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Sustainable Development Goal 14 of the United Nations aims to "conserve and sustainably use the oceans, seas and marine resources for sustainable development". Achieving this goal will require rebuilding the marine life-support systems that deliver the many benefits that society receives from a healthy ocean. Here we document the recovery of marine populations, habitats and ecosystems following past conservation interventions. Recovery rates across studies suggest that substantial recovery of the abundance, structure and function of marine life could be achieved by 2050, if major pressures-including climate change-are mitigated. Rebuilding marine life represents a doable Grand Challenge for humanity, an ethical obligation and a smart economic objective to achieve a sustainable future.

An important component of science-based fisheries policy is the provision of habitat adequate for population renewal. In Canada, the Fisheries Act pays little attention to managing fish habitat, and was further weakened by changes enacted in 2012. Specifically, determining the role of fish habitat in contributing to fisheries and fish stock recovery is challenging when many stocks have severely declined and no longer occupy former habitats. This study compared the abundance of juvenile fish in coastal vegetated habitats before and after collapse or decline of groundfish stocks in Atlantic Canada. This comparison was done by compiling past studies that surveyed juvenile Atlantic cod (Gadus morhua) and pollock (Pollachius virens) in vegetated habitats across three provinces. Two studies were repeated, and one that already had post-collapse data was analyzed to quantify long-term changes in juvenile abundance. In all three cases substantial reduction in juvenile abundance coincided with declines in adult stocks. However, juvenile fish still occur in coastal habitats and could aid in adult stock recovery. The current version of the Canadian Fisheries Act requires presence of an ongoing fishery to trigger habitat protection. This is problematic as low fish abundance may lead to lowered habitat protection and potentially habitat degradation, with less or lesser-quality habitat for fish in the future. Thus, recommendations are made to repeal the 2012 Fisheries Act changes and enhance current fish habitat legislation. Using a precautionary approach for coastal fish habitat management, particularly in valuing its potential for fish stock recovery, would strengthen Canadian fisheries management.

In New Zealand and Nova Scotia, lobster (Jasus edwardsii and Homarus americanus, respectively) is the most valuable export fishery. Although stock assessments and indicators assist in evaluating lobster fisheries, ecosystem effects are largely unknown, hindering ecosystem-based fisheries management (EBFM). We employed ecosystem models for the Cook Strait, New Zealand and western Scotian Shelf, Nova Scotia, Canada, to evaluate trade-offs between catches and ecosystem impacts in lobster fisheries from single- and multi-species perspectives. We ran simulations to independently determine exploitation rates that produced maximum sustainable yield (MSY) for lobster, and for all fished groups. We then ran simulations using these MSY exploitation rates simultaneously, and simulations to maximize multi-species MSY (MMSY). Our results indicate that current lobster exploitation rates in both regions are greater than those producing MSY, and have significant ecosystem impacts. Simulating multi-species fisheries, in both systems the sum of single-species MSY for all fished groups was less than the sum of catches where exploitation rates were run simultaneously. Runs maximizing MMSY across the entire ecosystem increased exploitation rates on many fished groups, and produced even greater total catch—yet with much greater ecological costs—and in Nova Scotia, collapses of sharks, large predators, and lobster themselves. As fisheries management moves towards multi-species and ecosystem-based approaches, we suggest that MMSY targets should be treated similarly to MSY—not as a target, but a limit. Even then, careful evaluation is required before implementation to ensure that there are no undesirable economic or ecological consequences.

Perennial seaweeds are dominant primary producers and foundation species along rocky shores, providing essential ecosystem functions and services. Although increasingly affected by various anthropogenic activities, the cumulative effects of multiple stressors are little known. We tested the interactive effects of nutrient enrichment and increased water temperatures on growth, nitrogen retention and carbon storage in juvenile Ascophyllum nodosum from Nova Scotia, Canada (44° 29.9′ N, 63° 31.7′ W) using a multi-factorial laboratory experiment. Temperature strongly affected growth, significantly reducing weight and length gain from 16 °C to 20 °C and 24 °C. Medium nutrient enrichment enhanced while high enrichment slowed rockweed growth at lower temperatures, yet these effects disappeared with warming. Nitrogen retention in rockweed tissue significantly increased with nutrient enrichment and decreased with warming, whereas carbon storage remained unaffected. These individual and interactive effects of nutrient loading and climate warming may alter the structure and function of rockweed habitats with potentially far-reaching ecological and economic consequences.

14 pages, 5 figures, 1 table, supporting information https://doi.org/10.1111/gcb.14512, Climate change effects on marine ecosystems include impacts on primary production, ocean temperature, species distributions, and abundance at local to global scales. These changes will significantly alter marine ecosystem structure and function with associated socio‐economic impacts on ecosystem services, marine fisheries, and fishery‐dependent societies. Yet how these changes may play out among ocean basins over the 21st century remains unclear, with most projections coming from single ecosystem models that do not adequately capture the range of model uncertainty. We address this by using six marine ecosystem models within the Fisheries and Marine Ecosystem Model Intercomparison Project (Fish‐MIP) to analyze responses of marine animal biomass in all major ocean basins to contrasting climate change scenarios. Under a high emissions scenario (RCP8.5), total marine animal biomass declined by an ensemble mean of 15%–30% (±12%–17%) in the North and South Atlantic and Pacific, and the Indian Ocean by 2100, whereas polar ocean basins experienced a 20%–80% (±35%–200%) increase. Uncertainty and model disagreement were greatest in the Arctic and smallest in the South Pacific Ocean. Projected changes were reduced under a low (RCP2.6) emissions scenario. Under RCP2.6 and RCP8.5, biomass projections were highly correlated with changes in net primary production and negatively correlated with projected sea surface temperature increases across all ocean basins except the polar oceans. Ecosystem structure was projected to shift as animal biomass concentrated in different size‐classes across ocean basins and emissions scenarios. We highlight that climate change mitigation measures could moderate the impacts on marine animal biomass by reducing biomass declines in the Pacific, Atlantic, and Indian Ocean basins. The range of individual model projections emphasizes the importance of using an ensemble approach in assessing uncertainty of future change, Financial support was provided by the German Federal Ministry of Education and Research (BMBF, grant no. 01LS1201A1) and through the Inter‐Sectoral Impact Model Intercomparison Project (ISI‐MIP). ABB acknowledges financial support from the NSERC CREATE Transatlantic Ocean Science and Technology Program (TOSST), HKL from the Natural Sciences and Engineering Research Council (NSERC) of Canada, and DPT from the Kann Rasmussen Foundation, Denmark

Climate change is shifting the abundance and distribution of marine species with consequences for ecosystem functioning, seafood supply, management and conservation. Several approaches for future projection exist but these have never been compared systematically to assess their variability. We conducted standardized ensemble projections including 6 global fisheries and marine ecosystem models, forced with 2 Earth-system models and 4 emission scenarios in a fished and unfished ocean, to derive average trends and associated uncertainties. Without fishing, mean global animal biomass decreased by 5% (±4%) under low and 17% (±11%) under high emissions by 2100, primarily driven by increasing temperature and decreasing primary production. These climate-change effects were slightly weaker for larger animals and in a fished ocean. Considerable regional variation ranged from strong biomass increases in high latitudes to strong decreases in mid-low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to differences among ecosystem or Earth-system models were similar, suggesting equal need for model improvement. Our ensemble projections provide the most comprehensive outlook on potential climate-driven ecological changes in the ocean to date. Realized future trends will largely depend on how fisheries and management adapt to these changes in a changing climate.

