Ocean acidification (OA) research has matured into a sophisticated experimental and theoretical scientific discipline, which now utilizes multiple stressor, mesocosm experiments, and mathematical simulation models to predict the near-future effects of continued acidification on marine ecosystems. These advanced methodological approaches to OA research also include the study of inter-specific interactions that could be disrupted if participant species exhibit differential tolerances to stressors associated with OA. The host-parasite relationship is one of the most fundamental ecological interactions, alongside competition and predation, which can regulate individuals, populations, and communities. The recent integration of competition and predation into OA research has provided great insight into the potential effects of differential tolerances to acidified seawater, and there is no reason to believe that expanding OA research to include parasitology will be less fruitful. This essay outlines our current, limited understanding of how OA will affect parasitism as an ecological process, describes potential pitfalls for researchers who ignore parasites and the effects of infection, and suggests ways of developing parasitology as a sub-field of OA research.
- Following a shark attack, local governments often rapidly respond by implementing indiscriminate shark culls. These culls have been demonstrated to have substantial localized and adverse effects on a variety of marine organisms, and therefore there is an increasing need for an eco-friendly alternative that maximizes both beachgoer and marine organismal safety.
- In response to such culls, the novel magnetic barrier technology, the Sharksafe Barrier was developed and rigorously tested on a variety of sharks implicated in shark attacks (e.g. bull sharks – Carcharhinus leucas and white sharks – Carcharodon carcharias). Although these studies exhibited promise in shark swim pattern manipulation and C. leucas exclusion, research was lacking in assessing if the technology could serve as an alternative to shark nets, or more specifically, if it could exclude motivated C. carchariasfrom bait.
- Using a 13 m × 13 m square exclusion zone, this study aimed to test the C. carchariasexclusion capabilities of the Sharksafe Barrier while additionally assessing the long-term structural integrity of the system.
- After 34 trials and approximately 255 hours of total video collected over two years, data illustrate that all interacting C. carcharias were successfully excluded from the baited Sharksafe Barrier region, whereas teleosts and other small elasmobranch species were not. In addition, the long-term deployment potential of this barrier system held promise owing to its ability to withstand harsh environmental conditions.
- Therefore, with the successful exclusion of a second large shark species, C. carcharias, from a baited region, continued long-term research and implementation of this system at other locations should be considered to assess its viability and overall success as a bather and shark protection system.
A Bayesian approach to parameter estimation in fisheries stock assessment is often preferred over maximum likelihood estimates, and fisheries management guidelines also sometimes specify that one or the other paradigm be used. However, important issues remain unresolved for the Bayesian approach to stock assessment despite over 25 years of research, development, and application. Here, we explore the consequence of a common practice in Bayesian assessment models: assigning a uniform prior to the logarithm of the parameter representing population scale (log-carrying capacity for biomass-dynamics models, or log-unfished recruits for age-structured models). First, we explain why the value chosen for the upper bound of this prior will affect parameter estimates and fisheries management advice given two properties that are met for many data-poor stock assessment models. Next, we use three case studies and a simulation experiment to show a substantial impact of this decision for data-limited assessments off the US West Coast. We end by discussing four methods for generating an informative prior on the population scale parameter, but conclude that these will not be suitable for many assessments. In these cases, we advocate that maximum likelihood estimation is a simple way to avoid the use of Bayesian priors that are excessively informative.
An ecologically and economically disruptive harmful algal bloom (HAB) affected much of the northeast Pacific margin in 2015, during a prolonged oceanic warm anomaly. Caused by diatoms of the genus Pseudo-nitzschia, this HAB produced the highest particulate concentrations of the biotoxin domoic acid (DA) ever recorded in Monterey Bay, California. Bloom inception followed strong upwelling during the spring transition, which introduced nutrients and eliminated the warm anomaly locally. Subsequently, moderate and intermittent upwelling created favorable conditions for growth and accumulation of HAB biomass, which was dominated by a highly toxigenic species, P. australis. High cellular DA concentrations were associated with available nitrogen for DA synthesis coincident with silicate exhaustion. This nutrient influence resulted from two factors: (1) disproportionate depletion of silicate in upwelling source waters during the warm anomaly, the most severe depletion observed in 24 years, and (2) silicate uptake by the dense diatom bloom.
