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International audience; Seagrass meadows and their associated biodiverse assemblages have declined globally due to environmental and anthropogenic stressors. Restoration of these critical habitats has the potential to reverse coastal biodiversity loss. Here, we tested the role of patch size (which can affect recruitment, food availability, and/or predation) in driving faunal colonization in an eelgrass (Zostera marina) restoration trial in Sweden. Eelgrass shoots were transplanted in plots with different configurations (continuous vs. checkerboard patterns with three patch sizes), and we followed invertebrate colonization (biodiversity and functional diversity) during the first two growing seasons. We found rapid faunal colonization following the transplantation of eelgrass shoots in all plots with invertebrate densities reaching 50-80% of the reference meadow after only one growing season (3 months). After two growing seasons (15 months), the faunal density, biodiversity, and functional diversity were similar to the reference meadow, despite eelgrass density and biomass still being lower than the reference meadow. Biodiversity, functional diversity, and community structure were similar among the different planted plots, that is, there was no indication that patch size influenced faunal colonization. We therefore consider that smaller patches embedded within larger restoration plots can be as effective for promoting biodiversity as continuous patches, with reduced costs and fewer shoots required. We also noted high natural variability between years both in the reference meadow and planted plots, showing the dynamic nature of seagrass ecosystems, and the importance of a well-planned monitoring scheme that considers the reference area and restored area within the same temporal scale.

Currents are unique drivers of oceanic phylogeography and so determine the distribution of marine coastal species, along with past glaciations and sea level changes. Here, we reconstruct the worldwide colonization history of eelgrass (Zostera marinaL.), the most widely distributed marine flowering plant or seagrass from its origin in the Northwest Pacific, based on nuclear and chloroplast genomes. We identified two divergent Pacific clades with evidence for admixture along the East Pacific coast. Multiple west to east (trans-Pacific) colonization events support the key role of the North Pacific Current. Time-calibrated nuclear and chloroplast phylogenies yielded concordant estimates of the arrival ofZ. marinain the Atlantic through the Canadian Arctic, suggesting that eelgrass-based ecosystems, hotspots of biodiversity and carbon sequestration, have only been present since ∼208 Kya (thousand years ago). Mediterranean populations were founded ∼53 Kya while extant distributions along western and eastern Atlantic shores coincide with the end of the Last Glacial Maximum (∼20 Kya). The recent colonization and 5-to 7-fold lower genomic diversity of Atlantic compared to the Pacific populations raises concern and opportunity about how Atlantic eelgrass might respond to rapidly warming coastal oceans.

Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems., This work was supported by the US NSF (OCE-1031061, OCE-1336206, OCE0-1336741, OCE-1336905) and the Smithsonian Institution. F.T. was supported by José Castillejo Award CAS14/00177. A.H.E. was supported by the FCT (Foundation for Science and Technology) through Project UIDB/04326/2020 and Contract CEECINST/00114/2018. This is Contribution 106 from the Smithsonian’s MarineGEO and Tennenbaum Marine Observatories Network and Contribution 4105 of the Virginia Institute of Marine Science, College of William & Mary.

While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change., This research was funded by National Science Foundation grants to J.E.D., J.J.S. and K.A.H. (NSF-OCE 1336206, OCE 1336905, and OCE 1336741). C.B. was funded by the Åbo Akademi University Foundation.

