Description: Rapid anthropogenic climate change is a major threat to ocean biodiversity, increasing the challenge for marine conservation. Strategic conservation planning, and more recently marine spatial planning (MSP) are among the most promising management tools to operationalize and enforce marine conservation. As yet, climate change is seldom incorporated into these plans, potentially curtailing the effectiveness of designated conservation areas under novel environmental conditions. Reliable assessment of current and future climate change threats requires the ability to map climate-driven eco-evolutionary changes and the identification of vulnerable and resistant populations. Here we explore the heretofore largely unrecognized value of information gained from physiological, ecological and evolutionary studies to MSP under ongoing climate change. For example, we explore how climate threats do not necessarily follow latitudinal gradients, such that both risk hotspots and refugia occur in mosaic distributions along species ranges - patterns that may be undetectable without knowledge of biological vulnerabilities at regional and local scales. Because co-occurring species can exhibit markedly different vulnerabilities to the same environmental changes, making ecological predictions requires, when possible, measuring the fundamental niches of key species (e.g., with the use of thermotolerance experiments). Forecasting also requires development of tools to identify the likelihood of community-level thresholds or tipping points (e.g., with the use of near-real world mesocosms), and assessment of the potential of populations for adaptation (e.g., with common garden experiments). Such research will facilitate better predictive models for the fate of populations, species, ecosystems and their functions. Ultimately, unfolding the complexity of the processes underlying climate change impacts will facilitate quantifying and reducing uncertainty in spatial planning decision processes and will enable the development of practical tools to validate adaptive conservation strategies.

Description: Human-induced climate change such as ocean warming and acidification, threatens marine ecosystems and associated fisheries. In the Western Baltic cod stock socio-ecological links are particularly important, with many relying on cod for their livelihoods. A series of recent experiments revealed that cod populations are negatively affected by climate change, but an ecological-economic assessment of the combined effects, and advice on optimal adaptive management are still missing. For Western Baltic cod, the increase in larval mortality due to ocean acidification has experimentally been quantified. Time-series analysis allows calculating the temperature effect on recruitment. Here, we include both processes in a stock-recruitment relationship, which is part of an ecological-economic optimization model. The goal was to quantify the effects of climate change on the triple bottom line (ecological, economic, social) of the Western Baltic cod fishery. Ocean warming has an overall negative effect on cod recruitment in the Baltic. Optimal management would react by lowering fishing mortality with increasing temperature, to create a buffer against climate change impacts. The negative effects cannot be fully compensated, but even at 3 °C warming above the 2014 level, a reduced but viable fishery would be possible. However, when accounting for combined effects of ocean warming and acidification, even optimal fisheries management cannot adapt to changes beyond a warming of +1.5° above the current level. Our results highlight the need for multi-factorial climate change research, in order to provide the best available, most realistic, and precautionary advice for conservation of exploited species as well as their connected socio-economic systems.

Description: Highlights • European Union Blue Growth is assessed by set of 18 indicators for 15 EU coastal states. • The results put into question that the EU has achieved comprehensive blue growth. • Unsustainable development is in particular driven by increasing fishing mortality. Abstract The Sustainable Development Goal for the oceans and coasts (SDG 14) as part of the 2030 Agenda can be considered as an important step towards achieving comprehensive blue growth. Here, we selected a set of 18 indicators to measure progress against SDG 14 for 15 EU coastal countries in the Baltic and the North Sea and the Atlantic Ocean since 2012. In our assessment we distinguish between a concept of weak and strong sustainability, assuming high and low substitution possibilities, respectively. Our results indicate that there are countries which managed to achieve sustainable development under both concepts of sustainability (most notably Estonia, achieving the strongest improvement), but that there are also countries which failed to achieve sustainable development under both concepts (most notably Ireland and Belgium, experiencing the strongest decline). Unsustainable development is in particular driven by increasing fishing mortality and reduced willingness to set total allowable catch in accordance with scientific advice.

