French Research Institute for Exploitation of the Sea
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Spatial variation of future trends in Atlantic upwelling cells from two CMIP6 models
No full textEastern Boundary Upwelling Systems (EBUS) are characterized by wind-triggered upwelling of deep waters along the coast. They are hotspots of biological productivity and diversity and therefore have a high economic, ecological and social importance. In the past, different methods using surface data have been used to estimate upwelling. Recently, the IPCC has suggested directly assessing vertical velocities as a promising method. We use this method to study the two Atlantic EBUS from CMIP6 models from the HadGEM3-GC3.1 and the CNRM6-CM6 family, for both the historical period and a high-emission future scenario with spatial resolutions in the ocean component ranging from 1 degrees to 1/12 degrees. The two major upwelling regions are divided in subregions depending on their seasonality. The vertical transport index shows similar values to a wind-derived Ekman index. Directly evaluating upwelling from transport processes further provides information about the depth of the upwelling, which has previously been identified as an important factor for nutrient availability. We show that depending on the subregion of the upwelling system, different cell structures can be seen in terms of depth and distance to the coast of maximum velocities. When looking at possible future changes, high interannual variability limits the significance of the trends but could indicate a poleward shift of the upwelling regions. A detailed comparison of the spatial structures and the distinction in subregions is important to explain contradictory trends in previous works
Combining transient dynamics and logistic‐asymptotic growth to study the recovery of two seabird populations after rat eradication
No full textUnderstanding demographic processes is crucial in ecology and conservation biology to assess how populations respond to environmental pressures. Although demographic parameters often react to disturbances, populations may remain in unstable age structures (transient dynamics) following such events. To explore the influence of transient dynamics in masked booby and red‐footed booby populations on Tromelin Island 15 years after rat eradication, we compared observed, transient, and asymptotic growth using count and capture–recapture (CR) data. CR data were used to estimate survival probability from Cormack–Jolly–Seber models and other vital rates such as breeding frequency and age at first breeding. We coupled asymptotic growth with a density‐dependent model for breeding site availability to project long‐term population growth. Both populations exhibited high adult survival (0.91–0.96) and breeding success (0.46–0.54). The masked booby juvenile survival was also high (0.86). Populations are expected to grow until breeding sites are saturated, in about a century. Comparison of asymptotic and transient growth suggests that population growth is linked to an intrinsic process and that both populations have undergone disruption in their age structure likely due to past predation by rats. Although the observed population growth appears to align more closely with transient growth, we could not entirely exclude the possibility that differences between asymptotic and observed growth rates may be due to data scarcity or age‐related variation in demographic parameters. Nevertheless, the study of transient dynamics allowed a better understanding of the differences observed between field counts and estimated asymptotic growth rates based on matrix population models
Nest Exposure to Marine Flooding and Impacts on Green Turtle (Chelonia Mydas) Embryos Under Rapid Sea Level Rise: The Role of Beach Geomorphology and Hydrodynamics
No full textClimate change-induced sea-level rise increases the risk of sea turtles' nests being flooded which could threaten their populations. However, impacts on embryonic development remain limited, and the mechanisms driving nest flooding are still poorly understood. Our multidisciplinary study aimed to determine the geomorphological and hydrodynamic factors exposing nests to flooding, and to better understand the effects of flooding on embryonic development under natural conditions. The research was conducted on Mayotte Island (France, Indian Ocean), where a seismic crisis between 2018 and 2020 caused subsidence, resulting in a relative rise in sea level. Thirty green turtle nests on a primary nesting reef beach were monitored from March to June 2022 using pressure sensors to measure flooding. The hydrodynamics were measured, and the beach morphology was mapped. Approximately 30% of the nests were flooded, mainly due to their relatively low position on the beach, with the flooding likely to have been influenced by water level fluctuations related to the tidal cycle. The early and late incubation phases were particularly sensitive to flooding. Emergence success was 1% for flooded nests, significantly lower than 85% for non-flooded nests. This study provides new insights and reveals that under natural conditions, nests are more sensitive to flooding than previously reported in controlled laboratory studies. However, flooding does not always directly impact embryonic mortality; other related factors may be involved, requiring further research
Quality Information Document. Ocean Monitoring Indicator VAR EXTREME SL (Sea level)
No full textThe VAR EXTREME SL indicators are based on the computation of the 99th and the 1st percentiles (that represent approximately the 1% highest and lowest values, respectively) of hourly sea levels derived from in situ sea level observations, following the same approach applied by Woodworth and Blackman (2004) to extreme sea levels. This method determines changes in the frequency distribution of the measured variables
Développement d'un indicateur d'abrasion des fonds marins par les arts de pêche trainants pour l'évaluation du bon état écologique des habitats benthiques
No full textCe document vise à expliciter la production des données d’abrasion superficielle des fonds marins par les arts trainants de 2012 à 2020 dans les eaux de France métropolitaines. Ce travail s’inscrit dans le contexte de la Directive Cadre « Stratégie pour le Milieu Marin » (DCSMM), coordonnée à l’échelle nationale par l’Office Français de la Biodiversité (OFB) et l’Institut Français pour la Recherche et l’Exploitation de la MER (Ifremer) et, au sein du descripteur 6 « Intégrité des fonds marins » de la directive, sous la responsabilité thématique du Bureau de Recherches Géologiques et Minières (BRGM). Les données d’abrasion sont exprimées par le SAR (Swept Area Ratio ou ratio d’aire abrasée). Le SAR est l’unité d’abrasion utilisée par le Conseil International pour l’Exploration de la Mer (CIEM ou ICES en anglais) pour évaluer la pression de pêche par les arts trainants sur les fonds marins (ICES, 2020). Pour cet indicateur, la surface abrasée est calculée en multipliant le linéaire d’une action de pêche par la largeur de l’engin de pêche. Le linéaire des actions de pêche est estimé à partir des informations fournies par les données du Vessel Monitoring System (VMS). La largeur des engins de pêches est estimée en fonction des caractéristiques des navires et des métiers (Eigaard et al., 2016). Ce document détaille la source et le format des données utilisées en entrée, le fonctionnement des modèles appliqués et développés pour l’estimation de l’abrasion ainsi que la méthode de calcul de l’incertitude. Deux types de produits sont fournis : - Des cartes annuelles au format GeoTiFF de 2012 à 2020 incluant l’abrasion médiane, les 1er et 3ème quartiles, et l’incertitude associée. - Des cartes mensuelles au format NetCDF, de Janvier 2012 à Décembre 2020 incluant l’abrasion médiane, les 1er et 3ème quartiles, et l’incertitude associée.