Kustekosystemen är mycket viktiga för både biologisk mångfald och ekosystemtjänster, men påverkas samtidigt negativt av ett kontinuerligt ökat nyttjande av kustzonen för boende och olika verksamheter. Ekologisk kompensation är ett förvaltningsverktyg som syftar till att gottgöra oundviklig skada på naturmiljöer, exempelvis arter, naturtyper, ekosystemfunktioner och upplevelsevärden, i samband med mänsklig verksamhet. Verktyget har dock hittills använts i mycket begränsad omfattning i grunda kustmiljöer. Inom projektet ECOCOA, finansierat av Naturvårdsverket, har vi fokuserat på att utvärdera förutsättningarna för ökad användning av ekologisk kompensation i kustområden, som ett av flera verktyg som kan stöda miljövården. Projektets slutrapport (Bergström m.fl. 2021) ger en övergripande bild av samtliga resultat, medan vi i föreliggande rapport ger en fördjupning av de mer konkreta problem som kan uppstå vid handläggning av miljöärenden i förvaltningen, och möjliga lösningar på kort och lång sikt. Rapporten riktar sig i första hand till handläggare som vill utveckla tillämpningen av ekologisk kompensation vid vattenverksamhetsärenden, till tekniska råd vid markoch miljödomstolar, samt miljökonsulter och andra som kan behöva insyn i hur ekologisk kompensation kan användas och vidareutvecklas inom svensk kustmiljöförvaltning. I rapporten återger vi hur man hanterar ekologisk kompensation i svenska kustområden idag, till exempel hur handläggare arbetar med att mäta skada och bedöma omfattningen av kompensationsbehov. Vi beskriver även problematiken med småskaliga anmälningspliktiga ärenden, där den sammanlagda påverkan från många små exploateringar ger upphov till betydande förluster av biologisk mångfald och ekosystemtjänster. Slutligen beskriver vi hur den så kallade särskilda fiskeavgiften, som syftar till att tillvarata fiskeintresset i samband med vattenverksamhetsfrågor, tillämpas idag, samt analyserar hur beräkningsgrunderna skulle kunna utvecklas för att stärka användningen av ekologisk kompensationen som verktyg. Vår sammanställning och utvärdering utgår från ett generellt ramverk som utvecklats inom ECOCOA för att skatta skada och identifiera kompensationsbehov. Ramverket baseras på en kaskadmodell, som visar kopplingar mellan ekosystemets struktur, funktion, ekosystemtjänster och nyttigheter för människor. Modellen kan användas för att synliggöra hur verksamheter påverkar arter och livsmiljöer och vilka kostnader och förluster detta medför. Ramverket kan även användas för att bedöma i vilken omfattning en föreslagen åtgärd faktiskt kompenserar för de förluster som verksamheten innebär. Här följer en kort sammanfattning av resultaten som presenteras i rapporten: • En enkätundersökning riktad till aktörer inom kustförvaltningen visar att ekologisk kompensation i praktiken tillämpas mycket sällan inom kustmiljöförvaltningen idag, och att det finns ett stort behov av att ta fram riktlinjer för dess tillämpning, som stöd till handläggare, konsulter, domstolar och andra aktörer. På en mer generell nivå omfattar detta även ett behov av att förbättra kunskapen om restaureringsmetoder samt att ta fram metoder för värdering av skador på naturvärden. Det finns även ett behov av resurser för Sammanfattning 6 handläggare i form av tid och stöd för att tillämpa ekologisk kompensation i kustförvaltningen. • En utvärdering av befintliga domslut för ett antal tillståndspliktiga (dvs. storskaliga) vattenverksamhetsärenden visar att biologisk mångfald och ekosystemtjänster mycket sällan beaktas på ett sätt som är i linje med Sveriges åtaganden inom till exempel konventionen för biologisk mångfald och EU:s biodiversitetstrategi, där en bärande princip är att ingen nettoförlust ska ske. Det finns ett förbättringsutrymme som borde kunna mötas direkt genom en ökad kunskapsdelning mellan aktörer, och en förbättrad praxis gällande tillämpning av ekologisk kompensation. Samtidigt uppstår flera mer komplexa frågor som berör till exempel behovet av en gemensam fysisk planering och identifiering av lämpliga kompensationsåtgärder, där ett kunskapsbyggande behövs. • Småskalig kustexploatering, exempelvis bryggbyggen och små muddringar, är en särskilt utmanande fråga. Enskilda små ingrepp är anmälningspliktiga (dvs. sällan tillståndspliktiga), och trots att det vid handläggningen av dessa ärenden ställs krav på miljöhänsyn kan det ofta inte bedömas som skäligt att kräva att exploatören själv utför ekologisk kompensation. Den sammanlagda påverkan av dessa många små ingrepp är dock betydande, och det är angeläget att utforma ett system där även småskalig vattenverksamhet kompenserar för sina miljökostnader. Vi undersöker hur ett system för ekologisk kompensation som även omfattar småskalig exploatering skulle kunna se ut, i relation till konceptet habitatbanker eller kompensationspooler, där exploatören kan bidra ekonomiskt till habitatrestaureringar i stället för att själv utföra dem. • Den särskilda fiskeavgiften syftar till att kompensera för skador från vattenverksamheter på fisket och skulle kunna betraktas som ett förvaltningsverktyg för kompensation av en viss typ av förlust. I rapporten utvärderar vi hur det rådande fiskeavgiftssystemet fungerar och utforskar hur det kan fungera ur ett kompensationsperspektiv, samt ger förslag på hur beräkningsmodellen kan utvecklas. Sammantaget finns det ett stort behov av att utveckla ekologisk kompensation som ett av de verktyg som kan bidra till att motverka den allt snabbare förlusten av biologisk mångfald och ekosystemfunktioner. Parallellt behövs ytterligare åtgärder för att stärka skyddet av de känsligaste livsmiljöerna i kustzonen, eftersom bevarande av fungerande livsmiljöer är att föredra som ett mer kostnadseffektivt verktyg än restaurering av störda miljöer.