Eelgrass (Zostera marina) beds provide important habitat and food sources for a wide range of associated species both above- and belowground. Organic enrichment and nutrient loading from anthropogenic sources can change eelgrass canopy structure and macroinfauna community composition, making them important indicators of ecosystem health. In Atlantic Canada, there is growing concern about the impacts of finfish aquaculture on eelgrass habitats. To quantify these effects, we examined differences in environmental parameters, eelgrass bed structure and macroinfauna communities at increasing distances from a finfish farm in Port Mouton Bay, Nova Scotia and a reference site in an adjacent bay. We also compared the results to recently published large-scale survey results from the Atlantic coast. Results indicate increased organic enrichment and decreased eelgrass biomass, shoot density, and macroinfauna biomass closer to the farm. Moreover, community structure significantly differed between sites with some sensitive species disappearing while tolerant species increased closer to the farm. Changes in the macroinfauna community could be linked to observed differences in environmental and eelgrass bed variables. Our results provide new insights into the impacts of finfish aquaculture on eelgrass habitats in Atlantic Canada. We discuss possible assessment and monitoring metrics that would enable managers and regulators to evaluate the risk and potential changes to eelgrass habitat as a result of finfish aquaculture.

The collapse of the Northwest Atlantic cod (Gadus morhua) stocks in the early 1990s led to widespread ecological changes offshore. Changes in coastal fish communities are less known, largely due to the lack of historical records and long-term, standardized research surveys in coastal ecosystems. We aimed to overcome this with a unique dataset known as the Fleming survey. From 1959 to 1964, a systematic beach-seine survey was conducted to examine juvenile cod abundance in 84 bays (42 of which were consistently sampled and therefore analysed) along the east coast of Newfoundland. In addition to cod, all other fish collected in the seines were recorded. These surveys were repeated from 1992 to 1996 after the cod collapse, and document a substantial reduction in a dominant inshore species—juvenile Atlantic cod. We show that total fish abundance declined significantly with the decrease of cod, whereas Shannon diversity and species evenness significantly increased. Species richness increased in some regions but decreased in others. We also found significant changes in the composition of the fish community likely due to a combination of release from predation from fewer large cod feeding in inshore areas as well as a release from competition from fewer juvenile cod occupying the coastal habitat. Region and the presence of vegetated habitats also significantly influenced the fish community. This study shows a strong reorganization of coastal fish communities after a large-scale fisheries collapse with implications for ecosystem-based and cross-ecosystem management.

Rising temperatures are changing the distribution and abundance of species worldwide, yet the magnitude of warming varies regionally. Atlantic Canada lies in a zone of significant warming and harbors many cold-adapted seaweeds of ecological and economic importance. Using a factorial laboratory experiment, we tested the effects of increasing water temperature on the survival, growth, and nutrient content of rockweeds (Ascophyllum nodosum, Fucus vesiculosus), Irish moss (Chondrus crispus), kelp (Laminaria digitata), and the invasive Codium fragile ssp. tomentosoides from Nova Scotia (44°29.9′N, 63°31.7′W). In June 2014, species were exposed to typical spring–summer water temperatures (12, 16, 20 °C), a predicted increase in summer temperature (23 °C), and potential heat wave temperatures in shallow waters (26, 29 °C) for 9 weeks. Chondrus crispus and L. digitata experienced highest growth at 12 °C, F. vesiculosus and Codium at 16 °C, and A. nodosum at 20 °C. Survival was lowest in L. digitata with no survival above 20 °C, followed by rockweeds with low survival above 23 °C, while C. crispus and Codium exhibited high survival at all temperatures. There was some evidence for temporary acclimation and short-term survival at higher temperatures. Temperature stress did not affect carbon content but some species showed increased tissue nitrogen, potentially changing nutritional quality and the ability to store and cycle nutrients. These species-specific responses to increasing water temperature will result in shifts in species composition along Atlantic Canada’s rocky shore, altering seaweed canopies, their ecosystem structure and function, and the services they provide.

Nitrogen loading from coastal watersheds is a principal factor associated with the decline in eelgrass bed health and cover in estuaries worldwide. We apply the Nitrogen Loading Model (NLM) framework developed in Waquoit Bay, Massachusetts to 7 estuaries in eastern New Brunswick. Using watershed-specific information on human population, wastewater production, atmospheric deposition, and land use in each watershed we estimate annual input of Total Dissolved Nitrogen (TDN) from point and non-point sources. We also estimate flushing time of each estuary using available hydrodynamic and bathymetric data incorporated in a tidal prism model. Finally, we validate the NLM results by testing the link between estimated nitrogen loading, flushing time and nitrogen signals in eelgrass tissue including nitrogen content and stable isotopes. Overall, total nitrogen load (kg TDN yr −1 ) was strongly dependent on watershed and estuary size, while loading rate per unit watershed area (yield) was linked to watershed population density. Atmospheric deposition was the largest contributor of nitrogen to all estuaries except one, where seafood processing effluent was the greatest source. Stable isotope analysis of eelgrass tissue reflected this distinction, with high δ 15 N values of 8–10‰ related to high wastewater loading, compared to 2–6.5‰ in the other estuaries that receive proportionally more atmospheric deposition. Tissue nitrogen content was positively related to nitrogen yields and loading rate per volume of estuary, highlighting the influence of variable watershed:estuary size ratio. Multiple regression analysis identified a significant interaction between nitrogen yield and flushing time on eelgrass tissue nitrogen content and isotopes, pointing to the mitigating effect an estuary's quick flushing time can have on the expression of nitrogen enrichment in primary producers. The compilation of new information on nitrogen loading to east Canadian estuaries is a novel contribution from a region where human influences are still at a relatively low level, and hence will add to existing information from cold temperate, mainly forested watershed-estuary environments.

Improving public awareness about the ocean can benefit the environment, economy, and society. However, low levels of ‘ocean literacy’ have been identified in many countries and can be a barrier for citizens to engage in environmentally responsible behavior or consider ocean-related careers. This study assessed the level of ocean valuation, knowledge, interaction and interest of public school students grade 7–12 (ages 12–18) in Nova Scotia, Canada, a region with strong connections with the sea. A survey was used in 11 public schools, with a total of 723 students participating in a quiz and survey. Many quiz questions were aligned with the ‘Ocean Literacy Principles’ established by the Ocean Literacy Campaign in the United States. Although the average quiz score was below 50%, students reported a high valuation of the marine environment and diverse interest in the oceans, including jobs and careers. There was a distinct difference in knowledge of biology-related questions and abiotic-related questions, with students having more knowledge of and interest in topics concerning ocean life. A significant positive correlation between knowledge and value indicated that ocean-literate students might value the marine environment more strongly. Students reporting greater interaction with the ocean also demonstrated higher knowledge levels, and students with higher knowledge levels were more likely to be interested in ocean-related jobs and careers. Participants׳ high valuation of the marine environment and interest in ocean jobs and careers suggests important links between ocean literacy and environmental and economic benefit, respectively. Enhancing interactions with the ocean through experiential learning could be the most effective way of improving ocean literacy as well as marine citizen- and stewardship.

