The paper examines structural distortions in contemporary scientific publishing and their implications for research quality, equity, ethics and environmental conservation. Despite being largely publicly funded, scientists continue to provide unpaid labour as reviewers and editors while facing increasing publication fees or subscription costs. The rapid proliferation of journals has intensified reviewer fatigue, reduced the availability of qualified referees, and contributed to declining peer-review quality. These conditions, combined with status biases and insufficient editorial oversight, seriously risk to undermine the reliability of published research. The expansion of predatory journals and exploitative open-access models further erodes trust in scientific communication. In a publish-or-perish environment driven by bibliometric evaluation, there is a proliferation of low-quality and fraudulent research, amplified by AI-generated content. This dynamic benefits commercial publishers, whose profit margins have grown sharply, while draining financial resources from academic institutions. The resulting "vampirization" of the research system exacerbates global inequities and contributes to an exponential increase in publications with limited scientific or societal impact. To counteract this trajectory, we propose that scientists prioritise journals governed by scientific societies or public institutions, and those that adopt ethical publishing practices, especially avoiding predatory publishers. Collective actions-such as mass resignations from editorial boards in response to unreasonable publication charges-are presented as effective strategies. Institutions are encouraged to shift evaluation criteria from quantity to quality, discourage unethical practices, and promote interdisciplinary collaboration, particularly in conservation science. We acknowledge the inherent imperfections of past systems but emphasise that the current drift poses significant risks, especially for fields informing environmental policy making. Declining primary research quality may cascade into misguided decision-making at all scales. We call for systemic reform, including an international accreditation system for journals and publishers based on transparent ethical standards and overseen by public research agencies. Ensuring access to reliable, high-quality scientific information is essential for supporting conservation, sustainability, and the broader societal role of science.

The seagrass Posidonia oceanica, endemic to the Mediterranean Sea, forms extensive meadows that provide a wide range of ecosystem services. However, P. oceanica meadows have declined in many parts of the Mediterranean due to human activities, particularly near large cities and ports, such as the Marseilles area (France, northwestern Mediterranean Sea). This decline has been especially pronounced in Prado Bay, located at the core of a 2-million-inhabitants metropolis, and has been linked to organic pollution from a river and an untreated sewage outfall, as well as to the construction of a marina and artificial beaches. In 1986, two permanent 36-m2 quadrats (PQs) were established and monitored until 2025 to assess potential natural recovery of the meadow following the implementation of a wastewater treatment plant and in the absence of further coastal development, in accordance with national and European Union (EU) policies for the protection of P. oceanica and marine habitats. Recolonization occurred at an unexpectedly high rate, reaching up to 8.6%/year, although with marked interannual variability. By 2025, P. oceanica cover (94% and 81% in the two PQs) indicated near-complete restoration, as small unvegetated patches can be a natural feature in healthy meadows. These results, from one of the longest datasets for seagrass monitoring, demonstrate that, once the drivers of P. oceanica decline are removed, passive restoration is a viable approach that can be achieved within a realistic timeframe. Our findings emphasise the need for coordinated anthropogenic stressor mitigation to support effective ecological restoration under the EU Nature Restoration Regulation.

Abstract Following the unprecedented marine heatwaves of summer 2022, extensive flowering of the endemic seagrass Posidonia oceanica was witnessed across the western Mediterranean. To unravel the causes of this event, we conducted a pan-Mediterranean analysis across 442 sites spanning all Mediterranean ecoregions, with 76% exhibiting flowering. Flowering differed regionally, with both highest flowering prevalence (over 90%) and flowering intensity (up to 0.75) recorded in the Liguro-Provençal and Balearic Seas. We demonstrate that regions experiencing large summer sea surface temperature anomaly with high marine heatwave cumulative intensity displayed the highest flowering intensity. The probability of flowering was very likely when marine heatwave cumulative intensity exceeded ⁓120°C days. These findings suggest that marine heatwaves trigger flowering in P. oceanica and, given the high energetic cost of sexual reproduction, continued ocean warming may shift energy allocation toward flowering. This shift could profoundly affect the species’ reproductive strategies, posing major challenges and uncertainties for its long-term evolution.