According to the EU Habitats directive, the Water Framework Directive, and the Marine Strategy Framework Directive, member states are required to map, monitor, and evaluate changes in quality and areal distribution of different marine habitats and biotopes to protect the marine environment more effectively. Submerged aquatic vegetation (SAV) is a key indicator of the ecological status of coastal ecosystems and is therefore widely used in reporting related to these directives. Environmental monitoring of the areal distribution of SAV is lacking in Sweden due to the challenges of large-scale monitoring using traditional small-scale methods. To address this gap, in 2020, we embarked on a project to combine Copernicus Sentinel-2 satellite imagery, novel machine learning (ML) techniques, and advanced data processing in a cloud-based web application that enables users to create up-to-date SAV classifications. At the same time, the approach was used to derive the first high-resolution SAV map for the entire coastline of Sweden, where an area of 1550 km2 was mapped as SAV. Quantitative evaluation of the accuracy of the classification using independent field data from three different regions along the Swedish coast demonstrated relative high accuracy within shallower areas, particularly where water transparency was high (average total accuracy per region 0.60-0.77). However, the classification missed large proportions of vegetation growing in deeper water (on average 31%-50%) and performed poorly in areas with fragmented or mixed vegetation and poor water quality, challenges that should be addressed in the development of the mapping methods towards integration into monitoring frameworks such as the EU directives. In this article, we present the results of the first satellite-derived SAV classification for the entire Swedish coast and show the implementation of a cloud-based SAV mapping application (prototype) developed within the frame of the project. Integr Environ Assess Manag 2021;00:1-12. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Estuaries are important nursery areas for many species and these habitats are often affected by anthropogenic activities. We investigate possible negative effects of pesticides and metals on penaeid shrimps in Maputo Bay, Mozambique. Shrimps and water samples were collected in three estuaries and one coastal area for biomarker and chemical analysis. Acetylcholinesterase (AChE) and glutathione-S transferase activities were analysed as biomarkers for pollutants. 37 different pesticides were analysed in water samples and shrimp muscle tissue was analysed for 10 metals. Risk assessment showed that the environmental thresholds were exceeded for several herbicides in three of four of the assessed nursery areas. Lower AChE activities were detected in shrimps captured close to an agriculture area and this location had the lowest shrimp densities. Metal analysis in shrimp showed low levels. Despite localized effects, results highlight the need to improve the regulation of pollutants in the Espirito Santo estuary in Maputo bay.

There is growing awareness that ocean life is under unprecedented stress caused by the loss of habitat and biodiversity resulting from human activities. Spatial management by establishing marine protected areas (MPAs) is proposed as an important method to conserve biodiversity, manage fisheries, and increase ecosystem resilience. However, a major challenge in spatial management is that most MPAs and networks of MPAs have been created with little regard to larval dispersal and connectivity within and outside protected areas. Because of the limited understanding of larval connectivity, it is therefore often unclear whether the MPAs are ecologically functional. Larval behavior and dispersal are particularly well studied in benthic crustaceans, making them excellent model organisms to address this challenge.