Recognizing the threat of additive risk Humans are accelerating the extinction rates of species in both terrestrial and marine environments. However, species extinctions have occurred across time for a variety of other reasons. Finnegan et al. looked at the extinction rates across marine genera (groups of species) over the past 23 million years to determine intrinsic extinction rates and what traits or regions correspond to the highest rates. Combining patterns of intrinsic extinction with regions of high anthropogenic threat revealed taxa and areas, particularly in the tropics, where the risk of extinction will be especially high. Science , this issue p. 567

Conference and workshops Ecopath 30 years – Modelling ecosystem dynamics: beyond boundaries with EwE, 4-14 November 2014, Barcelona, Spain.-- 2 pages, 1 figure, Invertebrate catches are increasing globally following the depletion and collapses of many finfish stocks (Anderson et al. 2011a; Anderson et al. 2011b), however stock assessments and management plans for invertebrates are rare. Recent fisheries research has aimed to understand fisheries impacts at the ecosystem scale, rather than traditional single-species approaches. We have employed an ecosystem modeling approach to explore the tradeoffs between invertebrate fisheries catches and their impacts on the associated reef ecosystem for an area on the south coast of Wellington, New Zealand. Fisheries for lobster (Jasus edwardsii), abalone (Haliotis australis and Haliotis iris), and urchin (Evechinus chloroticus) exist in this region, as well as traditional finfish fisheries

Over the past 60 years, low-trophic level fisheries have greatly expanded in terms of landings, target species, and the number of countries fishing, and are now prominent around the world. Hagfish (family Myxinidae) have been commercially fished in Asia since the 1940s where their skin is used as leather and their meat for human or animal consumption. Since the 1980s, the animals have been increasingly exploited on a global scale. Using landings and effort data supplied by government agencies and extracted from published literature, as well as government reports and assessments, we analyzed spatial and temporal patterns in hagfish fisheries in Atlantic Canada and worldwide. Exploitation patterns have been driven by the Asian market; after local hagfish stocks were depleted in the 1980s, fisheries expanded sequentially to the West and East coasts of North America and into New Zealand. In addition to strong spatial expansion, our results reveal some serial depletion patterns around the world, as previously documented in sea urchin and sea cucumber fisheries. In Atlantic Canada, the hagfish fishery has strongly expanded over the past 20 years with a 24-fold increase in both annual landings and fishing effort and a 10-fold increase in the number of NAFO units fished. The spatial expansion has been accompanied by some serial depletion of individual regions. Overall, hagfish fisheries around the world have not been very sustainable over the past 70 years. Given the poor knowledge of hagfish populations and their response to fishing, coupled with limited stock assessments and fisheries regulations, it is doubtful that current hagfish fisheries are more sustainable.

Model intercomparison studies in the climate and earth sciences communities have been crucial to build credibility and coherence for future projections. They have quantified variability among models, spurred model development, contrasted within- and among-model uncertainty, assessed model fits to historical data, and provided ensemble projections of future change under specified scenarios. Given the speed and magnitude of anthropogenic change in the marine environment, and consequent effects on food security, biodiversity, marine industries and society, the time is ripe for similar comparisons among models of fisheries and marine ecosystems. Here, we describe the Fisheries and Marine Ecosystem Model Intercomparison Project protocol version 1.0 (Fish-MIP v1.0), part of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), a cross-sectoral network of climate impact modellers. Given the complexity of the marine ecosystem, this class of models has substantial heterogeneity of purpose, scope, theoretical underpinning, processes considered, parameterizations, resolution (grain size) and spatial extent. This heterogeneity reflects the lack of a unified understanding of the marine ecosystem, and implies that the assemblage of all models is more likely to include a greater number of relevant processes than is any single model. The current Fish-MIP protocol is designed to allow these heterogeneous models to be forced with common Earth System Model (ESM) CMIP5 outputs under prescribed scenarios for historic (from 1950s) and future (to 2100) time periods; it will be adapted to CMIP6 in future iterations. It also describes a standardized set of outputs for each participating Fish-MIP model to produce. This enables the broad characterization of differences between, and uncertainties within, models and projections when assessing climate and fisheries impacts on marine ecosystems and the services they provide. The systematic generation, collation and comparison of results from Fish-MIP will inform understanding of the range of plausible changes in marine ecosystems, and improve our capacity to define and convey strengths and weaknesses of model-based advice on future states of marine ecosystems and fisheries. Ultimately, Fish-MIP represents a step towards bringing together the marine ecosystem modelling community to produce consistent ensemble medium- and long-term projections of marine ecosystems.

Seagrass beds and their associated species communities play key roles in coastal ecosystems. The importance of the ecological functions provided by eelgrass (Zostera marina) and macroinfauna are well understood; however, the spatial variation and linkage of the two are much less known. Here, we performed large-scale field surveys across three biogeographic regions in Atlantic Canada along the coasts of New Brunswick, Nova Scotia, and Newfoundland. First, we examined variation in eelgrass bed structure (shoot density, canopy height, biomass) and environmental parameters (tissue nitrogen and carbon, sediment organic content, microphytobenthos and annual algae) at 19 sites across the 3 regions. Next, we examined the variation in macroinfauna community composition and summary measures (species richness, diversity, total abundance, and biomass). We then linked the eelgrass bed structure and environmental variables to the macroinfauna community to determine what best explained observed patterns. Our results indicate that eelgrass bed structure and most environmental parameters varied at the site level, whereas most variation in the macroinfauna community was explained by region. Furthermore, the abundance of microphytobenthos was the best predictor of the macroinfauna community. We suggest that in moving forward with protecting and managing eelgrass habitats, eelgrass bed structure should be assessed on a site-by-site basis; however, benthic productivity (microphytobenthos) may be a useful tool in evaluating macroinfauna and ecosystem health on a region-scale.

