Mass mortality events (MMEs) are a key concern for the management of marine ecosystems. Specific stages and species are at risk and the causes may be single or cumulative pressure from a range of sources including pollutants, anthropogenic climate change or natural variability. Identifying risk and quantifying effects of plausible scenarios including MMEs are key to stakeholders and a quest for scientists. MMEs affect the whole ecosystem, but are traditionally only studied in relation to specific species, disregarding ecological feedbacks. Here we use an end-to-end ecosystem model adapted to the Nordic and Barents seas to evaluate the species-specific and ecological impacts for 50 years following an MME. MMEs were modeled as 10, 50, or 90% reduced recruitment for cod, herring and haddock, individually or in combination. The MME scenarios were compared to a base case model run that includes the current fishing mortality. All species showed declines in population biomass following an MME, increasing in duration and severity with increasing mortality. Cod biomass rebounded to the base case level within 3–13 years post the MME independent of scenario, while neither haddock nor herring fully rebounded to base case levels within the considered time horizon. Haddock responded much more variably to the mortality scenarios than cod or herring, with some scenarios yielding much higher levels of biomass than the base case. Herring responded negatively to all scenarios, leading to lower herring biomass and a steeper decline of the species than seen in the base case due to persistent harvest pressure. Corresponding responses showed that the demersal guild biomass increased substantially, while the pelagic guild biomass declined. Few effects were observed on the other guilds, including the top predators. Ecosystem effects as measured by ecological indicators were greatest after 5 years, but persisted through the entire model run. Fishery indicators showed the same features, but the responses were stronger than for the ecosystem indicators. Taken together this indicates long-term, ecological response to MMEs that can be described as regime shifts, highlighting the importance of using ecosystem models when evaluating effects of MMEs.
Existing marine bioregions covering the Pacific Ocean are conceptualised at spatial scales that are too broad for national marine spatial planning. Here, we developed the first combined oceanic and coastal marine bioregionalisation at national scales, delineating 262 deep-water and 103 reef-associated bioregions across the southwest Pacific. The deep-water bioregions were informed by thirty biophysical environmental variables. For reef-associated environments, records for 806 taxa at 7369 sites were used to predict the probability of observing taxa based on environmental variables. Both deep-water and reef-associated bioregions were defined with cluster analysis applied to the environmental variables and predicted species observation probabilities, respectively to classify areas with high taxonomic similarity. Local experts further refined the delineation of the bioregions at national scales for four countries. This work provides marine bioregions that enable the design of ecologically representative national systems of marine protected areas within offshore and inshore environments in the Pacific.
Elasmobranchs, extremely charismatic and threatened animals, still are an important economic source for fishers in many parts of the world, providing significant income through trade. Even though Greek seas host at least 67 elasmobranch species, our knowledge about their biology and ecology is to a large extent unknown. In the present study the integration of conventional (legislation, official data from fisheries landings and fish market value and import/export data) and unconventional (social media) sources of data, accompanied with the use of genetics, aim at outlining the elasmobranch fisheries and trade in Greece and identifying “weak spots” that sabotage their conservation. Results revealed that: (a) about 60% of the 68 specimens collected in fish markets were mislabelled, with that being very common for Prionace glauca and Mustelus spp., (b) Illegal fishing is a reality, c) Greece represents one of the top-three European Union southern countries in terms of elasmobranch market size, (d) Aegean Sea and especially its Northern part (Thermaikos Gulf and Thracian Sea) contributed to more than half of the M. mustelus Greek fisheries landings and (e) wholesale prices of elasmobranchs have remained stable during the last decade. Mislabelling and illegal trade of elasmobranchs are common ground in Greece. This context stems from incoherent and complex fisheries legislative framework due to institutional decoupling, discrepancies in the collection and analysis of fisheries-related data, thus substantially reducing the efficiency of the fisheries management in Greek seas.
Coupled wave – 3D-hydrodynamics model runs are performed to investigate thermal discharge release to coastal areas by means of including nearshore effects of wave-current dynamics. The study area comprises the vicinity of a power plant at Cerano, in South Italy, where cooling industrial waters are released to the sea. The implemented model is calibrated by using temperature measurements and sensitivity analyses are carried out for various relevant drivers and input parameters. Afterwards, the effect of thermal discharge is investigated through distinct hypothetical scenarios for a combination of metocean conditions and operational features of the power plant (modifying water discharge and temperature at its outlet). The model results of this representative array of conditions are intercompared and evaluated on the basis of heat dispersion rate and areas of influence, providing with useful insights on the numerical simulation of the process and the potential effects for the specific coastal area.