The eelgrass Zostera marina is an important foundation species of coastal areas in the Northern Hemisphere, but is continuing to decline, despite management actions. The development of new management tools is therefore urgent in order to prioritize limited resources for protecting meadows most vulnerable to local extinctions and identifying most valuable present and historic meadows to protect and restore, respectively. We assessed 377 eelgrass meadows along the complex coastlines of two fjord regions on the Swedish west coast-one is currently healthy and the other is substantially degraded. Shoot dispersal for all meadows was assessed with Lagrangian biophysical modeling (scale: 100-1,000 m) and used for barrier analysis and clustering; a subset (n = 22) was also assessed with population genetic methods (20 microsatellites) including diversity, structure, and network connectivity. Both approaches were in very good agreement, resulting in seven subpopulation groupings or management units (MUs). The MUs correspond to a spatial scale appropriate for coastal management of "waterbodies" used in the European Water Framework Directive. Adding demographic modeling based on the genetic and biophysical data as a third approach, we are able to assess past, present, and future metapopulation dynamics to identify especially vulnerable and valuable meadows. In a further application, we show how the biophysical approach, using eigenvalue perturbation theory (EPT) and distribution records from the 1980s, can be used to identify lost meadows where restoration would best benefit the present metapopulation. The combination of methods, presented here as a toolbox, allows the assessment of different temporal and spatial scales at the same time, as well as ranking of specific meadows according to key genetic, demographic and ecological metrics. It could be applied to any species or region, and we exemplify its versatility as a management guide for eelgrass along the Swedish west coast.

Maintaining and enabling evolutionary processes within meta‐populations are critical to resistance, resilience and adaptive potential. Knowledge about which populations act as sources or sinks, and the direction of gene flow, can help to focus conservation efforts more effectively and forecast how populations might respond to future anthropogenic and environmental pressures. As a foundation species and habitat provider, Zostera marina (eelgrass) is of critical importance to ecosystem functions including fisheries. Here, we estimate connectivity of Z. marina in the Skagerrak–Kattegat region of the North Sea based on genetic and biophysical modelling. Genetic diversity, population structure and migration were analysed at 23 locations using 20 microsatellite loci and a suite of analytical approaches. Oceanographic connectivity was analysed using Lagrangian dispersal simulations based on contemporary and historical distribution data dating back to the late 19th century. Population clusters, barriers and networks of connectivity were found to be very similar based on either genetic or oceanographic analyses. A single‐generation model of dispersal was not realistic, whereas multigeneration models that integrate stepping‐stone dispersal and extant and historic distribution data were able to capture and model genetic connectivity patterns well. Passive rafting of flowering shoots along oceanographic currents is the main driver of gene flow at this spatial–temporal scale, and extant genetic connectivity strongly reflects the “ghost of dispersal past“ sensu Benzie, 1999. The identification of distinct clusters, connectivity hotspots and areas where connectivity has become limited over the last century is critical information for spatial management, conservation and restoration of eelgrass.

Along the Swedish northwest coast, over 60% of the eelgrass meadows have been lost since the 1980s. Despite improved water quality, no recovery has occurred, and restoration is presently considered to mitigate historical losses. However, the factors preventing natural recovery of eelgrass are not known, and it is not clear if conditions would allow restoration. Here, we present the results from 5 years of field studies with the aim of identifying the key processes affecting eelgrass growth and survival at historical eelgrass areas. Continuous light measurements and comparison with historic eelgrass distribution indicate that maximum depth distribution has decreased locally with 1.5–2.3 m in areas that have lost large eelgrass beds in the last 10–30 years. Field studies suggest that wind-driven local resuspension of sediments that are no longer stabilized by eelgrass beds is the main cause behind the deteriorated light conditions. Field experiments show that a combination of low light condition and disturbance from drifting algal mats prevents eelgrass recovery in these areas, whereas the sulfide intrusion from the sediment and dislodgement of shoots by waves had little effect on growth and survival. These results suggest that local regime shifts acting on a scale of 40–200 ha have occurred after the loss of eelgrass beds, where increased sediment resuspension and proliferation of drifting algal mats act as feedback mechanisms that prevent both natural recovery and restoration of eelgrass. The feedbacks appear to be interacting and causing an accelerating loss of eelgrass that is presently spreading to neighboring areas.

