T3-7 | Marine pollution and other sources of ocean degradation

T3-7

Marine pollution and other sources of ocean degradation

Orals

| Tue, 03 Jun, 14:00–15:30 (CEST)|Room 1, Wed, 04 Jun, 16:00–17:30 (CEST)|Room 1

Posters on site

Posters virtual

Further information on the theme is available at: https://one-ocean-science-2025.org/programme/themes.html#T3

Orals: Tue, 3 Jun, 14:00–15:30 | Room 1

Chairperson: Wilfried Sanchez

14:00–14:10

OOS2025-640

The United States National Harmful Algal Bloom Observing Network: Scaling up regional early warning systems for aquaculture and fisheries

Clarissa Anderson, Quay Dortch, Josie Quintrell, Marc Suddleson, Greg Doucette, Tiffany Vance, and Mary Edmondson

The United States National Harmful Algal Bloom Observing Network (NHABON) brings together local, state, Tribal, regional and federal HAB observing capabilities to enable forecasting and early warning systems for harmful algal blooms that leverage economies of scale to provide sustained and reliable information needed to protect public health and food safety. NHABON is a multi-agency partnership that leverages decades of investment in the regional ocean observing systems forming the backbone of the NOAA Integrated Ocean Observing System.

In this presentation, I will discuss the emerging NHABON Community of Practice in the U.S., a regional alliance of the Global Ocean Observing System (GOOS), designed to unify early warning systems into a cohesive national network. Specifically, I will review development of the HAB Data Assembly Center: a centralized location for accessing HAB data products, cyberinfrastructure for processing near real-time plankton imagery and biotoxin data, a common code repository for machine learning models and training data sets, and data science and data management support for research teams issuing critical food safety alerts. I will provide examples of how regional systems in the U.S. can be coordinated through a national network, support technologies and monitoring programs to detect blooms, distribute forecasts and early warnings, and provide data and information products. The ultimate aim of NHABON is global access to sustained service delivery for operators and managers in aquaculture, fisheries, and public health.

How to cite: Anderson, C., Dortch, Q., Quintrell, J., Suddleson, M., Doucette, G., Vance, T., and Edmondson, M.: The United States National Harmful Algal Bloom Observing Network: Scaling up regional early warning systems for aquaculture and fisheries, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-640, https://doi.org/10.5194/oos2025-640, 2025.

14:10–14:20

OOS2025-1361

Physical processes impacting Harmful Algal Blooms (HABs) in Lampung Bay, Indonesia

Muhammad Chaidir Undu, Yannis Cuypers, Pascale Bouruet Aubertot, Estelle Masseret, Muawanah Muawanah, Antonio Lourenco, Nusapril Mulkan, Handayani Muliawati, Thomas Duhaut, Marine Herrmann, Christophe Maes, Mestiria Harbani Sitepu, Dona Setya, Kurnia Fathurhaman, Ari Setiawan, and Rizky Hidayatullah

Harmful algal blooms (HABs) have been considered as a worldwide issue as its occurrence devastates aquaculture industry through mass mortality of cultured fish in captivity. In addition, HABs also have the potential to harm human consuming marine products contaminated with toxins produced by harmful algae. In Indonesia, HABs events had been recorded in twelve marine areas of its archipelagos where member of dinoflagelata, for example Cochlodinium sp, Alexandrium sp, Dinophysis sp, Gymnodinium sp and Ceratium sp were reported as the dominant causative of blooming. The long-term trend in the emergence and severity of these HABs is believed to be driven primarily by the anthropic pressure resulting in an increase of nutrient input, providing a biogeochemical “climate’ favoring these HABs. However, HABs occur over short period of time and the prevision of their occurrence is extremely dificult. Physical processes influencing vertical/horizontal transport, water temperature and salinity and access to light are a key factor in this high frequency dynamics. This study aims to analyse physical processing impacting Harmful Algae Blooms (HABs) in Lampung Bay, Indonesia, particularly in Hurun Bay where the HABs frequently occur. Focus is notably made on turbulent water mixing which has a crucial impact on cysts resuspension, nutrients fluxes and access to light. With this aim, the Palhadin/Detoxiphy project (CNRS, IRD, IFI) was built on data of phytoplankton community, concentration of nutrients, physical oceanography process and meteorology of study site. Integrated data collections were conducted by weekly phytoplankton and nutrient concentrations sampling; monthly spatial sampling of nutrients and hydrology in the full Hurun bay and high frequency measurements of physical processes from moored sensors at various depths and meteorological sensors. In addition, the project also relies on numerical modeling covering a wider area for better understanding water circulation in Lampung Bay, notably through Lagrangian analyses of water surface water circulation. Preliminary results for 2023, show that the El Niño event throughout 2023 resulted in low rates of rainfall and a more extended dry season resulted in low nutrients input from landmass to the study site and eventually caused only weak HABs that year. In addition, maximum concentrations of chlorophyll-a were observed during the transitional between the wet and dry season as well as during the dry season. Physical analysis show that the bottom layer is extremely dynamic, with intrusion of cold saline water resulting in strong stratification that interacts with tides. This bottom dynamic has a strong impact on water mixing.

How to cite: Chaidir Undu, M., Cuypers, Y., Bouruet Aubertot, P., Masseret, E., Muawanah, M., Lourenco, A., Mulkan, N., Muliawati, H., Duhaut, T., Herrmann, M., Maes, C., Sitepu, M. H., Setya, D., Fathurhaman, K., Setiawan, A., and Hidayatullah, R.: Physical processes impacting Harmful Algal Blooms (HABs) in Lampung Bay, Indonesia, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1361, https://doi.org/10.5194/oos2025-1361, 2025.

14:20–14:30

OOS2025-78

ECOP

Informing the management of harmful algal blooms in estuaries

Emily Whitfield, Daniel Lemley, and Janine Adams

Global change pressures negatively impact the water quality of estuaries, often culminating in the proliferation of eutrophic symptoms that hinder the provision of important ecosystem services. The formation of harmful algal blooms (HABs) is a common ecosystem response in estuaries prone to eutrophication, typically resulting in adverse impacts on the quality and biotic functionality of the effected environment. Heterosigma akashiwo is one of the most problematic and widespread HAB species. It has been documented to cause severe economic losses in the fishery and aquaculture sector, with documented impacts reported in 17 countries. Recurrent high-biomass HABs comprising H. akashiwo are a feature of the permanently eutrophic Sundays and Swartkops estuaries in South Africa. In these case study ecosystems, these HABs have been shown to negatively impact the development of fish larvae and damage the gills of adult fish, while also being responsible for causing mass fish mortality events . This study investigated these sites and developed a predictive tool for H. akashiwo blooms to assist in water quality and catchment management. In-situ monitoring data were used to build an artificial neural network model to indicate which abiotic variables can be used to predict the presence or absence of H. akashiwo in each respective estuary. Additional in-situ data were then collected following a natural freshwater pulse event to determine whether (1) these hydrological resetting events serve to displace H. akashiwo populations and (2) how long it takes for populations to reestablish in the estuaries. The neural network model found that H. akashiwo presence was influenced by inorganic nutrient and light availability, while pH also played a role. For the Sundays Estuary, the presence of H. akashiwo was closely linked to depth and salinity, while dissolved silica had the largest influence in the Swartkops Estuary despite not being a nutrient required by H. akashiwo. Additionally, freshwater pulse events were largely ineffective as a long-term removal mechanism for H. akashiwo, with high-biomass HABs of the species returning within 4-5 months of the initial flood peak in both estuaries. Therefore, management of estuaries cannot rely solely on the natural flushing of an estuary to remove HABs. Instead, catchment management and water quality improvement are needed to reduce nutrient inputs and ensure freshwater inflow variability.

How to cite: Whitfield, E., Lemley, D., and Adams, J.: Informing the management of harmful algal blooms in estuaries, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-78, https://doi.org/10.5194/oos2025-78, 2025.

14:30–14:40

OOS2025-307

Anticipating microbiological risks in coastal area through innovative prediction models

Maxime Paris, Arthur Tré-Hardy, Léo Seyfried, Samuel Dupont, and Charlotte Dupont

The increasing human pressure on coastal ecosystems, coupled with climate change, ocean acidification population migration along the coast, poses significant challenges to the management and preservation of water quality. Current practices for monitoring microbial pollution, such as Escherichia coli levels, rely heavily on sparse, manual sampling, which offers limited temporal and spatial insights. This approach fails to capture the dynamic nature of contamination events and their potential impacts on public health, aquaculture, and coastal biodiversity, leading to delayed actions to address this contamination.

BiOceanOr, through the PREMICE project (project supported by the French government through i-Lab, funded by ADEME), addresses this critical gap by developing a comprehensive solution for predictive modeling of microbiological risks in coastal waters. Anchored in cutting-edge machine learning and IoT technology, PREMICE provides a proactive solution for understanding and anticipating contamination events.

This solution, branded as "i-plage," integrates high-frequency, connected microbiological measurement tools, predictive algorithms based on physico-chemical and biological parameters, and a user-friendly visualization interface. These innovations empower local authorities and stakeholders to take informed, timely actions, enhancing both ecological and public safety.

Key technical advancements within the PREMICE project include:

Real-time physico-chemical monitoring: A network of sensors measures parameters (temperature, salinity, turbidity, dissolved oxygen, E. coli...) These data streams, combined with historical and satellite data, provide a robust foundation for understanding coastal water dynamics.
Predictive microbiological models: Leveraging machine learning, PREMICE generates short-term forecasts of E. coli contamination risks. This predictive capability considers environmental drivers, (weather and hydrodynamic patterns), to anticipate potential risks
Scalable visualization platform: The interface offers an intuitive experience, designed for both professional stakeholders and the public. It enables real-time communication of risks and supports decision-making processes, from beach safety alerts to usages management.

The project is conducted in collaboration with leading environmental institutions, water treatment experts and integrates expertise across biology, data science, and coastal engineering. By focusing on high-risk coastal areas, such as the estuary of the Var river in France, PREMICE contributes with local stakeholders (i.e. Métropole Nice Côte d’Azur) to a better understanding of pollution dynamics and offers a scalable model for international application.

Overall, PREMICE exemplifies the integration of advanced technology for environmental monitoring, offering a paradigm shift from reactive to anticipatory management. By providing actionable insights and promoting sustainable practices, this innovation supports global efforts to protect vulnerable coastal ecosystems in the face of escalating anthropogenic and climate-induced challenges.