Biological invasions are a major driver of biodiversity loss, causing profound and often irreversible ecological changes. Among these invaders, the brown alga Rugulopteryx okamurae provides a striking example. Since its arrival in 2016 in Calanques National Park (Marseille, southern France), it has drastically transformed underwater landscapes by reshaping native algal communities. To better understand the mechanisms underlying its colonisation, we conducted an experimental study involving the complete removal of existing algae within experimental quadrats. Using the photoquadrat method, we monitored the spatio-temporal dynamics of algal succession. In parallel, we performed an independent field survey to quantify seasonal changes in biomass over time. Our results show that turf-forming algae, characterised by rapid growth, are the first to recolonise cleared surfaces. This initial colonisation phase is rapidly followed by the massive establishment of R. okamurae, which reached 100% cover within 1 year. This expansion was accompanied by a strong restructuring of benthic communities and a marked decline of native algae, whose relative abundances dropped below 2% over time, highlighting the species' ability to thrive after disturbance. In addition, we observed that the emergence of the invasive alga Asparagopsis armata in April significantly reduced R. okamurae cover, suggesting biotic interference and potential allelopathic competition. Overall, R. okamurae stands out as a highly impactful invader whose rapid dominance and interactions with other invasive species emphasise the urgent need to improve our understanding and management of marine invasions to mitigate biodiversity loss.

Marine forests play a vital role in shaping seascape complexity worldwide. In the Mediterranean Sea, they are mainly formed by macroalgal species belonging to the Cystoseira sensu lato group (i.e. Cystoseira, Ericaria and Gongolaria). These species are declining throughout Mediterranean coastlines due to multiple, often synergistic stressors. Among the principal biotic drivers of this regression is grazing by herbivores (i.e. the sea urchins Paracentrotus lividus and Arbacia lixula and the teleost Sarpa salpa), which can transform luxuriant marine forests into urchin barrens-ecosystems of reduced complexity, lower species richness and limited ecological function. A widely used management tool to preserve marine ecosystems is the implementation of Marine Protected Areas (MPAs), often including no-take zones (NTZs). In this context, we assessed the effectiveness of MPAs and NTZs in preserving Ericaria brachycarpa forests. To this end, two large-scale monitoring campaigns were conducted in the Nature Reserve of the Strait of Bonifacio (Corsica, France), the first in 2011 and the second in 2025. Sea urchin populations, algal cover and fish communities (in 2025 only) were surveyed using SCUBA diving. Our results revealed a drastic decline in E. brachycarpa cover, accompanied by a steady increase in urchin barrens and sea urchin abundance in NTZs between the two campaigns. Conversely, in fishing zones, E. brachycarpa populations remained stable while both urchin barrens and sea urchin abundance decreased. Synthesis and applications. This study demonstrates that NTZs can be counterproductive, as they may exacerbate the decline of marine forests by protecting sea urchins that are not effectively controlled by predators. We therefore call for a reassessment of management policies, including the targeted harvesting of herbivores where natural top-down control is absent.

Coralligenous reefs are among the most diverse Mediterranean ecosystems, particularly in the circalittoral zone. Shaped by calcified red algae, sponges, cnidarians, and bryozoans, they create a complex three-dimensional structure providing shelter for diverse fauna. These reefs develop either on steep rocky walls or as bioherms when calcified algae are the dominant organisms. Their structure and composition vary with location, depth, substrate, and environmental conditions. Assessing the status of such a complex ecosystem poses significant challenges. Ecosystem-based quality indices (EBQI) have already been applied successfully to various coastal Mediterranean habitats. Using a similar methodology, a new index, the Coralligenous Ecosystem-Based Quality Index (Cor-EBQI), was developed to assess the ecological status of the coralligenous ecosystem. The index incorporates the main functional compartments of these reefs, with each compartment weighted according to its importance in ecosystem functioning. Suitable descriptors were then selected to define five status classes for each compartment. A confidence index was also created to estimate data quality based on criteria such as methodology and expert judgement. Data from 63 sites along the French Mediterranean coast, including the Gulf of Lions, Provence, the French Riviera, Corsica, and Monaco, were analyzed. The ecological status ranged from bad to high, influenced by environmental conditions, geomorphology, anthropogenic pressures, and management practices. The Cor-EBQI is designed to meet the objectives of both the Habitats and Marine Strategy Framework Directives of the European Union. As such, it offers a practical tool for future monitoring networks across the Mediterranean Sea.