Eelgrass (Zostera marina) is the dominant perennial canopy-forming vegetation along the soft-sediment shores of the Northwest Atlantic. Eelgrass is considered an ecologically significant species in Atlantic Canada as it provides essential ecosystem functions and services and is an indicator of ecosystem health. Recent declines of eelgrass habitats highlight the need for methods quantifying the large-scale distribution of eelgrass throughout Atlantic Canada to monitor for further habitat loss. We used archived, high-resolution SPOT 6/7 satellite imagery to classify where vegetated habitats exist and if eelgrass was the dominant species. We focused on three bays in Nova Scotia: Port Mouton Bay, Port Joli Bay, and Jordan Bay. In 2015, field surveys were conducted to obtain training points, which were supplemented with visually identified points to perform a supervised classification based on the maximum likelihood classifier. We also performed an unsupervised classification, where clustering algorithms were used to build training sites for a maximum likelihood classifier without using field survey data. These two pixel-based approaches provided similar results across the different images. Regardless of classification type (supervised versus unsupervised), we found different levels of success for the three bays. In Port Joli Bay, we were able to calculate where vegetated habitats occurred and what was the dominant species. This provided bay-wide distribution maps and suggested that 8.61–11.10% of the bay was covered by eelgrass. In Port Mouton Bay, we were able to calculate vegetation presence from absence, and eelgrass habitats were qualitatively differentiated from seaweed habitats by incorporating substrate data and local ecological knowledge. In contrast, benthic habitats could not be classified in Jordan Bay, highlighting the importance of sufficient water clarity for classifying satellite imagery. Our study has implications for the monitoring, conservation and management of eelgrass and other vegetated coastal habitats in Atlantic Canada by providing bay-wide distribution maps, and a classification framework which requires no field survey points for ground truthing.

17 pages, 6 figures, 4 tables, 1 appendix, Eutrophication has caused strong shifts from perennial seagrass to opportunistic macroalgae and phytoplankton in many coastal ecosystems worldwide, yet responses of the primary-producer assemblage can vary with regional environmental and nutrient-loading conditions. The wider consequences of this variable primary-producer response on the associated animal community are little known. We used large-scale field surveys across 12 study sites with low or high eutrophication levels in two geographic provinces in Atlantic Canada to examine region-specific responses of macrofauna associated with eelgrass beds. In both regions, abundances of all groups increased with eutrophication, but species richness of mobile fishes and invertebrates decreased. Generally, filter feeders, epibenthic detritivores and some herbivores increased, while more hypoxia sensitive species declined. Small fishes and invertebrate predators increased with eutrophication mirrored by decreases in their prey. Despite similar general trends, our results show distinct shifts in species composition in each geographic region associated with differences in food availability and predation refuge offered by phytoplankton and opportunistic epiphytic or benthic macroalgae as well as tolerance to an increasingly hostile physico-chemical environment. So far, the continued persistence of eelgrass beds at our “highly” eutrophied sites indicates intermediate eutrophication levels with short-term benefits for some species. However, the loss of sensitive species and decrease in species richness highlight that eutrophication has already changed seagrass ecosystems in Atlantic Canada. Our work suggests that mitigating these changes will require regional-scale management, This work was funded by a National Science and Engineering Research Council (NSERC) Discovery grant to HKL, a NSERC Post-Graduate Doctoral Scholarship and Killam Trust Predoctoral Scholarship to ALS, and postdoctoral fellowships from the Spanish Ministry of Science and Technology and the European Community Marie-Curie Program through the International Outgoing Fellowships to MC

Eddy, T.D. ... et al.-- 14 pages, 6 figures, supporting Information, Since the 1950s, invertebrate fisheries catches have rapidly expanded globally to more than 10 million tonnes annually, with twice as many target species, and are now significant contributors to global seafood provision, export, trade and local livelihoods. Invertebrates play important and diverse functional roles in marine ecosystems, yet the ecosystem effects of their exploitation are poorly understood. Using 12 ecosystem models distributed worldwide, we analysed the trade-offs of various invertebrate fisheries and their ecosystem effects as well as ecological indicators. Although less recognized for their contributions to marine food webs, our results show that the magnitude of trophic impacts of invertebrates on other species of commercial and conservation interest is comparable with those of forage fish. Generally, cephalopods showed the strongest ecosystem effects and were characterized by a strong top-down predatory role. Lobster, and to a lesser extent, crabs, shrimp and prawns, also showed strong ecosystem effects, but at lower trophic levels. Benthic invertebrates, including epifauna and infauna, also showed considerable ecosystem effects, but with strong bottom-up characteristics. In contrast, urchins, bivalves, and gastropods showed generally lower ecosystem effects in our simulations. Invertebrates also strongly contributed to benthic–pelagic coupling, with exploitation of benthic invertebrates impacting pelagic fishes and vice versa. Finally, on average, invertebrates produced maximum sustainable yield at lower levels of depletion (~45%) than forage fish (~65%), highlighting the need for management targets that avoid negative consequences for target species and marine ecosystems as a whole, Key financial support for this project was provided by the Lenfest Ocean Program with a grant to HKL. MC was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011-303534 – to the BIOWEB project and by the Spanish National Program Ramon y Cajal. VC acknowledges support from NSERC, Canada. SM gratefully acknowledges the support provided by Defra project M1228 ‘Fizzyfish’

Ascophyllum nodosum (rockweed) is a dominant, habitat-forming seaweed on intertidal rocky shores in the North Atlantic and commercially harvested in Canada, Maine and Europe. Rockweed plant structure varies regionally, and several morphotypes have been identified in Atlantic Canada alone. Yet the regionality of canopy structure, associated species communities and the link between the two have not been well understood. Using large-scale field surveys and multivariate statistical approaches, we report distinct canopy structures between sites in southwest Nova Scotia and southwest New Brunswick, the two major rockweed harvesting areas in Atlantic Canada, as well as distinct associated community composition. We then demonstrate significant links between canopy and community structure. Importantly, plant and canopy structure, including length, circumference and density, were much better predictors of associated community structure than rockweed biomass, which is often used for single-species monitoring. Adding region or site as predictors further improved model fits. Therefore, measuring plant or canopy structure would strongly improve insight regarding ecosystem changes. Moreover, incorporating information about regional differences in canopy structure and the dependence of associated communities on those canopies is critical for spatially refined, ecosystem-based management of the rockweed harvest.

In Paris, France, December 2015, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to provide a "special report in 2018 on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways". In Nairobi, Kenya, April 2016, the IPCC panel accepted the invitation. Here we describe the response devised within the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) to provide tailored, cross-sectorally consistent impacts projections. The simulation protocol is designed to allow for (1) separation of the impacts of historical warming starting from pre-industrial conditions from other human drivers such as historical land-use changes (based on pre-industrial and historical impact model simulations); (2) quantification of the effects of additional warming up to 1.5 °C, including a potential overshoot and long-term effects up to 2299, compared to a no-mitigation scenario (based on the low-emissions Representative Concentration Pathway RCP2.6 and a no-mitigation pathway RCP6.0) with socio-economic conditions fixed at 2005 levels; and (3) assessment of the climate effects based on the same climate scenarios but accounting for simultaneous changes in socio-economic conditions following the middle-of-the-road Shared Socioeconomic Pathway (SSP2, Fricko et al., 2016) and differential bio-energy requirements associated with the transformation of the energy system to comply with RCP2.6 compared to RCP6.0. With the aim of providing the scientific basis for an aggregation of impacts across sectors and analysis of cross-sectoral interactions that may dampen or amplify sectoral impacts, the protocol is designed to facilitate consistent impacts projections from a range of impact models across different sectors (global and regional hydrology, global crops, global vegetation, regional forests, global and regional marine ecosystems and fisheries, global and regional coastal infrastructure, energy supply and demand, health, and tropical cyclones).

