The spread of invasive alien species is identified as one of the most important threats to freshwater ecosystems as they can modify their trophic structure, biomass and flows. The lower Saone River is one of the most biologically productive waterways in France. It has been in strong interaction with a wide range of human activities such as fisheries for at least three millennia. To implement an ecosystem based approach, an Ecopath static trophic model was used for the first time in this river to quantify the role of three invasive or expanding species over two contrasted periods (1988-1993 and 1994-2005). The parameters used in the model integrate on the one hand catch data from fishers (professional, amateur fishing gear users, and anglers), and on the other hand the available literature data on species biomass, diet and the expert assessments of scientists and managers. Species such as the filtering Asian clam Corbicula fluminea may explain the triggering of the ecosystem shift towards a functioning where summer phytoplankton blooms are rarer. In the high trophic levels, the great cormorant Phalacrocorax carbo appears to have low trophic impact while the development of a large population of European catfish Silurus glanis has a strong effect, maintaining important trophic flows in the ecosystem in substitution for the decrease in angling landings.

Art is a promising pathway to raise emotional engagement with nature, while enabling an indirect exposure to nature through aesthetic experience. However, the precise relationships between aesthetic experiences of art and experiences of nature remain unclear. The aim of this observational study is to highlight the effect of nature experiences on the aesthetic reception art, based on Early Modern paintings (16th-18th century). By focusing on marine ecosystems, that are difficult to directly interact with, the results presented are intended to explore whether marine activities and fish consumption affect the aesthetic reception of artworks depicting marine biodiversity. A photo-questionnaire survey based on four paintings has been conducted with 332 French participants with a diverse range of marine practices, fish consumption and artistic sensitivity. Fish consumption and value attributed to fish as food had a significant positive impact on the aesthetic reception, suggesting that taste and food consumption could be considered as a relevant nature aesthetic experience that elicits affective and emotional responses. Results also showed an indirect effect of fishing and diving on the aesthetic reception of paintings whose iconography relates with the observers’ experiences. These findings are of particular interest in both environmental psychology and ecological mediation through art. This study brings evidences of the connection between art and nature experiences, and that art could be an innovative way of experiencing nature. Finally, this study also highlights the need to broaden the scope of nature experiences, for instance by including food.

The specific identification of three major morphotypes of the tropical holopelagic Sargassum species causing massive strandings on the African and Caribbean coastlines was attempted by morphological characterisation as well as quantitative and qualitative analyses of several metabolites. Of the 25 morphological variables studied on 208 samples from the North Atlantic Ocean, 22 were used to establish a dichotomous identification key, allowing without any doubt the identification of each morphotype based on their morphological criteria alone. We also attempted to differentiate morphotypes using chemical fingerprintings (HR-MAS NMR) and markers by analysing pigment level and composition using High Pressure Liquid Chromatography, terpene profiles by Thin Layer Chromatography, phenolic compound levels by the Folin-Ciocalteu assay and structures by 2D Nuclear Magnetic Resonance spectroscopy, and fatty acid composition by Gas Chromatography. While pigment level and composition, terpene profiles, and phenolic contents were not discriminating, quantification of eight fatty acids enabled the differentiation of the three morphotypes. Furthermore, phlorotannin purification permitted their structural characterisation allowing discrimination between the three morphotypes. Our study highlights the potential of the free fatty acid profile and phlorotannin structure as good chemomarkers in order to discriminate between the three morphotypes of holopelagic Sargassum.

