Ocean science. Under-resourced, under threat

Predicting the Effects of Climate Change on the Fertility of Aquatic Animals Using a Meta-Analytic Approach

Given that reproductive physiology is highly sensitive to thermal stress, there is increasing concern about the effects of climate change on animal fertility. Even a slight reduction in fertility can have consequences for population growth and survival, so it is critical to better understand and predict the potential effects of climate change on reproductive traits. We synthesised 1894 effect sizes across 276 studies on 241 species to examine thermal effects on fertility in aquatic animals. Our meta-analysis revealed that external fertilisers tend to be more vulnerable to warming than internal fertilisers, especially in freshwater species. We also found that increased temperature is particularly detrimental for gametes and that under certain conditions, female fertility is more sensitive to warming than male fertility, challenging the prevailing view that males are more vulnerable. This work provides valuable new insights into the effects of temperature on fertility, with potential consequences for population viability.

Impacts of climate change on the distribution of venomous Conus (Gastropoda: Conidae) species in the Indo-Pacific region

Climate change is affecting the distribution of marine organisms worldwide, including venomous marine gastropods that offer risks to human health, but also potential pharmacological resources, such as Conus sp. Species Distribution Models (SDMs) are valuable tools for predicting species distribution under climate change. The objective of our study was to evaluate the potential distribution of Conus geographus and C. textile in the Indo-Pacific region under different climate change scenarios for 2050 and 2090. We constructed SDMs with MaxEnt for each species, using bioclimatic variables from Bio-ORACLE and NOAA, and occurrence data from GBIF. We projected the best-fit model for the present and different future climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5). We obtained high accuracy SDMs for C. geographus and C. textile, with Temperature and Primary Productivity as the main explanatory variables. Our future projections reveal that both species may react differently to climate change. Southeast Asia and Micronesia will continue to provide a climatically appropriate environment for both species; however, they may become more suitable for C. geographus and less suitable for C. textile. This may lead to a higher risk of human envenomation by C. geographus, but a lower risk by C. textile. A decreased suitability for C. textile may also lead to the loss of potential pharmacological resources among its range. Our study emphasizes how SDMs can be used to assess the future distribution of species with human health implications, which can aid in the monitoring of venomous marine species.

Temporal dynamics in zooplankton δ13C and δ15N isoscapes for the North Atlantic Ocean: Decadal cycles, seasonality, and implications for predator ecology

The limited amount of ecological data covering offshore parts of the ocean impedes our ability to understand and anticipate the impact of anthropogenic stressors on pelagic marine ecosystems. Isoscapes, i.e., spatial models of the distribution of stable isotope ratios, have been employed in the recent years to investigate spatio-temporal patterns in biogeochemical process and ecological responses. Development of isoscapes on the scale of ocean basins is hampered by access to suitable reference samples. Here we draw on archived material from long-running plankton survey initiatives, to build temporally explicit isoscape models for the North Atlantic Ocean (> 40°N). A total of 570 zooplankton samples were retrieved from Continuous Plankton Recorder archives and analysed for δ13C and δ15N values. Bayesian generalised additive models were developed to (1) model the relations between isotopic values and a set of predictors and (2) predict isotopic values for the whole of the study area. We produced yearly and seasonal isoscape models for the period 1998–2020. These are the first observation-based time-resolved C and N isoscapes developed at the scale of the North Atlantic Ocean. Drawing on the Stable Isotope Trajectory Analysis framework, we identify five isotopically distinct regions. We discuss the hydro-biogeochemical processes that likely explain theses modes, the differences in temporal dynamics (stability and cycles) and compare our results with previous bioregionalization efforts. Finally, we lay down the basis for using the isoscapes as a tool to define predator distributions and their interactions with the trophic environment. The isoscapes developed in this study have the potential to update our knowledge of marine predator ecology and therefore our capacity to improve their conservation in the future.

Measuring the Impact of Conservation: The Growing Importance of Monitoring Fauna, Flora and Funga

Many stakeholders, from governments to civil society to businesses, lack the data they need to make informed decisions on biodiversity, jeopardising efforts to conserve, restore and sustainably manage nature. Here we review the importance of enhancing biodiversity monitoring, assess the challenges involved and identify potential solutions. Capacity for biodiversity monitoring needs to be enhanced urgently, especially in poorer, high-biodiversity countries where data gaps are disproportionately high. Modern tools and technologies, including remote sensing, bioacoustics and environmental DNA, should be used at larger scales to fill taxonomic and geographic data gaps, especially in the tropics, in marine and freshwater biomes, and for plants, fungi and invertebrates. Stakeholders need to follow best monitoring practices, adopting appropriate indicators and using counterfactual approaches to measure and attribute outcomes and impacts. Data should be made openly and freely available. Companies need to invest in collecting the data required to enhance sustainability in their operations and supply chains. With governments soon to commit to the post-2020 global biodiversity framework, the time is right to make a concerted push on monitoring. However, action at scale is needed now if we are to enhance results-based management adequately to conserve the biodiversity and ecosystem services we all depend on.

Biogeography, diversity and environmental relationships of shelf and deep-sea benthic Amphipoda around Iceland

The waters around Iceland, bounding the Northern North Atlantic and the Nordic seas, are a region characterized by complex hydrography and seabed topography. This and the presence of the Greenland-Iceland-Faroe-Scotland ridge (GIFR) are likely to have a major impact on the diversity and distribution of the benthic fauna there. Biodiversity in this region is also under increasing threat from climate-induced changes, ocean warming and acidification in particular, affecting the marine realm. The aim of the present study was to investigate the biodiversity and distributional patterns of amphipod crustaceans in Icelandic waters and how it relates to environmental variables and depth. A comprehensive data set from the literature and recent expeditions was compiled constituting distributional records for 355 amphipod species across a major depth gradient (18–3,700 m). Using a 1° hexagonal grid to map amphipod distributions and a set of environmental factors (depth, pH, phytobiomass, velocity, dissolved oxygen, dissolved iron, salinity and temperature) we could identify four distinct amphipod assemblages: A Deep-North, Deep-South, and a Coastal cluster as well as one restricted to the GIFR. In addition to depth, salinity and temperature were the main parameters that determined the distribution of amphipods. Diversity differed greatly between the depth clusters and was significantly higher in coastal and GIFR assemblages compared to the deep-sea clusters north and south of the GIFR. A variety of factors and processes are likely to be responsible for the perceived biodiversity patterns, which, however, appear to vary according to region and depth. Low diversity of amphipod communities in the Nordic basins can be interpreted as a reflection of the prevailing harsh environmental conditions in combination with a barrier effect of the GIFR. By contrast, low diversity of the deep North Atlantic assemblages might be linked to the variable nature of the oceanographic environment in the region over multiple spatio-temporal scales. Overall, our study highlights the importance of amphipods as a constituent part of Icelandic benthos. The strong responses of amphipod communities to certain water mass variables raise the question of whether and how their distribution will change due to climate alteration, which should be a focus of future studies.