How to cite: Paris, M., Tré-Hardy, A., Seyfried, L., Dupont, S., and Dupont, C.: Anticipating microbiological risks in coastal area through innovative prediction models, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-307, https://doi.org/10.5194/oos2025-307, 2025.

14:40–14:50

OOS2025-321

ECOP

Improved modelling of the environmental impact of land-based pollution and multi-use operations in the North Sea.

Lotta Beyaard, Devanshi Pathak, Lőrinc Mészáros, and Ghada El Serafy

The coastal zone is heavily impacted by the increasing number of human activities, which degrade the marine environment and challenge the coexistence of coastal activities. To address these challenges, it is essential to strengthen the integration between Copernicus Marine Services and EU member state coastal systems to better understand the human-induced environmental impacts. The Horizon Europe FOCCUS project (Forecasting and Observing the Open-to-Coastal Ocean for Copernicus Users) aims to improve this integration by enhancing: in-situ and satellite coastal observations, hydrological and land-ocean products, and interfacing between ocean and coastal models. In this study, we demonstrate the efficacy of these advancements through two applications of the Dutch Continental Shelf Model (DCSM), a Delft3D Flexible Mesh model of the North Sea.

The first application focuses on far-field pollution mapping, caused by human activities such as dredging and land-based pollution. Within the existing DCSM, the transport of sediment and pollutants is refined through three adjustments: (i) incorporation of higher resolution remote sensing products, (ii) improved biogeochemical coupling with Copernicus Marine products and (iii) the use of enhanced pan-European hydrologic and land-ocean products. The resulting state-of-the-art pollution risk maps of sub-kilometre scale, with multi-year temporal coverage, will aid in monitoring the status of the marine environment, in support of the Marine Strategy Framework Directives and Sustainable Development Goal 14.1, which targets the reduction of marine pollution. The second coastal application assesses the environmental effects of multi-use offshore operations. The relevant biogeochemical and dynamic energy budget processes for aquaculture will be improved and incorporated into the aforementioned far-field pollution model. The modelled environmental impacts of multi-use operations can serve as a decision support tool for stakeholders involved in aquaculture, offshore energy and marine spatial planning in the North Sea. Such an interface provides scientific information on the coexistence of coastal activities, the core of the Maritime Spatial Planning Directive.

Through these applications we demonstrate the benefits of improved integration between EU Copernicus Marine services and the Dutch Member State Coastal System in characterising the environmental impacts of anthropogenic stressors on coastal and marine ecosystems, ultimately supporting sustainable and fair management practices.

FOCCUS is funded by the European Union (Grant Agreement No. 101133911). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HaDEA). Neither the European Union nor the granting authority can be held responsible for them.

How to cite: Beyaard, L., Pathak, D., Mészáros, L., and El Serafy, G.: Improved modelling of the environmental impact of land-based pollution and multi-use operations in the North Sea., One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-321, https://doi.org/10.5194/oos2025-321, 2025.

14:50–15:00

OOS2025-1048

The Clean and Healthy Ocean Integrated Program: A multistakeholder approach to address land-based pollution causing marine hypoxia

Kirsten Isensee, Jeremy James Sterling, Lorenzo Galbiati, Lucilla Minelli, Andreas Oschlies, and Caroline Slomp

Marine hypoxia (low or depleted oxygen in a water body) is a transboundary issue - it is not confined to a single country or a single region, but is a global concern with global impacts. Consequently, a programmatic approach that supports the identification and implementation of collaborative solutions at global, regional, and national levels is considered the most effective way to address the problem over the long-term. In recognition of this, the Clean and Healthy Ocean Integrated Program (CHO-IP) has been established by the Global Environment Facility (GEF) to address marine hypoxia through science-based action.

The CHO-IP offers an opportunity to implement the science-policy-society value chain approach, with a Global Coordination Project led by FAO, together with three multilateral development banks (ADB, CAF, EBRD) in partnership with IOC-UNESCO and GWP, as well as 14 Country Projects spanning Latin America, Africa, Asia and the Middle East spanning 9 Large Marine Ecosystems.

The overall goal of the program is to curb coastal hypoxia via the reduction of coastal pollution from agriculture, industrial, and municipal sources through policy, regulatory measures, infrastructure investments and nature-based solutions. This is the first time a GEF program focuses on the relationship between hypoxia and nutrient pollution. The Global Ocean Oxygen Network, an IOC-UNESCO working group, will be key to providing the scientific data, advice and connections required to achieve this goal and address challenges hampering action at this point, such as:

- a lack of comprehensive data on the causes and impacts of, and solutions to, marine hypoxia;
- policies and investments that do not sufficiently address nutrient pollution;
- limited access to innovative solutions, best management practices, and financing, restricting the adoption of cost-effective measures;
- fragmented and unconnected global efforts to tackle marine hypoxia fail to achieve significant transformative impacts.

We will present updated best practices for ocean oxygen measurement, data quality assessment and management, tailored and available for both scientific and practical applications. These practices are crucial for developing new methods to enhance the establishment, improvement, and sustainability of systems for monitoring nutrient pollution, oxygen levels, related data collection and reporting systems. We will also demonstrate how this links to the Global Ocean Oxygen Database and Atlas, which is expected to improve the interoperability of data produced via the CHO-IP and established databases worldwide.

How to cite: Isensee, K., Sterling, J. J., Galbiati, L., Minelli, L., Oschlies, A., and Slomp, C.: The Clean and Healthy Ocean Integrated Program: A multistakeholder approach to address land-based pollution causing marine hypoxia, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1048, https://doi.org/10.5194/oos2025-1048, 2025.

15:00–15:10

OOS2025-895

Analysis of the consequences of the socio-environmental conflict and its current impact on the degradation of coastal marine ecosystems. The case of Puerto Escondido in Puerto Jimenez, Costa Rica, as experiences of struggle and sustainable alternatives.

Randall Gerardo Rodríguez Quirós and Leslie Andrea Sisfontes Sandí

The Osa Peninsula is one of the most biodiverse regions in the world, holding 2.5 percent of the world's biodiversity. Although there are currently various protected areas, Osa Conservation Areas (ACOSA), this does not mean that the region's resources have not historically been exploited. This presentation will outline the results of a socioeconomic and environmental assessment of the community of Puerto Escondido, within the canton of Puerto Jiménez, as part of the FOCAL-PJ initiative's community strengthening and environmental protection efforts.

This area is geographically characterized by mangroves, with a large coastal front where rivers flow into the sea, and formations such as estuaries and beaches. Wetlands are among the ecosystems most affected by climate change and human activity, where they are replaced by monocultures and livestock farming.(Quesada, 2017). These oil palm monocultures resulted from a boom in the 1970s when they were introduced to the region (Mack-Rivas, 2019). These activities, along with urban development, have led to the destruction of the region's original natural environment, as well as harmful effects on humans, such as floods due to ecosystem changes.

Among the attempts to exploit resources is the case of the company Osa Productos Forestal, a transnational company that sought to exploit timber and foster urbanization, eventually dominating much of the land in the area. Additionally, the completion of the Southern Inter-American Highway, while it allowed greater land access to the region, also paved the way for more companies to venture into the agricultural sector, causing intense conflicts over land use.

Through of sociohistorical interviews, the experiences of the community were investigated, where for over 50 years, they have faced attempts to exploit natural resources and urbanization projects. Various studies have supported the impact and importance of government intervention in the conservation of the area (Lenin, 2017). By censuses and workshops in this participatory research, the current state of the locality has been diagnosed to understand its needs and issues, and how these relate to environmental degradation. Together, the research not only investigates the socio-historical attacks on the region's ecosystems, but also examines how, to this day, local people continue practices that may harm the ecosystem in order to generate economic sustenance.

In this community of over 100 households, waste management, employment options, infrastructure, land use, and other aspects have been analyzed. This is in addition to the actions taken by the FOCAL-PJ team across the rest of the peninsula, where projects such as rural tourism, artisanal fishing, and community linkages have been strengthened, improving the socio-ecological well-being. In the case of Puerto Escondido, it has been identified that the lack of employment and the absence of community organization are the main issues they face, with one of the consequences being the degradation of the coastal marine ecosystems.

The results of this research aim not only to generate a historical record of the community and strengthen local identity but also to present a series of proposals for sustainable productive alternatives to current practices.

How to cite: Rodríguez Quirós, R. G. and Sisfontes Sandí, L. A.: Analysis of the consequences of the socio-environmental conflict and its current impact on the degradation of coastal marine ecosystems. The case of Puerto Escondido in Puerto Jimenez, Costa Rica, as experiences of struggle and sustainable alternatives., One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-895, https://doi.org/10.5194/oos2025-895, 2025.

15:10–15:30

Discussion

Orals: Wed, 4 Jun, 16:00–17:30 | Room 1

Chairperson: Janine Adams

16:00–16:10

OOS2025-541

ECOP

Oil and gas developments on marine ecosystems off west africa

Mamadou Ndiaw Seck and M'bengue Bouya

Oil and gas developments on marine ecosystems off west africa

Mamadou N. Seck¹, Bouya MBengue^2,1, Alfredo García de Vinuesa¹, Sandra Kloff³, Bocar S. Baldé⁴, Marcos Llope¹

¹ Instituto Español de Oceanografía (IEO-CSIC), Centro Oceanográfico de Cádiz, (Spain)

²Mauritanian Institute of Oceanographic research and Fisheries (IMROP)

³Senegal centre de recherche oceanographique Dakar-Thiaroye (CRODT)

⁴ KLOFF, Sandra coordinador extranjero eNGO consultant BACOMAB (MAURITANIA)

The marine environment plays a key role in global climate regulation by sequestering carbon through different types of ecosystems (seagrass meadows, mangroves) what we know as blue carbon. However, some human activities (exploitation of non-renewable offshore energies: oil/gas), can have a considerable impact on marine ecosystems and therefore, directly and indirectly, on climate change.

Contrary to Europe, offshore non renewables are currently experiencing substantial expansion off West Africa and need to be considered within MSP and EBM perspective. This study focuses on offshore oil / gas exploitation in two areas of the region: (1) central Senegal, Sangomar project (2) border between Senegal and Mauritania, Greater Tortue Ahmeyim (GTA project).

