Plastic in the global oceans fulfills two of the three conditions for pollution to pose a planetary boundary threat because it is causing planetary-scale exposure that is not readily reversible. Plastic is a planetary boundary threat if it is having a currently unrecognized disruptive effect on a vital Earth system process. Discovering possible unknown effects is likely to be aided by achieving a fuller understanding of the environmental fate of plastic. Weathering of plastic generates microplastic, releases chemical additives, and likely also produces nanoplastic and chemical fragments cleaved from the polymer backbone. However, weathering of plastic in the marine environment is not well understood in terms of time scales for fragmentation and degradation, the evolution of particle morphology and properties, and hazards of the chemical mixture liberated by weathering. Biofilms that form and grow on plastic affect weathering, vertical transport, toxicity, and uptake of plastic by marine organisms and have been underinvestigated. Laboratory studies, field monitoring, and models of the impact of weathering on plastic debris are needed to reduce uncertainty in hazard and risk assessments for known and suspected adverse effects. However, scientists and decision makers must also recognize that plastic in the oceans may have unanticipated effects about which we are currently ignorant. Possible impacts that are currently unknown can be confronted by vigilant monitoring of plastic in the oceans and discovery-oriented research related to the possible effects of weathering plastic.
We provide evidence for temporal displacement of illegal discharges of oil from shipping, a major source of ocean pollution, in response to a monitoring technology that features variation in the probability of conviction by time of day. During the nighttime, evidence collected by Coast Guard aircraft using radar becomes contestable in court because the nature of an identified spot cannot be verified visually by an observer on board of the aircraft. Seasonal variation in time of sunset is used to distinguish evasive behavior from daily routines on board. Using data from surveillance flights above the Dutch part of the North Sea during 1992–2011, we provide evidence for a sudden increase in illegal discharges after sunset across the year. Our results show that even a tiny chance of getting caught and a mild punishment can have a major impact on behavior.
The Gulf of California (GC) is an unique large ecosystem characterized by its rich biodiversity, high biological productivity and endemism of marine life. However, as many other large ecosystems worldwide, it is subject to diverse anthropogenic pressures (overfishing, climate change, losses of biodiversity and habitats, and pollution). We reviewed over 150 studies dealing with contaminants in water, sediments and representative organisms from the GC, and here we discuss the main issues associated to the presence of metals, metalloids, persistent organic pollutants (POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), brominated diphenyl ethers (deca tri-a) (PBDEs), and several other pesticides), plastics, nutrients and algal blooms. The GC ecosystems have been subject to a wide range of pollution sources. Nevertheless, the pollution levels remain relatively low to moderate depending on the location and contaminant type. Contamination hotspots are found i) for metals and metalloids, in sites where mining spills have occurred and ii) for nutrients and pesticides, in wetlands that receive discharges from intensive agricultural and shrimp farming. We also identified sites where harmful algal blooms (HABs) have been observed. However, numerous coastal environments in GC, affected by pollution sources and events have yet been poorly studied. More detailed, extensive and comprehensive studies on the pollution levels and trends, transfer and toxic effects are still needed.
The disruption of the coral–algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.
Lionfish (Pterois miles) were observed avoiding coral pinnacles inhabited by the moray eels Gymnothorax flavimarginatus and G. javanicus in the northern Red Sea, Egypt. Release of lionfish (Standard Length 93–104 mm) in such coral pinnacles in November 2016 resulted in almost immediate predation by large moray eels (Total Length > 1 m). Predation by moray eels may be the key control mechanism of population growth in the native biogeographical range of Pterois spp. and may indirectly explain the success of the invasive populations. This is the first video-documented record of moray eels feeding on the lionfish P. miles.
Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a “natural experiment” to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other), our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.
