Scientific monitoring has recorded only a recent fraction of the oceans’ alteration history. This biases our understanding of marine ecosystems. Remote coral reef ecosystems are often considered pristine because of high shark abundance. However, given the long history and global nature of fishing, sharks’ vulnerability, and the ecological consequences of shark declines, these states may not be natural. In the Chagos archipelago, one of the remotest coral reef systems on the planet, protected by a very large marine reserve, we integrated disparate fisheries and scientific survey data to reconstruct baselines and long-term population trajectories of two dominant sharks. In 2012, we estimated 571,310 gray reef and 31,693 silvertip sharks, about 79 and 7% of their baseline levels. These species were exploited longer and more intensively than previously thought and responded to fishing and protection with variable and compensatory population trajectories. Our approach highlights the value of integrative and historical analyses to evaluate large marine ecosystems currently considered pristine.
As jellyfish interactions with humans increase in coastal waters, there is an urgent need to provide science-based management strategies to mitigate the negative socioeconomic impacts of jellyfish blooms and to exploit potential benefits of their ecosystem services. This Theme Section presents the latest advances in jellyfish research, from new sampling methods to food-web and life-cycle studies. The methodological advances presented will help to overcome difficulties in sampling due to the fluctuations in abundance and irregular distributions of jellyfish. The ecology of gelatinous species in marine food webs is explored through studying interactions between jellyfish and fish. Aspects of jellyfish life cycles, which often include both attached polyps and swimming medusae, are elucidated by locating the polyps and determining the factors that contribute to their success. Knowledge on all of these factors will be essential to understand the bloom dynamics of specific jellyfish groups.
Food production is responsible for a quarter of anthropogenic greenhouse gas (GHG) emissions globally. Marine fisheries are typically excluded from global assessments of GHGs or are generalized based on a limited number of case studies. Here we quantify fuel inputs and GHG emissions for the global fishing fleet from 1990–2011 and compare emissions from fisheries to those from agriculture and livestock production. We estimate that fisheries consumed 40 billion litres of fuel in 2011 and generated a total of 179 million tonnes of CO2-equivalent GHGs (4% of global food production). Emissions from the global fishing industry grew by 28% between 1990 and 2011, with little coinciding increase in production (average emissions per tonne landed grew by 21%). Growth in emissions was driven primarily by increased harvests from fuel-intensive crustacean fisheries. The environmental benefit of low-carbon fisheries could be further realized if a greater proportion of landings were directed to human consumption rather than industrial uses.
The seasonal occupancy and diel behaviour of sperm whales (Physeter macrocephalus) was investigated using data from long-term acoustic recorders deployed off east Antarctica. An automated method for investigating acoustic presence of sperm whales was developed, characterised, and applied to multi-year acoustic datasets at three locations. Instead of focusing on the acoustic properties of detected clicks, the method relied solely on the inter-click-interval (ICI) for determining presence within an hour-long recording. Parameters for our classifier were informed by knowledge of typical vocal behaviour of sperm whales. Sperm whales were detected predominantly from Dec-Feb, occasionally in Nov, Mar, Apr, and May, but never in the Austral winter or early spring months. Ice cover was found to have a statistically significant negative effect on sperm whale presence. In ice-free months sperm whales were detected more often during daylight hours and were seldom detected at night, and this effect was also statistically significant. Seasonal presence at the three east Antarctic recording sites were in accord with what has been inferred from 20th century whale catches off western Antarctica and from stomach contents of whales caught off South Africa.
The effects of anthropogenic global environmental change on biotic and abiotic processes have been reported in aquatic systems across the world. Complex synergies between concurrent environmental stressors and the resilience of the system to regime shifts, which vary in space and time, determine the capacity for marine systems to maintain structure and function with global environmental change. Consequently, an interdisciplinary approach that facilitates the development of new methods for the exchange of knowledge between scientists across multiple scales is required to effectively understand, quantify and predict climate impacts on marine ecosystem services. We use a literature review to assess the limitations and assumptions of current pathways to exchange interdisciplinary knowledge and the transferability of research findings across spatial and temporal scales and levels of biological organisation to advance scientific understanding of global environmental change in marine systems. We found that species‐specific regional scale climate change research is most commonly published, and “supporting” is the ecosystem service most commonly referred to in publications. In addition our paper outlines a trajectory for the future development of integrated climate change science for sustaining marine ecosystem services such as investment in interdisciplinary education and connectivity between disciplines.
