• Energy Research

Eelgrass Zostera marina L. meadows are major structural and trophic components of coastal ecosystems. The role of eelgrass in ecosystem functioning depends on biomass and production of the meadows, which can fluctuate greatly during an annual cycle and be major temporal drivers of changes in the coastal zone. We analysed magnitude and seasonality of eelgrass aboveground biomass, shoot density and production across temperature and latitude gradients over the majority of the species' distributional range, and investigated to what extent temperature and/or light drive differences in these values. Eelgrass phenology (timing of peak biomass, start and end of the growing season) showed strong effects of temperature and latitude, indicating that seasonality was considerably advanced in warm areas at low latitudes compared to cold areas at high latitudes. Magnitude of peak aboveground biomass, length of the growing season, mean annual shoot density and aboveground production did not change significantly with either temperature or latitude, indicating that these parameters were controlled mainly by other factors. Annual variation in aboveground biomass and shoot density was significantly smaller in areas with low summer temperature, indicating that while warm-water populations may show substantial temporal variation in biomass, cold-water meadows are less dynamic. These findings were supported by cold-water populations having a larger mean annual biomass and a greater investment in belowground parts. In all significant regressions, temperature was a better predictor of population dynamics than latitude. This indicates that eelgrass phenology might advance considerably in response to global warming, and suggests that the distributional range of this species might be moving northwards. Given the key role of eelgrass in coastal ecosystems, these climateinduced changes might entail substantial impacts on waterbirds, fish, invertebrates and other organisms exploiting these meadows. © Inter-Research 2014. Peer Reviewed

AbstractGlobal losses over the 20th century placed seagrass ecosystems among the most threatened ecosystems in the world, with eutrophication, and associated deterioration of the submarine light environment identified as the main driver. Growing appreciation of the ecological and societal benefits of healthy seagrass meadows has stimulated efforts to protect and restore them, largely focused on reducing nutrient input to coastal waters. Here we analyze a unique data set spanning 135 years on eelgrass (Zostera marina), the dominant seagrass of the northern hemisphere. We show that meadows in the Western Baltic Sea exhibited major declines relative to historic (1890–1910) reference due to the wasting disease in the 1930s followed by eutrophication peaking in the 1980s, but have only shown modest improvement despite major eutrophication mitigation, halving nitrogen input since the 1980s. Across the past century, we identified generally shallower colonization depths of eelgrass for a given submarine light penetration and, hence, increased apparent light requirements. This suggests that eelgrass recovery is limited by additional stressors. Our study indicates that bottom trawling and intense recent warming (0.5°C per decade, 1985–2018), which impact on deeper and shallower meadows, respectively, suppress eelgrass from fully recovering from eutrophication. Warming is most severe in shallow turbid waters, while clear‐water areas offer eelgrass refugia from warming in deeper, cooler waters; but trawling can prevent eelgrass from reaching these refugia. Efforts to reduce nutrient input and thereby improve water clarity have been instrumental in avoiding a catastrophic loss of eelgrass ecosystems. However, local‐scale future management must, in addition, reduce bottom trawling to facilitate eelgrass reaching deeper, cooler refugia, and increase resilience toward realized and further warming. Warming needs to be limited by meeting global climate change mitigation goals.

This is the data used in the for the publication Global seaweed productivity

7 pages, 4 figures.-- Data availability: No data was used for the research described in the article The world is struggling to limit greenhouse gas emissions and reduce the human footprint on nature. We therefore urgently need to think about how to achieve more with actions to address mounting challenges for human health and wellbeing from biodiversity loss, climate change effects, and unsustainable economic and social development. Nature-based Solutions (NBS) have emerged as a systemic approach and an important component of the response to these challenges. In marine and coastal spaces, NBS can contribute to improved environmental health, climate change mitigation and adaptation, and a more sustainable blue economy, if implemented to a high standard. However, NBS have been largely studied for terrestrial – particularly urban – systems, with limited uptake thus far in marine and coastal areas, despite an abundance of opportunities. Here, we provide explanations for this lag and propose the following three research priorities to advance marine and coastal NBS: (1) Improve understanding of marine and coastal biodiversity-ecosystem services relationships to support NBS better designed for rebuilding system resilience and achieving desired ecological outcomes under climate change; (2) Provide scientific guidance on how and where to implement marine and coastal NBS and better coordinate strategies and projects to facilitate their design, effectiveness, and value through innovative synergistic actions; (3) Develop ways to enhance marine and coastal NBS communication, collaboration, ocean literacy and stewardship to raise awareness, co-create solutions with stakeholders, boost public and policy buy-in, and potentially drive a more sustained investment. Research effort in these three areas will help practitioners, policy-makers and society embrace NBS for managing marine and coastal ecosystems for tangible benefits to people and marine life The study received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement MaCoBioS (contract no 869710), FutureMARES (contract no 869300) and REST-COAST (contract no 101037097) With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) Peer reviewed