Coral reefs serve as natural barriers that protect adjacent shorelines from coastal hazards such as storms, waves, and erosion. Projections indicate global degradation of coral reefs due to anthropogenic impacts and climate change will cause a transition to net erosion by mid-century. Here, we provide a comprehensive assessment of the combined effect of all of the processes affecting seafloor accretion and erosion by measuring changes in seafloor elevation and volume for five coral reef ecosystems in the Atlantic, Pacific, and Caribbean over the last several decades. Regional-scale mean elevation and volume losses were observed at all five study sites and in 77 % of the 60 individual habitats that we examined across all study sites. Mean seafloor elevation losses for whole coral reef ecosystems in our study ranged from −0.09 to −0.8 m, corresponding to net volume losses ranging from 3.4 × 106 to 80.5 × 106 m3 for all study sites. Erosion of both coral-dominated substrate and non-coral substrate suggests that the current rate of carbonate production is no longer sufficient to support net accretion of coral reefs or adjacent habitats. We show that regional-scale loss of seafloor elevation and volume has accelerated the rate of relative sea level rise in these regions. Current water depths have increased to levels not predicted until near the year 2100, placing these ecosystems and nearby communities at elevated and accelerating risk to coastal hazards. Our results set a new baseline for projecting future impacts to coastal communities resulting from degradation of coral reef systems and associated losses of natural and socioeconomic resources.
The subtropical ocean gyres are recognized as great marine accummulation zones of floating plastic debris; however, the possibility of plastic accumulation at polar latitudes has been overlooked because of the lack of nearby pollution sources. In the present study, the Arctic Ocean was extensively sampled for floating plastic debris from the Tara Oceans circumpolar expedition. Although plastic debris was scarce or absent in most of the Arctic waters, it reached high concentrations (hundreds of thousands of pieces per square kilometer) in the northernmost and easternmost areas of the Greenland and Barents seas. The fragmentation and typology of the plastic suggested an abundant presence of aged debris that originated from distant sources. This hypothesis was corroborated by the relatively high ratios of marine surface plastic to local pollution sources. Surface circulation models and field data showed that the poleward branch of the Thermohaline Circulation transfers floating debris from the North Atlantic to the Greenland and Barents seas, which would be a dead end for this plastic conveyor belt. Given the limited surface transport of the plastic that accumulated here and the mechanisms acting for the downward transport, the seafloor beneath this Arctic sector is hypothesized as an important sink of plastic debris.
We investigate motivations for people's intention to contribute towards increased protection of eight threatened and endangered marine species in the United States, using factor analysis and ordered response analysis applied to data from 7425 respondents to a national household survey conducted in 2010. We find that the strength of individuals' intention to contribute towards species conservation depends on how conservation programs are funded, which species are being targeted for conservation, individuals' knowledge of and prior interaction with these species, awareness of need, awareness of responsibility, altruism, environmental concern, and contextual forces. We argue that individuals who are predisposed to contribute to conservation are likely to be incentivized by messages that focus on charismatic species and reinforce altruistic motives, and ethical beliefs. Individuals with more fiscally conservative viewpoints are more likely to respond to messages about how conservation complements their political beliefs and improves economic conditions or their quality of life.
Natural resource management agencies implement conservation policies with the presumption that they are effective and of benefit to aquatic ecosystems. However, it is often difficult to decide what management action to implement and what will be most effective. Here we call for natural resource management agencies to fully adopt and implement evidence-based management (EBM) for conservation and fisheries management. We support this call by providing a primer on systematic reviews, a core tool in evidence synthesis but one that is rarely used in the context of fisheries management. We highlight the benefits and challenges associated with implementing EBM, with a particular focus on the routine decisions and management actions undertaken by natural resource practitioners. We submit that by adopting EBM, practitioners would have access to the best available evidence on the effectiveness of various management and conservation interventions, while providing defensible and credible evidence to inform decision-making processes and policies.
The growth of marine recreational activities raises the issues of the current lack of knowledge on these activities and the information required to assess their potential impacts. Indeed, the monitoring of unrecorded activities is a great challenge, especially when basic information, such as the size of the population practicing the different activities, is unknown. In this paper, the experience of the monitoring of marine recreational fishing was used to carry out a diagnosis study to assess the cost-effectiveness of survey methods used in France between 2004 and 2012. Costs of alternative surveys were balanced with data quality, and particular attention was paid to potential biases. Results showed that the involvement of citizens through diary surveys could be a cost-effective option when the recruitment of participants complied with randomness and representativeness requirements. The outcomes of this study provide useful insights to help managers and decision makers implement monitoring schemes in similar contexts.
Marine fisheries science is a broad field that is fundamentally concerned with sustainability across ecological, economic, and social dimensions. Ensuring the delivery of food, security, equity, and well-being while sustaining ecosystems in the face of rapid change is, by far, the main challenge facing marine fisheries. A tighter integration of modeling and empiricism is needed to confront this challenge. In particular, improved incorporation of empirically grounded and realistic representation of human behaviors into models will greatly enhance our ability to predict likely outcomes under alternative adaptive strategies. Challenges to this integration certainly exist, but many of these can be overcome via improved professional training that reduces cultural rifts between empiricists and modelers and between natural and social sciences, ideally ending the presumption that there is a divide between empiricism and modeling.
Drawing on seventy-four interviews, this article analyzes the rising importance since the mid-2000s of large marine protected areas (MPAs) as a policy for managing ocean conservation. Governments have initiated eighteen large MPAs (over 200,000 km2) since 2006, reflecting the emergence of a new large MPA norm in marine conservation. This norm, we argue, emerged because of the success of a few transnational nongovernmental organizations (NGOs) in identifying politically feasible large MPAs, and then forming ad hoc domestic coalitions to lobby for them. This explanation is in contrast to most of the literature on how and why norms diffuse internationally, as well as existing explanations for the rise of large MPAs, both of which emphasize the importance of cohesive coalitions of transnational NGOs lobbying in multilateral venues. This bottom-up, international norm diffusion strategy has made large MPAs a viable policy option, one national jurisdiction at a time. For instance, this strategy was a critical element in convincing the UK to create the Pitcairn Islands Marine Reserve (835,000 km2) in 2015. Given the politics underlying the formation of large MPAs, where political gains have been high, and corporate and societal resistance relatively low, the creation of more large MPAs would seem likely, as occurred in 2016 when the UK announced it would designate three more large MPAs by 2020, totalling over 1.4 million km2. Growing support for large MPAs as a conservation strategy could also embolden states to establish large MPAs in more politically and economically contested waters, including on the Pacific high seas.
The abundance and the distribution of trophic resources available for consumers influence the productivity and the diversity of natural communities. Nevertheless, assessment of the actual abundance of food items available for individual trophic groups has been constrained by differences in methods and metrics used by various authors. Here we develop an index of food abundance, the framework of which can be adapted for different ecosystems. The relative available food index (RAFI) is computed by considering standard resource conditions of a habitat and the influence of various generalized anthropogenic and natural factors. RAFI was developed using published literature on food abundance and validated by comparison of predictions versus observed trophic resources across various marine sites. RAFI tables here proposed can be applied to a range of marine ecosystems for predictions of the potential abundance of food available for each trophic group, hence permitting exploration of ecological theories by focusing on the deviation from the observed to the expected.
Spatial properties of landscapes modify the abundance and diversity of most animal assemblages in ways that need to be understood to plan and implement conservation initiatives, and evaluate their effectiveness. Seascape context (i.e. the spatial arrangement of ecosystems) mediates the effects of reserves on fish abundance, species richness and ecological processes in shallow coral reef and mangrove ecosystems; however, it is unclear whether this interaction exerts similar effects on reserves in other ecosystems. This study used baited remote underwater video stations (BRUVS) to test for combined effects of seascape context and reserves on fish abundance in seagrass meadows in Moreton Bay, Queensland, Australia. We demonstrate that the composition of harvested fishes in seagrass meadows was different in reserves and fished areas. Specifically, in reserves there was enhanced abundance of exploited rabbitfish Siganus fuscescens, a functionally important herbivore in local seagrass meadows. These reserve effects are not influenced by the area of seagrass meadows or seascape context they occur in (i.e. their spatial proximity to other ecosystems or the ocean). However, seascape context was directly correlated with the spatial distribution of harvested rabbitfish and emperors Lethrinus spp., which were more abundant in seagrass meadows nearer to the open ocean. Our results show that reserves and seascape context can shape spatial patterns in the abundance of harvested fishes in seagrass meadows, and that these effects may be operating on different components of fish assemblages. Further empirical data on how and where seascape features modify reserve performance are critical for effective conservation in seagrass and related ecosystems.
