This study examines the occurrence of humpback whale (Megaptera novaeangliae) song in the northeast Pacific from three years of continuous recordings off central California (36.713°N, 122.186°W). Song is prevalent in this feeding and migratory habitat, spanning nine months of the year (September–May), peaking in winter (November–January), and reaching a maximum of 86% temporal coverage (during November 2017). From the rise of song in fall through the end of peak occurrence in winter, song length increases significantly from month to month. The seasonal peak in song coincides with the seasonal trough in day length and sighting-based evidence of whales leaving Monterey Bay, consistent with seasonal migration. During the seasonal song peak, diel variation shows maximum occurrence at night (69% of the time), decreasing during dawn and dusk (52%), and further decreasing with increasing solar elevation during the day, reaching a minimum near solar noon (30%). Song occurrence increased 44% and 55% between successive years. Sighting data within the acoustic detection range of the hydrophone indicate that variation in local population density was an unlikely cause of this large interannual variation. Hydrographic data and modeling of acoustic transmission indicate that changes in neither habitat occupancy nor acoustic transmission were probable causes. Conversely, the positive interannual trend in song paralleled major ecosystem variations, including similarly large positive trends in wind-driven upwelling, primary productivity, and krill abundance. Further, the lowest song occurrence during the first year coincided with anomalously warm ocean temperatures and an extremely toxic harmful algal bloom that affected whales and other marine mammals in the region. These major ecosystem variations may have influenced the health and behavior of humpback whales during the study period.
Kelp farming is increasing along the temperate coastlines of the Americas and Europe. The economic, ecological, and social frameworks surrounding kelp farming in these new areas are in contrast with the conditions of progenitor kelp farming regions in China, Japan, and Korea.
Thus, identifying and addressing the environmental and social impacts of kelp farming in these regions is vital to ensuring the industry’s long-term sustainability. Here, a conceptual model of the human and natural systems supporting this nascent kelp aquaculture sector was developed using Maine, USA as a focal region. Potential negative impacts of kelp aquaculture were identified to be habitat degradation, overfishing of wild seeds, predation and competition with wild fish and genes, and transmission of diseases. Increased food security, improved restoration efforts, greater fisheries productivity, and alternative livelihoods development were determined to be potential positive impacts of kelp aquaculture. Changes in biodiversity and productivity resulting from either negative or positive impacts of kelp aquaculture were confirmed to have downstream effects on local fisheries and coastal communities. Recommendations to improve or protect the ecosystem services tangential to kelp farming include: define ecosystem and management boundaries, assess ecosystem services and environmental carrying capacity, pursue ecologically and socially considerate engineering, and protect the health and genetic diversity of wild kelp beds. Recommendations to ensure that kelp farming improves the well-being of all stakeholders include: increase horizontal expansion, expand and teach Best Management Practices, and develop climate change resiliency. Additionally, an integrated management strategy should be developed for wild and farmed kelp to ensure that kelp aquaculture is developed in the context of other sectors and goals.
Structures submerged in the sea by humans over millennia provide hard and longstanding evidence of anthropogenic influence in the marine environment. Many of these human-made reefs (HMRs) may provide opportunities for conservation despite having been created for different purposes such as fishing or tourism. In the middle of controversy around the costs and benefits of HMRs, a broad analysis of biodiversity and social values is necessary to assess conservation potential. This requires reframing HMRs as social–ecological systems, moving beyond comparisons with natural coral or rocky reefs to consider their roles as ecosystems in their own right; creating frameworks to track their type, number, size, units, location, characteristics, origins, social uses, and associated biodiversity locally and worldwide; and applying systematic assessment of conservation benefits in relation to stated conservation intentions. This integrative approach can catalyze learning, identify conservation opportunities, and inform positive management of HMRs into the future.