{en} Over the past decades, much research has focused on understanding the critical factors for marine extinctions with the aim of preventing further species losses in the oceans. Although conservation and management strategies are enabling several species and populations to recover, others remain at low abundance levels or continue to decline. To understand these discrepancies, we used a published database on abundance trends of 137 populations of marine mammals worldwide and compiled data on 28 potentially critical factors for recovery. We then applied random forests and additive mixed models to determine which intrinsic and extrinsic factors are critical for the recovery of marine mammals. A mix of life-history characteristics, ecological traits, phylogenetic relatedness, population size, geographic range, human impacts, and management efforts explained why populations recovered or not. Consistently, species with lower age at maturity and intermediate habitat area were more likely to recover, which is consistent with life-history and ecological theory. Body size, trophic level, social interactions, dominant habitat, ocean basin, and habitat disturbance also explained some differences in recovery patterns. Overall, a variety of intrinsic and extrinsic factors were important for species' recovery, pointing to cumulative effects. Our results provide insight for improving conservation and management strategies to enhance recoveries in the future.

Using large-scale field surveys across 12 estuaries in two provinces in Atlantic Canada, we analyzed changes in phytoplankton and benthic macroalgal communities as well as the canopy structure of eelgrass beds and quantified their carbon and nitrogen storage with increasing eutrophication. As eutrophication increased, phytoplankton biomass increased on average 1.8 times and phaeopigments doubled. Among macroalgae, the epiphytic Ulothrix speciosa increased 40 times in New Brunswick, and benthic Ulva lactuca 670 times in Prince Edward Island covering 61% of the bottom. Eelgrass showed a significant increase in leaf length and declines in shoot density and aboveground and belowground biomass, consistent with increased shading by opportunistic algae. As eelgrass biomass declined, so did the carbon storage capacity of the habitat. Nitrogen storage only declined in belowground eelgrass beds due to increasing tissue nitrogen content above ground with eutrophication. Despite province- and species-specific responses of primary producers to nutrient loading, principal component analysis revealed an overall shift from perennial eelgrass to opportunistic macroalgae and phytoplankton with eutrophication at the regional scale, indicating generalized eutrophication effects on primary producer assemblages.

Anderson, S. C., Branch, T. A., Ricard, D., and Lotze, H. K. 2012. Assessing global marine fishery status with a revised dynamic catch-based method and stock-assessment reference points. – ICES Journal of Marine Science, 69: . The assessment of fishery status is essential for management, yet fishery-independent estimates of abundance are lacking for most fisheries. Methods exist to infer fishery status from catches, but the most commonly used method is biased towards classifying fisheries as overexploited or collapsed through time and does not account for still-developing fisheries. We introduce a revised method that overcomes these deficiencies by smoothing catch series iteratively, declaring fisheries developing within three years of peak catch, and calibrating thresholds to biological reference points. Compared with status obtained from stock-assessment reference points for 210 stocks, our approach provides a more realistic assessment than the original method, but cannot be perfect because catches are influenced by factors other than biomass. Applied to FAO catches, our method suggests in 2006 32% of global fisheries were developing, 27% fully exploited, 25% overexploited, and 16% collapsed or closed. Although less dire than previous assessments, this still indicates substantial numbers of overexploited stocks. Probably because median exploitation rate decreased since 1992, our catch-based results do not reflect recent stabilization of assessed-stock biomass. Whether this outlook also applies to unassessed stocks can only be revealed with increased or more representative collection of biomass- and exploitation-rate trends.

18 pages, 9 figures, 5 tables, Marine vegetated habitats provide essential functions and services to ocean ecosystems and human well-being. It is unclear, however, how different habitat types compare. Using large-scale field surveys, we compared the canopy and community structure between eelgrass and rockweed beds in Atlantic Canada and assessed their nitrogen retention, carbon storage, and habitat services. We then used binary network models of predator–prey interactions to determine food-web structure and its robustness to species loss. Despite disparate 3-dimensional canopy structure, both habitats significantly enhanced overall abundance and diversity of associated flora and fauna, including several commercially important species. Significant differences occurred in the species assemblages within and between habitats and were attributed to different settlement opportunities, food availability, predation risk, and maneuverability. While eelgrass plants had higher nitrogen content, rockweed canopies maintained 8-fold greater biomass and, thus, 14-fold greater nitrogen and 8-fold greater carbon retention per unit area. Both rockweed and eelgrass food webs showed similarities to other temperate and tropical seagrass webs, yet their robustness to the loss of most connected species including primary producers was among the lowest; underscoring their vulnerability to disturbances affecting the functionally dominant primary producers. The present study demonstrates that marine vegetation provides important habitat, nitrogen, and carbon storage services, yet the extent of these services depends on the foundation species and its architecture. Changes in canopy structure will therefore have profound effects on associated food webs and ecosystem services. Thus, as increasing human pressures on coastal ecosystems threaten the continued supply of essential functions and services, the protection of marine vegetated habitats should be a management priority, This work was funded by an NSERC Discovery grant to H.K.L., a NSERC PGSD and Killam Trust Predoctoral Scholarship to A.L.S., and postdoctoral fellowships from the Spanish Ministry of Science and Technology and the European Community Marie-Curie Program through the International Outgoing Fellowships (Call: FP7-PEOPLE-2007-4-1-IOF) to M.C.

In recent decades, invertebrate fisheries have expanded in catch and value worldwide. One increasingly harvested group is sea cucumbers (class Holothuroidea), which are highly valued in Asia and sold as trepang or beche-de-mer. We compiled global landings, economic data, and country-specific assessment and management reports to synthesize global trends in sea cucumber fisheries, evaluate potential drivers, and test for local and global serial exploitation patterns. Although some sea cucumber fisheries have existed for centuries, catch trends of most individual fisheries followed boom-and-bust patterns since the 1950s, declining nearly as quickly as they expanded. New fisheries expanded five to six times faster in 1990 compared to 1960 and at an increasing distance from Asia, encompassing a global fishery by the 1990s. Global sea cucumber production was correlated to the Japanese yen at a leading lag. Regional assessments revealed that population declines from overfishing occurred in 81% of sea cucumber fisheries, average harvested body size declined in 35%, harvesters moved from near- to off-shore regions in 51% and from high- to low-value species in 76%. Thirty-eight per cent of sea cucumber fisheries remained unregulated, and illegal catches were of concern in half. Our results suggest that development patterns of sea cucumber fisheries are largely predictable, often unsustainable and frequently too rapid for effective management responses. We discuss potential ecosystem and human community consequences and urge for better monitoring and reporting of catch and abundance, proper scientific stock assessment and consider- ation of international trade regulations to ensure long-term and sustainable harvesting of sea cucumbers worldwide.