Payments for Ecosystem Services (PES) have emerged as a popular conservation tool, yet evaluation among different PES programs strategies remains piecemeal. We prospectively compare cost-effectiveness of general PES, collective payments for ecosystem services (CPES) and the transition from PES to Land Purchases or Easements (LPE). We analyze the economic cost using statistics data and literature data, and analyze the transaction cost with the ordinal variable. We develop the Emergy Analysis method with the InVEST Habitat Quality model, and utilize it to analyze and map the ecological effectiveness. This paper gives an example to assessing the cost-effectiveness of different PES programs. Based on the analysis, LPE strategy led to improved ecological effectiveness, lower cost and greater cost-effectiveness. The collective PES has lower cost than general PES. However, they demonstrate equal ecological effectiveness. Based on these outcomes, we analyze the factors that influence PES programs’ cost-effectiveness, including collective or group, market-based mechanism, economic incentive, transaction cost, contract scale etc. We conclude that minimal number of intermediaries, community/collective support and involvement constitute the key factors in improving the cost-effectiveness of ecological programs. However, we acknowledge the need for further studies on the subject.
Coral reef fishes are about 10% of commercial fishes worldwide. Their pollution is close to human’s health. Antibiotics are one group of emerging organic pollutants in the marine environment. However, little data is available on the bioaccumulation and dietary risks of antibiotics in coral reef fish from the South China Sea (SCS) or any other parts of the global coral reef environment. In this study, we examined 19 antibiotics in 18 species of coral reef fish collected from coastal and offshore regions in the SCS. The results revealed that 17 antibiotics were detected in the fishes. Their average concentrations ranged from 1.3×10-5 to 7.9×10-1 ng/g ww, which were at the lower end of the global range about antibiotic levels in fish. The average total antibiotic concentrations (∑19ABs) were significantly higher in the offshore fish (1.2 ng/g ww) than in the coastal fish (0.16 ng/g ww). Different fish species or the protection of mucus produced by coastal fish at severe environmental stress may cause the differences. Fluoroquinolones (FQs) accounted for 89% and 74% of the average ∑19ABs in the offshore and coastal fish, respectively. It may relate to their relative high aqueous solubility and adsorption ability to particles. The log BAFs (bioaccumulation factors) of the antibiotics ranged from -0.34 to 4.12. Norfloxacin, dehydrated erythromycin (DETM), and roxithromycin were bioaccumulative in some offshore fish samples with their log BAFs higher than 3.7. The results of trophic magnification factors (TMFs) demonstrated that DETM underwent significant trophic dilution while enoxacin underwent trophic magnification in the food web of coral reef fishes. The estimated daily intakes of antibiotics via fish consumption by China residents ranged from 2.0×10-4 to 2.7 ng/kg weight body/day, which was 3 to 8 orders of magnitude lower than the respective acceptable daily intakes.
This article explores the possible interplay between the envisioned agreement on biodiversity beyond national jurisdiction (“the envisioned BBNJ Agreement”) and the Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean (“the CAO Fisheries Agreement”). After summarizing the main provisions of the CAO Fisheries Agreement and the emerging elements of the envisioned BBNJ Agreement, the article considers ways in which the two agreements could be implemented consistently. However, a number of challenging questions remain, raising the specter of friction between the two regimes. The article concludes by calling on the negotiators of the envisioned BBNJ Agreement to consider these questions carefully, in the hope that the two Agreements can work together to ensure effective stewardship of the high seas portion of the Central Arctic Ocean.
In the ocean, plastic debris containing chemical additives is fragmented into smaller pieces that can be ingested by a wide range of organisms, potentially exposing them to additives. However, the levels of additives retained in marine plastic fragments have rarely been assessed. In this study, 141 plastic fragments from a beach in Kauai were analyzed piece-by-piece for 12 compounds, including UV stabilizers and brominated flame retardants. UV stabilizers (UV-326, UV-328, UV-327, and BP-12) were found in 13% of “small” fragments (4–7 mm) with levels of up to 315 μg/g and in 33% of “large” fragments (15–80 mm) with levels of up to 1130 μg/g. This observation suggests that exhaustive leaching of additives does not occur during fragmentation and that significant levels of additives, comparable to those of the original products, can be retained in fragments of marine plastic, indicating their importance as a vector of chemical additive exposure.
