis technique for cross-domain applications, leveraging the Attention-Enhanced Residual Network (AttenResNet18). This approach utilizes a one-dimensional attention mechanism to dynamically assign importance to each position within the input sequence, thereby capturing long-range dependencies and essential features, which reduces vulnerability to noise and enhances feature representation. Furthermore, we propose a Dynamic Balance Distribution Adaptation (DBDA) mechanism, which develops an MMD-CORAL Fusion Metric (MCFM) by combining CORrelation ALignment (CORAL) with Maximum Mean Discrepancy (MMD). Moreover, an adaptive factor is employed to dynamically regulate the balance between marginal and conditional distributions, improving adaptability to new and untested tasks. Experimental validation demonstrates that AttenResNet18 achieves an average accuracy of 99.89% on two rolling bearing datasets, representing a significant improvement in fault detection precision over existing methods. Full article

In the face of recent setbacks to coral reef conservation and restoration due to intensifying marine heat waves, new coral-focused strategies have been developed to accelerate natural processes of coral reef adaptation and recovery. In 2024, these “Reefs of Hope” strategies were endorsed by UNESCO as an Ocean Decade. This paper shares the progress made and methods used and translates the new paradigm into a proposed national coral-focused adaptation plan using Fiji as an example. The primary goal of any coral-focused adaptation plan should be to keep coral species alive despite increasingly lethal temperatures due to ocean warming and, in doing so, to retain as much genetic diversity as possible. This is done by translocating corals locally to secure cooler-water gene bank nurseries, with a focus on heat-adapted, bleaching-resistant corals, which are vital to adaptation. Secondary goals are to restore sexual reproduction to declining and rare coral species and to support natural larval-based recovery and adaptation processes via the creation of “regeneration patches”, which enhance and restore natural recovery processes while facilitating the spread of heat-adapted genetic diversity of both host and symbionts. The proposed plans create a new model of proactive coral-focused adaptation that other reef-owning nations might study, modify to national conditions, and seek funding to implement. These Fiji-based plans are now ready for the next step of national stakeholder input and refinements toward approval by the government and the coral reef conservation community. Full article

Coral reefs are essential to the cultural, ecological, and economic well-being of Hawai‘i’s communities, yet they face increasing threats from environmental changes and localized stressors, including coral disease. Detecting coral disease often relies on the visible appearance of lesions; however, in the case of black-band disease (BBD), this visual cue appears too late, as disease progression can cause an average rate of tissue loss of up to 5.7 cm² per day over two months, followed by partial or full colony mortality. Reflectance spectroscopy offers a promising tool for detecting subtle spectral changes associated with coral health before visible symptoms emerge, yet few studies have applied this method to coral disease. In situ spectroscopy was used to measure the spectral reflectance of health conditions in Montiporid corals at ‘Anini Reef, Kaua‘i, USA. Discriminant analysis revealed that visually identical tissue types—live tissue on colonies with BBD (live_D) and live tissue on colonies without BBD (live_L)—were spectrally distinct. In contrast, BBD lesions (disease) and adjacent tissue that appeared healthy (transition) exhibited similar spectral signatures. Analyses identified three spectrally distinct tissue health conditions with a misclassification rate of 12.8%. These findings highlight the potential of reflectance spectroscopy for early coral disease detection, which could improve response times and support more effective coral reef conservation efforts. Full article

Corals exhibit complex and diverse relationships with dinoflagellates of the family Symbiodiniaceae. Montiporid corals within Norfolk Island’s shallow water lagoonal reef systems have been observed to turn a deep fluorescent blue during winter, suggesting potential environmentally driven changes to their photoendosymbiosis. Here, we investigate the photoendosymbiosis of blue Montipora sp. corals over a year-long study, demonstrating that photosynthetic yield and Symbiodiniaceae densities vary seasonally, with the lowest photosynthetic yield occurring within winter periods. We also provide the first characterisation of Symbiodiniaceae species associated with corals from Norfolk Island, identifying blue Montipora sp. as predominantly associating with Cladocopium (formerly Clade C) genotypes (C3aap, C3ig, and C3aao). Finally, we also report on the impact of recent bleaching conditions (March 2024) on blue Montipora sp. photoendosymbiosis and find the genera is susceptible to increasing sea surface temperatures. Our findings provide insight into the unique biology of subtropical corals within this remote reef and the susceptibility of corals in the region to increasing sea surface temperatures. Full article