Global economic costs of aquatic invasive alien species

Much research effort has been invested in understanding ecological impacts of invasive alien species (IAS) across ecosystems and taxonomic groups, but empirical studies about economic effects lack synthesis. Using a comprehensive global database, we determine patterns and trends in economic costs of aquatic IAS by examining: (i) the distribution of these costs across taxa, geographic regions and cost types; (ii) the temporal dynamics of global costs; and (iii) knowledge gaps, especially compared to terrestrial IAS. Based on the costs recorded from the existing literature, the global cost of aquatic IAS conservatively summed to US$345 billion, with the majority attributed to invertebrates (62%), followed by vertebrates (28%), then plants (6%). The largest costs were reported in North America (48%) and Asia (13%), and were principally a result of resource damages (74%); only 6% of recorded costs were from management. The magnitude and number of reported costs were highest in the United States of America and for semi-aquatic taxa. Many countries and known aquatic alien species had no reported costs, especially in Africa and Asia. Accordingly, a network analysis revealed limited connectivity among countries, indicating disparate cost reporting. Aquatic IAS costs have increased in recent decades by several orders of magnitude, reaching at least US$23 billion in 2020. Costs are likely considerably underrepresented compared to terrestrial IAS; only 5% of reported costs were from aquatic species, despite 26% of known invaders being aquatic. Additionally, only 1% of aquatic invasion costs were from marine species. Costs of aquatic IAS are thus substantial, but likely underreported. Costs have increased over time and are expected to continue rising with future invasions. We urge increased and improved cost reporting by managers, practitioners and researchers to reduce knowledge gaps. Few costs are proactive investments; increased management spending is urgently needed to prevent and limit current and future aquatic IAS damages.

Plankton biogeography in the North Atlantic Ocean and its adjacent seas: Species assemblages and environmental signatures

Plankton biodiversity is a key component of marine pelagic ecosystems. They are at the base of the food web, control the productivity of marine ecosystems, and provide many provisioning and regulating ecological services. It is therefore important to understand how plankton are organized in both space and time. Here, we use data of varying taxonomic resolution, collected by the Continuous Plankton Recorder (CPR) survey, to map phytoplankton and zooplankton biodiversity in the North Atlantic and its adjacent seas. We then decompose biodiversity into 24 species assemblages and investigate their spatial distribution using ecological units and ecoregions recently proposed. Finally, we propose a descriptive method, which we call the environmental chromatogram, to characterize the environmental signature of each plankton assemblage. The method is based on a graphic that identifies where species of an assemblage aggregate along an environmental gradient composed of multiple ecological dimensions. The decomposition of the biodiversity into species assemblages allows us to show (a) that most marine regions of the North Atlantic are composed of coenoclines (i.e., gradients of biocoenoses or communities) and (b) that the overlapping spatial distribution of assemblages is the result of their environmental signatures. It follows that neither the ecoregions nor the ecological units identified in the North Atlantic are characterized by a unique assemblage but instead by a mosaic of assemblages that overlap in many places.

The rise of novelty in marine ecosystems: The Baltic Sea case

Global environmental changes have accelerated at an unprecedented rate in recent decades due to human activities. As a consequence, the incidence of novel abiotic conditions and biotic communities, which have been continuously emerging in the Earth system, has rapidly risen. Despite growing attention to the incidence and challenges posed by novelty in terrestrial ecosystems, novelty has not yet been quantified in marine ecosystems. Here, we measured for the rate of novelty (RoN) in abiotic conditions and community structure for three trophic levels, i.e., phytoplankton, zooplankton, and fish, in a large marine system - the Baltic Sea. We measured RoN as the degree of dissimilarity relative to a specific spatial and temporal baseline, and contrasted this with the rate of change as a measure of within-basin change over time. We found that over the past 35 years abiotic and biotic RoN showed complex dynamics varying in time and space, depending on the baseline conditions. RoN in abiotic conditions was smaller in the open Central Baltic Sea than in the Kattegat and the more enclosed Gulf of Bothnia, Gulf of Riga, and Gulf of Finland in the north. We found a similar spatial pattern for biotic assemblages, which resulted from changes in composition and stock size. We identified sea-surface temperature and salinity as key drivers of RoN in biotic communities. Hence, future environmental changes that are expected to affect the biogeochemistry of the Baltic Sea, may favor the rise of biotic novelty. Our results highlighted the need for a deeper understanding of novelty development in marine ecosystems, including interactions between species and trophic levels, ecosystem functioning under novel abiotic conditions, and considering novelty in future management interventions.

No evidence for fitness signatures consistent with increasing trophic mismatch over 30 years in a population of European shag Phalacrocorax aristotelis

As temperatures rise, timing of reproduction is changing at different rates across trophic levels, potentially resulting in asynchrony between consumers and their resources. The match-mismatch hypothesis (MMH) suggests that trophic asynchrony will have negative impacts on average productivity of consumers. It is also thought to lead to selection on timing of breeding, as the most asynchronous individuals will show the greatest reductions in fitness. Using a 30-year individual-level dataset of breeding phenology and success from a population of European shags on the Isle of May, Scotland, we tested a series of predictions consistent with the hypothesis that fitness impacts of trophic asynchrony are increasing. These predictions quantified changes in average annual breeding success and strength of selection on timing of breeding, over time and in relation to rising sea surface temperature (SST) and diet composition. Annual average (population) breeding success was negatively correlated with average lay date yet showed no trend over time, or in relation to increasing SST or the proportion of principal prey in the diet, as would be expected if trophic mismatch was increasing. At the individual level, we found evidence for stabilising selection and directional selection for earlier breeding, although the earliest birds were not the most productive. However, selection for earlier laying did not strengthen over time, or in relation to SST or slope of the seasonal shift in diet from principal to secondary prey. We found that the optimum lay date advanced by almost 4 weeks during the study, and that the population mean lay date tracked this shift. Our results indicate that average performance correlates with absolute timing of breeding of the population, and there is selection for earlier laying at the individual level. However, we found no fitness signatures of a change in the impact of climate-induced trophic mismatch, and evidence that shags are tracking long-term shifts in optimum timing. This suggests that if asynchrony is present in this system, breeding success is not impacted. Our approach highlights the advantages of examining variation at both population and individual levels when assessing evidence for fitness impacts of trophic asynchrony.

Strengthening the evidence base for temperature-mediated phenological asynchrony and its impacts

Climate warming has caused the seasonal timing of many components of ecological food chains to advance. In the context of trophic interactions, the match-mismatch hypothesis postulates that differential shifts can lead to phenological asynchrony with negative impacts for consumers. However, at present there has been no consistent analysis of the links between temperature change, phenological asynchrony and individual-to-population-level impacts across taxa, trophic levels and biomes at a global scale. Here, we propose five criteria that all need to be met to demonstrate that temperature-mediated trophic asynchrony poses a growing risk to consumers. We conduct a literature review of 109 papers studying 129 taxa, and find that all five criteria are assessed for only two taxa, with the majority of taxa only having one or two criteria assessed. Crucially, nearly every study was conducted in Europe or North America, and most studies were on terrestrial secondary consumers. We thus lack a robust evidence base from which to draw general conclusions about the risk that climate-mediated trophic asynchrony may pose to populations worldwide.