This study quantified climate-driven changes and spatial variability in key environmental drivers over four decades along Greenland's coastal and shelf marine ecosystems and evaluated their impacts on marine biota divided into six regions. We analyzed trends in sea ice concentration and seasonality, sea surface temperatures, salinity, and freshwater inputs from ice discharge and freshwater runoff. West, East, and Southeast Greenland were most impacted by climate change, driven by increasing sea surface temperatures (0.22-0.5 °C decade-1), freshwater inputs (10.14-24.93 Gt yr-1 decade-1), declining sea ice concentrations (3-5.3 % decade-1), and more open water days (10.92-23.9 days decade-1). The Northwest and Northeast regions appeared more resilient due to lower sea surface temperature increases (0.01-0.03 °C decade-1) and sea ice declines (0.5-2.1 % decade-1). Changes in Southwest Greenland were limited to sea surface temperature (0.27 °C decade-1) and freshwater runoff (7.66 Gt yr-1 decade-1) increases since the 1990s. Synthesized evidence from 94 marine biota time series showed 73 exhibiting significant changes, and 37 identified an environmental driver: sea ice (20), temperature (19), and runoff (2). Only four time series considered multiple drivers. Biota time series trends mirrored regional environmental changes; 78 % changed significantly in West, East and Southeast regions combined, 73 % in southwest, and 56 % in the northern regions. Fish, benthic flora, and benthic fauna responses remained unclear due to data gaps, underscoring the need for further research. In conclusion, our findings reveal widespread biological change linked to climate but with distinct regional patterns in environmental drivers and associated responses across Greenland.

Seagrasses are crucial marine ecosystems that have experienced declines due to anthropogenic and climate change impacts. The projected future climate change suggests additional seagrass losses, but no global-scale estimates are currently available on the potential changes in aboveground biomass of seagrasses. We modelled and quantified the current potential aboveground biomass (AGB) of seagrasses on the global scale and projected future AGB under contrasting Shared Socioeconomic Pathway (SSP) scenarios, from low emissions (SSP1-1.9) to high emissions (SSP3-7.0 and SSP5-8.5). A machine learning algorithm (Boosted Regression Trees) fitted a comprehensive AGB dataset against biological and anthropogenic meaningful predictors. The model performed with high accuracy (deviance explained: 0.83), highlighting the role of genus and temperature conditions in defining global AGB patterns. The model estimated a present-day average AGB of 133.83 gDW·m2 (DW, dry weight) and a total global AGB of 0.0673 Pg DW. Future projections were highly dependent on the emission scenario, with losses in AGB ranging between 4.25 % and 9.25 % and in overall AGB between 9.96 % and 10.26 % across scenarios. Particularly, the higher emission scenario projected severe regional losses along the coastlines of the Tropical Eastern Pacific, the Eastern Indo-Pacific, the Temperate Northern Pacific, and the Tropical Atlantic, and gains along the Temperate Southern Africa and the Arctic regions. Our global estimates underline that fulfilling the Paris Agreement, as well as conserving and monitoring populations most affected by combined anthropogenic pressures would help to limit seagrass AGB declines, thereby supporting the multiple ecological services of seagrasses.

AbstractWe studied the depth distribution and production of kelp along the Greenland coast spanning Arctic to sub‐Arctic conditions from 78 ºN to 64 ºN. This covers a wide range of sea ice conditions and water temperatures, with those presently realized in the south likely to move northwards in a warmer future. Kelp forests occurred along the entire latitudinal range, and their depth extension and production increased southwards presumably in response to longer annual ice‐free periods and higher water temperature. The depth limit of 10% kelp cover was 9–14 m at the northernmost sites (77–78 ºN) with only 94–133 ice‐free days per year, but extended to depths of 21–33 m further south (73 ºN–64 ºN) where >160 days per year were ice‐free, and annual production of Saccharina longicruris and S. latissima, measured as the size of the annual blade, ranged up to sevenfold among sites. The duration of the open‐water period, which integrates light and temperature conditions on an annual basis, was the best predictor (relative to summer water temperature) of kelp production along the latitude gradient, explaining up to 92% of the variation in depth extension and 80% of the variation in kelp production. In a decadal time series from a high Arctic site (74 ºN), inter‐annual variation in sea ice cover also explained a major part (up to 47%) of the variation in kelp production. Both spatial and temporal data sets thereby support the prediction that northern kelps will play a larger role in the coastal marine ecosystem in a warmer future as the length of the open‐water period increases. As kelps increase carbon‐flow and habitat diversity, an expansion of kelp forests may exert cascading effects on the coastal Arctic ecosystem.