Sangomar is an oil development located 90 km from the Delta of Sine-Saloum, an area that hosts an important mangrove forest that constitutes the main economic asset of the area. The GTA is a gas project 125 km from Saint-Louis, region that is being greatly impacted by climate change (e.g., coastal erosion and salination due to sea level rise) and that has an economy highly dependent on fisheries.

These two exploitation projects have significant impacts on the environment and local economies as they pose new risks (e.g. the Niger Delta oil spill in 2008 and 2009 caused destruction of several ecosystems, especially mangroves), introduce new pressures (release of chemicals and gas at the level of marine platforms) and change the patterns of sea use (fishing exclusion zones).

By using a range tools such as time series analysis, conceptual modelling techniques (with stakeholders) and bayesian belief networks we aim to better understand the trade-offs and risks that these two non-renewable developments pose on the respective marine ecosystems and the associated livelihoods as well as their external drivers in a rapidly changing geopolitical context. We expect that our results will contribute to inform decision-makers to better implement MSP in a context of climate change adaptation and mitigation.

Keywords: ecosystem-based management (EBM), political ecology, marine spatial planning (MSP), offshore energy, Bayesian Belief Networks (BBN), carbon stock, seagrass, mangroves.

How to cite: Seck, M. N. and Bouya, M.: Oil and gas developments on marine ecosystems off west africa , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-541, https://doi.org/10.5194/oos2025-541, 2025.

16:10–16:20

OOS2025-716

ECOP

A global history of bottom trawling and disturbance to continental shelf systems

Ciaran McLaverty, Callum Roberts, Maria Lourdes D. Palomares, Daniel Pauly, and Ruth Thurstan

The bottom trawling industry, which provides roughly one quarter of global seafood landings, has a great environmental cost. By dragging nets and other collection devices over the seabed, trawling degrades and impacts seabed habitats, catches a range of non-target species, and has potentially significant implications for our climate via disturbance of sedimentary carbon stocks. Despite this, we have a relatively poor understanding of how, when, and where, intense historical trawling impacts occurred on continental shelf seas. In this presentation, we describe our work to reconstruct the long, lost history of bottom trawling, from its growth in the North Sea during the 18^th century, to its global spread and industrialisation in the 1950s. We make use of sources such as national archives, government records, historical accounts, and popular media, to estimate the size and fishing power of early trawling fleets during the 19^th and early 20^th century. We combine this with descriptions of expanding trawling grounds and past trawling gears to map seabed impacts backwards in time. Latterly, we describe the expansion of bottom trawling post-1950 using trawling landings and effort data collated by the Sea Around Us Project (University British Columbia). We do this by allocating fleet data to fishing ports around the world, and subsequently modelling fishing effort and behaviour across the continental shelves for the period ca. 1950 to 2010. In doing so, we aim to provide a first synthesised global history of bottom trawling, as well as estimates of shelf seabed areas impacted by these activities. The results of this study are expected to shed new night light on the scale and extent of seabed disturbance caused by the bottom trawling industry, while emphasising the importance of historical context for addressing and managing contemporary marine conservation and today’s climate challenges.

How to cite: McLaverty, C., Roberts, C., Palomares, M. L. D., Pauly, D., and Thurstan, R.: A global history of bottom trawling and disturbance to continental shelf systems, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-716, https://doi.org/10.5194/oos2025-716, 2025.

16:20–16:30

OOS2025-1070

ECOP

Regulating underwater noise: from international legal framework to local initiatives

Anaëlle Boué

The presence of sound in the ocean is undeniable: initially of natural origin (from rain, storms, marine life, or seismic activity), underwater noise now also includes sounds produced by human activities. Anthropogenic underwater noise has increased significantly since the 20th century due to the expansion of human activities at sea, such as maritime traffic, port operations, the gas and oil industry, renewable marine energy projects, and military activities, thereby intensifying human-induced pressure on marine life. Scientific literature documents the impacts of underwater noise on marine biodiversity and categorizes its effects on marine life by severity: behavioral changes, masking, temporary hearing loss, permanent hearing loss, and lethal injuries.

Underwater noise is an environmental issue that has recently garnered attention from the international community, with its intersectoral and cross-border nature highlighting both the complexity and the necessity of studying how it can be addressed legally. The importance of regulating activities that generate underwater noise is clear: such regulation can immediately reduce noise emissions from regulated activities, which is essential for achieving Sustainable Development Goal 14 of the 2030 Agenda for Sustainable Development adopted by the United Nations General Assembly in 2015.

To date, no international treaty explicitly addresses anthropogenic underwater noise. In the absence of specific regulation, underwater noise emissions are governed in accordance with the traditional summa divisio of international environmental law, both by treaties aimed at combating pollution and by those focused on nature protection through species and habitat conservation. Among the relevant international conventions are the United Nations Convention on the Law of the Sea, the Convention on Biological Diversity, and the Convention on the Conservation of Migratory Species, along with regional treaties such as the Barcelona Convention for the Protection of the Mediterranean Sea against Pollution and its protocols, and the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea, and contiguous Atlantic Area. The governing bodies of these conventions have adopted various soft law instruments aimed at regulating underwater noise emissions, including guidelines, objectives, and action plans. In this context, local initiatives to reduce underwater noise are multiplying, with the adoption of regulations and recommendations by managers of marine protected areas, as well as the establishment of incentive measures by port authorities that include recommendations and financial incentives aimed at shipowners.

This presentation will aim to outline, on one hand, the international legal framework applicable to this newly recognized form of pollution and, on the other, the local initiatives to regulate it, while highlighting the challenges and issues surrounding their evolution.

How to cite: Boué, A.: Regulating underwater noise: from international legal framework to local initiatives, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1070, https://doi.org/10.5194/oos2025-1070, 2025.

16:30–16:40

OOS2025-1079

Assessing Anthropogenic Underwater Noise Pollution in the Mediterranean Sea and its Implications for Marine Ecosystem Protection and Restoration

Alessio Maglio and Maylis Salivas

The protection and restoration of marine ecosystems are paramount to meeting the Kunming-Montreal Global Biodiversity Framework’s (GBF) ambitious targets, especially in addressing biodiversity threats in ecologically sensitive regions like the Mediterranean Sea. Underwater noise pollution, primarily from human activities such as shipping, seismic exploration and maritime works, has emerged as a critical stressor for marine biodiversity, impacting species reliant on sound for navigation, communication, and survival. In 2023, the first comprehensive regional assessment of underwater noise in the Mediterranean was conducted by ACCOBAMS and UNEP/MAP, focusing on its effects on cetacean populations as indicator species of ecosystem health.

Utilizing innovative risk-based assessment methods, this work evaluates two critical indicators: impulsive noise (e.g., explosions, sonar, pile-driving) and continuous noise (mainly shipping-related) across sub-regions of the Mediterranean. Findings show that noise levels exceed tolerable thresholds in significant habitats, especially in the Western Mediterranean and Aegean sub-regions, where up to 35% of potential cetacean habitat is affected. Such results reveal unprecedent information about risks to the sustainability of key species in this area, highlighting the need of implementing effective area-based management approaches, such as marine protected areas and noise-mitigation policies, to protect and restore these ecosystems.

The results underscore the need for robust data on noise pollution to guide marine spatial planning and policy-making, supporting equitable management of marine resources. Mitigating noise pollution impacts is one essential component in fostering resilient and healthy marine ecosystems, a goal that can be effectively pursued through enhanced cross-sectoral collaboration, scientific innovation, and policy frameworks aligned with the Kunming-Montreal Global Biodiversity Framework.

How to cite: Maglio, A. and Salivas, M.: Assessing Anthropogenic Underwater Noise Pollution in the Mediterranean Sea and its Implications for Marine Ecosystem Protection and Restoration, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1079, https://doi.org/10.5194/oos2025-1079, 2025.

16:40–16:50

OOS2025-1335

Seawater organic pollution across three European Seas: insights from extra-large volume sampling and target analysis to inform policy prioritisation

Alice Carravieri, Giulio Mariani, Jaroslav Slobodnik, Peter Oswald, Yuriy Oleynik, Viktor Komorin, and Georg Hanke

Marine pollution by chemical contaminants is a major environmental concern in European waters. So far, most investigations have focused on pollution in specific marine regions, at varied temporal scales and using different analytical methods. This hinders comparability of marine pollution data across European regional seas and the identification of substances of concern at the European level. Furthermore, there is only limited information on contaminant concentrations in seawater, particularly in the mobile phase transporting the contaminants and indicating direct exposure. Here we provide the first pan-European survey on seawater concentrations of compounds of proved or potential concern over a short temporal window (three weeks in October 2021) using large-volume (700-800L/sample) transect sampling aboard the Oceanographic Research Vessel (RV) Belgica (now RV Boris Aleksandrov). The survey was organised by the European Union-funded project EU4EMBLAS, implemented by the United Nations Development Programme (UNDP). The seawater concentration of 332 organic substances was quantified in nine consecutive offshore transects through the North-Atlantic, the Mediterranean, and the Black Sea, via target and wide-target-screening analytical techniques, using Gas Chromatography-High Resolution Mass Spectrometry (HRGC-HRMS magnetic sector) and Gas Chromatography-Quadrupole Time of Flight (HRGC-QToF) technology. Overall, we detected 121 substances, of which 69 were present in all transects, including pesticides (e.g., α-, β-, γ-hexachlorocyclohexane, HCH; triallate; chlorpyriphos; biphenyl; anthraquinone), phosphorus flame retardants and plasticizers (e.g., tris(1-chloro-2-propyl) phosphate, TCPP), brominated flame retardants (e.g., 2,2,4,4'-tetrabromodiphenyl ether, BDE-47), industrial chemicals (polychlorinated biphenyls, PCBs) and fossil carbon combustion products (polycyclic aromatic hydrocarbon, PAHs). Seawater concentrations of detected substances ranged from 0.0002 pg L^-1 for tris(2-isopropylphenyl) phosphate (TIPPP) in the Central Mediterranean Sea, to 16 ng L^-1 and 20 ng L^-1 for anthraquinone and biphenyl, respectively, both in the Celtic Sea/Bay of Biscay. Transects with the highest diversity of detected compounds were located in the English Channel (99 substances) and in the Black Sea (98 substances). The Black Sea transect had the highest concentrations of several substances, including atrazine (15 ng L^-1), β-HCH (2.1 ng L^-1), terbuthylazine (1.8 ng L^-1), diphenamid (1.3 ng L^-1) and tebuconazole (1.1 ng L^-1). The spatial pattern of HCH isomers was noteworthy and unexpected, with 200-fold higher concentrations of β-HCH in the Black-Sea than in the Mediterranean, suggesting a Black-Sea specific β-HCH pollution spreading into the Mediterranean through the Turkish Straits. Large-scale surveys on marine pollution led by pan-European collaborations such as the one presented here have the potential to be very effective in informing the selection of substances with marine relevance for future monitoring programs under the Marine Strategy (MSFD) and Water (WFD) Framework Directives. Harmonised, efficient monitoring of marine contaminants in different environmental matrices across the EU is critical to assist Member States in achieving Good Environmental Status with respect to marine pollution.