The monitoring of beached litter along the coast is an onerous obligation enshrined within a number of legislative frameworks (e.g. the MSFD) and which requires substantial human resources in the field. Through this study, we have optimised the protocol for the monitoring of the same litter along coastal stretches within an MPA in the Maltese Islands through aerial drones, with the aim of generating density maps for the beached litter, of assisting in the identification of the same litter and of mainstreaming this type of methodology within national and regional monitoring programmes for marine litter. Concurrent and concomitant in situ monitoring of beached litter enabled us to ground truth the aerial imagery results. Results were finally discussed within the context of current and future MSFD monitoring obligations, with considerations made on possible future policy implications.
This paper evaluates the effectiveness of a public information campaign, which was conducted on a major Greek Island (Syros), aimed at reducing plastic waste - and specifically plastic bags - in the local coastal/marine environment. A choice experiment was conducted to evaluate the effects on individual preferences for reducing plastic waste pollution under different status of environmental awareness, after the information campaign. The evaluation process was quite independent of the information campaign. Two samples of respondents were taken; one consisting of participants in the environmental campaign and the other consisting of non-participants. The results show: (a) significant differences between the preferences of the two samples; (b) variations in the willingness to pay values between the two samples for protection of the coastal/marine environment, but; (c) not significant differences in their commitment to take action (i.e. in their willingness to alter their current plastic bag use behavior).
During the last fifty years, there has been a dramatic increase in the development of anthropogenic activities, and this is particularly threatening to marine coastal ecosystems. The management of these multiple and simultaneous anthropogenic pressures requires reliable and precise data on their distribution, as well as information (data, modelling) on their potential effects on sensitive ecosystems. Focusing on Posidonia oceanicabeds, a threatened habitat-forming seagrass species endemic to the Mediterranean, we developed a statistical approach to study the complex relationship between human multiple activities and ecosystem status. We used Random Forest modelling to explain the degradation status of P. oceanica (defined herein as the shift from seagrass bed to dead matte) as a function of depth and 10 anthropogenic pressures along the French Mediterranean coast (1700 km of coastline including Corsica). Using a 50 × 50 m grid cells dataset, we obtained a particularly accurate model explaining 71.3% of the variance, with a Pearson correlation of 0.84 between predicted and observed values. Human-made coastline, depth, coastal population, urbanization, and agriculture were the best global predictors of P. oceanica's degradation status. Aquaculture was the least important predictor, although its local individual influence was among the highest. Non-linear relationship between predictors and seagrass beds status was detected with tipping points (i.e. thresholds) for all variables except agriculture and industrial effluents. Using these tipping points, we built a map representing the coastal seagrass beds classified into four categories according to an increasing pressure gradient and its risk of phase shift. Our approach provides important information that can be used to help managers preserve this essential and endangered ecosystem.
In recent years, some scientists have expressed concern about the negative representation of the state of the oceans in the media. To examine this concern empirically, we analyzed the content of 169 articles in mainstream U.S. newspapers covering ocean-related research between 2001 and 2015. Content was categorized according to main issue, basis of evidence, causal attribution, presence of solutions and uncertainty, and coded for doom and gloom and optimistic language. Science journalism about ocean issues most commonly addressed climate change and the status of ocean species or populations. The majority of articles cited peer-reviewed research. Most articles attributed change to anthropogenic causes, although ocean science articles addressing climate change were less likely to do so. Uncertain language and solutions were observed in nearly half of all articles. Optimistic language outnumbered doom and gloom language across all categories. While doom and gloom language was identified in 10% of all articles, optimistic language was present in 27%.