Since 2011, the Caribbean coasts have been subject to episodic influxes of floating Sargassum seaweed of unprecedented magnitude originating from a new area "the Great Atlantic Sargassum Belt" (GASB), leading in episodic influxes and mass strandings of floating Sargassum. For the biofilm of both holopelagic and benthic Sargassum as well as in the surrounding waters, we characterized the main functional groups involved in the microbial nitrogen cycle. The abundance of genes representing nitrogen fixation (nifH), nitrification (amoA), and denitrification (nosZ) showed the predominance of diazotrophs, particularly within the GASB and the Sargasso Sea. In both location, the biofilm associated with holopelagic Sargassum harboured a more abundant proportion of diazotrophs than the surrounding water. The mean δ15N value of the GASB seaweed was very negative (-2.04‰), and lower than previously reported, reinforcing the hypothesis that the source of nitrogen comes from the nitrogen-fixing activity of diazotrophs within this new area of proliferation. Analysis of the diversity of diazotrophic communities revealed for the first time the predominance of heterotrophic diazotrophic bacteria belonging to the phylum Proteobacteria in holopelagic Sargassum biofilms. The nifH sequences belonging to Vibrio genus (Gammaproteobacteria) and Filomicrobium sp. (Alphaproteobacteria) were the most abundant and reached, respectively, up to 46.0% and 33.2% of the community. We highlighted the atmospheric origin of the nitrogen used during the growth of holopelagic Sargassum within the GASB and a contribution of heterotrophic nitrogen-fixing bacteria to a part of the Sargassum proliferation.

A significant challenge in the integration of ecosystem services into decision-making processes lies in effectively capturing the dynamics of marine socio-ecological systems, including their evolutionary pathways, equilibrium states, and tipping points. This paper explores the evolutionary trajectories of a vital marine ecosystem endemic to the Mediterranean Sea: the Posidonia oceanica seagrass meadows, in response to various drivers of change. A state-and-transition model is employed to assess the ecosystem services provided by P. oceanica across different states defined by selected transitions, such as overfishing, fragmentation, pollution, and invasion by non-native species. To apply this model, scientific expertise is combined with field data generated using the Ecosystem-Based Quality Index to evaluate the conservation status of P. oceanica. This integrated approach allows for the representation of the ecosystem services offered by the meadows across different states, leveraging ecological data. The findings highlight the disproportionate impact on provisioning services, particularly sea urchins and commercial fish production, which suffer the most under various stressors. Notably, when these services decline to critical levels, the meadows cease to provide significant benefits. Finally, a synthesized representation is presented, merging ecological insights with monitoring data, offering a framework that is more accessible to stakeholders and decision-makers.

The large-scale production and economy of French freshwater fisheries is not documented in the scientific literature. This article fills this knowledge gap by synthesizing the data collected since the post-war period, including a large part of the grey literature. France presents a wide variety of surface waters, benefiting from a reduction in pollution and a growing population with an emphasis on leisure activities and on locally sourced food products. Despite this favorable geographical, ecological and human situation, French freshwater fisheries have been in decline since the mid-1970s with a chronically negative trade balance for aquatic products. During this period, numbers of commercial fishers have decreased three-fold due to their affiliation to an agricultural status, and to their dependence on migratory species such as eel, shad and lamprey, which are all in decline. Simultaneously, numbers of anglers have also seen a slow but continuous decline, cushioned somewhat in the last 10 years thanks to the creation of sub-annual fishing cards and the expansion of the total to include the younger classes. Vestiges of a non-commercial fishery, similar to recreational subsistence fishing and employing gear such as dip nets, traps, long lines or even gillnets, have been maintained in a much reduced state around large rivers as well as in the marshes and estuaries of the Atlantic coast. In this detailed study of these different categories of fishing practices in the mid-2010s, we estimate numbers of fishers at 2 million active anglers, 4000 subsistence fishers, and 400 commercial fishers. Their catches are roughly 7600, 200 and 1200 tonnes/year, respectively, for a total of 9000 tonnes/year. The major part of the overall economic worth, estimated at 980,000 K€, is attributable to recreational fishers (anglers).