Climate-Driven Shifts in Marine Species Ranges: Scaling from Organisms to Communities

The geographic distributions of marine species are changing rapidly, with leading range edges following climate poleward, deeper, and in other directions and trailing range edges often contracting in similar directions. These shifts have their roots in fine-scale interactions between organisms and their environment-including mosaics and gradients of temperature and oxygen-mediated by physiology, behavior, evolution, dispersal, and species interactions. These shifts reassemble food webs and can have dramatic consequences. Compared with species on land, marine species are more sensitive to changing climate but have a greater capacity for colonization. These differences suggest that species cope with climate change at different spatial scales in the two realms and that range shifts across wide spatial scales are a key mechanism at sea. Additional research is needed to understand how processes interact to promote or constrain range shifts, how the dominant responses vary among species, and how the emergent communities of the future ocean will function.

Microplastic study reveals the presence of natural and synthetic fibres in the diet of King Penguins (Aptenodytes patagonicus) foraging from South Georgia

Marine ecosystems are experiencing substantial disturbances due to climate change and overfishing, and plastic pollution is an additional growing threat. Microfibres are among the most pervasive pollutants in the marine environment, including in the Southern Ocean. However, evidence for microfibre contamination in the diet of top predators in the Southern Ocean is rare. King Penguins (Aptenodytes patagonicus) feed on mesopelagic fish, which undergo diel vertical migrations towards the surface at night. Microfibres are concentrated in surface waters and sediments but can also be concentrated in fish, therefore acting as contamination vectors for diving predators feeding at depth. In this study, we investigate microfibre contamination of King Penguin faecal samples collected in February and March 2017 at South Georgia across three groups: incubating, chick-rearing and non-breeding birds. After a KOH digestion to dissolve the organic matter and a density separation step using a NaCl solution, the samples were filtered to collect microfibres. A total of 77% of the penguin faecal samples (36 of 47) contained microfibres. Fibres were measured and characterized using Fourier-Transform Infrared spectroscopy to determine their polymeric identity. Most fibres (88%) were made of natural cellulosic materials (e.g. cotton, linen), with only 12% synthetic (e.g. polyester, nylon) or semi-synthetic (e.g. rayon). An average of 21.9 ± 5.8 microfibres g^-1 of faeces (lab dried mass) was found, with concentrations more than twice as high in incubating penguins than in penguins rearing chicks. Incubating birds forage further north at the Antarctic Polar Front and travel longer distances from South Georgia than chick-rearing birds. This suggests that long-distance travelling penguins are probably more exposed to the risk of ingesting microfibres when feeding north of the Antarctic Polar Front, which might act as a semi-permeable barrier for microfibres. Microfibres could therefore provide a signature for foraging location in King Penguins.

Breakdown in spawning synchrony: A silent threat to coral persistence

The impacts of human and natural disturbances on coral reefs are typically quantified through visible damage (e.g., reduced coral coverage as a result of bleaching events), but changes in environmental conditions may also cause damage in less visible ways. Despite the current paradigm, which suggests consistent, highly synchronized spawning events, corals that reproduce by broadcast spawning are particularly vulnerable because their reproductive phenology is governed by environmental cues. Here, we quantify coral spawning intensity during four annual reproductive seasons, alongside laboratory analyses at the polyp, colony, and population levels, and we demonstrate that, compared with historical data, several species from the Red Sea have lost their reproductive synchrony. Ultimately, such a synchrony breakdown reduces the probability of successful fertilization, leading to a dearth of new recruits, which may drive aging populations to extinction.

Biological Assessment of Coral Reefs in Southern Puerto Rico: A Technical Approach for Coral Reef Protection Under the U.S. Clean Water Act

States and other jurisdictions may protect coral reefs using biological water quality standards outlined by the United States Clean Water Act (CWA). Such protection will require long-term, regional monitoring of the resource using biological indicators and a probability-based sampling design. A 60-station survey targeting nearshore linear coral reef was conducted across southern Puerto Rico in December 2011 to document the status of reef inhabitants using a probabilistic, regional sampling design. The quantity, type and condition of stony corals, fish, gorgonians and sponges were documented from each station, providing a robust representation of linear reef status and composition across the region. Fish represented 106 unique taxa and stony corals 32 unique taxa. Benthic organisms (stony corals, sponges and gorgonians) averaged nearly 12 colonies per square meter, more than half of which were gorgonians. Assessment results can be used as a baseline to compare with future regional surveys to quantify change in reef condition over time (trend). Both temporal and spatial changes can be expected after large-scale disturbances like hurricanes Maria and Irma in 2017. The indicators and probabilistic sampling design support the long-term regional monitoring envisioned by the Environmental Protection Agency to implement CWA protections in Puerto Rico and elsewhere.

Reproductive performance and diving behaviour share a common sea-ice concentration optimum in Adélie penguins (Pygoscelis adeliae)

The Southern Ocean is currently experiencing major environmental changes, including in sea-ice cover. Such changes strongly influence ecosystem structure and functioning and affect the survival and reproduction of predators such as seabirds. These effects are likely mediated by reduced availability of food resources. As such, seabirds are reliable eco-indicators of environmental conditions in the Antarctic region. Here, based on 9 years of sea-ice data, we found that the breeding success of Adélie penguins (Pygoscelis adeliae) reaches a peak at intermediate sea-ice cover (ca. 20%). We further examined the effects of sea-ice conditions on the foraging activity of penguins, measured at multiple scales from individual dives to foraging trips. Analysis of temporal organisation of dives, including fractal and bout analyses, revealed an increasingly consistent behaviour during years with extensive sea-ice cover. The relationship between several dive parameters and sea-ice cover in the foraging area appears to be quadratic. In years of low and high sea-ice cover, individuals adjusted their diving effort by generally diving deeper, more frequently and by resting at the surface between dives for shorter periods of time than in years with intermediate sea-ice cover. Our study therefore suggests that sea-ice cover is likely to affect the reproductive performance of Adélie penguins through its effects on foraging behaviour, as breeding success and most diving parameters share a common optimum. Some years, however, deviated from this general trend, suggesting that other factors (e.g. precipitation during the breeding season) might sometimes become preponderant over the sea-ice effects on breeding and foraging performance. Our study highlights the value of monitoring fitness parameters and individual behaviour concomitantly over the long-term to better characterize optimal environmental conditions and potential resilience of wildlife. Such an approach is crucial if we want to anticipate the effects of environmental change on Antarctic penguin populations.

Crowdsourcing conservation: The role of citizen science in securing a future for seagrass

Seagrass meadows are complex social-ecological systems. Understanding seagrass meadows demands a fresh approach integrating "the human dimension". Citizen science is widely acknowledged for providing significant contributions to science, education, society and policy. Although the take up of citizen science in the marine environment has been slow, the need for such methods to fill vast information gaps is arguably great. Seagrass meadows are easy to access and provide an example of where citizen science is expanding. Technological developments have been pivotal to this, providing new opportunities for citizens to engage with seagrass. The increasing use of online tools has created opportunities to collect and submit as well as help process and analyse data. Citizen science has helped researchers integrate scientific and local knowledge and engage communities to implement conservation measures. Here we use a selection of examples to demonstrate how citizen science can secure a future for seagrass.