How to cite: Carravieri, A., Mariani, G., Slobodnik, J., Oswald, P., Oleynik, Y., Komorin, V., and Hanke, G.: Seawater organic pollution across three European Seas: insights from extra-large volume sampling and target analysis to inform policy prioritisation, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1335, https://doi.org/10.5194/oos2025-1335, 2025.

16:50–17:00

OOS2025-1222

Spatial and temporal variations of the contamination in the Mediterranean Sea food webs (CONTAMPUMP ANR project)

Daniela Bănaru and the CONTAMPUMP team

The contamination of the marine environment by toxic, persistent, and biologically active substances and trace elements, of natural and anthropogenic origins, is a major problem worldwide, owing to its effects on the biodiversity and functioning of ecosystems, and its impact on the exploitation of marine resources, socio-economic activities and human health.

The CONTAMPUMP project (Plankton: biological PUMP of CONTAMinants in marine ecosystems, ANR-19-CE34-0001) concerned the study of the chemical contamination at the basis of marine food webs (plankton and both pelagic and benthic planktivores). Target contaminants have been selected among the priority substances of the Water Framework Directive (WFD) and MSFD lists: trace metals (ETMs), Hg, MMHg, PAHs, PCBs and pesticides. The main aim of this project was to determine the plankton exposome and to provide concepts and models of trophic transfer of contaminants from plankton to higher trophic levels.

During this project two campaigns (MERITE-HIPPOCAMPE from North to South of the Mediterranean Sea in April-Mai 2019, and CONTAMPUMP in Marseille Bay from February 2020 to November 2021) allowed to investigate the spatial and monthly variations of the contaminant concentrations in marine plankton food webs according to environmental factors. A total of 55 million liters of seawater were filtered. Different size classes of phytoplankton (0.7-2.7, 2.7-20, 20-60 µm) and zooplankton (60-200, 200-300, 300-500, 500-1000, 1000-2000 and > 2000 µm) were sampled during both campaigns. The biomass and composition of all plankton size classes were determined along with trophic markers (δ¹³C and δ¹⁵N). Additionally, mysids, mussels, fish and sediments were sampled in the Bay of Marseille.

Picoplankton and nanoplankton, which dominated the Mediterranean plankton biomass, represented the main sources of ETMs, Hg, MMHg and PAHs contamination in food webs. In contrast, PCBs and pesticides were particularly concentrated in microplankton and coastal areas (e.g Marseille Bay). The size of zooplanktonic organisms influenced the contamination level in different ways according to the type of contaminants (bioaccumulation for MMHg or biodilution for PAHs and most ETMs). The influence of the length of plankton food webs, short or long depending on nutrients and primary production, was highlighted, along with the importance of organisms’ trophic level (biomagnification for MMHg, PCBs and pesticides, and bioreduction for Hg, PAHs and most ETMs).

Plankton is more exposed to contaminants in human impacted sites. Terrestrial inputs and the resuspension of sediments highly influenced the monthly variations of contaminants in plankton in Marseille Bay. Mussels and fish presented particularly high PCBs values and a bioaccumulation with increasing size. Eventually, it was evidenced that food selection influenced contaminant concentrations in planktivorous species. Thus, according to the contaminants considered, trophic transfers from plankton to fishery resources resulted in bioreduction for some contaminants (e.g. most ETMs) or biomagnification (e.g. MMHg, PCBs).

Keywords: plankton exposome, trophic transfer, contaminants, spatial and temporal variations

How to cite: Bănaru, D. and the CONTAMPUMP team: Spatial and temporal variations of the contamination in the Mediterranean Sea food webs (CONTAMPUMP ANR project), One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1222, https://doi.org/10.5194/oos2025-1222, 2025.

17:00–17:10

OOS2025-1386

Bridging science and policy through data synthesis: Guiding environmental impact research and coastal management in Brazil

Aline Martinez, André Pardal, and Ronaldo Christofoletti

The rapid expansion of urbanization along Brazil’s coastline presents significant challenges for sustainable management, intensifying pressure on coastal-marine ecosystems through increased water contamination, demand for natural resources, and habitat degradation. Diagnosing the state of scientific knowledge is essential to identify gaps and environmental challenges, providing the foundation for informed decision-making and improved management strategies toward sustainable and resilient coasts. In this context, we have conducted scientific reviews integrated with governmental public data to support evidence-based decision-making, aligning research priorities with policy needs in Brazil, a developing nation of the Global South. With over 8,500 km of coastline, diverse marine ecosystems spanning from tropical to warm temperate climates, and half of its population living in coastal cities or nearby, Brazil faces critical environmental challenges, such as water pollution, coastal hardening, and overfishing. Climate change, governance inequalities, and poor management strategies in sustainability further intensify these challenges, reinforcing the need for actionable knowledge to inform policies. Our research synthesized data on different human stressors associated with coastal cities, evaluating their ecological impacts on coastal-marine ecosystems of Brazil. Pollution research has primarily focused on metal contamination driven by industrial development, while major chronic issues, such as untreated or poorly treated sewage in most coastal cities, remain overlooked. Furthermore, the environmental impacts of coastal hardening, through the construction of artificial structures in the marine environment, are not well known. Although 66 exotic species have been recorded on these structures, research remains centered on artificial reefs. Additionally, overfishing has contributed to declining fish stocks, yet its broader impacts on invertebrate species remain largely unknown. Meanwhile, the environmental consequences of tourism — a primary source of income of local communities along with fishing on the Brazilian coast — are still poorly understood. These efforts have revealed persistent knowledge gaps due to the spatial fragmentation of existing studies, highlighting the need for comprehensive baseline data to support local management strategies. As a key outcome of this work, we have been transforming our scientific findings into policy-oriented technical documents targeted at decision-makers, legislators, public managers, and the general public. These documents aim to raise awareness of environmental challenges, emphasize adopting nature-based solutions to mitigate ecosystem degradation and biodiversity loss, and advocate for the co-creation of sustainable management strategies to enhance ecosystem services and coastal resilience. Our work exemplifies how science can bridge the gap with public policy by translating complex ecological data into actionable recommendations to promote resilience in coastal cities but also to address the socio-environmental inequalities prevalent in developing nations.

How to cite: Martinez, A., Pardal, A., and Christofoletti, R.: Bridging science and policy through data synthesis: Guiding environmental impact research and coastal management in Brazil, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1386, https://doi.org/10.5194/oos2025-1386, 2025.

17:10–17:30

Discussion

Posters on site | Poster area "La Baleine"

Display time: Tue, 3 Jun, 17:00–Thu, 5 Jun, 20:00

P288

OOS2025-5

ECOP

Ecotoxicological effects of sunscreen derived UV filters on temperate marine organisms

Anneliese Hodge, Awadhesh Jha, Frances Hopkins, and Mahasweta Saha

Ultraviolet (UV) filters are active compounds which absorb, block, or scatter UV radiation, and are added to personal-care products (PCPs), such as sunscreens and cosmetics, to protect against photoaging and photocarcinogenesis. UV filters can be mineral-based (inorganic) or chemical-based (organic) and are considered contaminants of emerging concern (CEC) due to their widespread use and ubiquitous presence in the environment. UV filters can enter the marine environment through various pathways, including direct skin wash-off, wastewater effluent and industrial spills.

UV filters have been detected globally in wastewater, freshwater and marine environments; and have been recorded in multiple matrices including accumulation within aquatic biota, sediments and water columns. Media attention has particularly focused on the effects of sunscreens on corals in recent years; resulting in regulatory implementation on such compounds in areas such as Hawaii and Palau; however, very little research has been conducted on the effects of these compounds on temperate marine organisms.

Adopting a multidisciplinary approach, this research highlights the ecotoxicological effects of two contrasting sunscreen derived UV filters (benzophenone-3 and nano-titanium dioxide) on temperate marine organisms; including Isochrysis galbana and Mytilus galloprovincinalis, and analyses the potential of these compounds to bioaccumulate and undergo trophic transfer. The ecotoxicological effects are elucidated at a molecular, cellular and individual level.

Here, we subjected Isochrysis galbana to varying environmentally relevant concentrations of benzophenone-3 and nano-titanium dioxide in a series of experiments under ultraviolet lighting. Ecotoxicological effects including cell viability, growth, chlorophyll-a content, dimethylsulfoniopropionate (DMSP) concentration, oxidative stress markers, enzymatic activity and bioaccumulation was assessed using a range of techniques including flow cytometry, fluorescence, electron microscopy, gas chromatography, LC-MS and ICP-MS. Results so far have indicated that both benzophenone-3 and nano-titanium dioxide can result in significant effects to cell density and chlorophyll-a content, whilst nano-titanium dioxide can cause oxidative stress in the form of lipid peroxidation.

This research aligns with the UN Ocean Decade Vision of ‘A Clean Ocean – Where sources of pollution are identified, reduced, or removed.’ Whilst sunscreens and UV filters are important for human health, their environmental fate and effects on marine life must be elucidated to accurately target which compounds are safer for use and which should be highlighted for regulatory approaches.

Please note – this work is still ongoing, and results are still being collated. By the time of the congress in June 2025 – more results will be made available to share, particularly relating to the trophic-transfer potential to Mytilus galloprovincinalis.

How to cite: Hodge, A., Jha, A., Hopkins, F., and Saha, M.: Ecotoxicological effects of sunscreen derived UV filters on temperate marine organisms , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-5, https://doi.org/10.5194/oos2025-5, 2025.