The aim of this article is to study the early effects of a recent marine reserve on the fish population, the Palavas Coastal Marine Reserve (PCMR), created in 2016 on fishermen initiative. This recent reserve, covering 100 ha and located 2.6 km from the coast at N 43°30.6845, E 3°58.4635, constitutes almost entirely a protected zone, with a ban on any fishing activity. The abundance of the fish populations and the size and biomass of the target species have been studied for the period of the first 4 years of protection. An inventory of fish populations was carried out using the scuba diving transect method in the rocky substrate of three zones: a large enhanced protection zone (EPZ) where only navigation was allowed,, a small restricted zone (RZ), where scuba diving was admitted, and an off-reserve zone (ORZ). Monitoring of this recent reserve shows significant increases in overall abundance and changes in population assemblages within the third year of protection. The biomass of target species tripled in the EPZ showing a refuge effect despite the fact that the fishing ban was not always respected during this implementation period. However, the behaviour patterns of the fish, which are more or less fearful of divers depending on the study area, do not offer an adequate basis for determining differences in populations between the EPZ and the RZ.

IntroductionCoastal detrital bottoms (CDB) are one of the most extensive habitats of the continental shelf worldwide, in the upper levels of the circalittoral zone. Hosting a diverse community structured by sediment grain size, trophic interactions and calcified organisms, CDB exhibit important ecological functions. In the Mediterranean Sea, CDB are constituted by recent elements partly provided by adjacent infralittoral and circalittoral ecosystems. Since the 2010s, the offshore extension of many Marine Protected Areas (MPAs) has resulted in the incorporation of vast areas of CDB, raising the issue of their management. The Marine Strategy Framework Directive (MSFD) has embraced the concept of an ecosystem-based approach involving taking into account the functioning of marine habitats and their related ecosystem services. The purpose of this paper is to propose an ecosystem-based quality index (EBQI) tested on CDB from the north-western Mediterranean Sea, focusing mainly on epibenthic assemblages.MethodsThe first step has been to define a conceptual model of the CDB functioning, including the main trophic compartments and their relative weighting, then to identify appropriate assessment methods and potential descriptors. Twenty-nine sites were sampled along the coast of Provence and French Riviera (Southern France). Study sites were chosen with a view to encompassing a wide range of hydrological conditions and human pressures.ResultsVery well-preserved sites were found in Provence in areas without trawling and terrigenous inputs, while impacted and low-ES sites were located in the vicinity of urbanized areas. The cover of rhodoliths characterizes the seascape and might be an indicator of the good ES of CDB and reduced human pressure. However, the absence of rhodoliths may also be induced by natural phenomena.DiscussionThe EBQI designed for CDB proved representative and useful for a functional assessment based on epibenthic assemblages. However, some descriptors have shown their limitations and should be further explored. We highlight here the priority of establishing an index corresponding to a societal demand (e.g., European Directives, Barcelona convention) as a basis for a broad and large-scale assessment, for practical reasons. We stress the need to better apprehend the role of the macro-infauna and to extend this index over a wider geographical scale.

Abstract The aim of this article is to study the early effects of a recent marine reserve on the fish population, the Palavas Coastal Marine Reserve (PCMR), created in 2016 on fishermen initiative. This recent reserve, covering 100 ha and located 2.6 km from the coast at N 43°30.6845, E 3°58.4635, constitutes almost entirely a protected zone, with a ban on any fishing activity. The abundance of the fish populations and the size and biomass of the target species have been studied for the period of the first 4 years of protection. An inventory of fish populations was carried out using the scuba diving transect method in the rocky substrate of three zones: a large enhanced protection zone (EPZ) where only navigation was allowed,, a small restricted zone (RZ), where scuba diving was admitted, and an off-reserve zone (ORZ). Monitoring of this recent reserve shows significant increases in overall abundance and changes in population assemblages within the third year of protection. The biomass of target species tripled in the EPZ showing a refuge effect despite the fact that the fishing ban was not always respected during this implementation period. However, the behaviour patterns of the fish, which are more or less fearful of divers depending on the study area, do not offer an adequate basis for determining differences in populations between the EPZ and the RZ.

