French coastal network for carbonate system monitoring: the CocoriCO2 dataset

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Abstract

Since the beginning of the industrial revolution, atmospheric carbon dioxide (CO2) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30 %. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency.

To bridge this gap, an observation network was initiated in 2021 in the framework of the CocoriCO2 project. Six sites were selected along the French Atlantic and Mediterranean coastlines based on their importance in terms of shellfish production and the presence of high- and low-frequency monitoring activities. At each site, autonomous pH sensors were deployed, both inside and outside shellfish production areas, next to high-frequency CTD (conductivity–temperature–depth) probes operated through two operating monitoring networks. pH sensors were set to an acquisition rate of 15 min, and discrete seawater samples were collected biweekly in order to control the quality of pH data (laboratory spectrophotometric measurements) as well as to measure total alkalinity and dissolved inorganic carbon concentrations for full characterization of the carbonate system. While this network has been up and running for more than 2 years, the acquired dataset has already revealed important differences in terms of pH variations between monitored sites related to the influence of diverse processes (freshwater inputs, tides, temperature, biological processes). Data are available at https://doi.org/10.17882/96982 (Petton et al., 2023a).

 

Figure 1

Location of the high-frequency monitoring sites (blue dots) from the CocoriCO2 network. The pink and green dots indicate SOMLIT and REPHY low-frequency stations, respectively, from which nutrient data were acquired.

 

Conclusion and present status of the network

The network initiated in 2021 along the French coast area has provided essential data for the assessment of carbonate chemistry dynamics at various temporal scales and in contrasted coastal sites (shellfish farms located close to the shore vs. sites with no shellfish farming more subjected to oceanic conditions). The large number of sites and geographical coverage of the network has already allowed us to evaluate the influence of diverse physical, chemical, and biological processes (freshwater inputs, tides, temperature, biological processes), which we briefly presented in the present paper. The acquired dataset will undoubtedly be of great interest to the public and scientific communities in the future as our choice to base our network on existing monitoring activities not only allowed for providing reliable data at a very high acquisition rate and at a lower financial cost, but also allows for the possibility to rely on existing low-frequency datasets (chlorophyll, nutrients, organic matter concentrations, etc.) for assessing the interplay between biology and the chemical environment. However, autonomous time-series acquisition close to shellfish farming involves a number of challenges mostly related to intense biofouling pressure. It explained most invalidated data even when employing fortnightly manual cleaning protocols, which will require in the future the development of active and efficient antifouling solutions that are currently in development (localized chlorination, adapted wiper) in the framework of our project. Furthermore, the SeaFET technology is relatively novel when compared to more conventional temperature or conductivity sensors. We encountered disparities within the whole set of probes acquired with specific electrodes malfunctioning within just a few months of deployment, despite the manufacturer Sea-Bird indicating a minimum of 1-year service life. Adding complexity, a further issue emerged from June 2022 onwards: the SeaFET maintenance service has been suspended due to a lack of the DuraFET component. While the service will apparently resume by late 2023, this disruption has already resulted in temporal gaps within the time-series data. Additionally, evaluation of new sensors is underway with the objective of obtaining the reliability and accuracy of the already collected data.

 

Reference

Petton, S., Pernet, F., Le Roy, V., Huber, M., Martin, S., Macé, É., Bozec, Y., Loisel, S., Rimmelin-Maury, P., Grossteffan, É., Repecaud, M., Quemener, L., Retho, M., Manac’h, S., Papin, M., Pineau, P., Lacoue-Labarthe, T., Deborde, J., Costes, L., Polsenaere, P., Rigouin, L., Benhamou, J., Gouriou, L., Lequeux, J., Labourdette, N., Savoye, N., Messiaen, G., Foucault, E., Ouisse, V., Richard, M., Lagarde, F., Voron, F., Kempf, V., Mas, S., Giannecchini, L., Vidussi, F., Mostajir, B., Leredde, Y., Alliouane, S., Gattuso, J.-P., and Gazeau, F.: French coastal network for carbonate system monitoring: the CocoriCO2 dataset, Earth Syst. Sci. Data, 16, 1667–1688

https://doi.org/10.5194/essd-16-1667-2024, 2024.

Expé-1point5 publication in “One Earth”

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Here is a link to a publication by Olivier Ragueneau and Audrey Sabbagh, published on May 17 in the journal “One Earth.” It describes the philosophy and objectives of the experiment that has been co-led since 2020 by LEMAR (IUEM) and UMR MERIT (Université Paris Cité) as part of the Labos 1point5 collective. The Expé-1point5 aims to stimulate changes in laboratory research practices to reduce their greenhouse gas (GHG) emissions. As its title suggests, “From carbon to meaning,” it goes beyond the climate perspective to question the very meaning of our research activities under climate constraints: is it possible to maintain high-quality research, and even increase it, notably through the idea of ​​slow science, while reducing GHG emissions and improving the quality of life at work? The idea of ​​this article is to propose making research a transformation demonstrator to achieve environmentally and socially sustainable research.

Enjoy the reading!