Description: Highlights • Records of hard-bottom communities show regional differences in community dynamics. • Regionally, signs of regime shift were detected. • Shift can be explained by the decline of the foundation species Mytilus sp. • Modelling process revealed three environmental variables explaining the decline. • Regional differences in larval dispersal could explain contrary Mytilus recoveries. Abstract Ecological processes modulate ecosystem functioning and services. Foundation species are those exerting intense control on such processes as both their existence and loss have profound implications on the structure of ecological communities. For the distinction between random fluctuations and directional regime shifts in community composition, long-term records are of strategic need. In this study we present the monitoring of benthic hard-bottom communities over 11 years along seven stations in the SW Baltic Sea. Regional differences were found between the communities of Kiel and Lübeck bights, with the former area displaying signs of regime shift. The decline and near disappearance of the foundational species Mytilus edulis from settlement panels deployed in Kiel Bight correlated with three environmental variables: sea surface temperature, water current speed and chlorophyll a concentration. Thus, low spring temperatures, in some cases reinforced by local maxima of chlorophyll a, correlated with reduced recruitment of Mytilus. Moreover, regional differences of larval dispersal and population connectivity could explain the rapid recovery after disturbance of the mussel populations in Lübeck Bight in contrast to Kiel Bight. Our findings underscore the relevance of long-term monitoring programmes to detect the interactive impacts of global climatic and regional environmental drivers.

Description: Differentiating thermokarst basin sediments with respect to the involved processes and environmental conditions is an important tool to understand permafrost landscape dynamics and scenarios and future trajectories in a warming Arctic and Subarctic. Thermokarst basin deposits have complex sedimentary structures due to the variability of Yedoma source sediments, reworking during the Late Glacial to Holocene climate changes, and different stages of thermokarst history. Here we reconstruct the dynamic growth of thermokarst lakes and basins and related changes of depositional conditions preserved in sediment sequences using a combination of biogeochemical data and robust grain-size endmember analysis (rEMMA). This multi-proxy approach is used on 10 sediment cores (each 300–400 cm deep) from two key thermokarst sites to distinguish four time slices that describe the Holocene thermokarst (lake) basin evolution in Central Yakutia (CY). Biogeochemical proxies and rEMMA reveal fine-grained sedimentation with rather high lake levels and/or reducing conditions, and coarse-grained sedimentation with rather shallow lake levels and/or oxidizing (i.e. terrestrial) conditions in relation to distal and proximal depositional and post-sedimentary conditions. Statistical analysis suggests that the biogeochemical parameters are almost independent of thermokarst deposit sedimentology. Thus, the biogeochemical parameters are considered as signals of secondary (post-sedimentary) reworking. The rEMMA results are clearly reflecting grain-size variations and depositional conditions. This indicates small-scale varying depositional environments, frequently changing lake levels, and predominantly lateral expansion at the edges of rapidly growing small thermokarst lakes and basins. These small bodies finally coalesced, forming the large thermokarst basins we see today in CY. Considering previous paleoenvironmental reconstructions in Siberia, we show the initiation of thaw and subsidence during the Late Glacial to Holocene transition between about 11 and 9 cal kyrs BP, intensive and extensive thermokarst activity for the Holocene Thermal Maximum (HTM) at about 7 to 5 cal kyrs BP, severely fluctuating water levels and further lateral basin growth between 3.5 cal kyrs BP and 1.5 cal kyrs BP, and the cessation of thermokarst activity and extensive frost-induced processes (i.e. permafrost aggradation) after about 1.5 cal kyrs BP. However, gradual permafrost warming over recent decades, in addition to human impacts, has led to renewed high rates of subsidence and abrupt, rapid CY thermokarst processes.

Description: Anthropogenically-derived nitrogen input to the northern Indian Ocean has increased significantly in recent decades, based on both observational and model-derived estimates. This external nutrient source is supplied by atmospheric deposition and riverine fluxes, and has the potential to affect the vulnerable biogeochemical systems of the Arabian Sea and Bay of Bengal, influencing productivity and oceanic production of the greenhouse-gas nitrous-oxide (N 2 O). We summarize current estimates of this external nitrogen source to the northern Indian Ocean from observations and models, highlight implications for regional marine N 2 O emissions using model-based analyses, and make recommendations for measurement and model needs to improve current estimates and future predictions of this impact. Current observationally-derived estimates of deposition and riverine nitrogen inputs are limited by sparse measurements and uncertainties on accurate characterization of nitrogen species composition. Ocean model assessments of the impact of external nitrogen sources on regional marine N 2 O production in the northern Indian Ocean estimate potentially significant changes but also have large associated uncertainties. We recommend an integrated program of basin-wide measurements combined with high-resolution modeling and more detailed characterization of nitrogen-cycle process to address these uncertainties and improve current estimates and predictions.