Holopelagic Sargassum blooms in the tropical North Atlantic since 2011 are composed of two species, Sargassum natans and S. fluitans, and three morphotypes: S. natans VIII, S. natans I and S. fluitans III. The distinct morphology and the variations in space and time of the proportion of these three morphotypes suggest that they may have different physiology. For the first time, we have quantified the growth rates of these three morphotypes through in situ 9-day experiments on the coast of Martinique Island (French West Indies). Despite the non-optimal conditions for growth for these pelagic species and the short time of the experiment, we have observed that Sargassum fluitans III was growing faster (approximately twice as fast) than S. natans VIII and S. natans I. Sargassum natans I exhibited the slowest growth. The differences in tissue composition (CNP and CN natural isotopes) of morphotypes point to a greater benefit for S. fluitans III from the coastal localization of our experiment than for the two S. natans morphotypes, and suggest that S. natans I had achieved its last growth further offshore before our experiment. These contrasting growth performances are consistent with the dominance of S. fluitans III in recent observations in the Caribbean region and along the path from the Sargassum belt. This also makes this last morphotype the best candidate for cultivation. Making the distinction between the growth performances of morphotypes may improve the current predictive models about dispersal of these species.

Research exploring nature connectedness has shown that these relationships influence worldviews, values, attitudes and behaviors towards nature. In this context, natural areas that are difficult to access, such as aquatic ecosystems, lead to questions concerning the need for mediation tools capable of modulating human behavior through indirect exposure. Art has been recognized as an efficient lever in this objective, as it triggers emotional, cognitive and experiential interactions. Despite a growing interest in integrating art into environmental education, prior research has mainly focused on post-19th century art. We believe, however, that pre-19th century European art presents an opportunity to connect with nature while enhancing historical and cultural heritage. We thus propose a research framework dedicated to the quantifiable study of the interrelations between aesthetic experience, behaviors, and nature connectedness (especially relating to aquatic ecosystems) using a case study approach to examine aquatic nature as represented in pre-19th century European paintings.

The Tropical Atlantic is facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. As a contribution to this proliferation, an increase in nutrient inputs from the tropical rivers, in response to climate and land use changes or increasing urbanization, has been often suggested and widely reported in the scientific and public literature. Here we discuss whether changes in river nutrient inputs could contribute to Sargassum proliferation in the recent years or drive its seasonal cycle. Using long-term in situ and satellite measurements of discharge, dissolved and particulate nutrients of the three world largest rivers (Amazon, Orinoco, Congo), we do not find clear evidences that nutrient fluxes may have massively increased over the last 15 years. Moreover, focusing on year 2017, we estimate that along the year only 10% of the Sargassum biomass occurred in regions under river plume influence. While deforestation and pollution are a reality of great concern, our results corroborate recent findings that hydrological changes are not the first order drivers of Sargassum proliferation. Besides, satellite observations suggest that the major Atlantic river plumes suffered a decrease of phytoplankton biomass in the last two decades. Reconciling these observations requires a better understanding of the nutrient sources that sustain Sargassum and phytoplankton growth in the region.

The tropical Atlantic has been facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. The development of large-scale modeling of Sargassum transport and physiology is essential to clarify the link between Sargassum distribution and environmental conditions, and to lay the groundwork for a seasonal forecast at the scale of the tropical Atlantic basin. We developed a modeling framework based on the Nucleus for European Modelling of the Ocean (NEMO) ocean model, which integrates transport by currents and waves, and physiology of Sargassum with varying internal nutrients quota, and considers stranding at the coast. The model is initialized from basin-scale satellite observations, and performance was assessed over the year 2017. Model parameters are calibrated through the analysis of a large ensemble of simulations, and the sensitivity to forcing fields like riverine nutrient inputs, atmospheric deposition, and waves is discussed. Overall, results demonstrate the ability of the model to reproduce and forecast the seasonal cycle and large-scale distribution of Sargassum biomass.

The Port-Cros National Park (PCNP), established in 1963, was one of the earliest terrestrial and marine parks in the Mediterranean Sea. From 2012, it engaged in a major redefinition and extension of its territory (N-PCNP-New Port-Cros National Park). This case is particularly interesting insofar as the protected area has been competently and efficiently managed since its creation, and protection and management measures have been strictly implemented: in the Mediterranean, the PCNP has often been considered as a benchmark. Here, we critically analyse almost 60 years of the management of the biodiversity and the human uses, with their share of successes and failures, certain operations which are today regarded as errors, and a doctrine today of a priori non-interventionism, in contrast to the doctrine in vogue in the early years. Of particular interest is the change in outlook with regard to actions favouring flagship species, such as building a tower for bats, setting up artificial nests for seabirds, and constructing an artificial reef at sea. The question of the natural arrival of the wild boar, a native species, and the hostility of the public and some species-centred scientists, is particularly instructive. We analyse these changes in the light of the ongoing trends in concepts in ecology and nature conservation, and the shift from a species-centred to an ecosystem-centred approach. It is worth emphasizing that a critical review of almost 60 years of management is a very rare exercise in a national park anywhere in the world.

Works of art are testimonies to past civilizations and biodiversity, and provide fundamental information for guiding current conservation programs.The success of such programs requires an understanding of the reference state of ecosystems, which is rarely known because current references are in perpetual slippage toward the acceptance of degraded states.For this reason, international organizations are regularly alerted to the fact that fish and aquatic resources are threatened, signaling a major challenge for our societies.In this article we aim to enrich the historical and ecological knowledge of aquatic resources in Western Europe (Atlantic, North Sea, and Mediterranean Sea) by analyzing the taxonomic composition of aquatic biodiversity as represented in Early Modern paintings, using the statistical tools of numerical ecology.The geographic and temporal variations of the biodiversity represented in these paintings are interpreted according to environmental and human pressures, which we differentiate between using technical and socio-cultural "sieves."Our results highlight the natural and anthropic factors that shape the spatial and temporal variations of the aquatic species depicted.These species belong to significantly different periods and regions, with a convergence between the origin of the paintings and the biogeographic area of the species.We show an overall decrease over time of represented taxa, and particularly of continental and freshwater species.We discuss the results in the light of previous works of historical ecology, archeology, history, and biology.Finally, we discuss the relevance and potential future contributions of the method developed herein to better understand the past reference state of aquatic socio-ecosystems.

For almost 60 years, the management policy of the Port-Cros National Park (PCNP) has steadily progressed, in phase with human impacts, changes in doctrines and goals in the field of nature conservation, what was socially acceptable at a given time, a very active Scientific Council and a gradual shift from species-centered to ecosystem-based management. Here, we illustrate problems faced by a national park, together with responses or practices that are suited, or not, to an ecosystem-based approach. PCNP's doctrine has been to explain that the abundance of species fluctuates naturally, and that we must not be too hasty to intervene, that nature sometimes does things better than humans, that a national park is neither a zoo nor a botanical garden, and the purpose is not to artificially increase the species diversity. The management approach of the PCNP can constitute a source of lessons for nature protection and management.

Biodiversity is often defined erroneously as the number of species. The higher the number of species, the better the status or the health of a habitat is considered to be. Managers, stakeholders and environmentalists worldwide often prioritize the ‘species approach’. The protection of an iconic and endearing species is obviously easier than that of tiny zooplankton species, although the latter may play a far more important role than the former in the functioning of healthy ecosystems. The species approach has been widely favoured compared to the ecosystem approach. However, ‘species-by-species’ management is unrealistic. The problem is that the management of natural habitats is often driven by environmentalist lobbies on the basis of taxonomy (e.g. mammals, turtles, birds, iconic fish, flowering plants, etc.) and disciplinary lobbies (biology, benthos, pelagos, contaminants, currents, etc.). Ecosystems are units of biological and spatial organization that include all the organisms, their interactions, the functional compartments they belong to, along with the components of the abiotic environment. The concept of the socio-ecosystem is useful insofar as it emphasizes the fact that man is part of ecosystems. Here, the authors make use of four case studies, in the Mediterranean Sea, in an attempt to demonstrate the interest of a comprehensive, socio-ecosystem-based approach in the field of environmental management. They also highlight the importance of tackling the coupling between benthic and pelagic ecosystems and between terrestrial and marine ecosystems.