The mullet fishery system encompasses a complex arrange of ecological and socioeconomic factors interacting in multiple scales on the Southern-Southeastern Brazilian coast. Similarly, to other fisheries in developing countries, overfishing and poor governance have been threatening the resilience of the mullet fishery. In this paper, we explore aspects related to fisheries management from the perspective of the concept of resilience. The industrial and artisanal fishery sectors represent the different stakeholders. The main issues of concern are related to failures in the fisheries management to properly address equity in resource access and resource use sustainability among stakeholders. Asymmetry in technology and political and economic power affect food security and income generation especially for subsistence and small-scale fishing. Despite changes in rules-in-use, overfishing and conflicts between resource users are still relevant. Fishery dynamics and resource availability are greatly affected locally by forces such as pollution, urbanization, non-selective fishing, and regionally, by the El Niño Southern Oscillation (ENSO), and industrial (purse-seine) fishery. Considering the influence of ENSO on this fishery, a time span of at least 7 years to investigate this system could provide better answers to improve the management. Effective resilient fisheries should rely on three aspects. First, there should be a flexible fish allocation system based on ecosystem variability. Secondly, fish allocation should prioritize food security and poverty alleviation. Thirdly, a monitoring system should be implemented that takes into consideration ecosystem, fisheries and human dimensions to support a flexible and adaptive fisheries management, with resilient fisheries as an ultimate goal.
This study explored the ethics of provisioning wildlife to enhance tourist interactions at a whale shark tourism site in Oslob, Philippines. TripAdvisor comments (n = 947) and tourist surveys (n = 761) were used to better understand tourists' perceptions of whale shark provisioning in Oslob. The ethical decisions made were then critically assessed using utilitarian and animal welfare ethical philosophies. The majority of respondents supported whale shark provisioning, despite many being aware of the ethical complications of provisioning sharks for tourism purposes. Respondents justified their participation in this activity using mainly economic, human enjoyment, and animal welfare arguments. A utilitarian assessment of the potential costs and benefits of this activity highlighted the gaps in our knowledge regarding the economic and social benefits of this activity, as well as the negative impacts on the sharks’ welfare. Until such analyses are completed, significant ethical questions remain regarding the provisioning of these sharks.
Variable density dependence within multispecies fisheries results in species restructuring as exploitation intensifies that is poorly understood. We examined unique species-based records across 25 years of exploitation to evaluate patterns, consequences, and predictions of species replacements within three coral-reef fisheries. Body-size was an expected determinant of species replacements, as larger fishes were consistently replaced by smaller, faster-growing counterparts. However, many species with similar sizes and growth rates responded differently. Naso unicornis, a primary component of coral-reef fisheries across the Pacific, was one of the most resilient species to exploitation despite having a similar maximum size and growth as many large parrotfishes that slowly disappeared from landings. Assessments conducted for all primary target species revealed clear distinctions in compensatory responses: 31% had diminishing size structures, 18% had diminishing proportional contribution, but only 5% showed both. Standard approaches to fisheries management assume constant rates of size-and-age restructuring and rely upon metrics such as fishing-versus-natural mortality. Instead, a deeper appreciation for varying recruitment rates may help to (re)define fisheries management units and reduce complexity in multispecies fisheries. We last consider our results alongside traditional knowledge and management in the Pacific that clearly appreciated species responses, but have been lost over the years.
Wildlife tourism can provide sustainable livelihoods, but can also significantly impact vulnerable species if improperly managed. To manage these impacts whilst continuing to support livelihoods, it is important to know the interests of tourists. Using the Best-Worst scaling method, we identified taxa that were most important to scuba dive tourism on shallow soft sediment habitats in Southeast Asia. We further identified differences in interest between demographic groups. We then investigated the current conservation status and research effort into the species driving this branch of tourism. The highest ranked taxa included fishes and invertebrates such as cephalopods and crustaceans. More than 200 respondents indicated that the species most important to muck dive tourism are mimic octopus/wunderpus, blue ringed octopus, rhinopias, flamboyant cuttlefish and frogfish. Diver interests were most influenced by sex, age and dive experience. The extinction risk of six of the top ten species has not yet been assessed by the International Union for Conservation of Nature. On average, the species driving this multi-million dollar tourism industry had less than one paper published every two years over the past two decades. The lack of research and conservation effort toward these species is at odds with their economic and social importance. Considering their high economic tourism value and unknown vulnerability, there is an urgent need for more research on fauna from shallow soft sediment and other habitats important to tourism.
Microplastics can be present in the environment as manufactured microplastics (known as primary microplastics) or resulting from the continuous weathering of plastic litter, which yields progressively smaller plastic fragments (known as secondary microplastics). Herein, we discuss the numerous issues associated with the analysis of microplastics, and to a less extent of nanoplastics, in environmental samples (water, sediments, and biological tissues), from their sampling and sample handling to their identification and quantification. The analytical quality control and quality assurance associated with the validation of analytical methods and use of reference materials for the quantification of microplastics are also discussed, as well as the current challenges within this field of research and possible routes to overcome such limitations.
Coral reefs feed millions of people worldwide, provide coastal protection and generate billions of dollars annually in tourism revenue1. The underlying architecture of a reef is a biogenic carbonate structure that accretes over many years of active biomineralization by calcifying organisms, including corals and algae2. Ocean acidification poses a chronic threat to coral reefs by reducing the saturation state of the aragonite mineral of which coral skeletons are primarily composed, and lowering the concentration of carbonate ions required to maintain the carbonate reef. Reduced calcification, coupled with increased bioerosion and dissolution3, may drive reefs into a state of net loss this century4. Our ability to predict changes in ecosystem function and associated services ultimately hinges on our understanding of community- and ecosystem-scale responses. Past research has primarily focused on the responses of individual species rather than evaluating more complex, community-level responses. Here we use an in situ carbon dioxide enrichment experiment to quantify the net calcification response of a coral reef flat to acidification. We present an estimate of community-scale calcification sensitivity to ocean acidification that is, to our knowledge, the first to be based on a controlled experiment in the natural environment. This estimate provides evidence that near-future reductions in the aragonite saturation state will compromise the ecosystem function of coral reefs.
Aquatic acidification, caused by elevating levels of atmospheric carbon dioxide (CO2), is increasing in both freshwater and marine ecosystems worldwide. However, few studies have examined how acidification will affect oxygen (O2) transport and, therefore, performance in fishes. Although data are generally lacking, the majority of fishes investigated in this meta-analysis exhibited no effect of elevated CO2 at the level of O2 uptake, suggesting that they are able to maintain metabolic performance during a period of acidosis. Notably, the mechanisms that fish employ to maintain performance and O2 uptake have yet to be verified. Here, we summarize current data related to one recently proposed mechanism underpinning the maintenance of O2 uptake during exposure to aquatic acidification, and reveal knowledge gaps that could be targeted for future research. Most studies have examined O2 uptake rates while fishes were resting and did not calculate aerobic scope, even though aerobic scope can aid in predicting changes to whole-animal metabolic performance. Furthermore, research is lacking on different age classes, freshwater species and elasmobranchs, all of which might be impacted by future acidification conditions. Finally, this Review further seeks to emphasize the importance of developing collaborative efforts between molecular, physiological and ecological approaches in order to provide more comprehensive predictions as to how future fish populations will be affected by climate change.
As global average sea‐level rises in the early part of this century there is great interest in how much global and local sea level will change in the forthcoming decades. The Paris Climate Agreement's proposed temperature thresholds of 1.5°C and 2°C have directed the research community to ask what differences occur in the climate system for these two states. We have developed a novel approach to combine climate model outputs that follow specific temperature pathways to make probabilistic projections of sea‐level in a 1.5°C and 2°C world. We find median global sea‐level (GSL) projections for 1.5°C and 2°C temperature pathways of 44 and 50 cm, respectively. The 90% uncertainty ranges (5%–95%) are both around 48 cm by 2100. In addition, we take an alternative approach to estimate the contribution from ice sheets by using a semi‐empirical GSL model. Here we find median projections of 58 and 68 cm for 1.5°C and 2°C temperature pathways. The 90% uncertainty ranges are 67 and 82 cm respectively. Regional projections show similar patterns for both temperature pathways, though differences vary between the median projections (2–10 cm) and 95th percentile (5–20 cm) for the bulk of oceans using process‐based approach and 10–15 cm (median) and 15–25 cm (95th percentile) using the semi‐empirical approach.