In the Mediterranean Sea, seaweed marine forests, one of the most important benthic assemblages for the coastal ecosystem functioning, are shaping the rocky reefs. Among the Fucales, Gongolaria barbata (syn. Cystoseira barbata) is a several years living species usually growing in very shallow, sheltered and well-lit marine reef habitats and in coastal lagoons. The long-term change in its distribution in relation to a variety of disturbances has been assessed along the French Mediterranean coast, including Corsica and brackish lagoons, thanks to historical data dating back to the 19th century. The current distribution was established through an extensive survey conducted by snorkelling, encompassing approximately 3 000 km of coastline. A GIS analysis indicates that Gongolaria barbata can currently be considered as regionally extinct in French Catalonia and Western Provence and functionally extinct in the French Riviera. In Languedoc, the species is extinct in the open sea and only present in certain brackish lagoons despite severe repeated anoxic crises (malaïgues) and competition with a rich exotic flora introduced from the NE Atlantic and NW Pacific, especially the invasive Sargassum muticum. In contrast, the populations of G. barbata have remained stable in Eastern Provence and Corsica. The main possible causes of decline are uprooting, overgrazing by herbivores, habitat destruction and competition with introduced seaweeds. The relevance of ecological restoration of G. barbata populations was assessed.

Two Indian Ocean surgeon fish Paracanthurus hepatus individuals were observed near Saint-Raphaël (Provence, France, north-western Mediterranean Sea) in the late summer of 2024 in Posidonia oceanica seagrass and reef habitats. This species is very popular among aquarium hobbyists in Europe, and a growing number of mega-yachts, such as those which moor in the Saint-Raphaël marina, have seawater aquariums on board. Accidental or deliberate release from one such aquarium is the most probable origin of these individuals. The first individual was speared and the second one was no longer sighted after a September storm. Their establishment is unlikely; however, in the future, with the warming of Mediterranean waters and the rapid increase in the number of mega-yachts, this could change. Yacht owners and their staff should be informed of the risk posed by aquarium discharges.

Posidonia oceanica seagrass, endemic to the Mediterranean Sea, provides ecological goods and ecosystem services of paramount importance. In shallow and sheltered bays, P. oceanica meadows can reach the sea surface, with leaf tips slightly emerging, forming fringing and barrier reefs. During the 20th century, P. oceanica declined conspicuously in the vicinity of large ports and urbanized areas, particularly in the north-western Mediterranean. The main causes of decline are land reclamation, anchoring, bottom trawling, turbidity and pollution. Artificial sand nourishment of beaches has also been called into question, with sand flowing into the sea, burying and destroying neighbouring meadows. A fringing reef of P. oceanica, located at Saint-Mandrier-sur-Mer, near the port of Toulon (Provence, France), is severely degraded. Analysis of aerial photos shows that, since the beginning of the 2000s, it has remained stable in some parts or continued to decline in others. This contrasts with the trend towards recovery, observed in France, thanks to e.g., the legally protected status of P. oceanica, and the reduction of pollution and coastal developments. The sand nourishment of the study beach, renewed every year, with the sand being washed or blown very quickly (within a few months) from the beach into the sea, burying the P. oceanica meadow, seems the most likely explanation. Other factors, such as pollution, trampling by beachgoers and overgrazing, may also play a role in the decline.