Version 1, 2021.
Version 2, 04/2024 : Ajout des modèles « OTB_FULL_MED2 » et « OTT_FULL_MED » (Tableau 2) et du graphe correspondant en fin d’ANNEXE 1. Ces nouveaux modèles permettent désormais de distinguer explicitement les chaluts simples des chaluts jumeaux en Méditerranée et remplacent le modèle initial OTB_FULL_MED. Le développement de ces modèles est détaillé dans Certain et al. (2024). Mise à jour du Tableau A2-2 (Table de correspondance entre les arts traînants observés et les modèles utilisés) permettant de spécifier les cas d’utilisations de ces deux nouveaux modèles.
Version 3, 06/2025 : correction d’un paramètre du modèle SDN_DMF (Tableau 2). Le prédicteur devient KW (puissance du navire), au lieu de LHT (Longueur hors tout) initialement, ce qui était erroné
Ecological Indicators for Seagrass Meadow Status: Adopting Efficiency of Space Occupancy as a Reference
No full textCurrently used indicators such as shoot density and biomass are being questioned for their efficacy in reflecting seagrass ecological status. In the current study, meadows along the English Channel, Atlantic coast and Mediterranean coast of France were investigated. Multiple seagrass growth traits were tested for their efficacy in reflecting meadow carrying capacity. The distance of each meadow to the interspecific boundary line (dgrass), defined by the seagrass biomass-density relationship, was measured, and all meadows were classified using ordinal scaling into different levels of ecological status. Both inter- and intra-site differences, as well as temporal variations, were analysed. Correlation analyses were performed to determine patterns among dgrass and other biological variables. Sites varied in their carrying capacities based on seagrass species. Among Zostera marina (ZM) meadows, the Dinard site had the highest efficiency of space occupancy, and the Thau site had the least. Among the Nanozostera noltei (NZN) meadows, the Thau site had the highest efficiency of space occupancy, and the Arcachon site had the least. Among the two species, the NZN meadows had better efficiencies of space occupancy compared to the ZM meadows. Overall, both species had lower efficiencies compared to the most efficient plants studied worldwide. The dgrass was moderately inversely correlated with aboveground and belowground biomass and density and strongly inversely correlated with relative cover and leaf area index (LAI). The distribution of sites based on the biotic community followed a similar pattern to the distribution of sediment grain size. Higher relative algal cover was observed in sites with lower proportions of fine sand particles. Epifauna biomass or richness was more often associated with algal biomass and cover and sometimes with seagrass traits such as aboveground biomass or LAI, depending on the seagrass species. Endofauna was associated to seagrass growth traits or bare sediments, depending on the seagrass species. The current study differentiates between suitable and unsuitable plant morphometric traits for use as indicators. While traits such as shoot density are used extensively, the current study shows that relative cover and LAI may be much more reflective of ecological status. Temperature was the most influential factor on LAI, and sediment structure modified competition between seagrasses with algae. The current study highlights the importance of identifying site- and habitat-specific indicators. Future work from our study will further evaluate the environmental pressures faced by these four sites to characterize them based on conservation status
Micronutrient levels of global tropical reef fish communities differ from fisheries capture
No full textThe exceptional diversity of shallow-water marine fishes contributes to the nutrition of millions of people worldwide through coastal wild-capture fisheries, with different species having diverse nutritional profiles. Fishes in ecosystems are reservoirs of micronutrients with benefits to human health. Yet, the amount of micronutrients contained in fish species on coral reefs and in shallow tropical waters is challenging to estimate, and the micronutrients caught by fisheries remain uncertain.