This paper evaluates two stakeholder participatory workshops (local communities and tourism stakeholder) to support the development of a management plan for South Ari Atoll Marine Protected Area (SAMPA), Maldives. SAMPA is the largest MPA in the country declared by Maldives to preserve one of the largest whale shark aggregations in the world. However, to date it exists with no management plan to date. The objective of the workshops was to consult with stakeholders on a range of potential regulatory and governance mechanisms proposed for the MPA that can be included in a potential management plan. The paper finds that the two stakeholder workshops had, both functional and dysfunctional aspects that influenced the potential design of a management plan for SAMPA. Overall, the workshops represented a clear opportunity for collective learning and collaboration that fostered dialogue and deliberation. However, important and influential stakeholders were under-represented at the workshops. Furthermore, a reluctance of government to demonstrate how the outcomes of the workshop would be integrated in its decision-making left many participants feeling sceptical about the fairness, equity and effectiveness of the processes that would follow. With no management plan to date, this paper proposes that any future stakeholder process in SAMPA should be underpinned by well informed governance and regulatory options that have the support and commitment of the government which can ensure SAMPA's ecosystem services are sustained to benefit long-term human well-being.
Enrichment of the oceans with CO2 may be beneficial for some marine phytoplankton, including harmful algae. Numerous laboratory experiments provided valuable insights into the effects of elevated pCO2 on the growth and physiology of harmful algal species, including the production of phycotoxins. Experiments close to natural conditions are the next step to improve predictions, as they consider the complex interplay between biotic and abiotic factors that can confound the direct effects of ocean acidification. We therefore investigated the effect of ocean acidification on the occurrence and abundance of phycotoxins in bulk plankton samples during a long-term mesocosm experiment in the Gullmar Fjord, Sweden, an area frequently experiencing harmful algal blooms. During the experimental period, a total of seven phycotoxin-producing harmful algal genera were identified in the fjord, and in accordance, six toxin classes were detected. However, within the mesocosms, only domoic acid and the corresponding producer Pseudo-nitzschia spp. was observed. Despite high variation within treatments, significantly higher particulate domoic acid contents were measured in the mesocosms with elevated pCO2. Higher particulate domoic acid contents were additionally associated with macronutrient limitation. The risks associated with potentially higher phycotoxin levels in the future ocean warrants attention and should be considered in prospective monitoring strategies for coastal marine waters.
Fish traps are extensively used in tropical and subtropical reef fisheries. Despite this, there is a significant lack of extensive and consecutive research concerning the basic aspects of trap fishing. We herein compile the available information from the main coral and rocky reef fish trap fisheries, and compared their main aspects (i.e., mesh size, CPUE, catch composition, ghost fishing, and management) to assess the dynamics of these fisheries and their environmental impact. The analysis revealed that most fish stocks showed declining trends, with only few species under heavy management being capable of withstanding high fishing pressure. In other fisheries, due to fishing down the web, miscellaneous reef fish comprised the bulk of the catch, while the proportion of high-value landed species was insignificant. Gear restrictions remain the most common management method in trap fisheries; however, even the minimum mesh size has not been ubiquitously enforced, while due to great variability of targeted fish species, use of a uniform mesh size is highly unlikely. Other management tools, such as, restrictions in effort, size, and species, temporal and spatial closures were also widely used, but effective only when well enforced and interconnected. Rates of trap loss widely differed as well as the reported rates of ghost fishing mortality. In most cases, incorporation of escape panels resulted in almost complete elimination of ghost fishing. However, further research is required concerning these issues.
Despite an exponential increase in available data on marine plastic debris globally, information on levels and trends of plastic pollution and especially microplastics in the Arctic remains scarce. The few available peer-reviewed scientific works, however, point to a ubiquitous distribution of plastic particles in all environmental compartments, including sea ice. Here, we review the current state of knowledge on the sources, distribution, transport pathways and fate of meso- and microplastics with a focus on the European Arctic and discuss observed and projected impacts on biota and ecosystems.
The primary objective of this study is to develop a new weather routing system for vessel navigation in coastal and marginal seas based on the A-star algorithm. The cost function inherent in the original A-star algorithm is modified to account for oceanic and atmospheric conditions around the vessel of interest. Three options are introduced to search for optimal paths with the shortest travel distance, shortest travel time, and minimal fuel consumption. An avoidance algorithm for unsafe conditions is further incorporated to exempt any arbitrary area from the navigation solution. Furthermore, a compact ocean circulation model based on the Regional Ocean Modeling System executable on typical laptop PCs is configured for a vessel-borne weather routing system; the system is successfully applied to evaluate the optimal vessel paths in the Seto Inland Sea, where high-frequency tidal currents modified by complex topography make it essential to alter the vessel's speed.