Form–function relationships in plants underlie their ecosystem roles in supporting higher trophic levels through primary production, detrital pathways, and habitat provision. For widespread, phenotypically-variable plants, productivity may differ not only across abiotic conditions, but also from distinct morphological or demographic traits. A single foundation species, eelgrass Zostera marina, typically dominates north temperate seagrass meadows, which we studied across 14 sites spanning 32–61°N latitude and two ocean basins. Body size varied by nearly two orders of magnitude through this range, and was largest at mid-latitudes and in the Pacific Ocean. At the global scale, neither latitude, site-level environmental conditions, nor body size helped predict productivity (relative growth rate 1–2% day-1 at most sites), suggesting a remarkable capacity of Z. marina to achieve similar productivity in summer. Furthermore, among a suite of stressors applied within sites, only ambient leaf damage reduced productivity; grazer reduction and nutrient addition had no effect on eelgrass size or growth. Scale-dependence was evident in different allometric relationships within and across sites for productivity and for modules (leaf count) relative to size. Zostera marina provides a range of ecosystem functions related to both body size (habitat provision, water flow) and growth rates (food, carbon dynamics). Our observed decoupling of body size and maximum production suggests that geographic variation in these ecosystem functions may be independent, with a future need to resolve how local adaptation or plasticity of body size might actually enable more consistent peak productivity across disparate environmental conditions.

Eelgrass (Zostera marina) flowering development and seed production were assessed along a depth gradient at three sites during 2012 and 2013 to 1) describe the flowering seasonality in the Swedish west coast, and 2) evaluate methods using seeds for large-scale restoration, including harvesting, storage and separation of viable seeds using a vertical flume. Eelgrass flowering shoots were found in the field from June to October, reaching the highest densities in July and August (average 3.8 ± 0.5 shoots m−2). Flowering shoot densities decreased with depth, whereas shoot length, number of spathes, seeds/shoot and seed size increased with depth, resulting in the highest seed production at intermediate depths (2 m) in most bays and years. Because of low densities of flowering shoots, seed production in Sweden (on average 39–126 seeds m−2, Jul–Sep) was an order of magnitude lower than in other studied areas. Results showed that seed production differed 2.5–3.4 times between meadows and years, mainly driven by variation in seed production per shoot. This variation was only partly explained by temperature over the growing season, suggesting that other factors such as light and the amount of filamentous algal mats might also be important in flower development. Results suggest that flowering shoots should be harvested when >50% of the spathes have developing seeds, and that shoots should not be stored longer than 40 days in tanks to obtain an optimal release of viable seeds. A new mechanized method using a vertical flume to separate large amounts of viable seeds from the harvest is also presented.

Environmental compensation should address negative impacts from human activities on nature, including loss of biodiversity and ecosystem services. However, successful compensation, achieving no net loss, requires broad quantitative information on different types of losses and gains. We find that the scope of compensatory schemes varies in what is considered compensable, which makes it challenging to apply a conceptual approach consistently across schemes with different needs. We propose a flexible yet structured framework for determining which values should be compensated and how. Our framework focuses specifically on habitat deterioration and is illustrated with a case study involving loss of eelgrass habitat. The framework helps identify compensation needs and selects among suitable compensation options, merging science-based information with normative issues and local concerns. By integrating the ecosystem services cascade model, it encompasses aspects from biodiversity structure to human wellbeing. The framework prefers in-kind compensation because this targets the structure level and thus meets compensation needs in all subsequent levels of the cascade model; further, it is more likely to capture non-instrumental values (i.e. in nature) and reduce exposure to uncertainty. We highlight the importance of spatial aspects of ecosystem functions, services and their subsequent impacts on wellbeing. Although our selection hierarchy assumes a “similar and nearby” principle for habitat restoration (preference for in-kind/on-site), this criterion is not universal. We underscore the hierarchy’s implicit normative assumptions and suggest that apparent disagreement about who should benefit may be traced to an unresolved conflict between egalitarianism and utilitarianism.