Sea level rise is one of the major challenges facing humanity in the 21st century, and could compound the risks posed by tsunamis to coastal cities. The authors conducted computer simulations of tsunami inundation and propagation into Tokyo Bay, and analysed the risks that such events pose to the cities of Yokohama and Kawasaki, for different sea level rise scenarios (and assuming a high tide situation). The results show that unless significant investment in improved coastal defences is made, the area that can potentially be flooded by such events will gradually increase in the course of the 21st century. However, the risk to the life of the inhabitants of these cities will broadly remained unchanged until sea levels become +1.0 m higher than at present. From then, the risk of casualties taking place will rapidly increase, as the depth and velocity of the tsunami wave will substantially rise. Such results provide some indication regarding the long-term planning strategy to manage coastal defences around Tokyo Bay, highlighting the need to eventually reinforce coastal defences and the important contribution of tsunami evacuation to minimize casualties during such events.
he sustainability of dynamic natural systems often depends on their capacity to adapt to uncertain climate-related changes, where different management options may be combined to facilitate this adaptation. Salt marshes exemplify such a system. Marsh sustainability under rapid sea level rise requires the preservation of transgression zones - undeveloped uplands onto which marshes migrate. Whether these uplands eventually become marsh depends on uncertain sea level rise and natural dynamics that determine migration onto different land types. Under conditions such as these, systematically diversified management actions generally outperform ad hoc or non-diversified alternatives. This paper develops the first adaptation portfolio model designed to optimize the benefits of a migrating coastal system. Results are illustrated using a case study of marsh conservation in Virginia, USA. Results suggest that models of this type can enhance adaptation benefits beyond those available through current approaches.
Detection of microplastics (MPs) in biotic and abiotic matrices is relevant to evaluate how marine ecosystem’s exposure to these pollutants is of emerging environmental concern and at risk of loss of functionality and biodiversity. The presence of MPs was studied for the first time in the gut of benthic oysters (Crassostrea gigas) and in the water column in a eutrophic estuary under high anthropogenic pressure, in the southwestern Atlantic. Significant abundances of small plastic debris were found at all the sampling stations- mainly fibers, fragments, pellets, and beads. MPs were categorized and counted according to type, color, and size. Microfibers presented the highest percentage of abundance in the water column (98% with Van Dorn bottles and 72.73 % with a plankton net) as well as in oysters (91%). In water collected with Van Dorn bottles, the total MP concentrations ranged from 5900 to 782,000 particles/m3 and from 42.6 to 113.6 particles/m3 in samples collected with a plankton net. The widespread presence of fibers in all the assessed components could be related to the intense harbor activities in the area, such as the use of ropes for the mooring of boats and from fishing nets, as well as from domestic and industrial effluents. The presence of MPs in both the pelagic and benthic realms may imply risk for the animals that inhabit the estuary, and for human wellbeing, with respect to the potential transfer of MPs through the food web, affecting the provisioning of ecosystem services.
The extent of biofouling on recreational vessels has been used as a proxy for the presence of alien species and has been linked with vessel characteristics. However, the relationship between these factors and alien species numbers has not been examined, despite the importance of this metric for invasive species management. This study assessed physical characteristics, maintenance regimes and travel patterns of yachts and their relationship with the number of macro-invertebrate alien species present on vessels from four South African marinas. Overall, 88% of yachts were fouled with macro-invertebrate alien species. The only factor that influenced alien species numbers in the context of this study was the primary use of yachts, with cruising yachts supporting significantly more alien species than racing yachts. This is likely linked to differences in cleaning regimes, as racers are subject to rigorous and frequent cleaning. These findings suggest that cruising vessels may play a key role in the intra-regional transfer of alien species and that racing yachts likely pose a lower biosecurity threat.
Advances in ocean observing technologies and modeling provide the capacity to revolutionize the management of living marine resources. While traditional fisheries management approaches like single-species stock assessments are still common, a global effort is underway to adopt ecosystem-based fisheries management (EBFM) approaches. These approaches consider changes in the physical environment and interactions between ecosystem elements, including human uses, holistically. For example, integrated ecosystem assessments aim to synthesize a suite of observations (physical, biological, socioeconomic) and modeling platforms [ocean circulation models, ecological models, short-term forecasts, management strategy evaluations (MSEs)] to assess the current status and recent and future trends of ecosystem components. This information provides guidance for better management strategies. A common thread in EBFM approaches is the need for high-quality observations of ocean conditions, at scales that resolve critical physical-biological processes and are timely for management needs. Here we explore options for a future observing system that meets the needs of EBFM by (i) identifying observing needs for different user groups, (ii) reviewing relevant datasets and existing technologies, (iii) showcasing regional case studies, and (iv) recommending observational approaches required to implement EBFM. We recommend linking ocean observing within the context of Global Ocean Observing System (GOOS) and other regional ocean observing efforts with fisheries observations, new forecasting methods, and capacity development, in a comprehensive ocean observing framework.