P289

OOS2025-142

ECOP

Influence of Human Activities and Benthic Processes on Water Quality Dynamics in the Plum Island Estuary

(withdrawn)

Qi Ye and Cristina Schultz

P290

OOS2025-148

Interactions of Marine Pollution and Pelagic Communities in UK coastal habitats.

Michelle Devlin, Carolyn Graves, Naomi Greenwood, and Mike Best

The dynamic interplay between water quality and the pelagic community is pivotal to understanding aquatic ecosystems' health and functionality. Water quality, encompassing parameters such as nutrient concentrations, temperature, dissolved oxygen, and other pollutants can profoundly influence the composition, diversity, and behaviour of pelagic organisms. In turn, the activities and population dynamics of these organisms can significantly impact water quality through processes including nutrient cycling, organic matter decomposition, and the biogeochemical transformation of elements. New sampling and imagery technology to measure plankton communities has helped further our understanding of the complex changes that are occurring in impacted coastal systems and we present work that improves our understanding of the relationships between water quality and the pelagic community in UK waters. We demonstrate how water quality imbalances can lead to shifts in community structure; changes in key phytoplankton species during eutrophic conditions leading to changes in trophic structures that can impact on zooplankton and fisheries. We report how pelagic organisms, from microscopic phytoplankton to larger zooplankton are influenced by the water quality and climatic changes. Understanding these interactions is crucial for managing our coastal systems, continuing to accurately predict ecosystem responses to environmental changes, and prioritising management measures that mitigate the impacts of human activities in our and marine systems.

How to cite: Devlin, M., Graves, C., Greenwood, N., and Best, M.: Interactions of Marine Pollution and Pelagic Communities in UK coastal habitats. , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-148, https://doi.org/10.5194/oos2025-148, 2025.

P292

OOS2025-208

Tracing the Environmental Fate and Bioavailability of Anthropogenic Gadolinium

Vanessa Hatje, Franciele C. Novais, Ana Maria Orani, and Marc Metian

The distribution of rare earth elements (REE) in the environment is governed by their input, removal, transport, and biogeochemical cycling. Untangling these processes to understand REE cycles is now a major focus in marine geochemistry. Such knowledge is essential for predicting future changes along the land-ocean continuum driven by natural and anthropogenic factors, such as pollution and climate change. Some REE, particularly gadolinium (Gd), are also contaminants of emerging concern. Over the past 25 years, Gd concentrations have increased significantly in both freshwater and seawater systems due to the extensive use of Gd-based contrast agents in magnetic resonance imaging (MRI). While Gd³⁺ is highly toxic, it is administered in the form of non-toxic stable, soluble complexes that are rapidly excreted from the human body. However, these complexes mostly pass through wastewater treatment plants without removal, resulting in environmental contamination. This leads to substantial anomalies in normalized REE patterns and anthropogenic Gd may accumulate into biota, indicating that at least some fraction of Gd complexes is bioavailable. Their bioavailability may depend on the specific type of contrast agent (e.g., linear vs macrocyclic) and its environmental half-life, among other factors yet to be determined. Gd complexes are also bioaccessible to humans if ingested orally. This bioaccessibility raises concerns about the long-term health effects of gadolinium exposure. By combining REE measurements across multiple environmental matrices and using them as tracers of natural and anthropogenic processes, we examine the distribution and speciation of anthropogenic Gd in the environment, along with its potential implications for ecosystems and human health.

How to cite: Hatje, V., Novais, F. C., Orani, A. M., and Metian, M.: Tracing the Environmental Fate and Bioavailability of Anthropogenic Gadolinium, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-208, https://doi.org/10.5194/oos2025-208, 2025.

P293

OOS2025-309

ECOP

Contribution to the assessment of TCE contamination in coastal ecosystems of the Provence-Alpes-Côte d'Azur region

Chloé Jariel, Jean-Louis Gonzalez, Christophe Brach-Papa, Stéphanie Jacquet, Stéphane Mounier, Nicolas Briant, Pauline Le Monier, Teddy Sirreau, and Anne Grouhel

Technology Critical Elements (TCE) is an emerging family of contaminants including: Rare Earth Elements (REE), Platinum Group Elements (PGE), and "non-traditional" metals and metalloids. These elements have unique physico chemical properties (ductility, conductivity, fluorescence) (Dang et al, 2021). They are increasingly used in advanced technologies fields such as electronics, pharmaceuticals, and renewable energies. Despite their growing use, limited data exist regarding their impact on marine ecosystems, particularly in urban and industrial areas. This knowledge gap comes from the complexity of their analysis and their low concentrations in natural environments. Advances in chemical analysis enable to meet this challenge. Recent studies have shown that the biogeochemical cycles of TCEs can be disrupted by their increasing introduction into the environment (Abdou et al, 2019 ; Knappe et al, 2005). The objective of this project is to provide an assessment of TCE contamination in coastal environments. The study area corresponds to the coastline of the Provence-Alpes-Côte d'Azur (PACA, France) region. Results comes from an analysis of surface sediment samples collected during previous campaigns (SUCHIMED, CARTOCHIM, ROCCHSED). Given the wide variety of elements within the TCE family, this project focused on rare earths and platinum. The samples were analysed using triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-QQQ-MS) (CCEM, Nantes) to obtain Rare Earth concentrations measurements. Platinum concentrations were determined using Adsorptive cathodic Stripping Voltammetry (AdSV) (MIO, Toulon). Thanks to the archived samples analyzed, this presentation offers an inistial spatial study of the RRE and Pt contamination along the PACA region coastline over the last thirty years. Platinum’s results showed a sharp divergence in concentration depending on the study site. Higher concentrations are revealed in coastal areas near urban areas or rivers rich in anthropogenic inputs. We presume these increases are linked to anthropogenic activity. REE distribution profiles obtained, european shale normalized, are extremely diverse, reflecting the multiplicity of physico-chemical processes taking place in this zone. Each profile thus becomes the digital fingerprint of the site studied, and proves to be fairly stable over time.

How to cite: Jariel, C., Gonzalez, J.-L., Brach-Papa, C., Jacquet, S., Mounier, S., Briant, N., Le Monier, P., Sirreau, T., and Grouhel, A.: Contribution to the assessment of TCE contamination in coastal ecosystems of the Provence-Alpes-Côte d'Azur region, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-309, https://doi.org/10.5194/oos2025-309, 2025.

P295

OOS2025-576

EURAMET project 21GRD09 MetroPOEM: Metrology for the harmonisation of measurements of environmental pollutants in Europe

Dirk Arnold and Simon Jerome and the MetroPOEM

The MetroPOEM project is funded by EURAMET under the European Green Deal and the underlying ambition for zero pollution. The project aligns directly with global target 7 of the Kunming-Montreal Global Biodiversity Framework (GBF), which aims to ‘…reduce pollution risks and the negative impact of pollution from all sources by 2030…’

To support target 7 of the GBF requires the development of highly sensitive techniques to detect ultra-low levels of pollutant elements identified as environmental stressors, and to determine their isotope ratios, which are key parameters in the identification and attribution of sources of such pollutants.

Mass spectrometry is a key method for determination quantities of non-radioactive polluting elements and long-lived radionuclides as well as the isotope ratios of such elements, and the MetroPOEM project bridges the traceability gap between activity and mass-based measurements – particularly estimation of mass bias.

Underlying studies

SI-traceable high-precision methods were developed for isotope ratio determination of Li, B, Cr, Cd, Ni, Sb, Pb, and U in environmental matrices, focused on seawater as the model solution. Method development encompassed manual and automated methods for separating analytes from the matrix, evaluating different calibration approaches and instrumental isotope fractionation corrections, and estimating uncertainty budgets. Various single and multi-collector ICP-MS systems, as well as accelerator mass spectrometry, were used and their performances compared.

These findings support the development of methods for stable and radioactive isotope determination.

Radioactive standard solutions (⁹⁰Sr, ²³⁷Np, ^234,236U, ^239,240Pu, ²⁴¹Am) were distributed to partner laboratories for measurement. The results and data analysis were compiled as a comparison report, leading to a peer-reviewed publication draft.

Reference materials

A 250 litre of sea water sample was taken from the German EEZ (North Sea) for the development of two certified reference materials. This material was subjected to processing, including spiking with additional elements based on preliminary analysis and homogenisation.

Part of this candidate reference material was characterised for isotope ratios of Li, B, Cr, Cd, Ni, Sb, Pb, and U to generate a reference material with SI traceability for isotope ratios. Additionally, ~50×0,5L liquid RM aliquots of sea water were prepared, spiked with natural U, ²³⁷Np, ^239,240Pu and ²⁴¹Am.

A solid silica-based reference material, produced by sol-gel synthesis spiked with ^{234,235,236,238}U, ²³⁷Np,^239,240Pu and ²⁴¹Am, as well as ~10 kg of an inactive material for testing dissolution procedures.

These materials were characterised in accordance with the requirements of ISO 17034 by interlaboratory studies between the project partners, using techniques developed in the project, and will be available to the wider scientific community for method development and validation.

Outputs

Certified reference materials from the project will be available to the wider scientific community for method development and validation.

To support end users interested in developing or upgrading their capabilities. two Good Practice Guides on (i) measurement of radioactivity by mass spectrometric techniques, and (ii) sample treatment, uncertainties and mass bias quantification, are being drafted for issue by the end of the project.

Project outcomes thus support the aims of the GBF global target 5 by improving traceability of measurement.

How to cite: Arnold, D. and Jerome, S. and the MetroPOEM: EURAMET project 21GRD09 MetroPOEM: Metrology for the harmonisation of measurements of environmental pollutants in Europe, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-576, https://doi.org/10.5194/oos2025-576, 2025.

P296

OOS2025-597

ECOP

Detection and characterization of microalgae blooms based on multi-source information from in situ measurements and Earth Observation imagery: From data to end-user information

Josselin Aval, Simon Rebeyrol, Marc Lennon, Leo Seyfried, Samira Amraoui, and Charlotte Dupont

In the frame of the ESA Innovation project EO4HAB (Earth Observation for Harmful Algal Blooms detection and characterization, ref. ESA CfP/6-60008/23/I-DT-bgh), we propose to develop a pre-operational tool for the detection, characterization and prediction of microalgae blooms for aquaculture professional thanks to:

In situ physico-chemical and spectroradiometry data,
Multispectral and Hyperspectral satellite imagery.

