European Seas Research Articles

Three decades of change in the Skagerrak coastal ecosystem, shaped by eutrophication and coastal darkening

Global coastal ecosystems are under accelerating pressure from human activities and climate change. In this study we explore a long-term time series (mostly 1990–2016) from major Norwegian rivers, together with coastal time series from the Norwegian Skagerrak coast. The aims are to: 1) test long-term trends in riverine loadings to Skagerrak, changes in coastal water quality and pelagic and benthic species composition, and 2) to describe the relationships between human drivers (eutrophication and coastal darkening) and community structure of benthic communities. Riverine discharge and transport increased by 23–85% over the time period, corresponding to a 40–78% increase in concentrations of suspended particulate material in coastal waters and reduced surface salinity, connected to the reported coastal darkening of coastal waters. There was a worsening in ecological status for hard-bottom benthic communities (0–30 m) and a reduction in the lower growth depth limit of several macroalgae species. A structural shift in the community composition from macroalgae to increased abundance of animals was found to be related to increased coastal darkening and reduced eutrophication. The concentration of coastal inorganic nutrients (DIN, PO4) declined by 27–36%, in response to management efforts to reduce eutrophication in European regional seas. Results indicate that reduced eutrophication was related to increased ecological status of the deep soft-bottom community (350 m), with a reduction in opportunistic polychaetes and an increase in filter feeding bivalves. This work highlights how climate change and other human-induced changes in a boreal ecosystem intensifies land-ocean interactions, and calls for more adaptive monitoring, where traditional water quality programs and policies evolve iteratively as new information emerges and the major drivers of the systems change.

Redistribution of fisheries catch potential in Mediterranean and North European waters under climate change scenarios

The Mediterranean Sea is a hotspot of global warming where key commercial species, such as demersal and pelagic fishes, and cephalopods, could experience abrupt distribution shifts in the near future. However, the extent to which these range shifts may impact fisheries catch potential remains poorly understood at the scale of Exclusive Economic Zones (EEZs). Here, we evaluated the projected changes in Mediterranean fisheries catches potential, by target fishing gears, under different climate scenarios throughout the 21st century. We show that the future Mediterranean maximum catch potential may decrease considerably by the end of the century under high emission scenarios in South Eastern Mediterranean countries. These projected decreases range between −20 to −75 % for catch by pelagic trawl and seine, −50 to −75 % for fixed nets and traps and exceed −75 % for benthic trawl. In contrast, fixed nets and traps, and benthic trawl fisheries may experience an increase in their catch potential in the North and Celtic seas, while future catches by pelagic trawl and seine may decrease in the same areas. We show that a high emission scenario may considerably amplify the future redistribution of fisheries catch potential across European Seas, thus highlighting the need to limit global warming. Our projections at the manageable scale of EEZ and the quantification of climate-induced impacts on a large part of the Mediterranean and European fisheries is therefore a first, and considerable step toward the development of climate mitigation and adaptations strategies for the fisheries sector.

Predicting the impacts of climate change on the distribution of European syngnathids over the next century

At the latitudinal interval that encompasses Europe, due to the gradual seawater warming imposed by climate change, there is now continuing evidence for a widespread pattern of poleward range shifts, often translated by expansions in the northern leading edges of distribution and contraction episodes at the southern boundaries. As the distribution of biodiversity is far from static, it seems imperative that we can predict changes in species’ geographic ranges to potentially circumvent severe biodiversity losses in the near future. Here, we focus on syngnathids, flagship species and umbrella taxa for coastal marine ecosystems, and attempt to identify areas of environmental suitability in Europe over the next century, according to distinct greenhouse gas concentration trajectories. Our results seamlessly match the general and region-specific impacts of climate change projections for European seas. Especially within the Atlantic Coast, species are expected to continue poleward range shifts, with the hotspot of syngnathid diversity remaining around the Celtic-Biscay Shelf, albeit with slightly distinct species composition from that of present day. The most dramatic changes are expected within semi-enclosed areas such as the Baltic, the Mediterranean and the Black Sea, where present-day endemic species diversity is likely to plunge, especially under a ‘business-as-usual’ scenario. When looking at the potential protective role of ‘no-take’ marine protected areas (MPAs) on European syngnathids, a clear latitudinal asymmetry emerged. From the Atlantic diversity hotspot downwards, and especially in the Mediterranean and Black Sea, the current ‘no-take’ MPA layout, if it remains static, will not be especially effective in either safeguarding syngnathid diversity or delaying the expected gradual species disappearance. Europe needs to be prepared to implement, at a continental scale, coordinated conservation measures aimed at preventing (or delaying, at the very least) the loss of its marine endemic species. As umbrella species, conservation efforts aimed at syngnathids will surely have a positive impact on coastal ecosystems.