This research examines perceptions of the linkages between ecosystem services (ES) and social wellbeing in a small-scale fishing community in Bluefields, Jamaica. It analyzes the perceived changes to these linkages based on the impacts of a marine protected area (MPA) on this coastal social-ecological system. MPAs can have positive long-term social and ecological effects, but in the short-term they can negatively impact communities, and careful attention to these impacts is needed to achieve positive conservation outcomes. We conducted 42 semi-structured interviews and six focus groups discussions with community members in Bluefields. Key findings from this research include: 1) the importance of provisioning (e.g., fish, lobster) and cultural ES (e.g., cultural heritage, bequest values) and their bundled qualities to both fishers and non-fishers; 2) the perceived impact of the MPA is highest for inshore fishers, while offshore fishers/non-fishers reported few/no negative impacts; and 3) inshore fishers perceive being more marginalized in governance processes, despite reporting the greatest negative change to ES access and social wellbeing from MPA implementation. The results suggest that governance processes for coastal conservation must acknowledge the individual and shared values of coastal areas and traditional livelihoods to achieve long-term legitimacy and support.
Uncertainty is inherent in ecosystem modelling, however its effects on modelling results are often poorly understood or ignored. This study addresses the issue of structural uncertainty or, more specifically, model resolution and its impact on the analysis of ecosystem vulnerability to threats. While guidelines for node assignments exist, they are not always underlined with quantitative analysis. Different resolutions of a coral reef network are investigated by comparing the simulated network dynamics over time in various threat scenarios. We demonstrate that the error between a higher-resolution and a lower-resolution models increases, first slowly then rapidly with increased degree of node aggregation. This informs the choice of an optimal model resolution whereby a finer level of a food web representation yields only minimal additional accuracy, while increasing computational cost substantially. Furthermore, our analysis shows that species biomass ratio and the consumption ratio are important parameters to guide node aggregation to minimize the error.
Improving the use of scientific evidence in conservation policy has been a long-standing focus of the conservation community. A plethora of studies have examined conservation science-policy interfaces, including a recent global survey of scientists, policy-makers, and practitioners. This identified a list of top barriers and solutions to evidence use, which have considerable overlap with those identified by other studies conducted over the last few decades. The three top barriers – (i) that conservation is not a political priority, (ii) that there is poor engagement between scientists and decision-makers, and (iii) that conservation problems are complex and uncertain – have often been highlighted in the literature as significant constraints on the use of scientific evidence in conservation policy. There is also repeated identification of the solutions to these barriers. In this perspective, we consider three reasons for this: (1) the barriers are insurmountable, (2) the frequently-proposed solutions are poor, (3) there are implementation challenges to putting solutions into practice. We argue that implementation challenges are most likely to be preventing the solutions being put into practice and that the research agenda for conservation science-policy interfaces needs to move away from identifying barriers and solutions, and towards a detailed investigation of how to overcome these implementation challenges.
Human-made marine habitats such as artificial reefs are used to mitigate marine habitat degradation and aid conservation of species at risk. We used ROV and sonar to survey threatened rockfish (Sebastes spp.) and other groundfish species associated with 18 artificial and natural reefs along the south coast of BC, Canada. Using an information-theoretic approach, we found that community composition significantly differed between natural and artificial reefs. Artificial reefs had high variability in rockfish abundance, some supporting very high or low relative abundance. Natural reefs consistently supported intermediate rockfish abundances. Groundfish diversity was significantly greater on natural reefs than artificial reefs. Depth and relief were significant predictors for both abundance and species richness. Interestingly, rockfish abundance was negatively associated with proximity to nearest rockfish conservation area. This research is a first step in understanding causal mechanisms leading to differences between fish communities on artificial reefs in our study system, and which reef attributes may facilitate successful contributions to conservation. Though artificial reefs show promise in the conservation of some threatened species, the maintenance of diverse fish communities depends on protection of heterogenous natural reef communities.