Anthropogenic impacts on coastal areas have led to an increased degradation of marine environments globally. Eelgrass ecosystems are particularly susceptible to human induced stressors as they are sensitive to low light conditions and usually grow in shallow protected areas where pressure from coastal development is high. The extensive decline in coverage of eelgrass along the Swedish Northwest coast since the 1980s has largely been attributed to the effects of coastal eutrophication and overfishing. However, the impact on eelgrass from small-scale coastal development (docks and marinas) has never been investigated in this area. The aim of this study was to assess the local and large-scale effect of shading by docks and marinas on eelgrass habitats along the Swedish NW coast and to investigate the decision process behind small-scale exploitation to identify problems with the current legislation, which allows for continued exploitation of eelgrass. Through field assessments of eelgrass around docks and analysis of available data on eelgrass and dock distribution along the coast, the present study demonstrates that shading from docks reduced eelgrass coverage with on average 42–64% under and adjacent to the docks, and that floating docks affected larger areas and caused a much stronger reduction in eelgrass coverage (up to 100% loss) compared to docks elevated on poles (up to 70% reduction in coverage). The total eelgrass area negatively affected by docks and marinas along the NW coast was estimated to approximately 480 ha, an area corresponding to over 7% of the present areal coverage of eelgrass in the region. The analysis of decisions for dock construction showed that eelgrass was generally not assessed or considered in the decision process and that 69–88% of the applications were approved also in areas where eelgrass was present. Furthermore, marine protected areas only marginally reduced the approval of applications in eelgrass habitats. The continued small-scale development along the Swedish NW coast constitutes a significant threat to the already decimated coverage of eelgrass along the coast and changes in the management practices are needed in order to achieve both national and international goals on environmental status.

More than 50% of eelgrass habitats have disappeared from the Swedish NW coast in the last 30 years. Restoration is being proposed to assist recovery but little is known regarding methods suitable under Scandinavian conditions; e.g. short growing seasons and scouring by ice. In the present study we evaluated different restoration methods using shoots and seeds in a Swedish fjord and assessed if eelgrass could be successfully transplanted between sites with different depth and exposure. The study demonstrates that both shoot- and seed methods can be successfully used to restore eelgrass at this latitude. Survival and growth of unanchored single shoots, transplanted without sediment in shallow habitats (1.0-1.5 m) was very high (>500% increase in shoot density after 14 months). This restoration method showed 2-3.5 times higher growth rate and was 2-2.5 times faster compared with shoots anchored in the sediment and shoots transplanted in sediment cores, respectively, and is recommended for shallow habitats in Sweden. Growth within deeper habitats (3.0-4.5 m) was substantially tower (40% loss to 50% increase) due to light limitations and high winter mortality. Restoration using seeds distributed from mesh-bags showed very low seedling establishment rates (approximately 1%) making this method less cost-effective than transplanting single shoots in shallow habitats. However, growth of seedlings was high and this method is recommended for deep habitats with soft sediment where shoot transplantation is difficult. Despite dramatic differences in eelgrass morphology between habitats with different depth and exposure, all shoots within a planting site had the same morphology at the end of the study, independent of origin. A baseline genetic survey supported that the observed changes in morphology of transplants were due to a plastic response, suggesting that donor populations do not have to exactly match the morphology of the plants targeted for restoration. (C) 2016 Elsevier B.V. All rights reserved.

Cod stocks in the North Sea, including the Kattegat and the Skagerrak, have declined dramatically since the 1970s. Occasionally there is a high recruitment of juveniles in Kattegat/Skagerrak, without leading to the rebuilding of adult cod stocks despite reduced fishing mortality. In a biophysical model of egg and larval drift, we examined the potential importance of extant and historical spawning grounds for recruitment of cod in the Kattegat/Skagerrak seas using data of spawning stock biomass from the 1970s and from today's reduced stocks. The results suggest that Kattegat in the 1970s relied on largely locally retained (83%) larvae with little annual variation in recruitment. Kattegat also provided a substantial proportion of larvae recruiting in Swedish Skagerrak (72%). This is in contrast to present conditions where the Kattegat spawning stock has been reduced by 94%, and Kattegat only provides 34% of locally retained larvae and 30% to Swedish Skagerrak. Instead, the protected area in the Oresund and the Belt Sea are expected today to provide most larvae recruiting in Kattegat. Also, the inflow of larvae from the North Sea to Skagerrak and Kattegat can be significant although highly variable between years, with a positive correlation to the North-Atlantic Oscillation index (NAO). The rebuilding of healthy spawning areas in the Kattegat may be key for restoring local cod stocks in both Kattegat and along the Skagerrak coast. This poses a management challenge if cod with local ‘Kattegat’ adaptations, e.g., in terms of egg density and migration patterns, are lost or reduced to non-resilient densities.