The Origin of the Mangrove and Saltmarsh Snail Ellobium (Eupulmonata, Ellobiidae)

The pulmonate gastropod genus Ellobium has its greatest diversity in the modern Indo-West Pacific Region (IWP). Its origin, however, is traced to the Early Oligocene of the Northeastern Atlantic and the Western Tethys Region. Two Ellobium species are documented from the Rupelian of France and Italy and a new species is recorded from the Chattian of Hungary: Ellobium kerwaensis nov. sp. The first records in the IWP are known from the Early Miocene, suggesting an eastward range expansion of the genus around the Oligocene/Miocene boundary, when Ellobium became extinct in the European seas. Extant Ellobium species are bound to habitats above the high tide line in salt marshes and mangroves. Comparable environmental requirements are expected for the fossil congeners. Ellobium may derive from Eocene ancestors, such as the Bartonian Eoellobium heberti from the Northeastern Atlantic. Eoellobium is introduced in this paper as a new genus.

Site selection for European native oyster (Ostrea edulis) habitat restoration projects: An expert‐derived consensus

Abstract The European native oyster (Ostrea edulis) is a threatened keystone species which historically created extensive, physically complex, biogenic habitats throughout European seas. Overfishing and direct habitat destruction, subsequently compounded by pollution, invasive species, disease, predation and climate change have resulted in the functional extinction of native oyster habitat across much of its former range. Although oyster reef habitat remains imperilled, active restoration efforts are rapidly gaining momentum. Identifying appropriate sites for habitat restoration is an essential first step in long‐term project success. In this study, a three‐round Delphi process was conducted to determine the most important factors to consider in site selection for European native oyster habitat restoration projects. Consensus was reached on a total of 65 factors as being important to consider in site selection for European native oyster habitat restoration projects. In addition to the abiotic factors typically included in habitat suitability models, socio‐economic and logistical factors were found to be important. Determining the temporal and spatial variability of threats to native oyster habitat restoration and understanding the biotic factors present at a proposed restoration site also influence the potential for project scale‐up and longevity. This list guides site selection by identifying: a shortlist of measurable factors which should be considered; the relevant data to collect; topics for discussion in participatory mapping processes; information of interest from the existing body of local ecological knowledge; and factors underpinning supportive and facilitating regulatory frameworks.

MINDeSEA: exploring seabed mineral deposits in European seas, metallogeny and geological potential for strategic and critical raw materials

Abstract This study summarizes a compilation of studies and cartographical work on seabed mineral deposit types in pan-European seas developed under the GeoERA-MINDeSEA project. In total, 692 occurrences and 1194 individual mineral samples of volcanogenic massive sulfides and hydrothermal mineralization, ferromanganese crusts, phosphorites, marine placer deposits, polymetallic nodules, and their associated strategic and critical raw material (CRM) elements have been characterized. The GeoERA-MINDeSEA project has been built based on extensive studies carried out previously, which include geophysical surveys, sampling stations, underwater photography and remotely operated vehicle (ROV) surveys, and mineralogical, geochemical and isotopic studies. This study develops pan-European and national databases, and expands strategic and CRM knowledge through a compilation of mineral potential and metallogenic studies of CRM resources in European seas. For the first time, the GeoERA-MINDeSEA portal publishes harmonized marine mineral resource information, case studies and maps, and identifies potential areas for responsible resource exploration and extraction, strategic management, and marine spatial planning. This study also provides recommendations for future target areas, studies and standards to be used across Europe as part of this project.

