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Distributional shifts in species ranges provide critical evidence of ecological responses to climate change. Assessments of climate-driven changes typically focus on broad-scale range shifts (e.g. poleward or upward), with ecological consequences at regional and local scales commonly overlooked. While these changes are informative for species presenting continuous geographic ranges, many species have discontinuous distributions-both natural (e.g. mountain or coastal species) or human-induced (e.g. species inhabiting fragmented landscapes)-where within-range changes can be significant. Here, we use an ecosystem engineer species (Sabellaria alveolata) with a naturally fragmented distribution as a case study to assess climate-driven changes in within-range occupancy across its entire global distribution. To this end, we applied landscape ecology metrics to outputs from species distribution modelling (SDM) in a novel unified framework. SDM predicted a 27.5% overall increase in the area of potentially suitable habitat under RCP 4.5 by 2050, which taken in isolation would have led to the classification of the species as a climate change winner. SDM further revealed that the latitudinal range is predicted to shrink because of decreased habitat suitability in the equatorward part of the range, not compensated by a poleward expansion. The use of landscape ecology metrics provided additional insights by identifying regions that are predicted to become increasingly fragmented in the future, potentially increasing extirpation risk by jeopardising metapopulation dynamics. This increased range fragmentation could have dramatic consequences for ecosystem structure and functioning. Importantly, the proposed framework-which brings together SDM and landscape metrics-can be widely used to study currently overlooked climate-driven changes in species internal range structure, without requiring detailed empirical knowledge of the modelled species. This approach represents an important advancement beyond predictive envelope approaches and could reveal itself as paramount for managers whose spatial scale of action usually ranges from local to regional.

The distribution range of the American comb jelly Mnemiopsis leidyi has expanded across Europe for several decades, particularly in the eastern Atlantic and Mediterranean Sea. This study aims to assess its expansion along the French Atlantic coast, mainly in the Bay of Biscay and Iroise Sea, since the first record in 2014. Mnemiopsis leidyi is now clearly established along 500 km of coastline, from the coast of Lorient to Arcachon Bay, which is the southernmost colonised area in the eastern Atlantic to date. It will likely colonise the Spanish Gulf coast in the near future through natural dispersal via currents, as has occurred between the Gironde estuary and Arcachon Bay. We quantify that this species now colonises nearly 45% of the French coastline. The invaded area includes the main estuaries of the Seine, Loire, Gironde and Rhône rivers, where M. leidyi populations may constitute reservoirs for colonising other harbours through merchant vessel traffic via ballast water. Finally, the Marennes- Oléron Bay and Arcachon Bay are the two main spat-producing regions for the Pacific oyster Magallana gigas in France. As M. leidyi consumes bivalve larvae, the potential economic and ecological impacts on this shellfish industry are discussed.

Aim To investigate some of the environmental variables underpinning the past and present distribution of an ecosystem engineer near its poleward range edge. Location >500 locations spanning >7,400 km around Ireland. Methods We collated past and present distribution records on a known climate change indicator, the reef‐forming worm Sabellaria alveolata (Linnaeus, 1767) in a biogeographic boundary region over 182 years (1836–2018). This included repeat sampling of 60 locations in the cooler 1950s and again in the warmer 2000s and 2010s. Using species distribution modelling, we identified some of the environmental drivers that likely underpin S. alveolata distribution towards the leading edge of its biogeographical range in Ireland. Results Through plotting 981 records of presence and absence, we revealed a discontinuous distribution with discretely bounded sub‐populations, and edges that coincide with the locations of tidal fronts. Repeat surveys of 60 locations across three time periods showed evidence of population increases, declines, local extirpation and recolonization events within the range, but no evidence of extensions beyond the previously identified distribution limits, despite decades of warming. At a regional scale, populations were relatively stable through time, but local populations in the cold Irish Sea appear highly dynamic and vulnerable to local extirpation risk. Contemporary distribution data (2013–2018) computed with modelled environmental data identified specific niche requirements which can explain the many distribution gaps, namely wave height, tidal amplitude, stratification index, then substrate type. Main conclusions In the face of climate warming, such specific niche requirements can create environmental barriers that may prevent species from extending beyond their leading edges. These boundaries may limit a species’ capacity to redistribute in response to global environmental change.