Read the article:
“From carbon to meaning: Experimenting for sustainable science”

Claire Hellio, Knight of the French National Order of Merit

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Congratulations to our colleague Claire Hellio who has just been appointed “Knight of the National Order of Merit“! This national distinction has a threefold purpose: to reflect the dynamism of society, set an example, and recognize the diversity (cultural, social, and economic) of French society. Claire had already received in September 2023 the CNRS Innovation Medal.

These two distinctions reward her work in biotechnology, which aims to develop environmentally friendly solutions from marine-derived compounds for cosmetic products or antifouling, among others.

You can find the other personalities from Finistère appointed to the National Order of Merit in this article from Ouest-France.

 

Fish acoustics for monitoring the effects of overfishing and climate change on food security in West Africa

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An acoustic study, whose first author is a Senegalese former thesis student of Lemar, has revealed a notable northward shift in the spatial distribution of small pelagic fish species exploited in the waters of the Sub-Regional Fisheries Commission (northwest Africa). The results, covering a period of two decades of acoustic halieutic surveys conducted by sub-regional acoustics experts aboard the F. Nansen vessel (IMR, Norway), highlight the impact of rising sea surface temperature and changes in upwelling intensity on marine ecosystems in the sub-region. Mauritania and Senegal are observing a strong increase in sea surface temperature and a decrease in its primary productivity, while the region further north is experiencing a continuous increase in upwelling. Significant spatial anomalies in sea surface temperature have contributed to the northward shift of several small pelagic fish species, including Sardinella aurita (round sardinella), species highly prized in Senegal.

The study emphasizes that the Senegalo-Mauritanian zone has experienced the most pronounced warming of surface waters among all intertropical regions in the world in recent decades. The study identified significant anomalies in sea surface temperature around Cape Blanc and to the south, ranging from 0.1 to 0.3 °C per decade, influencing fish distribution. During the study period, Sardinella aurita displayed a northward shift of approximately 180 km, coinciding with an increase in sea surface temperatures and reduced primary productivity in the south. The northward shift of small pelagic fish poses potential economic and social challenges, particularly for countries such as Senegal, where fisheries are a source of numerous jobs and contribute to food security, and Mauritania, where fisheries contribute significantly to gross domestic product.

Fishmeal factories and fishing fleets are already contributing to severe overexploitation of small pelagics, particularly Sardinella aurita. The effects of climate change (cumulative with those of overexploitation) exacerbate the pressure on these valuable fishery resources. Changes in fish distribution can disrupt the entire marine food chain, affecting biomass production and species composition.

The study underscores the need for regular monitoring and increased research efforts to better understand the dynamics of this marine ecosystem and ensure the sustainability of fishery resources, vital for the countries concerned. This is particularly important for protecting food security and the economic well-being of coastal communities in West Africa.

The results call for strengthening national fisheries research structures, expertise in acoustic halieutics, and the need for sub-regional collaboration on transboundary fish stocks to prevent potential fishing-related conflicts and manage resources sustainably. Moreover, it is urgent to address overfishing and the impacts of fishmeal production, which adds an additional threat to the effects of climate change on exploited small pelagics.

The CRODT[1], IMROP[2], INRH[3], FD[4] and IRD, are committed to advancing marine research. They emphasize the importance of adaptive management strategies, concerted at the sub-regional level (countries of the Sub-Regional Fisheries Commission (CSRP)), to address current and future challenges posed by climate change and overfishing.

Scientific Contact

Patrice.Brehmer@ird.fr *

*Corresponding author of the scientific publication

Article Link (Springer nature, Scientific report)

Abdoulaye Sarre, Hervé Demarcq, Noel Keenlyside, Jens-Otto Krakstad, Salaheddine El Ayoubi, Ahmed Mohamed Jeyid, Saliou Faye, Adama Mbaye, Momodou Sidibeh, & Patrice Brehmer*. Climate change impacts on small pelagic fish distribution in Northwest Africa: trends, shifts, and risk for food security Scientific Report, 12434 (2024). https://doi.org/10.1038/s41598-024-61734-8

Photographs, including aerial and underwater:

https://multimedia.ird.fr/IRD/search.do?q=Brehmer+Patrice&lang=fr

 

[1] Centre de recherche océanographique de Dakar Thiaroye, Senegal

[2] Institut Mauritanien de Recherches Océanographiques et de Pêches

[3] Institut National de Recherche Halieutique, Morocco

[4] Fisheries Department, The Gambia

SILICON, from stardust to the living world

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For several decades, the « Silicon Group » of the Institut Universitaire Européen de la Mer (IUEM) has been studying the silicon cycle on an international scale. In 2020, it created the “Silica School”, whose major themes are summarized in this documentary film. Billions of years ago, silicon was created in the universe by stellar nucleosynthesis. It’s not beyond the realms of possibility that this element serves as the basis for other forms of life in the universe. On planet Earth, it is the second most abundant element, after oxygen. It is a component of numerous minerals whose interaction with the aqueous environment generates a chemical form that can be assimilated by living organisms. Although the oceanic silicon cycle is currently in equilibrium, disruptions are to be expected in the context of ongoing global change.

This documentary film has been imagined by Paul Treguer, produced by Sébastien Hervé and benefits from a collaboration with Océanopolis, the center for scientific, technical and industrial culture in Brest (France).