Over historical time, Berre Lagoon (SE France, NW Mediterranean Sea) had undergone various changes. These became more significant, transforming and even disruptive since the 19th century when the channel connecting the lagoon to the sea was deepened and the surrounding areas were industrialized and urbanized. Pollution and anoxic crises were major consequences. Concomitantly, many non-indigenous species (NIS) arrived in the lagoon. In recent years, climate change and freshwater input from a hydro-electric power plant have been the main drivers influencing the lagoon ecosystem. The major anoxic crisis of 2018 caused the lagoon ecosystem to collapse. In the following years, an increase in mean salinity linked with low precipitation in the regional watershed and the resulting lower freshwater input from the hydro-electric power plant caused rapid changes in ecological assemblages and favoured newly arrived NIS. An updated list of NIS and cryptogenic species (38 taxa according to the last census) is presented here. The species introduction rate has strongly increased since 2000, or at least the recognition rate. Temporal and spatial changes are discussed for major NIS in Berre Lagoon. The success of new NIS is interpreted as a consequence of the 2018 crisis, of global change and of re-marinization of the water body related to dryer periods and stricter freshwater input regulation.

In the Mediterranean Sea, overgrazing is a major factor in the degradation of algal communities. Marine protected areas (MPAs) are intended to ensure the conservation of biodiversity, but most Mediterranean MPAs are 'paper parks' (i.e. protected in theory, but with no enforcement) with inadequate protection. Along the French Mediterranean coast, less than 1% surface area of MPAs is actually protected by means of no-take zones (NTZs). This study examines the impact of different protection levels in the Calanques National Park, Marseilles, France, on the relationships among algal communities, herbivores, and predators. Using an ecosystem-based approach, we compared algal communities, sea urchin populations (Arbacia lixula and Paracentrotus lividus), and fish communities between NTZs and fishing zones. Our findings reveal that algal communities subjected to higher levels of protection (NTZs) are severely degraded, leading to a loss of habitat complexity. Fucoid marine forests are completely absent, replaced by encrusting algae (barren ground) or turf algae. Herbivore biomass (sea urchins and fish Sarpa salpa) is higher in the NTZs, and the presence of their predators does not cascade down to influence algal communities. We emphasize the importance of substrate topography as a key driver of sea urchin abundance. This MPA is insufficient to rebalance the trophic network and control herbivore populations. We strongly recommend implementing herbivore management measures to counterbalance the lack of natural predator-prey interactions. Moreover, the French policy of reinforcing sea urchin protection is counterproductive to preserving and restoring habitat complexity. Additionally, the practice of releasing thousands of juvenile sea urchins to restore populations should be discontinued.

The Mediterranean Sea, a biodiversity hotspot, faces significant threats from non-indigenous species (NIS), which drive biodiversity changes. Over the past century, the introduction of NIS has accelerated due to maritime traffic, aquaculture, and interoceanic canals, fostering biological invasions. Marine protected areas (MPAs), established to preserve biodiversity, are increasingly impacted. This review quantified and characterized French Mediterranean MPAs, analyzing non-indigenous macroalgae distribution based on the existing literature and the authors’ observations. Results revealed widespread occurrence, with the highest NIS richness in strictly regulated MPAs; their proximity to large harbors highlights the paramount importance of the introduction pathways. In addition, there is a significant knowledge gap regarding the distribution of NIS within MPAs, complicating efforts to monitor and study these species effectively. These findings highlight the challenges in monitoring and managing invasions and the urgent need for controlling primary and secondary invasion pathways, within and outside the MPAs, international collaboration to control them, and enhanced funding for NIS monitoring. Without adaptive management, even strictly protected MPAs are vulnerable to the escalating impacts of invasive species.

In the Mediterranean, the dune–beach ecosystem is characterized by the presence of thick deposits of dead leaves of the endemic seagrass Posidonia oceanica, called banquettes (Dune–Beach–Banquette ecosystem—DBB). This ecosystem plays an important role in the coupling between sea and land. The banquettes provide important ecosystem services: protection of beaches against erosion, contribution to the building of the dune, and a source of nitrogen for coastal vegetation. They are home to a rich and diverse invertebrate fauna that are consumed by other predatory invertebrates and seabirds. A conceptual model of the functioning of the DBB ecosystem and its relation with adjacent ecosystems has been outlined. When dead P. oceanica leaves return to the sea, which is the fate of most of the banquette, they constitute an important source of carbon and nutrients for coastal ecosystems and fisheries. Beach management, with the removal of banquettes and driftwood to meet the supposed requirements of beach users and tourists, is an ecological disaster, in addition to being an economic burden for coastal municipalities. Beach management methods that respect the interactions between the marine and terrestrial realms, which preserve the beaches from erosion and allow the return of the banquettes to the sea, and which take into account the real perceptions of beach users are feasible in the framework of the concept of the ‘ecological beach’.