The increasing anthropogenic disturbance on coastal ecosystems has threatened ecological interactions and ecosystems functioning. To investigate if human pressure affects the trophic structure of sandy beaches, mass-balanced models were applied on two Brazilian sandy beaches with distinct human impact degree. The food web models included detritus, phytoplankton, macroinvertebrates, fish and seabirds. Macroinvertebrates in non-urbanized sectors represented the highest production fraction consumed by predators. The energy transfer and the cycling indicator were more efficient in the non-urbanized sectors than urbanized ones. The results indicate that macroinvertebrates sensitive to direct human impact such as trampling are important to the trophic functioning of sandy beaches. Establishing a threshold for the number of beachgoers or dispersing recreational activities to avoid crowds may be tangible ways to mitigate the trampling impact on macroinvertebrates.
The interest of the general public, especially young people, in ocean and coastal issues is crucial, and yet high school students often do not consider scientific careers to be attractive. Raising student awareness of careers in marine science is not only a task for educators, but for scientists engaged in marine research as well. This paper summarises the experience of three years of international science camp organized for 15–19 year old students from countries of the Baltic Sea region (Europe) and discusses international science camps as a platform for encouraging interest in marine science.
The Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication (SSF-Guidelines) were agreed with extensive input from small-scale fishers themselves, and hold great promise for enhancing both small-scale fishers’ human rights and fisheries sustainability in a meaningful and context relevant manner. However, this promise will not be fulfilled without continued input from fishing communities as the SSF-Guidelines are implemented. This paper proposes that international conservation NGOs, with their extensive geographical and political networks, can act as a conduit for communication between small-scale fishing communities and other parties and thus catalyse implementation of the Guidelines. In order to do so, they will first need to demonstrate a genuine commitment to people-as-well-as-parks and the human rights based approach espoused in the SSF-Guidelines. This paper reviews current engagement of international conservation NGOs with human rights in fisheries; looks at their potential motivations for doing more; and identifies challenges in the way. It concludes with a proposal for how international conservation NGOs could play a critical part in catalysing the implementation of the SSF-Guidelines.
Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.
The degree to which a stock is depleted is one of the most important quantities in fisheries management because it is used to quantify the success of management and to inform management responses. However, stock depletion is extremely difficult to estimate, particularly with limited data. Using the RAM Legacy database, we developed a boosted regression tree (BRT) model to correlate depletion with a range of predictors calculated from catch data, making the model usable for many fisheries worldwide. The most important predictors were found to be catch trends obtained from linear regressions of scaled catch on time, including regression coefficients for the whole catch time series, the subseries before and after the maximum catch, and in recent years. Eight predictors explain about 80% of variation in depletion. There is a correlation of .5 between measured levels of depletion and the predictions of the BRT model. Predictions are less biased when the stock is fished down below half of the carrying capacity. The BRT model outperforms comparable existing catch-based depletion estimators and could be used to provide priors for depletion for data-poor stock assessment methods, or used more directly to provide estimates of the probability that depletion is below a given threshold value.
Transboundary water systems cover a substantial area of the planet and provide critical ecosystem services for much of the global population. The International Waters (IW) Focal Area of the Global Environment Facility (GEF) aims to improve cooperation among countries in governance of transboundary water systems. There is the need to assess the outcomes, outputs and impacts of GEF IW initiatives. The current Transboundary Diagnostic Analysis/Strategic Action Programme approach of the GEF uses indicators in three categories – process, stress and state. A Transboundary Waters Governance Assessment Framework is proposed that incorporates the three above indicator categories and includes four new indicator categories: governance architecture, stakeholder engagement, social justice and human well-being. These additional categories are considered necessary to bring assessment of GEF IW initiatives in line with current governance thinking. The indicator categories are sequential, starting with governance architecture and ending with human well-being as the ultimate objective.