Assessing cetacean surveys throughout the Mediterranean Sea: a gap analysis in environmental space

Heterogeneous data collection in the marine environment has led to large gaps in our knowledge of marine species distributions. To fill these gaps, models calibrated on existing data may be used to predict species distributions in unsampled areas, given that available data are sufficiently representative. Our objective was to evaluate the feasibility of mapping cetacean densities across the entire Mediterranean Sea using models calibrated on available survey data and various environmental covariates. We aggregated 302,481 km of line transect survey effort conducted in the Mediterranean Sea within the past 20 years by many organisations. Survey coverage was highly heterogeneous geographically and seasonally: large data gaps were present in the eastern and southern Mediterranean and in non-summer months. We mapped the extent of interpolation versus extrapolation and the proportion of data nearby in environmental space when models calibrated on existing survey data were used for prediction across the entire Mediterranean Sea. Using model predictions to map cetacean densities in the eastern and southern Mediterranean, characterised by warmer, less productive waters, and more intense eddy activity, would lead to potentially unreliable extrapolations. We stress the need for systematic surveys of cetaceans in these environmentally unique Mediterranean waters, particularly in non-summer months.

Predicting occurrence of juvenile shark habitat to improve conservation planning

Fishing and habitat degradation have increased the extinction risk of sharks, and conservation strategies recognize that survival of juveniles is critical for the effective management of shark populations. Despite the rapid expansion of marine protected areas (MPAs) globally, the paucity of shark-monitoring data on large scales (100s-1000s km) means that the effectiveness of MPAs in halting shark declines remains unclear. Using data collected by baited remote underwater video systems (BRUVS) in northwestern Australia, we developed generalized linear models to elucidate the ecological drivers of habitat suitability for juvenile sharks. We assessed occurrence patterns at the order and species levels. We included all juvenile sharks sampled and the 3 most abundant species sampled separately (grey reef [Carcharhinus amblyrhynchos], sandbar [Carcharhinus plumbeus], and whitetip reef sharks [Triaenodon obesus]). We predicted the occurrence of juvenile sharks across 490,515 km² of coastal waters and quantified the representation of highly suitable habitats within MPAs. Our species-level models had higher accuracy (ĸ ≥ 0.69) and deviance explained (≥48%) than our order-level model (ĸ = 0.36 and deviance explained of 10%). Maps of predicted occurrence revealed different species-specific patterns of highly suitable habitat. These differences likely reflect different physiological or resource requirements between individual species and validate concerns over the utility of conservation targets based on aggregate species groups as opposed to a species-focused approach. Highly suitable habitats were poorly represented in MPAs with the most restrictions on extractive activities. This spatial mismatch possibly indicates a lack of explicit conservation targets and information on species distribution during the planning process. Non-extractive BRUVS provided a useful platform for building the suitability models across large scales to assist conservation planning across multiple maritime jurisdictions, and our approach provides a simple for method for testing the effectiveness of MPAs.

Eight habitats, 38 threats and 55 experts: Assessing ecological risk in a multi-use marine region

Identifying the relative risk human activities pose to a habitat, and the ecosystem services they provide, can guide management prioritisation and resource allocation. Using a combination of expert elicitation to assess the probable effect of a threat and existing data to assess the level of threat exposure, we conducted a risk assessment for 38 human-mediated threats to eight marine habitats (totalling 304 threat-habitat combinations) in Spencer Gulf, Australia. We developed a score-based survey to collate expert opinion and assess the relative effect of each threat to each habitat, as well as a novel and independent measure of knowledge-based uncertainty. Fifty-five experts representing multiple sectors and institutions participated in the study, with 6 to 15 survey responses per habitat (n = 81 surveys). We identified key threats specific to each habitat; overall, climate change threats received the highest risk rankings, with nutrient discharge identified as a key local-scale stressor. Invasive species and most fishing-related threats, which are commonly identified as major threats to the marine environment, were ranked as low-tier threats to Spencer Gulf, emphasising the importance of regionally-relevant assessments. Further, we identified critical knowledge gaps and quantified uncertainty scores for each risk. Our approach will facilitate prioritisation of resource allocation in a region of increasing social, economic and environmental importance, and can be applied to marine regions where empirical data are lacking.

International marine environmental governance: A review

Impressive numbers of global and regional governmental and non-governmental organizations are working in the field of the marine environment and its resources. Many of these organizations operate within international legal frameworks ranging from comprehensive global conventions, such as the United Nations Convention on the Law of the Sea to regional agreements aiming at protection and development of regional seas. Characteristic for the management of these seas, both at the national and international level, is that sectoral approaches predominate. Over time, several initiatives have been taken to improve cooperation, coordination and integration to achieve greater coherence of policies and strategies between different organizations dealing with marine and maritime management, within and outside the United Nation system. However, the success has been limited. The weaknesses of international organizations depend fundamentally on problems at the national level. The international organizations are no stronger than their Contracting Parties allow them to be.

Ocean warming and acidification synergistically increase coral mortality

Organisms that accumulate calcium carbonate structures are particularly vulnerable to ocean warming (OW) and ocean acidification (OA), potentially reducing the socioeconomic benefits of ecosystems reliant on these taxa. Since rising atmospheric CO₂ is responsible for global warming and increasing ocean acidity, to correctly predict how OW and OA will affect marine organisms, their possible interactive effects must be assessed. Here we investigate, in the field, the combined temperature (range: 16–26 °C) and acidification (range: pH_TS 8.1–7.4) effects on mortality and growth of Mediterranean coral species transplanted, in different seasonal periods, along a natural pH gradient generated by a CO₂ vent. We show a synergistic adverse effect on mortality rates (up to 60%), for solitary and colonial, symbiotic and asymbiotic corals, suggesting that high seawater temperatures may have increased their metabolic rates which, in conjunction with decreasing pH, could have led to rapid deterioration of cellular processes and performance. The net calcification rate of the symbiotic species was not affected by decreasing pH, regardless of temperature, while in the two asymbiotic species it was negatively affected by increasing acidification and temperature, suggesting that symbiotic corals may be more tolerant to increasing warming and acidifying conditions compared to asymbiotic ones.

Towards a meaningful assessment of marine ecological impacts in life cycle assessment (LCA)

Human demands on marine resources and space are currently unprecedented and concerns are rising over observed declines in marine biodiversity. A quantitative understanding of the impact of industrial activities on the marine environment is thus essential. Life cycle assessment (LCA) is a widely applied method for quantifying the environmental impact of products and processes. LCA was originally developed to assess the impacts of land-based industries on mainly terrestrial and freshwater ecosystems. As such, impact indicators for major drivers of marine biodiversity loss are currently lacking. We review quantitative approaches for cause-effect assessment of seven major drivers of marine biodiversity loss: climate change, ocean acidification, eutrophication-induced hypoxia, seabed damage, overexploitation of biotic resources, invasive species and marine plastic debris. Our review shows that impact indicators can be developed for all identified drivers, albeit at different levels of coverage of cause-effect pathways and variable levels of uncertainty and spatial coverage. Modeling approaches to predict the spatial distribution and intensity of human-driven interventions in the marine environment are relatively well-established and can be employed to develop spatially-explicit LCA fate factors. Modeling approaches to quantify the effects of these interventions on marine biodiversity are less well-developed. We highlight specific research challenges to facilitate a coherent incorporation of marine biodiversity loss in LCA, thereby making LCA a more comprehensive and robust environmental impact assessment tool. Research challenges of particular importance include i) incorporation of the non-linear behavior of global circulation models (GCMs) within an LCA framework and ii) improving spatial differentiation, especially the representation of coastal regions in GCMs and ocean-carbon cycle models.

Error and bias in size estimates of whale sharks: implications for understanding demography

Body size and age at maturity are indicative of the vulnerability of a species to extinction. However, they are both difficult to estimate for large animals that cannot be restrained for measurement. For very large species such as whale sharks, body size is commonly estimated visually, potentially resulting in the addition of errors and bias. Here, we investigate the errors and bias associated with total lengths of whale sharks estimated visually by comparing them with measurements collected using a stereo-video camera system at Ningaloo Reef, Western Australia. Using linear mixed-effects models, we found that visual lengths were biased towards underestimation with increasing size of the shark. When using the stereo-video camera, the number of larger individuals that were possibly mature (or close to maturity) that were detected increased by approximately 10%. Mean lengths calculated by each method were, however, comparable (5.002 ± 1.194 and 6.128 ± 1.609 m, s.d.), confirming that the population at Ningaloo is mostly composed of immature sharks based on published lengths at maturity. We then collated data sets of total lengths sampled from aggregations of whale sharks worldwide between 1995 and 2013. Except for locations in the East Pacific where large females have been reported, these aggregations also largely consisted of juveniles (mean lengths less than 7 m). Sightings of the largest individuals were limited and occurred mostly prior to 2006. This result highlights the urgent need to locate and quantify the numbers of mature male and female whale sharks in order to ascertain the conservation status and ensure persistence of the species.

Climate change impacts on marine water quality: The case study of the Northern Adriatic sea

Climate change is posing additional pressures on coastal ecosystems due to variations in water biogeochemical and physico-chemical parameters (e.g., pH, salinity) leading to aquatic ecosystem degradation. With the main aim of analyzing the potential impacts of climate change on marine water quality, a Regional Risk Assessment methodology was developed and applied to coastal marine waters of the North Adriatic. It integrates the outputs of regional biogeochemical and physico-chemical models considering future climate change scenarios (i.e., years 2070 and 2100) with site-specific environmental and socio-economic indicators. Results showed that salinity and temperature will be the main drivers of changes, together with macronutrients, especially in the area of the Po' river delta. The final outputs are exposure, susceptibility and risk maps supporting the communication of the potential consequences of climate change on water quality to decision makers and stakeholders and provide a basis for the definition of adaptation and management strategies.

Disciplinary reporting affects the interpretation of climate change impacts in global oceans

Climate change is affecting marine ecosystems, but different investigative approaches in physical, chemical, and biological disciplines may influence interpretations of climate-driven changes in the ocean. Here, we review the ocean change literature from 2007 to 2012 based on 461 of the most highly cited studies in physical and chemical oceanography and three biological subdisciplines. Using highly cited studies, we focus on research that has shaped recent discourse on climate-driven ocean change. Our review identified significant differences in spatial and temporal scales of investigation among disciplines. Physical/chemical studies had a median duration of 29 years (n = 150) and covered the greatest study areas (median 1.41 × 10(7) km(2) , n = 148). Few biological studies were conducted over similar spatial and temporal scales (median 8 years, n = 215; median 302 km(2) , n = 196), suggesting a more limited ability to separate climate-related responses from natural variability. We linked physical/chemical and biological disciplines by tracking studies examining biological responses to changing ocean conditions. Of the 545 biological responses recorded, a single physical or chemical stressor was usually implicated as the cause (59%), with temperature as the most common primary stressor (44%). The most frequently studied biological responses were changes in physiology (31%) and population abundance (30%). Differences in disciplinary studies, as identified in this review, can ultimately influence how researchers interpret climate-related impacts in marine systems. We identified research gaps and the need for more discourse in (1) the Indian and other Southern Hemisphere ocean basins; (2) research themes such as archaea, bacteria, viruses, mangroves, turtles, and ocean acidification; (3) physical and chemical stressors such as dissolved oxygen, salinity, and upwelling; and (4) adaptive responses of marine organisms to climate-driven ocean change. Our findings reveal that highly cited biological studies are rarely conducted on scales that match those of physical and chemical studies. Rather, we suggest a need for measuring responses at biologically relevant scales.

New Approaches to Marine Conservation Through the Scaling Up of Ecological Data

In an era of rapid global change, conservation managers urgently need improved tools to track and counter declining ecosystem conditions. This need is particularly acute in the marine realm, where threats are out of sight, inadequately mapped, cumulative, and often poorly understood, thereby generating impacts that are inefficiently managed. Recent advances in macroecology, statistical analysis, and the compilation of global data will play a central role in improving conservation outcomes, provided that global, regional, and local data streams can be integrated to produce locally relevant and interpretable outputs. Progress will be assisted by (a) expanded rollout of systematic surveys that quantify species patterns, including some carried out with help from citizen scientists; (b) coordinated experimental research networks that utilize large-scale manipulations to identify mechanisms underlying these patterns;

Habitat use and sex-specific foraging behaviour of Adélie penguins throughout the breeding season in Adélie Land, East Antarctica

BACKGROUND

Marine predators are ecosystem sentinels because their foraging behaviour and reproductive success reflect the variability occurring in the lower trophic levels of the ecosystem. In an era of environmental change, monitoring top predators species can provide valuable insights into the zones of ecological importance that need to be protected. In this context, we monitored the Adélie penguin (Pygoscelis adeliae) as a bio-indicator near Dumont d'Urville, an area of the East Antarctic sector currently being considered for the establishment of a Marine Protected Area (MPA), using GPS-based tracking tags during the 2012/13 austral summer breeding season.

RESULTS

The habitat use and foraging areas of the penguins differed by breeding stage and sex and were strongly associated with patterns in bathymetry and sea-ice distribution. The first trips, undertaken during the incubation phase, were longer than those during the guard phase and were associated with the northern limit of the sea-ice extent. During the guard phase, birds strongly depended on access to a polynya, a key feature in Antarctic marine ecosystem, in the vicinity of the colony. The opening of the ice-free area was synchronous with the hatching of chicks. Moreover, a sex-specific use of foraging habitat observed only after hatching suggests sex-specific differences in the diet in response to intra-specific competition.

CONCLUSIONS

Sea-ice features that could be affected by the climate change were important factors for the use of foraging habitat by the Adélie penguins. The extent of the foraging area observed in this study is congruent with the area of the proposed MPA. However, both penguin behavior and their environment should be monitored carefully.

Long-term patterns in estuarine fish growth across two climatically divergent regions

Long-term ecological datasets are vital for investigating how species respond to changes in their environment, yet there is a critical lack of such datasets from aquatic systems. We developed otolith growth 'chronologies' to reconstruct the growth history of a temperate estuarine fish species, black bream (Acanthopagrus butcheri). Chronologies represented two regions in south-east Australia: South Australia, characterised by a relatively warm, dry climate, and Tasmania, characterised by a relatively cool, wet climate. Using a mixed modelling approach, we related inter-annual growth variation to air temperature, rainfall, freshwater inflow (South Australia only), and El Niño-Southern Oscillation events. Otolith chronologies provided a continuous record of growth over a 13- and 21-year period for fish from South Australia and Tasmania, respectively. Even though fish from Tasmania were sourced across multiple estuaries, they showed higher levels of growth synchronicity across years, and greater year-to-year growth variation, than fish from South Australia, which were sourced from a single, large estuary. Growth in Tasmanian fish declined markedly over the time period studied and was negatively correlated to temperature. In contrast, growth in South Australian fish was positively correlated to both temperature and rainfall. The stark contrast between the two regions suggests that Tasmanian black bream populations are more responsive to regional scale environmental variation and may be more vulnerable to global warming. This study highlights the importance of examining species response to climate change at the intra-specific level and further validates the emerging use of growth chronologies for generating long-term ecological data in aquatic systems.

Climate change and decadal shifts in the phenology of larval fishes in the California Current ecosystem

Climate change has prompted an earlier arrival of spring in numerous ecosystems. It is uncertain whether such changes are occurring in Eastern Boundary Current Upwelling ecosystems, because these regions are subject to natural decadal climate variability, and regional climate models predict seasonal delays in upwelling. To answer this question, the phenology of 43 species of larval fishes was investigated between 1951 and 2008 off southern California. Ordination of the fish community showed earlier phenological progression in more recent years. Thirty-nine percent of seasonal peaks in larval abundance occurred earlier in the year, whereas 18% were delayed. The species whose phenology became earlier were characterized by an offshore, pelagic distribution, whereas species with delayed phenology were more likely to reside in coastal, demersal habitats. Phenological changes were more closely associated with a trend toward earlier warming of surface waters rather than decadal climate cycles, such as the Pacific Decadal Oscillation and North Pacific Gyre Oscillation. Species with long-term advances and delays in phenology reacted similarly to warming at the interannual time scale as demonstrated by responses to the El Niño Southern Oscillation. The trend toward earlier spawning was correlated with changes in sea surface temperature (SST) and mesozooplankton displacement volume, but not coastal upwelling. SST and upwelling were correlated with delays in fish phenology. For species with 20th century advances in phenology, future projections indicate that current trends will continue unabated. The fate of species with delayed phenology is less clear due to differences between Intergovernmental Panel on Climate Change models in projected upwelling trends.

IMOS National Reference Stations: a continental-wide physical, chemical and biological coastal observing system

Sustained observations allow for the tracking of change in oceanography and ecosystems, however, these are rare, particularly for the Southern Hemisphere. To address this in part, the Australian Integrated Marine Observing System (IMOS) implemented a network of nine National Reference Stations (NRS). The network builds on one long-term location, where monthly water sampling has been sustained since the 1940s and two others that commenced in the 1950s. In-situ continuously moored sensors and an enhanced monthly water sampling regime now collect more than 50 data streams. Building on sampling for temperature, salinity and nutrients, the network now observes dissolved oxygen, carbon, turbidity, currents, chlorophyll a and both phytoplankton and zooplankton. Additional parameters for studies of ocean acidification and bio-optics are collected at a sub-set of sites and all data is made freely and publically available. Our preliminary results demonstrate increased utility to observe extreme events, such as marine heat waves and coastal flooding; rare events, such as plankton blooms; and have, for the first time, allowed for consistent continental scale sampling and analysis of coastal zooplankton and phytoplankton communities. Independent water sampling allows for cross validation of the deployed sensors for quality control of data that now continuously tracks daily, seasonal and annual variation. The NRS will provide multi-decadal time series, against which more spatially replicated short-term studies can be referenced, models and remote sensing products validated, and improvements made to our understanding of how large-scale, long-term change and variability in the global ocean are affecting Australia's coastal seas and ecosystems. The NRS network provides an example of how a continental scaled observing systems can be developed to collect observations that integrate across physics, chemistry and biology.

Regional status assessment of stony corals in the US Virgin Islands

States may protect coral reefs using biological water quality standards outlined by the Clean Water Act. This requires biological assessments with indicators sensitive to human disturbance and regional, probability-based survey designs. Stony coral condition was characterized on a regional scale for the first time in the nearshore waters of the US Virgin Islands (USVI). Coral composition, abundance, size, and health were assessed at 66 stations in the St. Croix region in fall 2007 and at 63 stations in the St. Thomas and St. John region in winter 2009. Indicators were chosen for their sensitivity to human disturbance. Both surveys were probability-based (random) designs with station locations preselected from areas covered by hardbottom and coral reef substrate. Taxa richness was as high as 21 species but more than half the area of both regions exhibited taxa richness of <10 species in the 25 m(2) transect area. Coral density was as high as 5 colonies m(-2) but more than half the area of both regions had <2 colonies m(-2). Both regions showed similar dominant species based on frequency of occurrence and relative abundance. Because of large colony sizes, Montastrea annularis provided more total surface area and live surface area than more abundant species. The surveys establish baseline regional conditions and provide a foundation for long-term regional monitoring envisioned by the USVI Department of Planning and Natural Resources. The probabilistic sampling design assures the data can be used in Clean Water Act reporting.

Climate-change impacts on sandy-beach biota: crossing a line in the sand

Sandy ocean beaches are iconic assets that provide irreplaceable ecosystem services to society. Despite their great socioeconomic importance, beaches as ecosystems are severely under-represented in the literature on climate-change ecology. Here, we redress this imbalance by examining whether beach biota have been observed to respond to recent climate change in ways that are consistent with expectations under climate change. We base our assessments on evidence coming from case studies on beach invertebrates in South America and on sea turtles globally. Surprisingly, we find that observational evidence for climate-change responses in beach biota is more convincing for invertebrates than for highly charismatic turtles. This asymmetry is paradoxical given the better theoretical understanding of the mechanisms by which turtles are likely to respond to changes in climate. Regardless of this disparity, knowledge of the unique attributes of beach systems can complement our detection of climate-change impacts on sandy-shore invertebrates to add rigor to studies of climate-change ecology for sandy beaches. To this end, we combine theory from beach ecology and climate-change ecology to put forward a suite of predictive hypotheses regarding climate impacts on beaches and to suggest ways that these can be tested. Addressing these hypotheses could significantly advance both beach and climate-change ecology, thereby progressing understanding of how future climate change will impact coastal ecosystems more generally.

Predicting current and future global distributions of whale sharks

The Vulnerable (IUCN) whale shark spans warm and temperate waters around the globe. However, their present-day and possible future global distribution has never been predicted. Using 30 years (1980-2010) of whale shark observations recorded by tuna purse-seiners fishing in the Atlantic, Indian and Pacific Oceans, we applied generalized linear mixed-effects models to test the hypothesis that similar environmental covariates predict whale shark occurrence in all major ocean basins. We derived global predictors from satellite images for chlorophyll a and sea surface temperature, and bathymetric charts for depth, bottom slope and distance to shore. We randomly generated pseudo-absences within the area covered by the fisheries, and included fishing effort as an offset to account for potential sampling bias. We predicted sea surface temperatures for 2070 using an ensemble of five global circulation models under a no climate-policy reference scenario, and used these to predict changes in distribution. The full model (excluding standard deviation of sea surface temperature) had the highest relative statistical support (wAICc  = 0.99) and explained ca. 60% of the deviance. Habitat suitability was mainly driven by spatial variation in bathymetry and sea surface temperature among oceans, although these effects differed slightly among oceans. Predicted changes in sea surface temperature resulted in a slight shift of suitable habitat towards the poles in both the Atlantic and Indian Oceans (ca. 5°N and 3-8°S, respectively) accompanied by an overall range contraction (2.5-7.4% and 1.1-6.3%, respectively). Predicted changes in the Pacific Ocean were small. Assuming that whale shark environmental requirements and human disturbances (i.e. no stabilization of greenhouse gas emissions) remain similar, we show that warming sea surface temperatures might promote a net retreat from current aggregation areas and an overall redistribution of the species.