The warming trend of the Mediterranean Sea is a long-term process. It has resulted in a northwards and westwards range expansion and abundance increase of thermophilic species, both native and non-indigenous, and in a shrinking of the range of cold-affinity species. Marine heatwaves (MHWs) are relatively short-term extreme episodes that are responsible for spectacular mortality events in some species and have been extensively reported in the literature. In contrast, the species that benefit from MHWs (the ‘winners’) have been much less studied. A record-breaking MHW occurred in 2022 in the north-western Mediterranean Sea. We focus on three ‘winner’ species, the thermophilic green macroalgae Penicillus capitatus and Microdictyon umbilicatum and the endemic seagrass Posidonia oceanica. Penicillus capitatus, which is mainly present in the area as an inconspicuous turf of entangled filaments (espera stage), produced the erect paintbrush-like stage where sexual reproduction takes place. Microdictyon umbilicatum, usually uncommon, bloomed to the point of clogging fishing nets. Finally, a mass flowering of P. oceanica occurred in late August–September, followed the following year (April–May 2023) by the extensive production and dissemination of fruits and seeds. Both processes, the long-term warming trend and one-off heatwaves, both ‘losers’ and ‘winners’, shape the change in structure and functioning of Mediterranean ecosystems.

Infralittoral rocky reefs (IRR) are a coastal marine habitat subject to various anthropogenic pres-sures in the Mediterranean. An ecological assessment using an ecosystem-based approach appears essential to guide sustainable environmental management practices and meet the requirements of the European Union Marine Strategy and Habitats Directive. For this, the reef-EBQI has been developed at 96 sites along the French Mediterranean coast. We show an overall 'good' and 'moderate' IRR status based on the reef-EBQI. The status appears sensitive to the level of pressure, but more to local specificities. Management and geomorphology did not significantly impact the status. Comparing reef-EBQI scores with another ecosystem-based index, ECOfast, revealed a positive correlation but dissimilarities. Thus, the reef-EBQI is suitable for long-term monitoring in the Mediterranean but interpreting ecological status requires careful handling. Further work should include abiotic factors such as geomorphology and a suitable quantitative pressure index.

Conservation of ecosystems is an important tool for climate change mitigation. Seagrasses, mangroves, saltmarshes and other marine ecosystems have particularly high capacities to sequester and store organic carbon (blue carbon), and are being impacted by human activities. Calls have been made to mainstream blue carbon into policies, including carbon markets. Building on the scientific literature and the French voluntary carbon standard, the 'Label Bas-Carbone', we develop the first method for the conservation of Posidonia oceanica seagrasses using carbon finance. This methodology assesses the emission reduction potential of projects that reduce physical impacts from boating and anchoring. We show how this methodology was institutionalized thanks to a tiered approach on key parameters including carbon stocks, degradation rates, and decomposition rates. We discuss future needs regarding (i) how to strengthen the robustness of the method, and (ii) the expansion of the method to restoration of seagrasses and to other blue carbon ecosystems.

The Mediterranean Sea is worldwide the area most affected by introduced species. The Suez Canal (Lessepsian species) and shellfish aquaculture are the main routes for introduction, in addition to shipping (fouling, clinging and ballast waters). Two non-indigenous Lophocladia (Montagne) F.Schmitz species have been recorded from the Mediterranean Sea: the Red Sea and Indian Ocean L. lallemandii (Montagne) F.Schmitz and the western tropical Atlantic Ocean L. trichoclados (C.Agardh) F.Schmitz. On the basis of molecular data, Golo et al. (2023, 2024) concluded that the species which invaded the Mediterranean only belongs to the western Atlantic L. trichoclados. Until the mid-2010s, the north of the western basin was the only Mediterranean area not invaded by this species. In the present paper, we report for the first time the presence of L. trichoclados from this region in Provence and Corsica. Interestingly, L. trichoclados does not occur and bear reproductive organs in spring but in autumn and winter, although it is a species of tropical affinity.