Along the northwest coast of Sweden, over 50% of Zostera marina L. (eelgrass) meadows have vanished since the 1980s. With the improvement of conditions, there is a growing interest to restore lost habitats, but methods are lacking for restoration of eelgrass beds at high latitudes where long winters create special challenges. We assessed if seed planting could be used for large-scale restoration, with the aim to identify the major causes of seed and seedling loss and to determine which planting method best increases restoration success. In the laboratory, we identified optimal conditions for long-term seed storage and demonstrated that eelgrass seeds can be successfully stored for 8 mo before being planted in the spring. However, field studies did not find an increased seedling establishment in seeds planted in the spring of 2013 compared to those planted in the fall of 2012. Field results suggest that the main causes for the seed loss were seed predation from crabs, seed transport by currents and bioturbation by lugworms, while the main processes affecting shoot development were light availability and physical disturbance. Covering the seeds with a layer of sand increased seedling establishment 2 to 6 times compared to uncovered seeds, probably through the reduction of seed predation and seed transport, and could potentially be developed as a method to reduce losses during restoration. In addition, positive feedback mechanisms (i.e. sediment resuspension and drifting macroalgae mats) may also prevent natural recovery and restoration success. However, high seed loss (on average 98.6%) and high shoot mortality pose a challenge that need to be addressed before restoration using seeds can be recommended for large-scale restoration.

Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment but global estimates are uncertain partly due to spatio-temporal heterogeneity between areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass (Zostera marina) beds spanning the distributional range of the Northern Hemisphere. Depth profiles revealed three patterns of vertical distribution where POC either increased, decreased or showed no distinct pattern with sediment depth. These categories exhibited distinct profiles of δ13C and C:N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high carbon density. Though high POC did not always translate into high carbon density, this large-scale dataset evidences that the variability in organic matter source in response to natural and anthropogenic environmental changes affects the potential role of eelgrass beds as POC sinks, particularly where eelgrass decline is observed.

10 pages, 7 figures, 1 table, supplementary material https://doi.org/10.1016/j.pocean.2018.10.008, In Antarctica, summer is a time of extreme environmental shifts resulting in large coastal phytoplankton blooms fueling the food web. Despite the importance of the microbial loop in remineralizing biomass from primary production, studies of how microzooplankton communities respond to such blooms in the Southern Ocean are rather scarce. Microzooplankton (ciliate and dinoflagellate) communities were investigated combining microscopy and 18S rRNA sequencing analyses in the Amundsen Sea Polynya during an extensive summer bloom of Phaeocystis antarctica. The succession of microzooplankton was further assessed during a 15-day induced bloom microcosm experiment. Dinoflagellates accounted for up to 59 % of the microzooplankton biomass in situ with Gymnodinium spp., Protoperidium spp. and Gyrodinium spp. constituting 89 % of the dinoflagellate biomass. Strobilidium spp., Strombidium spp. and tintinids represented 90 % of the ciliate biomass. Gymnodinium, Gyrodinium and tintinnids are known grazers of Phaeocystis, suggesting that this prymnesiophyte selected for the key microzooplankton taxa. Availability of other potential prey, such as diatoms, heterotrophic nanoflagellates and bacteria, also correlated to changes in microzooplankton community structure. Overall, both heterotrophy and mixotrophy appeared to be key trophic strategies of the dominant microzooplankton observed, suggesting that they influence carbon flow in the microbial food web through top-down control on the phytoplankton community, This work was supported by the Swedish Research Council [grant 2008-6430] to S. Bertilsson and L. Riemann and [grant 824-2008-6429] to P.-O. Moksnes and J. Havenhand, and by the US National Science Foundation through the ASPIRE project [NSF OPP-0839069] to P. Yager

Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37 degrees of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas insitu water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions. NSF BIO-OCE [1336206, 1336741, 1336905] info:eu-repo/semantics/publishedVersion

Adaptation to local conditions is a fundamental process in evolution; however, mechanisms maintaining local adaptation despite high gene flow are still poorly understood. Marine ecosystems provide a wide array of diverse habitats that frequently promote ecological adaptation even in species characterized by strong levels of gene flow. As one example, populations of the marine fish Atlantic cod (Gadus morhua) are highly connected due to immense dispersal capabilities but nevertheless show local adaptation in several key traits. By combining population genomic analyses based on 12K single nucleotide polymorphisms with larval dispersal patterns inferred using a biophysical ocean model, we show that Atlantic cod individuals residing in sheltered estuarine habitats of Scandinavian fjords mainly belong to offshore oceanic populations with considerable connectivity between these diverse ecosystems. Nevertheless, we also find evidence for discrete fjord populations that are genetically differentiated from offshore populations, indicative of local adaptation, the degree of which appears to be influenced by connectivity. Analyses of the genomic architecture reveal a significant overrepresentation of a large ~5 Mb chromosomal rearrangement in fjord cod, previously proposed to comprise genes critical for the survival at low salinities. This suggests that despite considerable connectivity with offshore populations, local adaptation to fjord environments may be enabled by suppression of recombination in the rearranged region. Our study provides new insights into the potential of local adaptation in high gene flow species within fine geographical scales and highlights the importance of genome architecture in analyses of ecological adaptation.

Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment, but global estimates are uncertain partly owing to spatio-temporal heterogeneity between and within areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass ( Zostera marina ) beds spanning the distributional range of the Northern Hemisphere. Depth profiles of particulate organic carbon (POC) revealed three patterns of vertical distribution where POC either increased, decreased or showed no pattern with sediment depth. These categories exhibited distinct profiles of δ 13 C and C:N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high carbon density. Nevertheless, this large-scale dataset provides evidence that the variability in organic matter source in response to natural and anthropogenic environmental changes affects the potential role of eelgrass beds as POC sinks, particularly where eelgrass decline is observed.

Valuing nature’s benefits in monetary terms is necessary for policy-makers facing trade-offs in how to spend limited financial resources on environmental protection. We provide information to assess trade-offs associated with the management of seagrass beds, which provide a number of ecosystem services, but are presently impacted by many stressors. We develop an interdisciplinary framework for valuing multiple ecosystem services and apply it to the case of eelgrass (Zostera marina), a dominant seagrass species in the northern hemisphere. We identify and quantify links between three eelgrass functions (habitat for fish, carbon and nitrogen uptake) and economic goods in Sweden, quantify these using ecological endpoints, estimate the marginal average value of the impact of losing one hectare of eelgrass along the Swedish northwest coast on welfare in monetary terms, and aggregate these values while considering double-counting. Over a 20 to 50 year period we find that compared to unvegetated habitats, a hectare of eelgrass, including the organic material accumulated in the sediment, produces an additional 626 kg cod fishes and 7,535 wrasse individuals and sequesters 98.6 ton carbon and 466 kg nitrogen. We value the flow of future benefits associated with commercial fishing, avoided climate change damages, and reduced eutrophication at 170,000 SEK in 2014 (20,700 US$) or 11,000 SEK (1,300 US$) annualized at 4%. Fish production, which is the most commonly valued ecosystem service in the seagrass literature, only represented 25% of the total value whereas a conservative estimate of nitrogen regulation constituted 46%, suggesting that most seagrass beds are undervalued. Comparing these values with historic losses of eelgrass we show that the Swedish northwest coast has suffered a substantial reduction in fish production and mineral regulation. Future work should improve the understanding of the geographic scale of eelgrass functions, how local variables affect the value of these functions, and how to defensibly aggregate a multitude of economic values.

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors. National Science Foundation [OCE-1031061] info:eu-repo/semantics/publishedVersion

Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010 ‒ 2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼ 4.5 individuals × 1,000 m(-2) within a depth range of 1,100 ‒ 1,500 m (overall observed depth range 841-2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (