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 coral reef



A Review of Statistical and Machine Learning Approaches for Coral Bleaching Assessment

Sarkar, Soham, Hazra, Arnab

arXiv.org Machine Learning

Coral bleaching is a major concern for marine ecosystems; more than half of the world's coral reefs have either bleached or died over the past three decades. Increasing sea surface temperatures, along with various spatiotemporal environmental factors, are considered the primary reasons behind coral bleaching. The statistical and machine learning communities have focused on multiple aspects of the environment in detail. However, the literature on various stochastic modeling approaches for assessing coral bleaching is extremely scarce. Data-driven strategies are crucial for effective reef management, and this review article provides an overview of existing statistical and machine learning methods for assessing coral bleaching. Statistical frameworks, including simple regression models, generalized linear models, generalized additive models, Bayesian regression models, spatiotemporal models, and resilience indicators, such as Fisher's Information and Variance Index, are commonly used to explore how different environmental stressors influence coral bleaching. On the other hand, machine learning methods, including random forests, decision trees, support vector machines, and spatial operators, are more popular for detecting nonlinear relationships, analyzing high-dimensional data, and allowing integration of heterogeneous data from diverse sources. In addition to summarizing these models, we also discuss potential data-driven future research directions, with a focus on constructing statistical and machine learning models in specific contexts related to coral bleaching.


Deep Learning Models for Coral Bleaching Classification in Multi-Condition Underwater Image Datasets

Macrohon, Julio Jerison E., Hung, Gordon

arXiv.org Artificial Intelligence

Coral reefs support numerous marine organisms and are an important source of coastal protection from storms and floods, representing a major part of marine ecosystems. However coral reefs face increasing threats from pollution, ocean acidification, and sea temperature anomalies, making efficient protection and monitoring heavily urgent. Therefore, this study presents a novel machine-learning-based coral bleaching classification system based on a diverse global dataset with samples of healthy and bleached corals under varying environmental conditions, including deep seas, marshes, and coastal zones. We benchmarked and compared three state-of-the-art models: Residual Neural Network (ResNet), Vision Transformer (ViT), and Convolutional Neural Network (CNN). After comprehensive hyperparameter tuning, the CNN model achieved the highest accuracy of 88%, outperforming existing benchmarks. Our findings offer important insights into autonomous coral monitoring and present a comprehensive analysis of the most widely used computer vision models.


13 inspiring photos of thriving deep-sea animals

Popular Science

A recent Schmidt Ocean Institute expedition off the coast of Uruguay discovered at least 30 suspected new species and explored a sunken warship. An octopus moves around deep-sea corals at 1,612 meters (about 5,288 feet) during a remotely operated vehicle, or ROV, dive near the historic HMS'Challenger's' oceanographic station 320, where the country's first coral samples were collected almost 150 years ago. Breakthroughs, discoveries, and DIY tips sent every weekday. An expedition led by a team of scientists from Uruguay discovered that the South American nation's deep-sea coral reefs are thriving and teeming with life. The reefs are primarily home to numerous species that were recently listed as vulnerable to extinction.


AI-Driven Marine Robotics: Emerging Trends in Underwater Perception and Ecosystem Monitoring

Raine, Scarlett, Fischer, Tobias

arXiv.org Artificial Intelligence

Marine ecosystems face increasing pressure due to climate change, driving the need for scalable, AI-powered monitoring solutions. This paper examines the rapid emergence of underwater AI as a major research frontier and analyzes the factors that have transformed marine perception from a niche application into a catalyst for AI innovation. We identify three convergent drivers: environmental necessity for ecosystem-scale monitoring, democratization of underwater datasets through citizen science platforms, and researcher migration from saturated terrestrial computer vision domains. Our analysis reveals how unique underwater challenges - turbidity, cryptic species detection, expert annotation bottlenecks, and cross-ecosystem generalization - are driving fundamental advances in weakly supervised learning, open-set recognition, and robust perception under degraded conditions. We survey emerging trends in datasets, scene understanding and 3D reconstruction, highlighting the paradigm shift from passive observation toward AI-driven, targeted intervention capabilities. The paper demonstrates how underwater constraints are pushing the boundaries of foundation models, self-supervised learning, and perception, with methodological innovations that extend far beyond marine applications to benefit general computer vision, robotics, and environmental monitoring.


A Biomimetic Way for Coral-Reef-Inspired Swarm Intelligence for Carbon-Neutral Wastewater Treatment

Messinis, Antonis

arXiv.org Artificial Intelligence

With increasing wastewater rates, achieving energy-neutral purification is challenging. We introduce a coral-reef-inspired Swarm Interaction Network for carbon-neutral wastewater treatment, combining morphogenetic abstraction with multi-task carbon awareness. Scalability stems from linear token complexity, mitigating the energy-removal problem. Compared with seven baselines, our approach achieves 96.7\% removal efficiency, 0.31~kWh~m$^{-3}$ energy consumption, and 14.2~g~m$^{-3}$ CO$_2$ emissions. Variance analysis demonstrates robustness under sensor drift. Field scenarios--insular lagoons, brewery spikes, and desert greenhouses--show potential diesel savings of up to 22\%. However, data-science staffing remains an impediment. Future work will integrate AutoML wrappers within the project scope, although governance restrictions pose interpretability challenges that require further visual analytics.