This article presents data from a citizens jury-inspired deliberative workshop held to tease out stakeholder views of management priorities for a section of the North Sea: the Dogger Bank. As this article reveals, the lessons learned from the Dogger Bank workshop advocate not simply what is required for managing one particular ocean commons, but also highlight some of the public participation research design failings, taking public participation in resource management further by adding to the literature and theoretical discussions on the public sphere. Analysis of the citizens jury-inspired deliberative workshop also highlights the critical issue of power inherent, yet often unacknowledged, in public participation in environmental management. Stakeholder opinions uncovered through workshop discussions also show how commons are viewed today – as an economic resource-- highlighting the trend of the mainstreaming of the commodification of the commons.
This report summarizes the results of a rapid vulnerability assessment (July 2016) and adaptation strategy planning (September 2016) workshops for 10 focal resources in the Territory and National Marine Sanctuary of American Samoa by engaging with stakeholders, including village leaders, community members, resource managers, local government representatives, and business owners that rely on the resources with the goal of increasing climate resilience in the region.
Many sea-level rise (SLR) assessments focus on populations presently inhabiting vulnerable coastal communities1, 2, 3, but to date no studies have attempted to model the destinations of these potentially displaced persons. With millions of potential future migrants in heavily populated coastal communities, SLR scholarship focusing solely on coastal communities characterizes SLR as primarily a coastal issue, obscuring the potential impacts in landlocked communities created by SLR-induced displacement. Here I address this issue by merging projected populations at risk of SLR1 with migration systems simulations to project future destinations of SLR migrants in the United States. I find that unmitigated SLR is expected to reshape the US population distribution, potentially stressing landlocked areas unprepared to accommodate this wave of coastal migrants—even after accounting for potential adaptation. These results provide the first glimpse of how climate change will reshape future population distributions and establish a new foundation for modelling potential migration destinations from climate stressors in an era of global environmental change.
The capability of animals to emit light, called bioluminescence, is considered to be a major factor in ecological interactions. Because it occurs across diverse taxa, measurements of bioluminescence can be powerful to detect and quantify organisms in the ocean. In this study, 17 years of video observations were recorded by remotely operated vehicles during surveys off the California Coast, from the surface down to 3,900 m depth. More than 350,000 observations are classified for their bioluminescence capability based on literature descriptions. The organisms represented 553 phylogenetic concepts (species, genera or families, at the most precise taxonomic level defined from the images), distributed within 13 broader taxonomic categories. The importance of bioluminescent marine taxa is highlighted in the water column, as we showed that 76% of the observed individuals have bioluminescence capability. More than 97% of Cnidarians were bioluminescent, and 9 of the 13 taxonomic categories were found to be bioluminescent dominant. The percentage of bioluminescent animals is remarkably uniform over depth. Moreover, the proportion of bioluminescent and non-bioluminescent animals within taxonomic groups changes with depth for Ctenophora, Scyphozoa, Chaetognatha, and Crustacea. Given these results, bioluminescence has to be considered an important ecological trait from the surface to the deep-sea.
Over the last 30 years, a range of different livelihoods have been provided and implemented in fishing and coastal communities in the Philippine with mixed success and sustainability by the fisher and household. This paper reports on an analysis of livelihood projects for fishing communities and households implemented in the Philippines and the identification of lessons learned and factors which can lead to an improved success and sustainability rate for livelihood projects and programs. The analysis identified primary factors that are critical to improving the success and sustainability rate of livelihood interventions.