La posidonie Posidonia oceanica est endémique de la Méditerranée. C’est une plante à fleurs issue d’ancêtres terrestres qui sont retournés au milieu marin, comme l’on fait plus tard les ancêtres des cétacés. Elle est l’espèce ingénieure d’un écosystème que ses caractéristiques rapprochent des forêts terrestres. Cet écosystème fournit à l’Homme des services considérables : pêche, production de sable alimentant les plages, protection des plages contre l’érosion, séquestration du CO2, etc. Les principales menaces qui pesaient, au xxe siècle, sur la posidonie étaient la pollution, l’urbanisation littorale et la surpêche. Aujourd’hui, tout au moins au sein de l’Union européenne, ce sont l’ancrage, le chalutage, et la surpêche. En outre, la destruction des banquettes de feuilles mortes de posidonies sur les plages, pour le supposé confort des baigneurs, est une très grave erreur écologique et économique. Quant au réchauffement climatique, il ne constitue pas une réelle menace pour la posidonie.

Over the centuries, the Mediterranean Sea has been significantly impacted by biological invasions, hosting more than 1000 non-indigenous species. In the early 2000s, the brown alga Rugulopteryx okamurae, native to the northwestern Pacific Ocean, was introduced to the Thau Lagoon (Occitania, France) due to extensive shellfish farming activities. Since 2016, this species has proliferated, completely covering the rocky habitats along the Marseille coasts (Provence, France) and becoming the dominant alga. The impact of R. okamurae on flora and fauna was investigated by comparing rocky benthic assemblages of invaded and non-invaded sites. Results showed a change in the communities, with a significant decrease in species diversity and a homogenization of algal and invertebrate populations in invaded sites. Rugulopteryx okamurae is a habitat transformer species inducing a significant habitat shift. Rugulopteryx okamurae also seems to affect the different algal strata of the benthic community, thus impacting the entire canopy. However, a weak effect of R. okamurae was observed on the functional structure of native algal communities, comparing invaded and non-invaded areas. This lack of structural variation between these zones could be explained by the degradation of habitats within the Calanques National Park, due to decades of intense overgrazing by Sarpa salpa and sea urchins. But an impact on the ecosystem functioning should not be excluded. It is noteworthy that R. okamurae, a species presumed to prefer colder waters, has shown resistance to successive marine heat waves, allowing it to continue spreading and dominating without impairment.

Since 2011, massive new strandings of holopelagic Sargassum have been reported on the coasts of the Caribbean, northern Brazil, Guiana, and West Africa, causing severe economic and ecological damage. Three common morphotypes (S. fluitans III, S. natans I, and S. natans VIII) were identified as responsible for these catastrophic events, with dominance shifts between them over time. However, the taxonomic status of these holopelagic Sargassum morphotypes remains unclear. Using an integrative taxonomy framework, combining a morphological study and molecular analyses, this study aimed to clarify their taxonomic status. Morphological analyses of 54 characters revealed no intermediate form between the three morphotypes, with the overall shape, nature of the axis, and size and shape of blades and vesicles being the most discriminating. An analysis of mitochondrial (IGS, cox2, cox3, mt16S rRNA, and nad6) and plastid (rbcL) markers confirmed the genetic divergence among the three morphotypes, with a lower level of divergence between the two S. natans morphotypes. Without additional molecular characterization, these morphotypes cannot be classified as three distinct species. However, due to their distinct morphological characteristics and sympatry within drifting aggregations, a revision of holopelagic species names is proposed, with Sargassum fluitans var. fluitans (for S. fluitans III), Sargassum natans var. natans (for S. natans I), and S. natans var. wingei (for S. natans VIII). This revision provides necessary clarity on the species involved in inundations of the tropical Atlantic.