Marine biota is currently exposed to plastic pollution. The biological effects of plastics may vary according to polymer types (e.g. polystyrene, polyethylene, acrylate), size of particles (macro, micro or nanoparticles) and their shape. There is a considerable lack of knowledge in terms of effects of nanoplastics (NP) to marine biota particularly of polymers like polymethylmethacrylate (PMMA). Thus, this study aimed to assess its ecotoxicological effects using a battery of standard monospecific bioassays with four marine microalgae (Tetraselmis chuii, Nannochloropsis gaditana, Isochrysis galbana and Thalassiosira weissflogii) and a marine rotifer species (Brachionus plicatilis). The tested PMMA-NP concentrations allowed the estimation of median effect concentrations for all microalgae species. T. weissflogii and T. chuii were respectively the most sensitive (EC50,96h of 83.75 mg/L) and least sensitive species (EC50,96h of 132.52 mg/L). The PMMA-NP were also able to induce mortality in rotifers at concentrations higher than 4.69 mg/L with an estimated 48 h median lethal concentration of 13.27 mg/L. A species sensitivity distribution curve (SSD), constructed based on data available in the literature and the data obtained in this study, reveal that PMMA-NP appears as less harmful to marine biota than other polymers like polystyrene.
While plastic items like bottles, bags, and balloons are highly visible litter and well-known as ugly eyesores and hazards to wildlife, there is another form of plastic that is generally not visible but is far more numerous and may be equally or more hazardous in the environment. This is microplastic, small pieces ranging from 5 mm in size down to microscopic. Microplastics are categorized as primary microplastic – that which was always tiny, and secondary microplastic-which results from the fragmentation of larger pieces. As with larger pieces, microplastics represent a variety of different polymers, such as polyethylene, polystyrene, etc. They are found in a variety of shapes, including spheres, fragments, films, and fibers. In the past decade there has been a great amount of study on microplastics – where they come from, where they are found, how organisms interact with them, and what effects they may have on the organisms and the ecosystem. Most of these studies have focused on the marine environment since that is where they were initially detected, but they have subsequently been found to be abundant in freshwater and terrestrial environments as well. This review examines the research, emphasizing aquatic environments, and suggests avenues for improving future research.
Marine microplastic particles (MPs,<5 mm) exhibit wide ranges of densities,sizes, and shapes, so that the entire MPs“ensemble”at every time instant can be character-ized by continuous distributions of these parameters. Accordingly, this community ofparticles demonstrates distributions of dynamical properties, such as sinking or risingvelocity, critical shear stress, and the re-suspension threshold. Moreover, all the MPs’properties vary significantly with the time spent in marine environment and withparticular conditions experienced by the particle on its journey. A brief review of thepresent-day numerical efforts towards prediction of MPs transport shows the prevalenceof the Lagrangian particle tracking approach, especially for floating litter. In a broadercontext, the present practice of MPs transport modelling follows the“selective”strategy(e.g., only a certain sub-class of MPs, or specific processes, are considered, sometimes in onlyone- or two-dimensional setting). The heterogeneous nature of MPs, their enormous longevityand movability in marine environment, and the wide spectrum of the involved environ-mental processes suggest further integration (or coupling) of different models in future, aswell as application of other types of models (ensemble modeling, chaos theory approaches,machine learning, etc.) to the problems of MPs transport and fate in the marine environment.Key words:microplastics, transport, modelling.
The dissemination of marine environmental protection information in social networks is not comprehensive and objective. In order to remedy this defect, this paper proposes a dynamic analysis method of marine environmental protection information dissemination oriented to social network. The dynamic analysis method is introduced into the social marine environmental protection information dissemination to achieve regional dissemination of marine environmental protection information. This method is more efficient and easier to operate. It can effectively spread the expanding operation of social marine environmental protection information, and the amount of marine environmental protection information dissemination on the network unit can be obtained by dynamic analysis. The experiment shows that compared with the previous algorithms, the proposed method has better performance and more prominent expansibility.