Recent concerns about changing elasmobranch populations have prompted the need to understand their patterns of distribution and abundance through non-destructive sampling methods. Since scientific divers represent a small portion of the total number of divers worldwide, the use of non-scientific divers could drastically increase the number of observations needed to monitor broad-scale, long-term trends. Here, we use 83,940 surveys collected by trained volunteer divers to examine spatial and temporal trends of the most frequently sighted elasmobranch species in the greater-Caribbean, the yellow stingray (Urobatis jamaicensis). Despite being relatively common and listed as Least Concern on the IUCN Red List, little is known about the status of this species. In total, yellow stingrays were observed on 5,658 surveys (6.7% sighting frequency) with the highest occurrence in the regions surrounding Cuba. Overall, sighting frequency declined from 20.5% in 1994 to 4.7% in 2007—a standardized decline rate of −0.11. However, these trends were not consistent in all regions. The strongest decline occurred in the Florida Keys, the most sampled region, where trends were similar among all areas, habitats and depths. In contrast, sighting frequency significantly increased in Jamaica where large fishes are severely depleted. We discuss possible explanations for these changes including habitat degradation, exploitation and changes in trophic interactions. Our results suggest large-scale changes in yellow stingray abundance that have been unnoticed by the scientific community. Thus, our study highlights the value of non-scientific divers for collecting data that can be used to understand population trends of otherwise poorly studied species.

Human-mediated disturbances such as fishing, habitat modification, and pollution have resulted in significant shifts in species composition and abundance in marine ecosystems which translate into degradation of food-web structure. Here, we used a comparative ecological modelling approach and data from two food webs (North-Central Adriatic and South Catalan Sea) and two time periods (mid-late 1970s and 1990s) in the Mediterranean Sea to evaluate how changes in species composition and biomass have affected food-web properties and the extent of ecosystem degradation. We assembled species lists and ecological information for both regions and time periods into stochastic structural and mass-balance food-web models, and compared the outcomes of 22 food-web properties. Our results show strong similarities in structural food-web properties between the North-Central Adriatic and South Catalan Seas indicating similar ecosystem structure and levels of ecological degradation between regions and time periods. In contrast, a comparison with other published marine food webs (Caribbean, Benguela, and US continental shelf) suggested that Mediterranean webs are in an advanced state of ecological degradation. This was reflected by lower trophic height, linkage density, connectance, omnivory, species involved in looping, trophic chain length and fraction of biomass at higher trophic levels, as well as higher generality and fraction of biomass at lower trophic levels. An analysis of robustness to simulated species extinction revealed lower robustness to species removals in Mediterranean webs and corroborated their advanced state of degradation. Importantly, the two modelling approaches used delivered comparable results suggesting that they both capture fundamental information about how food webs are structured.

Evidence for severe declines in large predatory fishes is increasing around the world. Because of its long history of intense fishing, the Mediterranean Sea offers a unique perspective on fish population declines over historical timescales. We used a diverse set of records dating back to the early 19th and mid 20th century to reconstruct long-term population trends of large predatory sharks in the northwestern Mediterranean Sea. We compiled 9 time series of abundance indices from commercial and recreational fishery landings, scientific surveys, and sighting records. Generalized linear models were used to extract instantaneous rates of change from each data set, and a meta-analysis was conducted to compare population trends. Only 5 of the 20 species we considered had sufficient records for analysis. Hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (IsurusoxyrinchusandLamnanasus), and thresher sharks (Alopiasvulpinus) declined between 96 and 99.99% relative to their former abundance. According to World Conservation Union (IUCN) criteria, these species would be considered critically endangered. So far, the lack of quantitative population assessments has impeded shark conservation in the Mediterranean Sea. Our study fills this critical information gap, suggesting that current levels of exploitation put large sharks at risk of extinction in the Mediterranean Sea. Possible ecosystem effects of these losses involve a disruption of top-down control and a release of midlevel consumers.

Coastal ecosystems are among the most productive yet increasingly threatened marine ecosystems worldwide. Particularly vegetated habitats, such as eelgrass (Zostera marina) beds, play important roles in providing key spawning, nursery and foraging habitats for a wide range of fauna. To properly assess changes in coastal ecosystems and manage these critical habitats, it is essential to develop sound monitoring programs for foundation species and associated assemblages. Several survey methods exist, thus understanding how different methods perform is important for survey selection. We compared two common methods for surveying macrofaunal assemblages: beach seine netting and underwater visual census (UVC). We also tested whether assemblages in shallow nearshore habitats commonly sampled by beach seines are similar to those of nearby eelgrass beds often sampled by UVC. Among five estuaries along the Southern Gulf of St. Lawrence, Canada, our results suggest that the two survey methods yield comparable results for species richness, diversity and evenness, yet beach seines yield significantly higher abundance and different species composition. However, sampling nearshore assemblages does not represent those in eelgrass beds despite considerable overlap and close proximity. These results have important implications for how and where macrofaunal assemblages are monitored in coastal ecosystems. Ideally, multiple survey methods and locations should be combined to complement each other in assessing the entire assemblage and full range of changes in coastal ecosystems, thereby better informing coastal zone management.

This paper describes the motivation for the creation of the Vulnerability, Impacts, Adaptation and Climate Services (VIACS) Advisory Board for the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6), its initial activities, and its plans to serve as a bridge between climate change applications experts and climate modelers. The climate change application community comprises researchers and other specialists who use climate information (alongside socioeconomic and other environmental information) to analyze vulnerability, impacts, and adaptation of natural systems and society in relation to past, ongoing, and projected future climate change. Much of this activity is directed toward the co-development of information needed by decision-makers for managing projected risks. CMIP6 provides a unique opportunity to facilitate a two-way dialog between climate modelers and VIACS experts who are looking to apply CMIP6 results for a wide array of research and climate services objectives. The VIACS Advisory Board convenes leaders of major impact sectors, international programs, and climate services to solicit community feedback that increases the applications relevance of the CMIP6-Endorsed Model Intercomparison Projects (MIPs). As an illustration of its potential, the VIACS community provided CMIP6 leadership with a list of prioritized climate model variables and MIP experiments of the greatest interest to the climate model applications community, indicating the applicability and societal relevance of climate model simulation outputs. The VIACS Advisory Board also recommended an impacts version of Obs4MIPs and indicated user needs for the gridding and processing of model output.