Wave Energy in Brittany (France)—Resource Assessment and WEC Performances

Refined numerical wave energy resource assessments are required to reduce uncertainties in the evaluation of available power and energy production. However, to restrict the computational cost, a great part of wave hindcast simulations cover a limited time range (below ten years) or rely on coarse spatial resolutions while routinely ignoring tide-induced modulations in wave conditions. Complementing resource assessments conducted in the North-West European shelf seas, we here exploited a 27-year hindcast database (1994–2020) set up at a spatial resolution of 200 m along the coast of France and integrating the effects of tidal currents on waves. This evaluation was conducted in three water depths from offshore to nearshore (60, 40 and 20 m) around Brittany, one of the most energetic regions along the coast of France. We investigated the performances of a series of thirteen state-of-the-art wave energy converters with respect to installation depth range. Beyond confirming the interest of western Brittany in energy exploitation, the results exhibited the first ranking between devices, thus promoting the interests of Oceantec in offshore waters (60 m), Wave Dragon in intermediate waters (40 m), and Oyster and WaveStar C6 in shallow waters (20 m).

Country-specific assessment of mismanaged plastic packaging waste as a main contributor to marine litter in Europe

Land-based litter and leakages from inadequate waste management are among the primary sources of marine litter. Plastic packaging and small non-packaging plastic items (PPSI) represent the most extensive application of virgin plastics produced and the largest fraction of post-consumer plastic waste. Moreover, PPSI are amongst the top recognizable litter items recorded on European beaches. This study aimed to estimate mismanaged PPSI waste generated in 33 countries in Europe, as well as in coastal territories bordering European seas. A material flow analysis was performed for each country for 2012 and 2018. The results indicate that most countries generated higher amounts of PPSI waste in 2018, both in absolute amounts and per capita. We estimate that 26.1 million tons of PPSI waste were generated in 2018 in the whole region, corresponding to 42.9 kg per capita (compared to 38.7 kg in 2012). This was also the case for mismanaged PPSI waste, with 3.01 million tons estimated for 2018, compared to 2.90 million tons in 2012, even if most countries managed to reduce their shares of mismanaged PPSI waste. Furthermore, differences in litter pressure around the regional seas are clear, with 90% of the estimated mismanaged PPSI in European coastal territories being generated in the Mediterranean and the Black Sea regions. Limitations related to data gaps and reporting lead to significant uncertainties in our estimations, even if the study made use of officially reported data from European countries. Our study suggests that reductions in the share of mismanaged PPSI waste seem to be mainly driven by efforts at the end-of-life stages of plastics (i.e., waste collection, recycling, disposal) but that these were not sufficient to offset higher amounts of PPSI waste generated in 2018, compared to 2012. Furthermore, exports of plastic waste, including from EU countries, may result in intensified shares of mismanaged PPSI. Responses on both waste management and waste prevention are needed to transition to a circular economy and to reduce the amount of plastic waste that ends up in the marine environment.

Ten priority questions for increasing the consistency and success in hatchery production of the European flat oyster for habitat restoration

The European flat oyster, Ostrea edulis, once formed extensive reef habitats throughout European seas and estuaries. These reefs are now largely functionally extinct, yet interest and support for their restoration is rapidly growing. A major bottleneck to scaling up oyster reef restoration is the lack of available oysters to supply the growing demand. This study aimed to identify the ten questions which, if answered, would increase the consistency and success in hatchery production of O. edulis for habitat restoration. Candidate questions were submitted by representatives from twelve commercial and research hatcheries across Europe. The list of 98 candidate questions were collaboratively discussed by experts from nine research hatcheries across eight countries in Europe, to identify the top ten questions via an iterative and open process. Questions were grouped into the following themes: conditioning and feeding, larval rearing, disease and water quality, hatchery protocol, genetics, and hatchery management. There were several overarching topics spanning these themes, including diet optimisation, maximising the effective population size, and developing the technical skillbase in order to increase hatchery production to meet the projected increase in demand for oyster seed for habitat restoration efforts. We anticipate this list will provide a starting point for collaborative research efforts across Europe, as well as assisting policy makers and funders in identifying key knowledge gaps.