This project involves two complementary French SME companies: Hytech-imaging and BiOceanOr. While the ambition of Hytech-imaging is to develop and generalize the uses of spectral imaging, BiOceanOr aims to offer water quality monitoring and forecasting services to its customers.

Several innovations are addressed in this project:

Exploitation of in situ spectroradiometry data (hydraspectra – CSIRO).
Exploitation of a very large database of samples in Chile (MOWI).
Development of species-specific bio-optical models.
Take into account adjacency effects.
Explore several approaches for bloom prediction.
Evaluate the interest of high revisit EO (Earth Observation) from nanosatellite constellations.

The methodology includes two main steps:

Detect and characterize the blooms based on the in situ spectroradiometry (hydraspectra – CSIRO) and physico-chemical (MOWI) data.
Use the in situ information to extend the detection and characterization using multispectral (S2/S3/VIIRS) and hyperspectral (PRISMA/EnMAP) satellite data.

For both steps, physics-based (radiative transfer modeling and inversion), empirical (spectral indices) and data-driven (machine and deep learning) approaches are considered.

Two sites are studied: Spencer Gulf (Australia) and Lake Region (Chile).

The main challenges addressed are:

Use of in situ detection and characterization data to calibrate the estimation of the satellite BOA (Bottom Of Atmosphere) reflectance. In particular, species-specific bio-optical models must be implemented.
Consideration of adjacency effects that can affect the satellite BOA reflectance, with use of a distance-to-the-coast metric. Evaluation of atmospheric correction imperfections as a source of uncertainties (aerosols, reflections, etc.).
Consideration of sensor noise that affects the satellite BOA reflectance.
Estimation and propagation of uncertainties that are essential to demonstrate the usability of the data.

The presentation will summarize the results of the EO4HAB project, including in situ detection, large scale bloom detection, characterization of blooms on a local scale and prediction.

How to cite: Aval, J., Rebeyrol, S., Lennon, M., Seyfried, L., Amraoui, S., and Dupont, C.: Detection and characterization of microalgae blooms based on multi-source information from in situ measurements and Earth Observation imagery: From data to end-user information, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-597, https://doi.org/10.5194/oos2025-597, 2025.

P297

OOS2025-714

Tackling plastic pollution in Kingston, Jamaica: How cleanup enables systematic change

Suleman Audu, Jade-Ashley Carberry, Michael McCarthy, and Matthias Egger

Ranked as one of the world’s largest natural harbor and recognized as a Ramsar site for wetland conservation, Kingston Harbour plays a vital role for Jamaica’s biodiversity and economy. A system of gullies in Kingston serves to manage stormwater and mitigate flooding by channeling it into Kingston Harbour. However, these gullies have become sources of solid waste contamination, primarily plastics, due to improper waste disposal upstream. During heavy rains, floods can cause gullies to become heavily polluted with plastic and other municipal debris. This waste causes serious harm to the local environment, and especially to mangroves. Here, we present how The Grace Kennedy Foundation, Clean Harbours of Jamaica, and The Ocean Cleanup partnered to create a novel solution that combines technology, data insights, and stakeholder involvement to successfully address plastic pollution in Kingston Harbour. At gully mouths, a series of Interceptor Barriers were installed to capture floating trash, involve pertinent parties, and support upstream initiatives aimed at a sustainable resolution to the ongoing issue. The operation, together with other initiatives like beach and mangrove cleanups involving volunteers and local communities, has directly intercepted nearly two million kilograms of rubbish from the harbor. The project’s offloading site has become a hub of community engagement and learning, brightly decorated and frequently visited by schoolchildren from across the region. Furthermore, a multi-year research project was launched with the University of the West Indies to quantify the benefits of the project on the mangroves and associated ecosystem services. This project provides a hands-on example of how cleanups act as catalysts within a community – providing solutions to remove existing plastic pollution while enabling a community to drive systemic change further upstream.

How to cite: Audu, S., Carberry, J.-A., McCarthy, M., and Egger, M.: Tackling plastic pollution in Kingston, Jamaica: How cleanup enables systematic change, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-714, https://doi.org/10.5194/oos2025-714, 2025.

P298

OOS2025-823

Impact of an Abnormal or Degraded Environment on Small Pelagic Fisheries: The Case of Sardine (Sardina pilchardus) and Horse Mackerel (Trachurus trachurus)

Billal Meradef, Mohamed Kacher, and Yousra Zaoui

This study is an analysis of the impact of an abnormal or degraded environment on the fishing of sardines and horse mackerels. The study is based on data from the 2014 and 2015 sampling surveys named ALPEL in Algeria. The results of this study suggest that, for individuals sampled during the ALPEL surveys in 2014 and 2015: the recorded environmental parameters (Temperature, Salinity, Chlorophyll) during these surveys have little or no influence on the recruitment levels of juvenile sardines and horse mackerels in Algerian waters; a high probability that there are no nursery areas or spawning areas in these waters for both sardines and horse mackerels; finally, it is highly likely that the young recruits (juveniles of sardines and horse mackerels) found in Algerian waters originate from spawning areas located in the northern Mediterranean, outside of Algerian waters. Such a situation does not allow for a traditional rational management approach to the exploitation of these two species, thus causing significant socio-economic issues in the small pelagic fishery in Algeria.

How to cite: Meradef, B., Kacher, M., and Zaoui, Y.: Impact of an Abnormal or Degraded Environment on Small Pelagic Fisheries: The Case of Sardine (Sardina pilchardus) and Horse Mackerel (Trachurus trachurus), One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-823, https://doi.org/10.5194/oos2025-823, 2025.

P299

OOS2025-863

All oil spills are not created equally: A view from the bacterial world

Wade Jeffrey, Pamela Benz, Melissa Brock, Melissa Ederington-Hagy, Erika Headrick, Katelyn Houghton, Josette Hutchenson, Sabine Matallana-Surget, Lisa Nigro, Rachel Richardson, Arianna Simmering, and Lisa Waidner

Investigations of the relationships between crude oil and bacterioplankton have provided clues into how crude oil constituents are degraded, and how anthropogenic spills affect system nutrient cycling and food webs. The Deepwater Horizon oil spill in 2010 re-invigorated the investigation of how marine bacteria respond to oil spills. While much of the historical research and initial efforts focused on the biodegradation of oil, it became quickly apparent that much of the bacterial community was affected negatively by oil. Environmental conditions often altered those responses. Herein we present a summary of results, both published and unpublished, indicating that based on the bacterial responses to oil, it is difficult to produce universal conclusions on the effects of oil spills on marine bacterial communities, confounding both the impacts of the spills, but also the best response to mitigate the effects. In the northern Gulf of Mexico, summer was the worst time to have a spill, but also when Deepwater Horizon occurred. Exposure to sunlight created a myriad of responses depending on the duration and spectral quality of that exposure, but was also dependent on the source of the oil. Those that generated the greatest inhibition to community growth, also produced the greatest changes in bacterial community structure, including variability in known oil degrading bacterial groups. Responses were altered even more when clean-up methods were included in the analyses. The use of Corexit 9500A in combination with oil and sunlight increased the stress response of bacteria. While burning oil reduced some toxic components of oil, subsequent exposure to sunlight increased the toxic response. These results indicate that microbial responses to oil spills are dependent on the source of the oil, solar conditions, and the time and location of the spill complicating the ability to predict oil spill effects.

How to cite: Jeffrey, W., Benz, P., Brock, M., Ederington-Hagy, M., Headrick, E., Houghton, K., Hutchenson, J., Matallana-Surget, S., Nigro, L., Richardson, R., Simmering, A., and Waidner, L.: All oil spills are not created equally: A view from the bacterial world, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-863, https://doi.org/10.5194/oos2025-863, 2025.

P300

OOS2025-1016

ECOP

Distribution of Heavy metals in Blue crabs (Callinectes sapidus) in the Okerenkoko and Kurutie communities

Amaka Michael and Abraham Ekperusi

The utilization of Blue crabs (Callinectes sapidus) as bio indicators for environmental monitoring is crucial in the evaluation of heavy metal contamination in Estuaries. This study investigates the distribution and concentration of heavy metals—lead (Pb), mercury (Hg), arsenic (As), nickel (Ni), cadmium (Cd), and chromium (Cr)—in blue crabs (Callinectes sapidus) in the Okerenkoko and Kurutie communities. A total of 20 crab samples, comprising male and female crabs were analyzed to assess the levels of contamination and the potential health risks to humans. The analysis was conducted using Atomic Absorption Spectrometry (AAS). Results show that nickel and cadmium concentrations (0.702mg/kg and 0.373mg/kg) were highly significant in both male and female crabs from both communities while lead and mercury mean concentrations (0.764mg/kg and 0.284mg/kg) were significantly higher in male crabs than in females in Okerenkoko. The health risk assessment revealed that the estimated daily intake (EDI) of these metals exceeded safe consumption limits, particularly for lead and mercury however, the health index quotient reveals that children and adults (5.646 and 2.581) are prone to health risks from consuming crabs in Kurutie community than Okerenkoko community. The findings indicate significant environmental pollution likely stemming from industrial activities, with serious implications for both the local ecosystem and public health.

Keywords: Heavy metals, pollution, contamination, health risk

How to cite: Michael, A. and Ekperusi, A.: Distribution of Heavy metals in Blue crabs (Callinectes sapidus) in the Okerenkoko and Kurutie communities, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1016, https://doi.org/10.5194/oos2025-1016, 2025.

P301

OOS2025-1019

Bringing Sargassum Observation and Prediction to Decision Makers

Audrey Hasson, Marc Lucas, and Joaquin Trinanes

The Sargassum Working Group (SWG) of GEO Blue Planet will showcase its activities, addressing the ongoing challenges posed by Sargassum seaweed blooms across the tropical Atlantic and coastal regions. Since 2011, Sargassum blooms have affected coastal communities, harming tourism, fishing, health, and ecosystems. The SWG is working on innovative monitoring, prediction, and response strategies to mitigate these impacts. By advancing remote sensing, in situ observation, and predictive modeling, the group enhances real-time detection, forecasting, and data sharing, following FAIR principles (Findable, Accessible, Interoperable, and Reusable).

The SWG has been recognised as the monitoring and prediction expert group of the UNESCO/IOC and the UNEP Cartagena Convention SPAW RAC.