With the rising adoption of machine learning (ML) and deep learning (DL) applications, the demand for deploying these algorithms closer to sensors has grown significantly, particularly in sensor-driven use cases such as predictive maintenance (PM) and condition monitoring (CM). This study investigated a novel application-oriented approach to representing interpretable ML inference as deep neural networks (DNNs) regarding the latency and energy efficiency on the edge, to tackle the problem of inefficient, high-effort, and uninterpretable-implementation ML algorithms. For this purpose, the interpretable deep neural network representation (IDNNRep) was integrated into an open-source interpretable ML toolbox to demonstrate the inference time and energy efficiency improvements. The goal of this work was to enable the utilization of generic artificial intelligence (AI) accelerators for interpretable ML algorithms to achieve efficient inference on edge hardware in smart sensor applications. This novel approach was applied to one regression and one classification task from the field of PM and validated by implementing the inference on the neural processing unit (NPU) of the QXSP-ML81 Single-Board Computer and the tensor processing unit (TPU) of the Google Coral. Different quantization levels of the implementation were tested against common Python and C++ implementations. The novel implementation reduced the inference time by up to 80% and the mean energy consumption by up to 76% at the lowest precision with only a 0.4% loss of accuracy compared to the C++ implementation. With the successful utilization of generic AI accelerators, the performance was further improved with a 94% reduction for both the inference time and the mean energy consumption. Full article

The ecological restoration of tropical islands, such as the Xisha Islands, is critical for sustainable development but is hindered by extreme environmental conditions and nutrient-poor coral sand soils. This study assessed the adaptive strategies of two introduced landscape species, Acacia auriculiformis and Nerium oleander, by comparing their leaf physiological and biochemical traits across three treatments: native coral sand (SS2), coral sand amended with garden soil (SS1), and a garden soil control (GZ). Results revealed differentiated physiological adaptation strategies: N. oleander exhibited a ‘conservative tolerance’ strategy, characterized by maintaining higher levels of soluble proteins and the non-enzymatic antioxidant GSH, whereas A. auriculiformis employed an ‘active defense’ strategy, significantly upregulating its enzymatic antioxidant system (SOD activity increased by up to 58.80% in coral sand compared to the control). Soil amendment was crucial for improving plant performance by fundamentally altering the soil’s physicochemical properties and nutrient status. Specifically, amending coral sand with garden soil (SS1 vs. SS2) resulted in a threefold increase in both soil organic carbon (from 3.81 to 11.63 g kg⁻¹) and water content (from 0.04% to 0.12%), while also increasing available phosphorus by over 50% and reducing the extreme soil alkalinity. This amelioration of the soil environment directly enhanced plant antioxidant capacity and overall growth performance. These findings provide a scientific basis for plant introduction on tropical islands, demonstrating that success depends on matching species-specific adaptive strategies with appropriate soil improvement techniques. Full article

Mediterranean rocky reef habitats are ecologically valuable yet increasingly degraded due to cumulative human pressures, necessitating efficient, large-scale ecological status assessments to inform management. Macroalgal communities are widely used as indicators of rocky reef conditions and are typically assessed via photoquadrat sampling. However, the manual annotation of benthic images remains time-consuming and costly. This study evaluates the performance of CoralNet (version 1.0), an AI-assisted image annotation platform, using a pre-annotated dataset of 2537 photoquadrat images from 89 rocky reef sites in the Aegean Sea, Greece, classified into 23 taxonomic and morphofunctional groups. Half of the dataset was used to iteratively train CoralNet classifiers, while the remainder was used to compute the reef-EBQI index and compare ecological status estimates with those derived from manual annotations. The classifier accuracy improved with training volume, reaching 67% using the entire dataset. Reef-EBQI scores derived from CoralNet showed 87% agreement with the manual classifications. Despite challenges and limitations, AI-assisted annotation proved effective in regional-scale ecological assessments based on broad taxonomic and morphofunctional categories. Automated tools like CoralNet can reduce post-processing bottlenecks and enable scalable, cost-effective monitoring, especially when integrated with standardized protocols and citizen science initiatives. Full article

Coral reef ecosystems are home to diverse marine flora and fauna. However, these ecosystems are threatened by an array of environmental and anthropogenic factors. Here, we investigated coral reef diversity, structure, and health status, and identified their key environmental drivers. Coral reef data were collected from Koh Seh Island, located inside the Marine Fisheries Management Area in the Kep archipelago. We found that the reef cover largely comprised live corals (64%, mainly Porites and Tubinaria species), followed by Zoanthids (15%) and sand/rubble (15%). Based on Ward’s hierarchical cluster analysis, coral communities were grouped into three zones: East, South, and West zones. Coral diversity was slightly higher in the East zone, though not statistically significant. Zone East showed a positive association with sediment loads and water temperature. Elevated levels of salinity, dissolved oxygen, and pH were characteristic of the East and South zones, whereas the West zone was distinguished by deeper water conditions. We also found that Favites was the key indicator for coral communities in the East zone, which features shallow, high-DO, high-pH waters with more sediments, strong currents, and significant human activities like fishing and transportation. Goniastrea species were abundant in the South and East zones, making it the indicator taxon, while the West zone had no indicator, suggesting that coral species are sparse in this zone. Interestingly, only a few dead corals were found, and no signs of diseases were detected around the Koh Seh coral reefs. This may reflect the effectiveness of joint protection efforts by Marine Conservation Cambodia and the Marine Fisheries Department in Kep province. Overall, our study provides a valuable baseline for assessing future changes in benthic reefs and coral communities on Koh Seh island, throughout the Kep Archipelago and its surrounding areas. Full article