Developing the workforce to meet the needs of the blue economy will require changing undergraduate marine science programs to provide a wider range of skills developed by “doing” rather than just “reading.” Students also need training on how to effectively work in a team, critically analyze data, and be able to clearly communicate key points. With that in mind, we developed a new undergraduate course (called Ocean Observing) focused on conducting research by analyzing data collected and delivered to shore in near real time from the growing global network of ocean observatories. The course structure is based on student teams that use data to develop a range of data products, many of which have been suggested by state and federal agencies as well as from maritime companies. Students can take the Ocean Observing course repeatedly throughout their undergraduate career. A complimentary second entry course (called Oceanography House) was developed to entrain freshmen first-term students into research on their first semester on campus. The Ocean Observing course has increased the number of marine science majors and the overall diversity of the marine science program and resulted in a dramatic increase in the number of independent student theses conducted each year. Over the last 10 years, student data profiles from the course emphasize the importance of conducting research in a public way so students can partake in the “adventure” of research before the outcome is known. To increase the public visibility of these “adventures,” collaborations between departments across the campus have developed nationally broadcast documentaries and outreach materials. Going forward, we seek to build on this success by developing an accelerated Masters of Operational Oceanography and link these undergraduate students with external companies through externships and coordinated research projects.
Nearshore fish populations are in decline in the main Hawaiian Islands, and effective, sustainable management is needed. There has been increasing emphasis on the value of ecosystem-based management and the conservation of essential fish habitat, but policy is encumbered by a lack of supporting information. This study uses science and technology to support traditional knowledge in identifying juvenile fish habitats, providing a basis for effective resource management in a rural Hawaiian community. Building on existing local knowledge of nearshore resources, we quantitatively assessed juvenile fish-habitat associations. We conducted fine-scale in situ ecological surveys of juvenile reef fishes and their habitats, and produced detailed benthic habitat maps using GIS and interpretation of satellite imagery, from which we extracted multi-scale seascape variables. Canonical correspondence analysis was used to assess fish-habitat relationships at multiple scales. Depth, coral cover, structural complexity, scattered rock and coral habitat, and distance to shore emerged as primary factors associated with juvenile reef fish abundance. We identified the habitat associations of 2 important food resource species in the study area of Hā‘ena, Kaua‘i: the convict tang Acanthurus triostegus sandvicensis, an endemic subspecies, and the redlip parrotfish Scarus rubroviolaceus. Results from this study played an important role in the successful approval of the Hā‘ena community-based fishery management plan by the state governing agency. We argue that an ecosystem-based co-management approach, informed by conventional survey methods, remote sensing technology, and traditional knowledge, can help to ensure the sustainability of fisheries worldwide.
We assessed the potential role played by two vital Northeastern Pacific Ocean forage fishes, the Pacific sand lance (Ammodytes personatus) and Pacific herring (Clupea pallasii), as conduits for the vertical transfer of microfibres in food webs. We quantified the number of microfibres found in the stomachs of 734 sand lance and 205 herring that had been captured by an abundant seabird, the rhinoceros auklet (Cerorhinca monocerata). Sampling took place on six widely-dispersed breeding colonies in British Columbia, Canada, and Washington State, USA, over one to eight years. The North Pacific Ocean is a global hotspot for pollution, yet few sand lance (1.5%) or herring (2.0%) had ingested microfibres. In addition, there was no systematic relationship between the prevalence of microplastics in the fish stomachs vs. in waters around three of our study colonies (measured in an earlier study). Sampling at a single site (Protection Island, WA) in a single year (2016) yielded most (sand lance) or all (herring) of the microfibres recovered over the 30 colony-years of sampling involved in this study, yet no microfibres had been recovered there, in either species, in the previous year. We thus found no evidence that sand lance and herring currently act as major food-web conduits for microfibres along British Columbia's outer coast, nor that the local at-sea density of plastic necessarily determines how much plastic enters marine food webs via zooplanktivores. Extensive urban development around the Salish Sea probably explains the elevated microfibre loads in fishes collected on Protection Island, but we cannot account for the between-year variation. Nonetheless, the existence of such marked interannual variation indicates the importance of measuring year-to-year variation in microfibre pollution both at sea and in marine biota.