Key initiatives include establishing an Integrated Observing System to coordinate data from various sources and continuing the development of the Sargassum Information Hub to centralize information on monitoring and prediction. Additionally, the SWG is working to design community-led decision-support tools to help local stakeholders respond effectively. A priority for SWG is fostering international and regional cooperation, advancing technical standards for data interoperability, and engaging citizen scientists. This collaborative, data-driven approach aims to create robust early-warning systems and deliver actionable insights for sustainable coastal management and the achievement of Sustainable Development Goals in affected regions

How to cite: Hasson, A., Lucas, M., and Trinanes, J.: Bringing Sargassum Observation and Prediction to Decision Makers, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1019, https://doi.org/10.5194/oos2025-1019, 2025.

P302

OOS2025-1038

ECOP

Overview of EMODnet Chemistry eutrophication data: Informing a strategy for monitoring under the EU Marine Strategy Framework Directive

Claudia Mendes, Marco Palma, and Georg Hanke

We aimed to assess eutrophication in situ data coverage in the EU marine regions to inform a data acquisition strategy for the eutrophication assessments under the Marine Strategy Framework Directive (MSFD). We analysed eutrophication datasets provided by the European Marine Observation and Data Network (EMODnet) Chemistry covering the Atlantic, Baltic, Black, Mediterranean and North Seas, between 2012 and 2021. For each marine region, we assessed spatial temporal coverage of nutrients, including Dissolved Inorganic Nitrogen, Total Nitrogen, Dissolved Inorganic Phosphorus, and Total Phosphate, as well as surface concentrations of Chlorophyll a and bottom concentrations of Dissolved Oxygen. We identified >3M valid data entries with heterogeneous spatial-temporal coverage across EU marine regions and subregions. The gaps identified will be used to 1) identify opportunities to consolidate monitoring approaches in terms of scale, methodologies, and parameters coverage 2) improve MSFD reporting 3) further promote sharing of eutrophication data into EMODnet Chemistry. Overall, this work will contribute to ensure wider, more comparable and higher-quality eutrophication datasets, hence strengthening the eutrophication assessments under the MSFD.

How to cite: Mendes, C., Palma, M., and Hanke, G.: Overview of EMODnet Chemistry eutrophication data: Informing a strategy for monitoring under the EU Marine Strategy Framework Directive, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1038, https://doi.org/10.5194/oos2025-1038, 2025.

P303

OOS2025-1080

Safeguarding our Marine Environment: The Fundamental Role of Investigating Emerging Plastic-Derived Contaminants

Imma Tolosa, Badreddine Barhoumi, David Huertas, Christine Ferrier-Pagès, and Philippe Bersuder

The pervasive presence of plastic derived pollution in marine environments, along with other sources of contamination, has contributed to the emergence of various chemical contaminants that pose significant risks to aquatic ecosystems and human health. Among these contaminants of concern are per- and polyfluoroalkyl substances (PFAS, also called forever chemicals), legacy flame retardants such as polybrominated diphenyl ethers (PBDEs), alternative brominated flame retardants, organophosphate flame retardants and plasticizers (OPEs), and phthalate esters (PAEs). PFAS, known for their persistence and bioaccumulative properties, are widely used in industrial applications and consumer products. Similarly, flame retardants like PBDEs, alternative brominated flame retardants, and OPEs are added to plastics to reduce flammability but can leach into the environment, leading to widespread contamination. Phthalates, used as plasticizers, are another group of chemicals that can migrate from plastics into the marine ecosystem. This abstract outlines the critical need to investigate these emerging plastic-derived contaminants, focusing on their sources, distribution in sediments and seafood, and the effects of leaching additives on marine organisms such as corals and algae. By examining a sediment core from the Caribbean Sea, we used radiometric dating to trace the temporal trends of legacy and alternative flame retardants and plasticizer additives, identifying potential sources. Furthermore, the effects of leaching additives from plastics on marine organisms are of particular concern. Corals and algae, which are foundational species in marine ecosystems, can be adversely affected by these contaminants. Our studies have shown that chemicals leached from polystyrene debris cause physiological stress on coral nubbins. Algae, as primary producers, can also experience reduced photosynthetic efficiency and altered growth patterns due to exposure to organophosphate flame retardants. Additionally, our research indicates that corals bioconcentrate some of these chemicals, with adverse effects intensified by rising water temperatures. These studies provide valuable insights into the combined effects of chemical exposure from plastic debris and ocean warming, highlighting the potential threat of plastic pollution to sensitive ecosystems. Additionally, by analyzing PFAS in seafood, such as fish and shellfish from a North African ecosystem, we assessed the potential human health risks associated with consuming contaminated seafood. In conclusion, safeguarding our marine environment requires a comprehensive understanding of the sources, distribution, and effects of emerging plastic-derived contaminants. By employing advanced analytical techniques and interdisciplinary approaches, researchers can enhance our understanding of these pollutants and guide the development of effective strategies to protect marine biodiversity and human health.

How to cite: Tolosa, I., Barhoumi, B., Huertas, D., Ferrier-Pagès, C., and Bersuder, P.: Safeguarding our Marine Environment: The Fundamental Role of Investigating Emerging Plastic-Derived Contaminants, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1080, https://doi.org/10.5194/oos2025-1080, 2025.

P304

OOS2025-1146

Lithium: an emerging environmental challenge for coastal ecosystems

Nathalie Vigier and the ERC Adv project "SeaLi2Bio" team

Lithium consumption has surged dramatically since 2010, primarily driven by the boost of high-tech devices like mobile phones and laptops, as well as the increasing adoption of Li-ion batteries for electric vehicles and energy storage systems. Among all metals, lithium exhibits the most significant growth in demand over the past 15 years. Consequently, current lithium consumption already surpasses the natural oceanic input from rivers, while recycling rates remain notably low (less than 5% globally). Recent studies have documented instances of lithium pollution in riverine systems, raising concerns about potential contamination of littoral zones, which serve as the ultimate sink for various pollutants.

At the interface between continents and the ocean, littoral environments provide critical ecosystem services and their natural biodiversity is exceptional. While microplastics, organic pollutants and other trace metals such as Cu, Hg, and Zn are widely monitored and investigated in ecotoxicological studies, lithium has received little attention yet.

To address this emerging issue, the ERC SeaLi2Bio project investigates the biogeochemical cycling of lithium in coastal environments and assess its potential risks for marine species and human health. We develop new and automated geochemical and isotopic techniques for measuring Li levels and Li isotopes in environmental, biological and marine samples, using last generation TQ-ICP-MS and MC-ICP-MS instruments. Lithium contamination and its recent evolution is determined on different continents through the study of estuarian waters and sentinel species. Ecotoxicologists experimentally determine Li bioaccumulation rates in coastal species and seafood. Biologists work on the Li transfer in cells and in tissues and identify the role of membrane transporters at play in marine species. Modelers use environmental and biological data to anticipate Li environmental risks related to future consumption and recycling scenarios.

By combining these approaches, we aim to quantify the extent of lithium pollution in coastal ecosystems, identify vulnerable species and habitats, and predict future trends. Our findings will provide crucial insights for developing effective strategies to mitigate the environmental risks associated with lithium and ensure the sustainability of coastal ecosystems facing increasing anthropogenic pressures.

How to cite: Vigier, N. and the ERC Adv project "SeaLi2Bio" team: Lithium: an emerging environmental challenge for coastal ecosystems, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1146, https://doi.org/10.5194/oos2025-1146, 2025.

P305

OOS2025-1383

Satellite based dredge plume monitoring to protect coastal ecosystems

Robrecht Moelans, Els Knaeps, and David Doxaran

Dredging operations are essential to protect coastlines, safe navigation and ensuring access to harbours. With threats of sea level rise, flooding and more extreme storms, the need for dredging operations will only increase and their sustainable implementation will be key.

One of the key aspects to control during dredging, is the release of sediments in the water and increase of turbidity during dredging, which can degrade water quality and harm sensitive ecosystems. Imposing turbidity limits where dredging contractors have to comply with, is common in most parts of the world. However, there are various sources of turbidity near the dredging area: from resuspension, to dredged bottom sediments and outflows from rivers. Hence, a turbidity increase is not necessarily linked to a (nearby) dredging activity. It is therefore key to understand the extent of the dredge plume and natural background turbidity to avoid unacceptable ecological impacts, adhere to the directives in place but also to avoid unnecessary shutdowns.

We have developed a method for a dedicated dredge plume monitoring based on Earth Observation data. This method allows to assess the turbidity of the dredge plume but also its extent and impact on the nearby ecosystem. First, a satellite database of dredge plumes was compiled, including several large dredging sites around the world. The database is complemented with an automated Artificial intelligence based plume delineation. This plume delineation automatically recognizes the plumes in the images and derived the near field dredging plume. In a second step, optical properties of the dredge plumes are evaluated. This is done by developing a dredge plume spectral library from the database and by collecting field samples during dredging activities. These field samples are analysed and interpreted to understand their optical properties (light attenuation, absorption, scattering and backscattering, turbidity and fluorescence per units of suspended particulate matter and chlorophyll-a concentrations). Finally we will present the results of our new dredge plume algorithm, adapted for the specific conditions of a dredging site.

How to cite: Moelans, R., Knaeps, E., and Doxaran, D.: Satellite based dredge plume monitoring to protect coastal ecosystems, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1383, https://doi.org/10.5194/oos2025-1383, 2025.

P306

OOS2025-1411

Impact of bottom trawling on shelf sea biogeochemistry and carbon storage: insights from a sediment-pelagic biogeochemical model

Beatriz Arellano Nava, Paul R. Halloran, Timothy M. Lenton, Evgeniy Yakushev, and Anfisa Berezina

Coastal and shelf sediments play a key role in the storage and recycling of Carbon and other nutrients, significantly contributing to the regulation of Earth's climate. These processes can be affected by anthropogenic disturbance, with bottom trawling likely to be among the most impactful. While the ecological impacts of trawling are well-documented, its effects on nutrient recycling and carbon storage remain less understood. First-order estimates have assumed that trawling promotes a significant remineralisation of organic carbon that elevates seawater CO2 and results in a large CO2 flux to atmosphere. Further observational and modelling studies indicate that sediment reworking from trawling can profoundly affect biogeochemical processes and increase CO2 emissions. Here we we explore the interaction of different factors, and consider the coupled sediment water column system to quantify the feedbacks and processes translating dissolved carbon release into seawater and the changes in surface water CO2 concentration that control the air-sea CO2 flux. Using a sediment-pelagic biogeochemical model that incorporates biogeochemical, carbonate chemistry, and basic ecosystem processes, we provide insights on how trawling can influence different biogeochemical processes and the resulting changes in carbon storage under different disturbance regimes.