Fully protected areas (FPAs) help preserving biodiversity and reversing the global decline of fishery resources. Stocks of the European spiny lobster Palinurus elephas (Fabr. 1787), among the most precious gourmet seafood worldwide, are currently facing a dramatic decline. Previous attempts of recovery based on fishery restrictions or active post-larval restocking in marine reserves provided unsuccessful outcomes. Here we present results of a 5-year restocking program carried through a Collaborative Fishery Research (CFR) project, in three ad-hoc established FPAs replenished using below-legal size wild juveniles. Results showed that Catch per Unit Effort (CPUE) in terms of both density and biomass burst (by ca. 300–700%) just 2 years since FPAs establishment, regardless of location. We also report tangible spillover effects (ca. 30–50% increase in density and biomass CPUE outside the FPAs) by the end of the program. Data from a 15-years lasting monitoring of a pilot FPA established in 1998, where the restocking protocol was conducted and protection kept in force once restocking ceased, demonstrated the persistence in time of restocking’ benefits. We foster that creation of FPAs assisted with local restocking under oriented CFR programs can represent an option for the recovery of European spiny lobster stocks from overfishing.
Studies related to the evaluation of plastics in freshwaters have been increasing in recent years because approximately 80% of plastic items found in the sea are from inland waters. Despite the ecological relevance of these surveys, no information has been available until now about the hazard related to plastic mixtures in freshwaters. To fill this knowledge gap, we carried out a study aimed to assess the environmental risk associated with the “cocktail” of plastics and environmental pollutants adsorbed on their surface in one of the larger European freshwater basins. Plastic debris was collected by a manta trawl along one transect each in four of the Italian subalpine great lakes (Lake Maggiore, Como, Iseo and Garda) and administered to zebra mussels (Dreissena polymorpha), a useful freshwater biological model present in all these lakes. We estimated a plastic density from 4908 MPs/km2 (Lake Iseo) to 272,261 MPs/km2 (Lake Maggiore), while the most common polymers found were polyethylene and polypropylene, with percentages varying between 73% and 100%. A biomarkers suite consisting of 10 different endpoints was performed after 7 days of exposure to investigate the molecular and cellular effects of plastics and related adsorbed pollutants. The main results highlighted a diffuse but different toxicity due to plastics for each lake, and there were significant changes in the antioxidant and detoxifying enzyme activities in Lake Maggiore, Iseo and Garda, an increase in protein carbonylation in L. Como, and a cellular viability decrease of approximately 30% for zebra mussels from L. Iseo and Garda. Despite this variability in the endpoints' responses, the application of the biomarker response index showed a similar environmental hazard due to plastics for all the sampled lakes.
Global warming is heating the Antarctic circumpolar deep water (CDW), which comes into direct contact with the diverse and abundant macrobenthic communities thriving on the continental shelf of the Weddell Sea (WS). A set of 16 current meters deployed along more than 3000 km coastline revealed that tidal currents drive CDW intrusions onto the WS continental shelf and they can increase the temperature near the seabed by ~2.7 °C. The ongoing ocean warming trend may expose macrobenthic assemblages to ambient temperatures >2 °C by the end of the century with dramatic consequences for communities which have evolved during millions of years in near geophysical isolation under rather constant environmental conditions with temperatures <0 °C. These stenothermal communities have long generation times (therefore, reduced opportunity to mutate) and require hundreds of years for adaptation.
Results from 135 benthic stations along the study area showed that macrobenthic communities in the southeastern section of the WS are the most vulnerable to the increase of temperature near the seabed given their high component of sessile organisms. Besides a dramatic marine biodiversity loss, the eventual demise of these communities, which provide habitat structure for a large number of species that can build up >87 g C m−2, will cause the liberation of thousands of tons of carbon to the environment. Macrobenthic communities colonizing the recently opened shelf in the Larsen A and B bays may not have the chance to reach the type of mature assemblage inhabiting the eastern WS shelf. The highest temperatures derived from CDW intrusions were recorded in the Filchner-Ronne region, suggesting that the consequences of the thermal impact could develop faster here than in the rest of the WS. Thus, these macrobenthic communities may show the effects of warming earlier than those thriving in other regions of the WS shelf. Global warming seriously threats the abundant and highly diverse macrobenthic communities of the Antarctic continental shelf.