Predicting coral species richness: the effect of input variables, diversity and scale

Coral reefs are facing a biodiversity crisis due to increasing human impacts, consequently, one third of reef-building corals have an elevated risk of extinction. Logistic challenges prevent broad-scale species-level monitoring of hard corals; hence it has become critical that effective proxy indicators of species richness are established. This study tests how accurately three potential proxy indicators (generic richness on belt transects, generic richness on point-intercept transects and percent live hard coral cover on point-intercept transects) predict coral species richness at three different locations and two analytical scales. Generic richness (measured on a belt transect) was found to be the most effective predictor variable, with significant positive linear relationships across locations and scales. Percent live hard coral cover consistently performed poorly as an indicator of coral species richness. This study advances the practical framework for optimizing coral reef monitoring programs and empirically demonstrates that generic richness offers an effective way to predict coral species richness with a moderate level of precision. While the accuracy of species richness estimates will decrease in communities dominated by species-rich genera (e.g. Acropora), generic richness provides a useful measure of phylogenetic diversity and incorporating this metric into monitoring programs will increase the likelihood that changes in coral species diversity can be detected.

Incorporating climate science in applications of the US endangered species act for aquatic species

Aquatic species are threatened by climate change but have received comparatively less attention than terrestrial species. We gleaned key strategies for scientists and managers seeking to address climate change in aquatic conservation planning from the literature and existing knowledge. We address 3 categories of conservation effort that rely on scientific analysis and have particular application under the U.S. Endangered Species Act (ESA): assessment of overall risk to a species; long-term recovery planning; and evaluation of effects of specific actions or perturbations. Fewer data are available for aquatic species to support these analyses, and climate effects on aquatic systems are poorly characterized. Thus, we recommend scientists conducting analyses supporting ESA decisions develop a conceptual model that links climate, habitat, ecosystem, and species response to changing conditions and use this model to organize analyses and future research. We recommend that current climate conditions are not appropriate for projections used in ESA analyses and that long-term projections of climate-change effects provide temporal context as a species-wide assessment provides spatial context. In these projections, climate change should not be discounted solely because the magnitude of projected change at a particular time is uncertain when directionality of climate change is clear. Identifying likely future habitat at the species scale will indicate key refuges and potential range shifts. However, the risks and benefits associated with errors in modeling future habitat are not equivalent. The ESA offers mechanisms for increasing the overall resilience and resistance of species to climate changes, including establishing recovery goals requiring increased genetic and phenotypic diversity, specifying critical habitat in areas not currently occupied but likely to become important, and using adaptive management. Incorporación de las Ciencias Climáticas en las Aplicaciones del Acta Estadunidense de Especies en Peligro para Especies Acuáticas.

Climate change, marine environments, and the US Endangered species act

Climate change is expected to be a top driver of global biodiversity loss in the 21st century. It poses new challenges to conserving and managing imperiled species, particularly in marine and estuarine ecosystems. The use of climate-related science in statutorily driven species management, such as under the U.S. Endangered Species Act (ESA), is in its early stages. This article provides an overview of ESA processes, with emphasis on the mandate to the National Marine Fisheries Service (NMFS) to manage listed marine, estuarine, and anadromous species. Although the ESA is specific to the United States, its requirements are broadly relevant to conservation planning. Under the ESA, species, subspecies, and "distinct population segments" may be listed as either endangered or threatened, and taking of most listed species (harassing, harming, pursuing, wounding, killing, or capturing) is prohibited unless specifically authorized via a case-by-case permit process. Government agencies, in addition to avoiding take, must ensure that actions they fund, authorize, or conduct are not likely to jeopardize a listed species' continued existence or adversely affect designated critical habitat. Decisions for which climate change is likely to be a key factor include: determining whether a species should be listed under the ESA, designating critical habitat areas, developing species recovery plans, and predicting whether effects of proposed human activities will be compatible with ESA-listed species' survival and recovery. Scientific analyses that underlie these critical conservation decisions include risk assessment, long-term recovery planning, defining environmental baselines, predicting distribution, and defining appropriate temporal and spatial scales. Although specific guidance is still evolving, it is clear that the unprecedented changes in global ecosystems brought about by climate change necessitate new information and approaches to conservation of imperiled species. El Cambio Climático, los Ecosistemas Marinos y el Acta Estadunidense de Especies en Peligro.

A time-domain nuclear magnetic resonance study of Mediterranean scleractinian corals reveals skeletal-porosity sensitivity to environmental changes

Mediterranean corals are a natural model for studying global warming, as the Mediterranean basin is expected to be one of the most affected regions and the increase in temperature is one of the greatest threats for coral survival. We have analyzed for the first time with time-domain nuclear magnetic resonance (TD-NMR) the porosity and pore-space structure, important aspects of coral skeletons, of two scleractinian corals, Balanophyllia europaea (zooxanthellate) and Leptopsammia pruvoti (nonzooxanthellate), taken from three different sites on the western Italian coast along a temperature gradient. Comparisons have been made with mercury intrusion porosimetry and scanning electron microscopy images. TD-NMR parameters are sensitive to changes in the pore structure of the two coral species. A parameter, related to the porosity, is larger for L. pruvoti than for B. europaea, confirming previous non-NMR results. Another parameter representing the fraction of the pore volume with pore sizes of less than 10-20 μm is inversely related, with a high degree of statistical significance, to the mass of the specimen and, for B. europaea, to the temperature of the growing site. This effect in the zooxanthellate species, which could reduce its resistance to mechanical stresses, may depend on an inhibition of the photosynthetic process at elevated temperatures and could have particular consequences in determining the effects of global warming on these species.

Predicting evolutionary responses to climate change in the sea

An increasing number of short-term experimental studies show significant effects of projected ocean warming and ocean acidification on the performance on marine organisms. Yet, it remains unclear if we can reliably predict the impact of climate change on marine populations and ecosystems, because we lack sufficient understanding of the capacity for marine organisms to adapt to rapid climate change. In this review, we emphasise why an evolutionary perspective is crucial to understanding climate change impacts in the sea and examine the approaches that may be useful for addressing this challenge. We first consider what the geological record and present-day analogues of future climate conditions can tell us about the potential for adaptation to climate change. We also examine evidence that phenotypic plasticity may assist marine species to persist in a rapidly changing climate. We then outline the various experimental approaches that can be used to estimate evolutionary potential, focusing on molecular tools, quantitative genetics, and experimental evolution, and we describe the benefits of combining different approaches to gain a deeper understanding of evolutionary potential. Our goal is to provide a platform for future research addressing the evolutionary potential for marine organisms to cope with climate change.