30 pages, 11 figures, 1 table, Marine ecosystems have been influenced by human activities throughout history, with a general intensification and diversification of human impacts over time. Yet only recently have we begun to reconstruct the resulting changes in marine populations and ecosystems, and their consequences for human well-being. In this chapter, we present the use of ecological indicators and food-web models as tools to analyse historical changes in marine species and ecosystems. Because marine ecosystems are inherently complex, ecological indicators can help describe them and their changes in simpler terms. Commonly used indicators include species occurrence and abundance, functional group presence such as feeding types, habitat builders or filter feeders, as well as species traits such as body size or trophic ecology. These can be reconstructed for past time periods and used to analyse changes in individual populations or across multiple species over time, thereby providing insight into changes in marine species and ecosystems. A step further, food webs combine multiple species or functional groups and aim to represent the more complex relationships and interactions within marine ecosystems. These can range from qualitative, conceptual food-web illustrations to quantitative modelling approaches that can be used to analyse emerging food-web properties and changes in food-web structure and functioning. We provide a wide range of examples on how different indicators and models have been used and discuss the advantages and disadvantages of different approaches. Finally, we provide an outlook on their potential to advance marine historical research in the future

The Wadden Sea is the world's largest intertidal ecosystem and one of the most productive coastal areas worldwide. People have fished and hunted marine resources in the Wadden Sea since its origin ∼7500 years ago, but have since depleted the majority of formerly important species and their supporting habitats. Most of these changes have been lost from memory. Here, I reconstructed the history of fishing and marine resource use in the Wadden Sea using a multi-disciplinary approach that combines archaeological, historical, fisheries, and ecological records. Early farmers and settlers used a great variety of coastal mammals, birds, fish, and shellfish from ∼5000–500 years ago. During the Middle Ages (500–1500 ad ) fish gained in importance over birds, mammals, and shellfish, and fishing gradually replaced hunting and gathering along the coast. About 1000 years ago, freshwater and migrating fish stocks in European inland lakes and rivers declined because of overfishing and habitat degradation. This induced an expansion and commercialization of marine fisheries along the coast, first for herring and oysters in the 12th and 13th centuries, later for haddock and cod in the 16th century. Exploitation of birds and whales was also commercialized and some species started to decline with increasing exploitation pressure. During Modern Times (1500–1800 ad ), commercial fisheries further developed for rays, flatfish, lobster, and shrimp along the coast and for sturgeon and salmon in the estuaries. Intensification of exploitation in the 19th century led to strong depletion of many coastal resources and several fisheries collapsed in the early 1900s. As a result, new fisheries were developed for formerly less valued species but many declined or collapsed before the end of the 20th century. Today, the only remaining commercial fisheries target shrimp, blue mussels, and cockles. On the other side, conservation efforts have recovered some formerly exploited species, especially birds and seals. Meanwhile, fishing has been gradually replaced by tourism and nature conservation along the coast. The history of the Wadden Sea may serve as an example for a coastal region that sustained people for millennia, was heavily exploited and transformed over time, but still shows some potential for recovery where protection and restoration efforts are integrated into coastal management plans.

Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over 23 million years, taxonomic membership and geographic range size consistently explain a large proportion of extinction risk variation in six major taxonomic groups. We assess intrinsic risk-extinction risk predicted by paleontologically calibrated models-for modern genera in these groups. Mapping the geographic distribution of these genera identifies coastal biogeographic provinces where fauna with high intrinsic risk are strongly affected by human activity or climate change. Such regions are disproportionately in the tropics, raising the possibility that these ecosystems may be particularly vulnerable to future extinctions. Intrinsic risk provides a prehuman baseline for considering current threats to marine biodiversity.

The open oceans comprise most of the biosphere, yet patterns and trends of species diversity there are enigmatic. Here, we derive worldwide patterns of tuna and billfish diversity over the past 50 years, revealing distinct subtropical "hotspots" that appeared to hold generally for other predators and zooplankton. Diversity was positively correlated with thermal fronts and dissolved oxygen and a nonlinear function of temperature (approximately 25 degrees C optimum). Diversity declined between 10 and 50% in all oceans, a trend that coincided with increased fishing pressure, superimposed on strong El Niño-Southern Oscillation-driven variability across the Pacific. We conclude that predator diversity shows a predictable yet eroding pattern signaling ecosystem-wide changes linked to climate and fishing.

Todays Wadden Sea is a heavily human-altered ecosystem. Shaped by natural forces since its origin 7,500 years ago, humans gradually gained dominance in influencing ecosystem structure and functioning. Here, we reconstruct the timeline of human impacts and the history of ecological changes in the Wadden Sea. We then discuss the ecosystem and societal consequences of observed changes, and conclude with management implications. Human influences have intensified and multiplied over time. Large-scale habitat transformation over the last 1,000 years has eliminated diverse terrestrial, freshwater, brackish and marine habitats. Intensive exploitation of everything from oysters to whales has depleted most large predators and habitat-building species since medieval times. In the twentieth century, pollution, eutrophication, species invasions and, presumably, climate change have had marked impacts on the Wadden Sea flora and fauna. Yet habitat loss and overexploitation were the two main causes for the extinction or severe depletion of 144 species (similar to 20% of total macrobiota). The loss of biodiversity, large predators, special habitats, filter and storage capacity, and degradation in water quality have led to a simplification and homogenisation of the food web structure and ecosystem functioning that has affected the Wadden Sea ecosystem and coastal societies alike. Recent conservation efforts have reversed some negative trends by enabling some birds and mammals to recover and by creating new economic options for society. The Wadden Sea history provides a unique long-term perspective on ecological change, new objectives for conservation, restoration and management, and an ecological baseline that allows us to envision a rich, productive and diverse Wadden Sea ecosystem and coastal society.

Ambient UV radiation has substantially increased during the last decades, but its impact on marine benthic communities is hardly known. The aim of this study was to globally compare and quantify how shallow hard-bottom communities are affected by UV during early succession. Identical field experiments in 10 different coastal regions of both hemispheres produced a consistent but unexpected pattern: (i) UV radiation affected species diversity and community biomass in a very similar manner, (ii) diversity and biomass were reduced to a larger extent by UVA than UVB radiation, (iii) ambient UV levels did not affect the composition of the communities, and (iv) any UV effects disappeared during species succession after 2–3 months. Thus, current levels of UV radiation seem to have small, predictable, and transient effects on shallow marine hard-bottom communities.

European colonization of North America severely altered terrestrial and aquatic ecosystems alike. Here, we integrate archaeological, historical, and recent data to derive the ecological history of the Quoddy Region, Bay of Fundy, Canada, an upwelling region rich in marine diversity and productivity. We document successive changes on all trophic levels from primary producers to top predators over the last centuries. Our objectives were to (1) construct a baseline of ''what was natural in the coastal ocean,'' and (2) analyze the sequence and potential interaction of multiple human impacts. Archaeological records highlight the abundance and diversity of marine species used by indigenous people over the last 2000-3000 years. Europeans colonized the area in the late 1700s and rapidly transformed the environment by multiple ''top-down'' (exploitation), ''bottom-up'' (nutrient loading), and ''side-in'' (habitat destruction, pollution) impacts. Most large vertebrates were severely overexploited by 1900, leading to the extinction of three mammal and six bird species. Diadromous fish dramatically declined after river dam- ming in the early 1800s, and recovery was prevented by subsequent river pollution. Over- fishing of groundfish stocks started in the late 1800s, gradually leading to a final collapse in the 1970s. In the 20th century, decline of traditional fisheries induced a shift to low trophic level harvesting and aquaculture, which increased exponentially over the past 20 years. Eutrophication caused shifts in seaweed and phytoplankton communities: Some long- lived rockweeds were replaced by annual bloom-forming algae, and diatoms were replaced by dinoflagellates. Today, the once unique Quoddy Region shows the most common signs of degradation found in highly impacted coastal areas worldwide. Multiple human influences have altered abundance and composition of every trophic level in the food web and reduced upper trophic levels by at least one order of magnitude. We highlight cumulative and indirect effects that impair the ability to predict and manage highly impacted coastal ecosystems. On the other hand, simple protection and restoration measures in the 20th century led to the recovery of some species. It is these successes that provide guidance for a more sus- tainable interaction of humans with their marine environment.