Aim: The introduction of aquatic non-indigenous species (ANS) has become a major driver for global changes in species biogeography. We examined spatial patterns and temporal trends of ANS detections since 1965 to inform conservation policy and management.Location: Global. Methods: We assembled an extensive dataset of first records of detection of ANS (1965–2015) across 49 aquatic ecosystems, including the (a) year of first collection, (b) population status and (c) potential pathway(s) of introduction. Data were analysed at global and regional levels to assess patterns of detection rate, richness and trans-port pathways.Results: An annual mean of 43 (±16 SD) primary detections of ANS occurred—one new detection every 8.4 days for 50 years. The global rate of detections was rel-atively stable during 1965–1995, but increased rapidly after this time, peaking at roughly 66 primary detections per year during 2005–2010 and then declining marginally. Detection rates were variable within and across regions through time. Arthropods, molluscs and fishes were the most frequently reported ANS. Most ANS were likely introduced as stowaways in ships’ ballast water or biofouling, although direct evidence is typically absent.Main conclusions: This synthesis highlights the magnitude of recent ANS detections, yet almost certainly represents an underestimate as many ANS go unreported due to limited search effort and diminishing taxonomic expertise. Temporal rates of detec-tion are also confounded by reporting lags, likely contributing to the lower detection rate observed in recent years. There is a critical need to implement standardized, repeated methods across regions and taxa to improve the quality of global-scale comparisons and sustain core measures over longer time-scales. It will be fundamen-tal to fill in knowledge gaps given that invasion data representing broad regions of the world's oceans are not yet readily available and to maintain knowledge pipelines for adaptive management. Fil: Bailey, Sarah A.. Great Lakes Laboratory For Fisheries And Aquatic Scienc; Canadá Fil: Brown, Lyndsay. Marine Scotland Science; Reino Unido Fil: Campbell, Marnie L.. Deakin University; Australia Fil: Canning-Clode, João. Marine And Environmental Sciences Centre; Portugal Fil: Carlton, James T.. Williams College. Maritime Studies Program; Estados Unidos Fil: Castro, Nuno. Marine And Environmental Sciences Centre; Portugal Fil: Chainho, Paula. Marine And Environmental Sciences Centre; Portugal Fil: Chan, Farrah T.. Great Lakes Institute For Enviromental Research; Canadá Fil: Creed, Joel C.. Universidade do Estado de Rio do Janeiro; Brasil Fil: Curd, Amelia. Ifremer Institut Francais de Recherche Pour L'exploitation de la Mer; Francia Fil: Darling, John. United States Environmental Protection Agency; Estados Unidos Fil: Fofonoff, Paul. Smithsonian Environmental Research Ctr; Estados Unidos Fil: Galil, Bella S.. The Steinhardt Museum Of Natural History; Israel Fil: Hewitt, Chad L.. Murdoch University; Australia Fil: Inglis, Graeme J.. National Institute Of Water & Atmospheric Research Lt; Nueva Zelanda Fil: Keith, Inti. Charles Darwin Foundation; Ecuador Fil: Mandrak, Nicholas E.. University Of Toronto Scarborough; Canadá Fil: Marchini, Agnese. University of Pavia; Italia Fil: McKenzie, Cynthia H.. Fisheries And Ocean Canada. Northwest Atlantic Fisheries Centre; Canadá Fil: Occhipinti‐Ambrogi, Anna. University of Pavia; Italia Fil: Ojaveer, Henn. University of Tartu; Estonia Fil: Pires‐Teixeira, Larissa M.. Universidad de Lisboa; Portugal. Universidade do Estado do Rio de Janeiro; Brasil Fil: Robinson, Tamara B.. Stellenbosch University; Sudáfrica Fil: Ruiz, Gregory M.. United States Environmental Protection Agency; Estados Unidos Fil: Seaward, Kimberley. National Institute of Water & Atmospheric Research Ltd.; Nueva Zelanda Fil: Schwindt, Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina Fil: Son, Mikhail O.. Institute of Marine Biology; Ucrania Fil: Therriault, Thomas W.. Pacific Biological Station; Canadá Fil: Zhan, Aibin. Chinese Academy of Sciences; República de China

International audience; A citizen monitoring program (Phenomer) of marine water discolorations caused by high biomass phytoplankton development (Harmful Algal Blooms, HABs) was conducted in 2013, 2014 and 2015 in the coastal waters of Brittany (France). This project aimed to explore the feasibility of acquiring scientifically valuable data on water discolorations phenomena through a citizen science approach, extending the surface area of monitored coastal waters by means of citizen observations. During the three years of the project implementation, respectively 14, 32 and 28 warnings were sampled and recognized as phytoplankton water discolorations. Respectively, 7, 24 and 14 phenomena were observed outside of routine monitoring points. Citizen observations contributed towards evaluating the extension of red discolorations caused by Noctiluca scintillans and the duration and impact on marine fauna of green discolorations of Lepidodinium chlorophorum. A bivalve mortality event coincided with a dark-brown phytoplankton bloom characterized by the dominance of the toxic raphidophytes Heterosigma akashiwo and Pseudochattonella verruculosa, whose presence indicate a new potential hazard in Brittany. Interview analysis of citizen observations showed that the contributors to Phenomer are generally well-informed on environmental issues and concerned about the status of the marine environment. Phenomer demonstrates the complementary value of citizen science programs to routine phytoplankton monitoring, as well as providing scientific information on water discolorations phenomena, whose observations over a large territory have rarely been structured. The advantages and limits shown by the Phenomer project will help to optimize future applications of citizen science approaches for phytoplankton and HAB studies.

