Technological improvements have significantly shifted our fundamental knowledge of the ocean, particularly the deep sea. However, the lack of cost-effectiveness and accessibility in technologies remains a limiting factor in our scientific understanding of the deep ocean. Research vessels have traditionally served as the primary platforms for ocean observations, particularly deep-sea ecosystems. These vessels are equipped to deploy various instruments, including autonomous and tethered robots, to observe biological, chemical, and physical components of the deep ocean.

Despite the progress made, traditional and contemporary tools still suffer from several limitations. While these tools have enhanced our understanding, more precise mapping of small-scale topography and its role in creating ecological heterogeneity has exposed significant geographical and knowledge gaps. The geographic scope of large-scale research is primarily restricted to the North Pacific and Atlantic Oceans, leading to the undersampling of other regions of the world’s ocean. Although current deep-sea robots enable finer-scale observations, they have limited flexibility, autonomy, and operational depth. Deep-sea operations have prohibitively high-cost barriers, in part due to the high cost for procurement for instrumentation and deployment (i.e., vessel time). Despite over 200 years of oceanographic research, several key interdisciplinary questions about the deep-sea remain unresolved: (1) How many organisms live in the ocean? (2) Who they are? (3) What ecosystem services do they provide? (4) How do the ocean’s various components interact?

For more accurate and comprehensive observations of the ocean, we will build off the momentum for low-cost alternatives to deep-sea instrumentation for regular ocean sampling by proposing a technological roadmap. This includes developing a roadmap with initiatives such as "Shipboard Technology Excellence Procedures" and tech-based decision guides tailored to the available equipment, and a repository of all associated standard operating procedures. We also propose concrete actions to improve capacity building across institutions and nations through FAIR collaborations. For instance, establishing local groups to coordinate efforts and train members, alongside a global organizing body, could facilitate the tracking of samples, projects, and personnel to streamline sampling and analysis. Finally, we outline a series of actions aimed at bridging the gaps between science, policy, and society to ensure the benefits of deep-sea research extend beyond the scientific community.

How to cite: Annasawmy, P., Elegbede, I., Lejzerowicz, F., A. Sandoval, J., M.Smith, L., and Le Mézo, T.: The capabilities and limitations of ship-based technologies in understanding deep-sea ocean ecosystems: Paving the way for robots, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-48, https://doi.org/10.5194/oos2025-48, 2025.

Traditional methods for marine habitat mapping are often time-consuming and rely on sparse sampling. To overcome these limitations, a new method has been developed for large-scale mapping of benthic marine habitats. By deploying several synchronized autonomous underwater drones and using AI, this new approach enables large-scale, continuous, and high-precision seabed mapping and monitoring at depths down to 200 meters.

Several survey areas covering up to 10 hectares were surveyed focusing on ecologically significant habitats such as Posidonia seagrass meadows, kelp forests, and sensitive areas like harbor access zones. The aim was to precisely detect, map marine habitats and individual species, thus contributing to environmental impact assessment for a coastal civil engineering project and the exploration of relevant metrics for long-term monitoring. This solution has also been used for fiber optic cable localization and coupling estimation for Distributed Acoustic Sensing (DAS) experiments and enables the precise detection of subsea infrastructure and obstacles, such as unexploded ordnance (UXOs).

As a result, this solution enhances the understanding and the ability to better monitor benthic habitats while also supporting more effective risk management and operational planning. Its capacity to conduct large-scale mapping and long-term monitoring of benthic ecosystems opens new perspectives for the monitoring and sustainable management of marine resources.

How to cite: Huguenin, L., Chenevier, Q., Sladen, A., Eceiza, A., and Mittaine, F.: Benthic habitat mapping using UAV photogrammetry and machine learning algorithms, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1264, https://doi.org/10.5194/oos2025-1264, 2025.

Marine bioacoustics, the study of how marine organisms produce and are affected by sound, has become a cornerstone in ocean conservation efforts. Underwater microphones, known as hydrophones, can be used for ecosystem health monitoring, species distribution studies, impact assessment, anti-poaching and compliance, marine protected area management, climate change research and restoration efforts. However, the high cost and complexity of current autonomous hydrophone recording systems limit accessibility, particularly in educational and community science contexts, and in developing countries. Most autonomous hydrophone recording units are prohibitively expensive, exceeding US $3,000, while cheaper implementations lack the necessary recording and power supply characteristics, preventing cost-effective setup deployment of hydrophones.