To Value or Not to Value? Status of Mapping and Assessment of Marine Ecosystem Services in the European Seas

To Value or Not to Value? Status of Mapping and Assessment of Marine Ecosystem Services in the European Seas

Assessment of OLCI-A Derived Aquatic Optical Properties Across European Seas

Assessment of OLCI-A Derived Aquatic Optical Properties Across European Seas

Coherent and Cross-compliant Ocean Governance for Delivering the Green Deal for European Seas

Coherent and Cross-compliant Ocean Governance for Delivering the Green Deal for European Seas

Aggregating Sea Surface Hydrodynamic Forecasts From Multi-Models for European Seas

Aggregating Sea Surface Hydrodynamic Forecasts From Multi-Models for European Seas

Climate-induced changes in ocean productivity and food-web functioning are projected to markedly affect European fisheries catch

In European waters, climate-induced changes in ocean conditions will alter marine ecosystems, leading to potential repercussions for the European fisheries and the status of exploited species. Here, we used a new version of the EcoTroph model, forced by a regional high-resolution coupled hydrodynamic-ecosystem model, to investigate the effects of climate change on biomass and catch in 15 areas (ICES divisions) of the European Atlantic shelf ecosystems. Based on the projected changes in temperature, zooplankton and benthic secondary producers, we modeled the changes in biomass and catch at each trophic level by the end of the 21st century. We projected that total biomass and catch for the whole Atlantic European seas would decrease by 11.5 and 10.0%, respectively, by 2090-2099 relative to 2013-2017 under a ‘no mitigation’ greenhouse gases emissions scenario (RCP8.5). The projected decrease in catch is 310000 or 240000 t by 2090-2099 under a high (RCP8.5) or a moderate (RCP4.5) emissions scenario, respectively. Some areas, such as the Celtic Sea, would be more affected than others, while the climate impact on the bentho-demersal biomass and catches would be more pronounced, especially toward the higher trophic levels. Our study suggests that climate change may strongly impact European fisheries, with ecological consequences and potential socio-economic repercussions. Future studies using alternative climate and ecosystem models would allow the exploration of uncertainties in projected biomass and catch. While fisheries management is required to adapt to these changes, the projected impacts on catch cannot be avoided without aggressive mitigation of greenhouse gas emissions.

Testing the bottom-up hypothesis for the decline in size of anchovy and sardine across European waters through a bioenergetic modeling approach

Small pelagic fish have shown a general decrease in size and body condition over the past two decades in several European regional seas. Although the underlying processes are still not well understood, recent studies point to a bottom-up control. In order to better understand how the environment impacts the main individual life history traits, which themselves control the dynamic of the population, we developed a comparative approach between two species, European anchovy and sardine, and across three regions of the Northeast Atlantic and Mediterranean Sea: the English Channel in the north, to the Bay of Biscay and the Gulf of Lion in the south. We developed a bioenergetic modeling framework based on the Dynamic Energy Budget theory (DEB). Our DEB models were forced using two different representations of the lower trophic levels, POLCOMS-ERSEM and SEAPODYM models. Our models were calibrated for the Bay of Biscay and then projected on to the other regions, over the early 2000s (period with bigger fish) and the early 2010s (period with smaller fish). The environment alone, temperature and zooplankton, explained a significant part of the observed regional differences in growth. However, the temporal trends simulated by the lower trophic levels models, when transcribed through bioenergetics, could not explain the strong decrease in length and weight that occurred in the Bay of Biscay (-30 % in weight for anchovy and −20 % for sardine) and in the Gulf of Lion (-30 % for anchovy and −50 % for sardine). Through a scenario approach, we estimated that a decrease in zooplankton quality could be a significant driver of the observed decrease in size both in the Bay of Biscay and in the Gulf of Lion (decrease in assimilable energy of 4 to 5 % and 15 to 17 % in the Bay of Biscay and the Gulf of Lion, respectively). For such a decrease in size, a zooplankton biomass of the same quality should have been reduced by between 17 and 31 % in the Bay of Biscay over a 10- to 15-year period, while no biologically realistic estimations were obtained for the Gulf of Lion. The validity of these proposed changes in biomass and quality is discussed in context of alternative explanations.