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium-and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/)., Cefas Science Excellence fund; [TKP2020-NKA-16], This study is dedicated to our co-author, the late Prof. Olaf Weyl, whose sudden passing during field work in November 2020 was received by us with great sadness. This study represents a contribution to the term of reference 'd' (Advance knowledge base to further develop indicators to evaluate the status and impact of non-indigenous species in marine environments) of the ICES working group on Introductions and Transfers of Marine Organisms. The participation of GHC was supported by the Cefas Science Excellence fund. AW and AF were supported by TKP2020-NKA-16 project.

Data that can be used to monitor biodiversity through time are essential for conservation and management. The reef-forming worm, Sabellaria alveolata (L. 1767) is currently classed as ‘Data Deficient’ due to an imbalance in the spread of data on its distribution. Little is known about the distribution of this species around Ireland. Using data archaeology, we collated past and present distribution records and discovered that S. alveolata has a discontinuous distribution with large gaps between populations. Many regions lack data and should be targeted for sampling. Biodiversity surveys revealed that S. alveolata supported diverse epibiotic algal communities. Retrograding (declining) reefs supported greater infaunal diversity than prograding (growing) reefs or sand, suggesting that S. alveolata is a dynamic ecosystem engineer that has a lasting legacy effect. Similar research should be carried out for other Data Deficient species, habitats and regions. Such data are invaluable resources for management and conservation.

WOS:000464891100006; International audience; The honeycomb worm Sabellaria alveolata is capable of building extensive bioconstructions, including what are currently considered Europe's largest biogenic reefs. The size and volume of these bioconstructions, however, vary greatly, such that not all habitats engineered by S. alveolata may be easily identified as reefs. Given that European environmental legislation protects marine habitats that are classified as "reefs", it is important to identity a clear set of definition criteria. Furthermore, quantifiable and unequivocal criteria are also needed to evaluate the ecological (health) state of these reefs, in order to best monitor and protect them. Here we propose new terminology to describe the physical appearance of these bioconstructions and attempt to link these physical criteria to the physiological state of the tube-building polychaete. We tested whether a bioconstruction displaying outward signs of growth is built by "healthy" worms devoid of physiological stress by analysing three macromolecules (carbohydrates, proteins, lipids), four polar lipid fatty acids, six neutral lipid fatty acid markers and three metabolic enzymes (citrate synthase, catalase and superoxide dismutase). The worms were sampled in bioconstructions of different "Type" (veneer vs. hummock), "Phase" (progradation vs. retrogradation), and "Shore Level" (high shore vs. low shore) at Champeaux in Mont-Saint-Michel Bay, France. Our results show that worms sampled in retrograding reefs (i.e. displaying signs of erosion and colonisation by epibionts such as oysters or mussels), were less physiologically stressed than worms sampled in prograding bioconstructions, possibly due to lower intraspecific competition and hence greater food availability. We therefore suggest management measures should encompass the whole mosaic of biogenic construction Types and Phases. We propose the inclusion of the polar lipid fatty acid arachidonic acid, in combination with the activity of two metabolic enzymes, citrate synthase and superoxide dismutase, as the three key biochemical markers to consider for quantitative information on the physiological state of this particular ecosystem engineer. Our results also revealed the influence of both sex and size on fatty acid and enzyme levels, highlighting the importance of taking into account both these variables when sampling and subsequently pooling individuals by sex and size category for laboratory analyses. Once seasonal and site variation have been addressed, these biochemical indicators could be examined in parallel with S. alveolata bioconstruction physical criteria as part of a European-wide protocol for monitoring ecological status in this potential reef habitat.

Several concepts revolve around the term “marine landscapes”: all of them are nourished by aggregating data from multiple sources and disciplines. The SINP (Systeme d’Information sur la Nature et les Paysages) is the French marine biodiversity and landscape building block in the global marine data infrastructure pyramid. Within this information system marine landscapes have been apprehended in both a pictorial and an ecological manner, therefore the usages of the SINP depend on the adopted definition. Through examples we argue that by increasing the availability of the massive volumes of cross-domain data necessary for apprehending landscapes, regardless of the chosen definition, the SINP can play a role in defining and refining our understanding of marine landscapes.