Launched under the auspices of POGO (pogo-ocean.org) and the International Quiet Ocean Experiment (IQOE – iqoe.org), our Task Team on Low-Cost Hydrophones for Research, Education, and Citizen Science was created in 2023 to promote affordable hydrophone technology dedicated to research, education, and community science. Our project proposes to develop and test a low-cost, open-source, modular, and autonomous hydrophone recording system that breaks down these barriers, fostering innovation and broadening participation in marine research, conservation, and restoration.

Here, we present our prototype design, including hydrophone ceramics with a frequency response range from 10 Hz to 100 kHz and an effective sensitivity of -180 dB re V/uPa. It will be calibratable for accuracy and reliability in data collection. Our proposed data logger is based on an ARM Cortex M7 microchip that can handle sample rates up to 768 kHz and is designed for field use with longevity contingent on programmable settings.

We believe that the potential of aquatic bioacoustics is currently untapped due to the prohibitive costs and technical expertise required, confining its use to professional circles. By democratising access to this technology, we would like to unlock new opportunities for conservation efforts and uniform educational engagement worldwide.

How to cite: Chapuis, L., Burca, M., Gridley, T., Mouy, X., Nath, A., Nedelec, S., Roberts, M., Seeyave, S., Theriault, J., Urban, E., Williams, R., and Zimmer, W.: Development of a low-cost hydrophone for research, education, and community science, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-71, https://doi.org/10.5194/oos2025-71, 2025.

Marine ecosystem dynamics in the context of climate change is a growing scientific, political and social concern requiring regular monitoring through appropriate observational technologies and studies. Thus, a wide range of tools comprising chemical, biogeochemical, physical, and biological sensors, as well as other platforms exists for marine monitoring. However, their high acquisition and maintenance costs are often a major obstacle, especially in low-income developing countries. We designed an advanced low-cost synoptic marine ecosystem observation system that operates at relatively high temporal frequencies, named PlasPi TDM. This instrument is an improved version of the camera system (PlasPI marine cameras) developed in 2020 by Autun Purser from the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (Germany), and collaborators. It incorporates several innovative developments such as multispectral (records the spectrum of any object photographed), temperature and pressure sensors. The PlasPi TDM operates to a depth of 200 meters. The various field deployments demonstrate the operational capability of the PlasPi TDM for different applications and illustrate its considerable potential for in-situ observations and marine surveillance in Africa. This device is intended as an open-source project and its continued development is encouraged for a more integrated, sustainable and low-cost ocean observing system.

Keywords: PlasPi TDM, Marine observations, Citizen science, Physical oceanography, Underwater imaging.

How to cite: Zinzindohoué, C. G. F., Schoening, T., Lima, E. B., and Fiedler, B.: PlasPi TDM: Augmentation of a low-cost camera platform for advanced underwater physical-ecological observations, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-72, https://doi.org/10.5194/oos2025-72, 2025.

Growing interest in oceanology and oceanography has made it possible to determine the fundamental role of the oceans in sustaining life on Earth, and to discover that aquatic environments offer a rich biodiversity and a privileged habitat for many species. Aquatic environments also contribute to the economies of many countries through fishing, aquaculture, and coastal tourism, they are a major source of food for the world’s population. Nevertheless, the presence of pathogenic microorganisms in coastal waters can have a negative impact on human and animal health, as well as on marine ecosystems. Bacteria of the Vibrio spp genus, for example, shelter many species that are pathogenic to humans and marine fauna [1]. Although the seasonal dynamics of their abundance are now recognized, better knowledge of their abundance on a finer temporal scale and of their spatial distribution requires the use of in-situ measuring instruments for real-time monitoring of these bacterial populations in water. Early detection of abnormally high levels of these bacteria will enable rapid and appropriate health decisions to be taken. Thanks to the integration of new digital and engineering technologies, new types of sensors are making it possible to direct research towards enhanced biomonitoring of the oceans. However, the few sensors able to monitor marine bacteria, are still very bulky, heavy and costly and can’t be quickly deployed in certain environments such as coastal areas, to perform high resolution monitoring [2] [3].