Recovery of an isolated coral reef system following severe disturbance

Coral reef recovery from major disturbance is hypothesized to depend on the arrival of propagules from nearby undisturbed reefs. Therefore, reefs isolated by distance or current patterns are thought to be highly vulnerable to catastrophic disturbance. We found that on an isolated reef system in north Western Australia, coral cover increased from 9% to 44% within 12 years of a coral bleaching event, despite a 94% reduction in larval supply for 6 years after the bleaching. The initial increase in coral cover was the result of high rates of growth and survival of remnant colonies, followed by a rapid increase in juvenile recruitment as colonies matured. We show that isolated reefs can recover from major disturbance, and that the benefits of their isolation from chronic anthropogenic pressures can outweigh the costs of limited connectivity.

Effects of two decades of rising sea surface temperatures on sublittoral macrobenthos communities in Northern Ireland, UK

We examined whether two decades of rising sea surface temperatures have resulted in significant changes in the benthic community and frequency of occurrence of Northern and Southern species in three areas of Northern Ireland, using visual census data collected by SCUBA surveys undertaken during two periods: pre-1986 and post-2006. We found little evidence to suggest that rising sea surface temperatures have contributed to the changes in benthic assemblage structure between the pre-1986 and post-2006 surveys. However, there were slight but not significant declines in extreme Northern species at Rathlin Island, and increases in the mean number and frequency of occurrence of extreme Southern species in all three areas. There were also substantial declines in the spatial presence of 7 extreme Northern species and notable increases in distribution of 19 extreme Southern species. In contrast, there were no clear trends in the intermediate to Northern and intermediate to Southern species. These results suggest that rising sea surface temperatures have had significant impacts on the occurrence of rarer marine invertebrate species at the edges of their biogeographic range however the trends differed between areas in Northern Ireland.

Inferred global connectivity of whale shark Rhincodon typus populations

Ten years have passed since the last synopsis of whale shark Rhincodon typus biogeography. While a recent review of the species' biology and ecology summarized the vast data collected since then, it is clear that information on population geographic connectivity, migration and demography of R. typus is still limited and scattered. Understanding R. typus migratory behaviour is central to its conservation management considering the genetic evidence suggesting local aggregations are connected at the generational scale over entire ocean basins. By collating available data on sightings, tracked movements and distribution information, this review provides evidence for the hypothesis of broad-scale connectivity among populations, and generates a model describing how the world's R. typus are part of a single, global meta-population. Rhincodon typus occurrence timings and distribution patterns make possible a connection between several aggregation sites in the Indian Ocean. The present conceptual model and validating data lend support to the hypothesis that R. typus are able to move among the three largest ocean basins with a minimum total travelling time of around 2-4 years. The model provides a worldwide perspective of possible R. typus migration routes, and suggests a modified focus for additional research to test its predictions. The framework can be used to trim the hypotheses for R. typus movements and aggregation timings, thereby isolating possible mating and breeding areas that are currently unknown. This will assist endeavours to predict the longer-term response of the species to ocean warming and changing patterns of human-induced mortality.

Extreme climatic event drives range contraction of a habitat-forming species

Species distributions have shifted in response to global warming in all major ecosystems on the Earth. Despite cogent evidence for these changes, the underlying mechanisms are poorly understood and currently imply gradual shifts. Yet there is an increasing appreciation of the role of discrete events in driving ecological change. We show how a marine heat wave (HW) eliminated a prominent habitat-forming seaweed, Scytothalia dorycarpa, at its warm distribution limit, causing a range contraction of approximately 100 km (approx. 5% of its global distribution). Seawater temperatures during the HW exceeded the seaweed's physiological threshold and caused extirpation of marginal populations, which are unlikely to recover owing to life-history traits and oceanographic processes. Scytothalia dorycarpa is an important canopy-forming seaweed in temperate Australia, and loss of the species at its range edge has caused structural changes at the community level and is likely to have ecosystem-level implications. We show that extreme warming events, which are increasing in magnitude and frequency, can force step-wise changes in species distributions in marine ecosystems. As such, return times of these events have major implications for projections of species distributions and ecosystem structure, which have typically been based on gradual warming trends.

Warming off southwestern Japan linked to distributional shifts of subtidal canopy-forming seaweeds

To assess distributional shifts of species in response to recent warming, historical distribution records are the most requisite information. The surface seawater temperature (SST) of Kochi Prefecture, southwestern Japan on the western North Pacific, has significantly risen, being warmed by the Kuroshio Current. Past distributional records of subtidal canopy-forming seaweeds (Laminariales and Fucales) exist at about 10-year intervals from the 1970s, along with detailed SST datasets at several sites along Kochi's >700 km coastline. In order to provide a clear picture of distributional shifts of coastal marine organisms in response to warming SST, we observed the present distribution of seaweeds and analyzed the SST datasets to estimate spatiotemporal SST trends in this coastal region. We present a large increase of 0.3°C/decade in the annual mean SST of this area over the past 40 years. Furthermore, a comparison of the previous and present distributions clearly showed the contraction of temperate species' distributional ranges and expansion of tropical species' distributional ranges in the seaweeds. Although the main temperate kelp Ecklonia (Laminariales) had expanded their distribution during periods of cooler SST, they subsequently declined as the SST warmed. Notably, the warmest SST of the 1997–98 El Niño Southern Oscillation event was the most likely cause of a widespread destruction of the kelp populations; no recovery was found even in the present survey at the formerly habitable sites where warm SSTs have been maintained. Temperate Sargassum spp. (Fucales) that dominated widely in the 1970s also declined in accordance with recent warming SSTs. In contrast, the tropical species, S. ilicifolium, has gradually expanded its distribution to become the most conspicuously dominant among the present observations. Thermal gradients, mainly driven by the warming Kuroshio Current, are presented as an explanation for the successive changes in both temperate and tropical species' distributions.

Long-term breeding phenology shift in royal penguins

The Earth's climate is undergoing rapid warming, unprecedented in recent times, which is driving shifts in the distribution and phenology of many plants and animals. Quantifying changes in breeding phenology is important for understanding how populations respond to these changes. While data on shifts in phenology are common for Northern Hemisphere species (especially birds), there is a dearth of evidence from the Southern Hemisphere, and even fewer data available from the marine environment. Surface air temperatures at Macquarie Island have increased by 0.62°C during the 30-year study period (0.21°C decade⁻¹) and royal penguins (Eudyptes schlegeli) commenced egg laying on average three days earlier in the 1990s than during the 1960s. This contrasts with other studies of Southern Ocean seabirds; five of nine species are now breeding on average 2.1 days later than during the 1950s. Despite the different direction of these trends, they can be explained by a single underlying mechanism: resource availability. There was a negative relationship between the Southern Annular Mode (SAM) and median laying date of royal penguins, such that low-productivity (low SAM) years delayed laying date. This accords with the observations of other seabird species from the Antarctic, where later laying dates were associated with lower sea ice and lower spring productivity. The unifying factor underpinning phenological trends in eastern Antarctica is therefore resource availability; as food becomes scarcer, birds breed later. These changes are not uniform across the region, however, with resource increases in the subantarctic and decreases in eastern Antarctica.