Perhaps the most pressing issue in predicting biotic responses to present and future global change is understanding how environmental factors shape the relationship between ecological traits and extinction risk. The fossil record provides millions of years of insight into how extinction selectivity (i.e., differential extinction risk) is shaped by interactions between ecological traits and environmental conditions. Numerous paleontological studies have examined trait-based extinction selectivity; however, the extent to which these patterns are shaped by environmental conditions is poorly understood due to a lack of quantitative synthesis across studies. We conducted a meta-analysis of published studies on fossil marine bivalves and gastropods that span 458 million years to uncover how global environmental and geochemical changes covary with trait-based extinction selectivity. We focused on geographic range size and life habit (i.e., infaunal vs. epifaunal), two of the most important and commonly examined predictors of extinction selectivity. We used geochemical proxies related to global climate, as well as indicators of ocean acidification, to infer average global environmental conditions. Life-habit selectivity is weakly dependent on environmental conditions, with infaunal species relatively buffered from extinction during warmer climate states. In contrast, the odds of taxa with broad geographic ranges surviving an extinction (>2500 km for genera, >500 km for species) are on average three times greater than narrow-ranging taxa (estimate of odds ratio: 2.8, 95% confidence interval = 2.3–3.5), regardless of the prevailing global environmental conditions. The environmental independence of geographic range size extinction selectivity emphasizes the critical role of geographic range size in setting conservation priorities.

Little is known about the cumulative effects of multiple (.2) environmental controls on species performance and interactions in aquatic ecosystems. We asked how changes in climatic (temperature, ultraviolet radiation) and ecological controls (nutrients, grazing) affect recruitment of the green macroalga Enteromorpha intestinalis,which forms destructive algal blooms in coastal ecosystems worldwide. We designed factorial laboratory experiments to analyze the recruitment response to (1) single and combined effects of nutrient enrichment, grazing pressure, and grazer species composition and (2) the cumulative effects of ultraviolet (UV) radiation, temperature, nutrients, and grazing. Recruitment of E. intestinalis increased exponentially with nutrient enrichment. Grazers could control algal recruitment until a nutrient threshold was reached depending on grazer species composition. Snails ( Littorina littorea) had strong negative effects on recruit density, whereas amphipods (Gammarus oceanicus ) had weak grazing effects and favored algal recruitment through excretion when nutrient supply was low. Temperature and nutrients both enhanced algal recruitment but also the effects of grazers, which led to a significant three-way interaction among these factors. Similarly, effects of UV radiation depended on grazer presence and temperature. When grazers were absent, UV radiation reduced recruitment at 11 and 17 8C but enhanced recruitment at 58C. No effects were seen in the presence of grazers. Our results indicate that multiple human influences, such as climate change, eutrophication, and food web alterations, have interdependent effects and the potential for synergistically enhancing the development of macroalgal blooms in coastal ecosystems.

A key question in ecology is which factors control species diversity in a community1, 2, 3. Two largely separate groups of ecologists have emphasized the importance of productivity or resource supply, and consumers or physical disturbance, respectively. These variables show unimodal relationships with diversity when manipulated in isolation4, 5, 6, 7, 8. Recent multivariate models9, 10, however, predict that these factors interact, such that the disturbance–diversity relationship depends on productivity, and vice versa. We tested these models in marine food webs, using field manipulations of nutrient resources and consumer pressure on rocky shores of contrasting productivity. Here we show that the effects of consumers and nutrients on diversity consistently depend on each other, and that the direction of their effects and peak diversity shift between sites of low and high productivity. Factorial meta-analysis of published experiments confirms these results across widely varying aquatic communities. Furthermore, our experiments demonstrate that these patterns extend to important ecosystem functions such as carbon storage and nitrogen retention. This suggests that human impacts on nutrient supply11 and food-web structure12, 13 have strong and interdependent effects on species diversity and ecosystem functioning, and must therefore be managed together.

The combined and interactive effects of climatic and ecological factors are rarely considered in marine communities. We designed a factorial field experiment to analyze (1) the interactive effects of ambient UV radiation and consumers; and (2) the effects of photosynthetically active radiation (PAR 400 to 700 nm), UVA (320 to 400 nm) and UVB (280 to 320 nm) radiation on a marine hard-bottom community in Nova Scotia, NW Atlantic. Species recruitment and succession on ceramic tiles were followed for 5 mo. We found strong negative UV effects on biomass and cover of the early colonizing macroalga Pilayella littoralis, whereas UVB was more harmful than UVA radiation. Consumers, mainly gammarid amphipods, increased P. littoralis biomass when UV was excluded, probably through fertilization. These initially strong and interacting UV and consumer effects on total biomass and cover diminished as species succession progressed. Species diversity was not affected by experimental treatments, but significant shifts in species composition occurred, especially at the recruitment stage. Red algae were most inhibited by UV, whereas sedentary invertebrates and some brown algae tended to increase under UV exposure. Consumers suppressed green and filamentous brown algae, but favored the other groups. Again, these effects diminished during the later stages of succession. We conclude that UV radiation can be a significant structuring force in early successional benthic communities, and that consumers can mediate its effects.

Macroalgal blooms are a growing environmental problem in eutrophic coastal ecosystems world wide. These blooms are dominated typically by only one out of several co-occurring opportunistic species, which are all favored by increased nutrient loads. We asked whether pronounced dominance of filamentous Pilayella littoralis Kjellm. (Phaeophyceae) over foliose Enteromorpha intestinalis L. (Chlorophyceae) in the Baltic Sea can be explained by interspecific physiological differences. In laboratory experiments, we analyzed uptake kinetics of nitrate, ammonium, and phosphate and the time dependency of uptake rates for both species. We further examined growth rates and nutrient assimilation in relation to single and combined enrichment with nitrate and phosphate, and three different nitrogen sources. Overall, we did not detect distinct differences in uptake, growth, and assimilation rates between P. littoralis and E. intestinalis. Minor differences and the related advantages for single species are discussed. Highest maximal uptake rates were found for ammonium, followed by nitrate and phosphate. Strong time dependency of uptake occurred, with the highest rates during the first 15 to 30 min. Nitrate enrichment had far more of an effect on growth than phosphate. Enrichment with urea, ammonium, and nitrate significantly increased growth rates without interspecific differences. A larger surface area to volume (SA/V) ratio in Pilayella compared with Enteromorpha did not translate into greater physiological capacity. We conclude that species dominance patterns in macroalgal blooms are not always a direct result of different ecophysiological traits among species. Ecological traits such as susceptibility to herbivory are important factors in determining species distribution in the field.