How to cite: Arellano Nava, B., Halloran, P. R., Lenton, T. M., Yakushev, E., and Berezina, A.: Impact of bottom trawling on shelf sea biogeochemistry and carbon storage: insights from a sediment-pelagic biogeochemical model , One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1411, https://doi.org/10.5194/oos2025-1411, 2025.

Posters virtual | online

Display time: Tue, 3 Jun, 17:00–Thu, 5 Jun, 20:00

vP74

OOS2025-431

Intensified Human Activities Shape the Dynamics of Sediment Organic Matter in a Highly-Disturbed Estuary

Xiaoping Huang, Yunchao Wu, and Jia Yang

Human activities have greatly accelerated changes in the levels of organic matter within marine sediments. However, the long-term consequences of these changes on organic matter in estuarine environments remain unclear. This study investigates the impacts of human activities on sediment organic matter (SOM) dynamics in the Pearl River Estuary (PRE), a highly disturbed estuary comprising three zones: terrestrial (T), fresh-seawater mixing (M), and marine (S). Sediment cores (210Pb) were utilized to analyze physicochemical parameters, including total organic carbon (TOC), total nitrogen (TN), isotopic compositions (δ¹³C and δ¹⁵N), and fluorescence signatures of sediment dissolved organic matter, encompassing humic-like components (C1, C2, and C3) as well as protein-like components (C4, C5, and C6). The results show that in the T zone, TOC, TN, and δ15N increased, while δ¹³C, C1, and the humification index (HIX) decreased, indicating reduced terrestrial inputs and increased contributions from human activities, such as domestic discharge. In the M zone, TOC and TN decreased, but the slower reduction in the C/N ratio suggests a slower decline in TN compared to organic carbon. Additionally, C1, C6, and HIX decreased post-1980, reflecting a reduction in terrestrial sources and a significant rise in anthropogenic influence. In the S zone, the C/N ratio remained relatively stable before 1980, but a notable decline in terrestrial inputs was observed after 1980, especially post-2000. Overall, the contribution from terrestrial sources decreases along the salinity gradient over time, particularly in the M zone. Human-induced terrestrial alterations significantly impact the preservation of m SOM within the PRE, particularly in the T and M zones, amid intensified anthropogenic activities. Moreover, the increase in Fe (III) in the T zone substantially enhances the content of SOM, although intensified anthropogenic activities diminish its preservation capacity. This study provides crucial insights into the dynamics of SOM in a highly disturbed estuary over the past 40 years, emphasizing the potential effects of intensified human activities on the preservation of SOM in estuarine ecosystems.

How to cite: Huang, X., Wu, Y., and Yang, J.: Intensified Human Activities Shape the Dynamics of Sediment Organic Matter in a Highly-Disturbed Estuary, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-431, https://doi.org/10.5194/oos2025-431, 2025.

vP75

OOS2025-717

ECOP

Monitoring of shellfish banks sediments in the Ría of Arousa (Galicia, Spain)

Natalia Bienzobas Montávez, Julio Fernandes de Oliveira, Jose Guitián, Angela Fontán-Bouzas, and Ana Bernabeu

The main drivers of the continuous decline in shellfish productivity along the intertidal sandbanks in the Ría de Arousa (Galicia, Spain) since the last decade are unknown. While the impact of increasing temperatures and abrupt decreases in salinity has been extensively studied, there is a lack of information about the physicochemical quality of the sediments, which is essential for marine resources protection guidelines. Moreover, the shellfish community suggests that a decrease in the sediment grain size and the presence of contaminants (e.g., heavy metals) may also have contributed to the reduction in shellfish productivity.

To test this hypothesis, we monitored the environmental status of the sediments along four shellfish sandbanks in the southern margin of the Ria de Arousa which currently differ in bivalve productivity. Since 2022, we conducted a seasonal sediment sampling strategy obtaining an extensive dataset of grain size and heavy metal concentrations (i.e., Cr, Zn, Cu, Ni , and Pb). Our analysis shows that harvest sediments mainly consist of sand with a low percentage of mud which tends to increase in the two banks near river mouths. As expected, coarser grain sizes prevent the accumulation of heavy metals. Statistical analysis reveals that heavy metal concentrations vary according to natural processes, suggesting that their concentration in the sediments is not likely contributing to the decline in the abundance of shellfish individuals. Our findings provide valuable information that might help to improve the management of such traditionally productive environments.

How to cite: Bienzobas Montávez, N., Fernandes de Oliveira, J., Guitián, J., Fontán-Bouzas, A., and Bernabeu, A.: Monitoring of shellfish banks sediments in the Ría of Arousa (Galicia, Spain), One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-717, https://doi.org/10.5194/oos2025-717, 2025.

vP76

OOS2025-173

Fate of Organic Nitrogen in Estuaries: A Hotspot for the Interaction, Mixing, and Biological Activity of Terrestrial and Marine Sources

Yunchao Wu, Jinlong Li, and Xiaoping Huang

Estuaries are key areas for terrestrial material transport and marine biogeochemical processes, particularly those of dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON). However, the fate of DON in estuaries with a high runoff remains poorly understood. We explored the translocation and transformation of DON in the Pearl River Estuary (PRE) and adjacent coastal areas of southern China based on DON concentrations, optical and fluorescence characteristics, and molecualr composition. The distribution of DIN was primarily influenced by freshwater‐seawater mixing. In contrast, biological processes and freshwater‐seawater mixing shaped the distribution of DON. High levels of DON in the terrestrial‐dominated zone were predominantly anthropogenic sources through terrestrial inputs, whereas DON in the freshwater‐seawater mixing zone and seawater‐based zone were mainly influenced by biological activities. DON exhibits fast dilution in low‐salinity areas and retention in moderate‐salinity areas (freshwater‐seawater mixing area) in summer and winter, while undergoes a rapid decrease in open water areas during winter. Consequently, DON in the PRE and adjacent coastal areas exhibited nonconservative mixing despite seasonal variations. At the molecular level, tDON exhibited reduced unsaturation and aromaticity, coupled with an elevated abundance of DON compounds containing one‑nitrogen atom (1 N-DON, 53.17 %) and compounds containing carbon, hydrogen, oxygen, nitrogen, and sulfur (CHONS) (27.46 %). It was evident that lignin was depleted while more oxygenated tannin compounds were generated in the freshwater-seawater mixing zone. This transformation is attributed to heightened biological activities, likely influenced by the priming effect of terrestrial nutrient inputs. In summer, the prevailing plume combined with biological activities in the strong mixing area and outer estuary increased the abundance of 3 N-DON molecules and a concurrent rise in the abundance of DON compounds containing only carbon, hydrogen, oxygen, and nitrogen (CHON), DON compounds containing carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus (CHONSP), and CHONS. This trend also underscores the expanding role of marine plankton and microbes in the utilization of DON compounds containing carbon, hydrogen, oxygen, nitrogen, and phosphorus (CHONP). These findings provide novel insights into the role of DON in nitrogen biogeochemical processes in river‐dominated estuaries and adjacent coastal areas and revealed the details of tDON transformation processes at the molecular level in a river-dominated estuary and underline the estuarine hydrodynamics involved in transporting and altering DON within the estuary.

How to cite: Wu, Y., Li, J., and Huang, X.: Fate of Organic Nitrogen in Estuaries: A Hotspot for the Interaction, Mixing, and Biological Activity of Terrestrial and Marine Sources, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-173, https://doi.org/10.5194/oos2025-173, 2025.

vP77

OOS2025-443

The metabolic network response and tolerance mechanism of Thalassia hemprichii under high sulfide based on widely targeted metabolome and transcriptome

Wenqian Qi, Zhijian Jiang, Xu Long, Songlin Liu, Yunchao Wu, and Xiaoping Huang

The costal eutrophication induced by human activities leads to increased sulfide level in sediments, which has been identified to cause great decline of global seagrass beds. The seagrass Thalassa hemprichii, one of the tropical dominant seagrasses in the Indo-Pacific, is facing a potential threat from sulfide, which could be easily reduced from sulfate in porewater induced by global climate change and eutrophication. However, its response and tolerance mechanism of metabolism to high sulfide is unclear. Thus, the current study investigated the physiological response and programmed metabolic network of T. hemprichii by mesocosm experiment for 3 weeks using combined physiology, stable isotopes, widely targeted metabolomics, transcriptomics, and microbial diversity. High sulfide reduced the sediment microbial diversity, while enhanced sediment sulfate reduced bacterial and δ³⁴S. The exposure to sulfide enhanced root δ³⁴S, while decreased leaf δ³⁴S of T. hemprichii. High sulfide was shown to inhibit photosynthesis via damaging PSII, which further reduced ATP production. In turn, a large number of up-regulated differently expressed genes in energy metabolism, especially in oxidative phosphorylation, were responded to compensate high energy requirement. High sulfide also promoted autophagy by overexpressing the genes related to phagocytosis and phagolysosome. Meanwhile, metabolomic profiling revealed that the contents of many basal metabolites such as carbohydrates and amino acids were reduced in both leaves and roots, as to provide more energy and synthesize stress-responded secondary metabolites. The genes related with nitrate reduction and transportation were up-regulated to promote N uptake for sulfide detoxification. High sulfide specially enhanced thiamine in roots, while enhanced jasmonic acid and flavonoids in leaves. The distinct difference of metabolites accumulation between roots and leaves might be related with the sulfide level and growth-defense trade-off. Collectively, our work highlights the specific mechanism for response and tolerance of T. hemprichii to high sulfide, providing new insights related to the seagrass strategies employed to resist sulfide, and seagrass restoration by the addition of exogenous substance.

How to cite: Qi, W., Jiang, Z., Long, X., Liu, S., Wu, Y., and Huang, X.: The metabolic network response and tolerance mechanism of Thalassia hemprichii under high sulfide based on widely targeted metabolome and transcriptome, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-443, https://doi.org/10.5194/oos2025-443, 2025.