The Coralscapes Dataset: Semantic Scene Understanding in Coral Reefs

Sauder, Jonathan, Domazetoski, Viktor, Banc-Prandi, Guilhem, Perna, Gabriela, Meibom, Anders, Tuia, Devis

arXiv.org Artificial Intelligence

Coral reefs are declining worldwide due to climate change and local stressors. To inform effective conservation or restoration, monitoring at the highest possible spatial and temporal resolution is necessary. Conventional coral reef surveying methods are limited in scalability due to their reliance on expert labor time, motivating the use of computer vision tools to automate the identification and abundance estimation of live corals from images. However, the design and evaluation of such tools has been impeded by the lack of large high quality datasets. We release the Coralscapes dataset, the first general-purpose dense semantic segmentation dataset for coral reefs, covering 2075 images, 39 benthic classes, and 174k segmentation masks annotated by experts. Coralscapes has a similar scope and the same structure as the widely used Cityscapes dataset for urban scene segmentation, allowing benchmarking of semantic segmentation models in a new challenging domain which requires expert knowledge to annotate. We benchmark a wide range of semantic segmentation models, and find that transfer learning from Coralscapes to existing smaller datasets consistently leads to state-of-the-art performance. Coralscapes will catalyze research on efficient, scalable, and standardized coral reef surveying methods based on computer vision, and holds the potential to streamline the development of underwater ecological robotics.


From underwater to aerial: a novel multi-scale knowledge distillation approach for coral reef monitoring

Contini, Matteo, Illien, Victor, Barde, Julien, Poulain, Sylvain, Bernard, Serge, Joly, Alexis, Bonhommeau, Sylvain

arXiv.org Artificial Intelligence

Drone-based remote sensing combined with AI-driven methodologies has shown great potential for accurate mapping and monitoring of coral reef ecosystems. This study presents a novel multi-scale approach to coral reef monitoring, integrating fine-scale underwater imagery with medium-scale aerial imagery. Underwater images are captured using an Autonomous Surface Vehicle (ASV), while aerial images are acquired with an aerial drone. A transformer-based deep-learning model is trained on underwater images to detect the presence of 31 classes covering various coral morphotypes, associated fauna, and habitats. These predictions serve as annotations for training a second model applied to aerial images. The transfer of information across scales is achieved through a weighted footprint method that accounts for partial overlaps between underwater image footprints and aerial image tiles. The results show that the multi-scale methodology successfully extends fine-scale classification to larger reef areas, achieving a high degree of accuracy in predicting coral morphotypes and associated habitats. The method showed a strong alignment between underwater-derived annotations and ground truth data, reflected by an AUC (Area Under the Curve) score of 0.9251. This shows that the integration of underwater and aerial imagery, supported by deep-learning models, can facilitate scalable and accurate reef assessments. This study demonstrates the potential of combining multi-scale imaging and AI to facilitate the monitoring and conservation of coral reefs. Our approach leverages the strengths of underwater and aerial imagery, ensuring the precision of fine-scale analysis while extending it to cover a broader reef area.


ARMADA: Attribute-Based Multimodal Data Augmentation

Jin, Xiaomeng, Kim, Jeonghwan, Zhou, Yu, Huang, Kuan-Hao, Wu, Te-Lin, Peng, Nanyun, Ji, Heng

arXiv.org Artificial Intelligence

In Multimodal Language Models (MLMs), the cost of manually annotating high-quality image-text pair data for fine-tuning and alignment is extremely high. While existing multimodal data augmentation frameworks propose ways to augment image-text pairs, they either suffer from semantic inconsistency between texts and images, or generate unrealistic images, causing knowledge gap with real world examples. To address these issues, we propose Attribute-based Multimodal Data Augmentation (ARMADA), a novel multimodal data augmentation method via knowledge-guided manipulation of visual attributes of the mentioned entities. Specifically, we extract entities and their visual attributes from the original text data, then search for alternative values for the visual attributes under the guidance of knowledge bases (KBs) and large language models (LLMs). We then utilize an image-editing model to edit the images with the extracted attributes. ARMADA is a novel multimodal data generation framework that: (i) extracts knowledge-grounded attributes from symbolic KBs for semantically consistent yet distinctive image-text pair generation, (ii) generates visually similar images of disparate categories using neighboring entities in the KB hierarchy, and (iii) uses the commonsense knowledge of LLMs to modulate auxiliary visual attributes such as backgrounds for more robust representation of original entities. Our empirical results over four downstream tasks demonstrate the efficacy of our framework to produce high-quality data and enhance the model performance. This also highlights the need to leverage external knowledge proxies for enhanced interpretability and real-world grounding.


ReefGlider: A highly maneuverable vectored buoyancy engine based underwater robot

Macauley, Kevin, Cai, Levi, Adamczyk, Peter, Girdhar, Yogesh

arXiv.org Artificial Intelligence

There exists a capability gap in the design of currently available autonomous underwater vehicles (AUV). Most AUVs use a set of thrusters, and optionally control surfaces, to control their depth and pose. AUVs utilizing thrusters can be highly maneuverable, making them well-suited to operate in complex environments such as in close-proximity to coral reefs. However, they are inherently power-inefficient and produce significant noise and disturbance. Underwater gliders, on the other hand, use changes in buoyancy and center of mass, in combination with a control surface to move around. They are extremely power efficient but not very maneuverable. Gliders are designed for long-range missions that do not require precision maneuvering. Furthermore, since gliders only activate the buoyancy engine for small time intervals, they do not disturb the environment and can also be used for passive acoustic observations. In this paper we present ReefGlider, a novel AUV that uses only buoyancy for control but is still highly maneuverable from additional buoyancy control devices. ReefGlider bridges the gap between the capabilities of thruster-driven AUVs and gliders. These combined characteristics make ReefGlider ideal for tasks such as long-term visual and acoustic monitoring of coral reefs. We present the overall design and implementation of the system, as well as provide analysis of some of its capabilities.