To assess whether micronutrient deficiencies could be addressed through specific fisheries management actions, we first require a quantification of the potentially available micronutrients contained in biodiverse reef fish assemblages. Here, we therefore undertake a broad heuristic assessment of available micronutrients on tropical reefs using ensemble species distribution modelling and identify potential mismatches with micronutrients derived from summarising coastal fisheries landings data.
We find a mismatch between modelled estimates of micronutrients available in the ecosystem on the one hand and the micronutrients in small-scale fisheries landings data. Fisheries had lower micronutrients than expected from fishes in the modelled assemblage. Further, fisheries were selective for vitamin A, thus resulting in a trade-off with other micronutrients. Our results remained unchanged after accounting for the under-sampling of fish communities and under-reporting of small-scale fisheries catches—two major sources of uncertainty.
This reported mismatch indicates that current estimates of fished micronutrients are not adequate to fully assess micronutrient inventories. However, small-scale fisheries in some countries were already selective towards micronutrient mass, indicating policies that target improved access, distribution and consumption of fish could leverage this existing high micronutrient mass.
Enhanced taxonomic resolution of catches and biodiversity inventories using localised species consumption surveys could improve understanding of nature-people linkages. Improving fisheries reporting and monitoring of reef fish assemblages will advance the understanding of micronutrient mismatches, which overall indicate a weak uptake of nutritional goals in fisheries practices.
The decoupling between micronutrients in ecosystems and in fisheries catches indicates that social, economic, and biodiversity management goals are not shaped around nutritional targets—but this is key to achieve a sustainable and healthy planet for both people and nature.
Read the free Plain Language Summary for this article on the Journal blog
Benthic Indicators for Monitoring Bottom‐Trawl Fishing Impacts
No full textThere is increasing interest in developing indicators to assess the state of benthic communities in shelf seas primarily affected by bottom trawling. Yet, many indicators have been developed in specific geographic regions making it difficult to determine their broader applicability. In the study, we systematically evaluated the complementarity, sensitivity, and specificity of 18 indicators in response to the pressure of bottom trawling using a shared dataset with broad regional representation. We found distinct clusters of indicators with similar response patterns. In addition, we identified the type of indicator that is most sensitive to bottom-trawling pressur
Passive sampling in support of biota monitoring of hydrophobic substances under the Water Framework Directive
No full textThis paper presents an approach to apply aquatic passive sampling (PS) in regulatory chemical water quality monitoring in Europe. Absorption-based passive sampling is well developed and suitable for the sampling of hydrophobic chemicals, some of which are European Water Framework Directive priority substances with Environmental Quality Standards (EQS) derived for biota. Considering a chemical activity approach to chemical risk assessment, we propose equilibrium concentration in lipids (from passive water sampling) as a reference value for measured concentrations in biota. Through existing PS-fish datasets, we show a growing body of evidence supporting the use of lipid-based contaminant concentrations at equilibrium with water derived from PS as a conservative proxy of levels of these chemicals in fish. We propose a procedure that includes PS as a first, animal-free screening step of a tiered approach, followed by more conventional fish analyses when PS indicates these are needed to confirm EQSbiota exceedance. This paper reviews fish-passive sampler datasets, provides a reasoning for the proposed procedure and discusses how to broadly put it into monitoring practice. PS offers the possibility of well-defined standardised monitoring approaches that can help overcome the natural variability challenges associated with measurements in biota across member states and simplify EQSbiota compliance
A 12,000-year dinoflagellate cyst record on the Vancouver Island Margin, Canada: tracing past climatic, primary productivity and oceanographic conditions
No full textThis study investigated dinoflagellate cyst records spanning the latest Pleistocene to the late Holocene on the Vancouver Island margin, identifying 14 autotrophic and 26 heterotrophic taxa. Four dinoflagellate cyst zones were defined and related to paleoclimatic and paleoceanographic conditions. Zone I (~14–~11.6 cal kyr BP) showed the lowest primary productivity (PP), indicated by the lowest total cyst concentrations, with Brigantedinium spp. dominant in assemblages. This was likely due to cooler conditions associated with glacial meltwater input and/or weak coastal upwelling. Zone II (~11.6–~10.6 cal kyr BP) showed a slight increase in total cyst concentrations, a rapid increase in Operculodinium centrocarpum sensu Wall and Dale 1966 and the highest Nematosphaeropsis labyrinthus abundances. This zone was linked to reduced meltwater input and increased coastal upwelling, promoting primary productivity. Zone III (~11.6–~8.2 cal kyr BP) showed a rapid increase in PP, with total cyst concentrations peaking and autotrophic taxa reaching their highest abundances. This was associated with strengthened California Undercurrent and increased upwelling, coinciding with the highest insolation intensity. The high Impagidinium abundances indicated more open ocean conditions. A sharp increase in Operculodinium centrocarpum-truncate processes during ~9–8.2 cal kyr BP may be related to the 8.2 ka event and decelerated sea-level rise. Zone IV (~8.2–~2.3 cal kyr BP) indicated gentle fluctuations in PP, with an overall total cyst concentrations decline, reaching the lowest around 8.0 cal kyr BP, followed by a slight increase at ~6.5 cal kyr BP, and subsequent stabilization