Пленерът „Художници, Балчик, любов – среща на европейски морета“ – двадесет години присъствие на картата на съвременното българско изкуство

Over its 20-year existence, the plein air “Artists, Balchik, Love – A Meeting of European Seas” has accumulated a rich history. In all editions so far, 55 artists have taken part. This report analyzes the works created during the plein air, as well as the trends that have emerged as genres and stylistics. It is natural for so many different participants to see a great variety of paintings and creative results. Some of them even started whole cycles of works. The landscape genre dominates (natural, sea, and urban landscapes), but we also observe more decorative and abstract compositions. The authors are studied by the type of genre in which they have worked, comparing their individual creativity and outlining general trends. One of the main conclusions is that, in such a long-term plein air, most of the trends characteristic of Bulgarian painting over the past two decades can be observed.

Приложение към: Силвия Басева. Пленерът „Художници, Балчик, любов – среща на европейски морета“ – двадесет години присъствие на картата на съвременното българско изкуство

Приложение към: Силвия Басева. Пленерът „Художници, Балчик, любов – среща на европейски морета“ – двадесет години присъствие на картата на съвременното българско изкуство

Status and Trends in the Rate of Introduction of Marine Non-Indigenous Species in European Seas

Invasive alien species are a major worldwide driver of biodiversity change. The current study lists verified records of non-indigenous species (NIS) in European marine waters until 2020, with the purpose of establishing a baseline, assessing trends, and discussing appropriate threshold values for good environmental status (GES) according to the relevant European legislation. All NIS records were verified by national experts and trends are presented in six-year assessment periods from 1970 to 2020 according to the European Union Marine Strategy Framework Directive. Altogether, 874 NIS have been introduced to European marine waters until 2020 with the Mediterranean Sea and North-East Atlantic Ocean hosting most of the introductions. Overall, the number of new introductions has steadily increased since 2000. The annual rate of new introductions reached 21 new NIS in European seas within the last six-year assessment period (2012–2017). This increase is likely due to increased human activities and research efforts that have intensified during the early 21st century within European Seas. As Europe seas are not environmentally, nor geographically homogenous, the setting of threshold values for assessing GES requires regional expertise. Further, once management measures are operational, pathway-specific threshold values would enable assessing the effectiveness of such measures.

European journalists and the sea: Contexts, motivations, and difficulties.

The media play an important role in informing us about new developments in our understanding of the sea and raising awareness about its sustainability. However, press coverage of marine issues seems to be modest, compared with the importance oceans have in our lives. In this study, we examine science journalists' working contexts, motivations, and difficulties in writing about the sea in Europe. We conducted semi-structured interviews with 26 journalists who write for quality newspapers from 13 European countries. We found that the recent production of press news on marine issues is mainly conditioned by working contexts in newspapers, the personal and professional interests of journalists, and the available resources to write news. More studies are needed to compare our findings, including with other regions outside Europe.

A gigantic bizarre marine turtle (Testudines: Chelonioidea) from the Middle Campanian (Late Cretaceous) of South-western Europe

Marine turtles were common in the subtropical Upper Cretaceous epi-continental seas that once washed the coasts of the ancient European archipelago. But unlike its contemporaneous faunas from North America, in Europe no taxon surpassed the 1.5 m shell-length. Here, the remains of a new large marine turtle, Leviathanochelys aenigmatica gen. et sp. nov., from the Middle Campanian of the Southern Pyrenees are described. Anatomical and histological evidence concur in identifying the specimen as a basal chelonioid. The new taxon autapomorphically differs from other marine turtles by possessing an additional process on the anteromedial side of the pelvis, and an acetabulum directed strongly ventrally. Based on the pelvis size, it is likely that Leviathanochelys was as large as Archelon, thus becoming one of the largest marine turtles found to ever exist. The large body size of the new taxon could have evolved as a response to the unique habitat conditions of the European Cretaceous archipelago seas. The presence of the accessory pubic process further suggests the occurrence of an additional insertion point of the Musculus rectus abdominis, which together with the paleohistologic evidences support the hypothesis that the new taxon had an open marine pelagic lifestyle.