Uncommon records of fishes may evidence local or global changes in fish composition resulting from environmental change or anthropogenic activities. Significant records of uncommon marine fishes, including migrant, non-native, cryptic, rare and threatened species, collected in French waters or by French vessels in European waters, observed by scuba divers or beachgoers, are reported for the year 2018. They include first, new, rare and unusual records for the following 52 species: Hexanchus griseus, Squatina squatina, Gymnura altavela, Acipenser sturio, A. gueldenstaedtii, Dalophis imberbis, Nemichthys curvirostris, Eurypharynx pelecanoides, Maulisia mauli, M. microlepis, Sagamichthys schnakenbecki, Melanostomias bartonbeani, Astronesthes niger*, Leptostomias gladiator*, Chlorophthalmus agassizi, Magnisudis atlantica, Evermannella balbo, Regalecus glesne, Luvarus imperialis, Raniceps raninus, Fistularia cf. petimba*, Trigla lyra, Lepidotrigla dieuzeidei, Micrenophrys lilljeborgii, Howella atlantica*, Pomatomus saltatrix, Serranus cabrilla, Caranx crysos, Seriola rivoliana, Trachinotus ovatus, Lobotes surinamensis, Sarpa salpa, Chelon ramada, Pseudoscopelus altipinnis*, Trachinus draco, Parablennius pilicornis, P. ruber, Buenia affinis, B. jeffreysii, Chromogobius zebratus, Didogobius splechtnai, Gammogobius steinitzi, Gobius couchi, G. kolombatovici, Lebetus sp., Speleogobius trigloides, Thorogobius macrolepis, Vanneaugobius dollfusi, Siganus rivulatus*, Lepidocybium flavobrunneum, Hyperoglyphe sp. et Pegusa cf. nasuta, among which six, marked with an asterisk (*), represent additions to the Checklist of the marine fishes from metropolitan France and one, N. curvirostris, is a first record for the Mediterranean.

Le règlement européen relatif aux espèces exotiques envahissantes (EEE) (1143/20141) fournit une liste d’EEE réglementées à l’échelle européenne. A ce jour, sur les 66 EEE de cette liste, seulement deux sont des espèces non indigènes (ENI) marines. L’objectif du présent travail est de proposer une liste d’espèces à réglementation à l’échelle nationale (selon les articles L411-5 dit de Niveau 1 et L411-6 dit de Niveau 2 du Code de l’Environnement2), suivant une nouvelle procédure d’analyse de risques décrite sommairement ci-dessous.

Uncommon fish records may reflect local or global changes of fish composition resulting from environmental changes or anthropogenic activities. Significant records of uncommon marine fishes, including migrant, non-native, cryptic, rare and threatened species, collected in French waters or by French vessels in European waters, observed by scuba divers or beachgoers, are reported for the year 2019. They include first, new, rare and unusual records for the following 33 species: Tetronarce nobiliana, Gymnothorax unicolor, Maulisia mauli, Salmo trutta, Grammonus ater, Photostomias guernei, Ijimaia loppei, Echiodon drummondii, Holocentrus adscensionis, Nerophis lumbriciformis, Scorpaena scrofa, Lepidotrigla dieuzeidei, Eutelichthys leptochirus, Liparis montagui, Mycteroperca rubra, Serranus cabrilla, Remora remora, Caranx crysos, Naucrates ductor, Trachurus picturatus, Seriola rivoliana, Argyrosomus regius, Parablennius pilicornis, Pseudoscopelus astronesthidens, Deltentosteus collonianus, Didogobius schlieweni, Didogobius splechtnai, Gobius couchi, Gobius gasteveni, Lebetus guilleti, Synapturichthys kleinii, Lagocephalus lagocephalus and Mola mola, among which I. loppei, H. adscensionis and P. astronesthidens represent first records for the French waters and additions to the Checklist of the marine fishes from metropolitan France. Photostomias guernei is a first record for the Bay of Biscay, found close the French EEZ.

International audience; The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and gibberellic acid, two molecules commonly used in seed priming. Dinoflagellates were revived from sediments dated to approximately 150 years ago (156 ± 27, 32 cm depth), extending the known record age of cyst viability previously established as around one century. A culture suspension of sediments mixed with melatonin and gibberellic acid solutions as biostimulants exhibited germination of 11 dinoflagellate taxa that could not be revived under controlled culture conditions. The biostimulants revived some dinoflagellates from century‐old sediments, including the potentially toxic species Alexandrium minutum. The biostimulants showed positive effects on germination on even more ancient cysts, showing dose‐dependent effects on the germination of Scrippsiella acuminata. Concentrations of 1, 10, and 100 µM melatonin and gibberellic acid promoted germination. In contrast, 1000 µM solutions, particularly for melatonin, drastically decreased germination, suggesting a potential noxious effect of high doses of these molecules on dinoflagellate revival. Our findings suggest that melatonin and gibberellic acid are involved in the stimulation of germination of dinoflagellate cysts. These biostimulants can be used to germinate long‐term stored dinoflagellate cysts, which may promote studies of ancient strains in the resurrection ecology research field.