In this study, we propose to develop a new measuring tool for in situ monitoring of microbial populations. It’s a small tool, can be used by non-expert personnel and would enable monitoring in all types of aquatic environments. The sensor under development uses a molecular biology approach based on sandwich hybridization using nucleotide probes complementary to an RNA sequence of the target bacteria, and a colorimetric revelation to quantify bacteria.  The procedure has already been used to detect Vibrio spp bacteria [4]. To make the system autonomous, the methodology used will be transferred to an integrated, reusable platform currently under development. This will enable rapid analysis of small volumes, as well as a reduction in the volumes of reagents used, and, consequently, lowering the final analytical cost. To optimize the device development time, the use of rapid prototyping methods such as stereolithography 3D printing was employed for the fabrication of most system components. Similarly, literature-validated subsystems were used and adapted to meet the methodology requirements. The platform will enable several functional blocks to be built, such as the distribution of calibrated microvolumes via three-way solenoid valves, a magnetic trap for capturing functionalized beads and a block for optical signal detection. A low-cost multispectral detector was fabricated by 3D printing to create this functional block. A proportional relationship can be established between the target concentration and the absorbance measured by the detector.

[1] C. Baker-Austin et al., Nat Rev Dis Primers. 4(1):1-19, (2018)

[2] C.Scholin et al., Oceanog., 22(2):158-167, (2009)

[3] D. Fries et al., Microscopy and Microanalysis. 13(S02):514-515, (2007)

[4] E. Da-Silva., Environ Sci Pollut Res. 24(6):5690-5700, (2017)

How to cite: Agranier, E., Manes, C.-L., Vuillemin, R., Groc, M., Venzac, B., Baudart, J., and Raimbault, V.: Automated analytical method for monitoring micro-organisms in marine waters, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-616, https://doi.org/10.5194/oos2025-616, 2025.

Citizen science monitoring of coastal ecosystem is essential for expanding data coverage in vast, understudied regions, often with limited monitoring capabilities. It helps address data gaps while engage communities directly in conservation efforts, building public awareness and stewardship for ocean health. Here, we present two citizen science initiatives led by early career ocean professionals, members of the NF-POGO Alumni Network for the Ocean (NANO), with support from the Nippon Foundation and the Partnership for Observation of the Global Ocean, to monitor coastal and marine ecosystems.

Launched in 2018, SAGITTA (Social Agitation for Temperature Analysis) aims at collecting water column temperature profile from coastal areas. The project provides a compact, user-friendly, low-cost temperature profiler that is scientifically reliable. SAGITTA comprises three main components: the profiler device, a web data portal, and an ocean literacy program. The probe internal components include temperature and pressure sensors, a battery, and a microSD card for data storage. Its internal components and housing are in the final stages of development, with design and materials optimized for durability, waterproofing, and cost-effectiveness. The latest version of the probe has undergone waterproofing and durability testing in a pressure chamber and on the field, alongside a professional CTD. Additionally, a smartphone application has been developed, which will allow users to operate the probe, and visualize the recorded data. Over the next year, significant improvements to the SAGITTA web portal will enhance integration with the smartphone app, improving data accessibility and user experience.

As part of NANO’s global project “A global study of coastal Deoxygenation, Ocean Acidification and Productivity at selected sites” (NANO-DOAP), the Bangladeshi team developed the C4CEM application in 2022. C4CEM focuses on engaging the local communities in monitoring species diversity, active fishing zones, and plastic pollution in coastal ecosystems across Bangladesh. The initiative includes freely available Android application (NANO-DOAP C4CEM), which allows trained citizen scientists to capture geo-referenced photographs (including latitude and longitude) with their smartphone camera. The application enables the recording of data on fish (species common/scientific name, length, weight, and fishing duration), plankton counts, ecosystem resources, and plastic items. Each geo-referenced image is immediately transferred to the C4CEM database, where data for various categories (fish, plankton, resources, plastic, and environmental conditions) are stored separately. Data can be downloaded as a CSV files containing timestamps, user names, geographic coordinates, and photo links. Expert review of these images is required to accurately identify species, resources, and plastic items. This citizen science-based approach has been successful in identifying active fishing zones, biodiversity hotspots, macroplastic accumulation areas, and regions suitable for biodiversity conservation. Initially designed to Bangladesh coastal areas, C4CEM is currently being tested by NANO-DOAP members in other countries.

By engaging a diverse range of citizen scientists – including high school students, fishers, and local communities – SAGITTA and C4CEM can empower participants to contribute valuable data on coastal and marine ecosystems through accessible, cost-effective methods. Both projects not only have the potential to improve data collection but also significantly enhance ocean literacy, fostering greater community engagement in ocean conservation efforts.

How to cite: Sarker, S., Das, N., Huda, A. N. M. S., Chowdhury, G. W., Krug, L., and Seeyave, S.: Taking Science to the Community: Innovative Approaches for Affordable Coastal Ecosystem Monitoring, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-646, https://doi.org/10.5194/oos2025-646, 2025.