The effectiveness of mussel caging for active microplastics (MPs) biomonitoring was investigated for the first time by comparing abundance and characteristics (shape, size, color and type of polymers) of MPs ingested by caged depurated blue mussels with those ingested by native mussels collected at the same sites and with those found in their surrounding environment (surface water and sediments). Mussels were exposed along a pollution gradient originating from a wastewater treatment plant discharge and near an abandoned coastal landfill. After 6 weeks of deployment, the majority (93%) of clean transplanted mussels had ingested MPs with a mean number of items ranging from 0.61 to 1.67 items/g. The occurrence, abundance and properties of MPs ingested by caged mussels were similar to those found in native mussels. Among the debris items detected in caged and native mussels, fragments were the most predominant type, consistent with the MPs found in their surrounding environment. MPs sizes were very similar whether in the water, sediments and both caged and native mussels, with a dominance of items <150 μm. Although some polymers were under-represented or totally absent in the caged mussels compared to overlying seawater or surrounding sediment, there was a good overlap in polymer types proportion being found between caged mussels and sediments (Morisita's index of similarity = 0.93) or seawater (0.86). Polystyrene dominated all samples in all the different matrices. Our study suggests that blue mussels caging may be a promising tool for MPs biomonitoring making monitoring more reliable with an accurate assessment of the biological effects of MPs over a predetermined exposure period. However, further methodological improvements should be considered to define a uniform protocol for blue mussels caging to allow spatial and temporal microplastics active biomonitoring.
Most fisheries management systems rely on a set of regulatory measures to achieve desired objectives. Controls on catch and effort are usually supplemented with gear restrictions, minimum landing sizes, and in the framework of the new common fisheries policy, limitation of discards and by-catch. However, the increasing use of spatial management measures such as conservation areas or spatial and temporal area closures faces new challenges for fishery managers. Here we present an integrated spatial framework to identify areas in which undersized commercial species are more abundant. Once these areas are identified they could be avoided by fishers, minimizing the fishing impact over the immature fraction of the stocks. In particular we applied this methodology to two species of megrim, Lepidorhombus whiffiagonis and L. boscii, in North Atlantic Iberian waters (ICES Divisions 8c and 9a), analyzing fishery-independent data provided by bottom-trawl surveys and environmental data through Bayesian spatial models. Results show that species exhibit species-specific spatial patterns, and we identified sensitive areas that could be used for conservation purposes. We discuss integrating technical measures together (e.g. Minimum Conservation Reference Size and spatial closures) could be a more effective approach for fishery management and this case study could be extended to other species.
We highlight the potential benefits of adopting Ecosystem-based Fishery Management (EBFM). We compare the EBFM implementation with the more traditional single-stock approach. We show the contribution of the portfolio theory to the EBFM, which can be achieved by selecting an optimal portfolio to maximise the average revenues and minimise the variance. We use this approach to construct two frontiers: the ecosystem efficient frontier, which considers stock interactions (the variance-covariance matrix), and the stock efficient frontier, only considering individual stock variances.
We also define two risk gaps. The first gap shows the reduction in the standard deviation per unit of revenue that the fleet could have achieved if they had decided to use the optimal portfolio of the stock frontier instead of the historical portfolio. The second gap reflects the reduction in the standard deviation per unit of revenue when the management moves from the stock frontier to the ecosystem frontier portfolio.
This approach is adapted to the Basque inshore fleet. According to our results, taking the single-stock approach as the benchmark, the EBFM would obtain the same historical revenue while reducing the risk by 23%. Alternatively, allowing the same level of risk, it could achieve a 21% increase in revenues.
Coastal and estuarine ecosystems, such as mangroves, tidal marshes and seagrass meadows, provide a range of ecosystem services, but have seen extensive degradation and decline. Effective protection and rehabilitation of coastal ecosystems requires an understanding of how efforts may improve associated ecosystem services. In this study, we present a spatially-explicit angler catch function to predict boat-based recreational catch as a function of ecosystem and angler characteristics. We developed a choice model to investigate where recreational anglers launch their boats and fish in southeast Australia. By linking the recreational catch models with a choice model, we were able to quantify welfare gains of ecosystem rehabilitation. We found welfare gains across fishing locations varied widely due to heterogeneous coverage of seagrass. The welfare gains of different fishing locations ranged from near-zero in areas of low seagrass coverage, to AU $19.18 (10% increase in seagrass area) and to AU $85.55 (30% increase) per trip in location of high seagrass coverage. Given two million fishing trips occurring per year in Port Phillip Bay, and one million in Western Port, the aggregated welfare gain could scale up to AU $6.2 million with a 10% increase in seagrass coverage, and AU $22 million per annum with a 30% increase in seagrass. We also calculated the welfare loss associated with total loss of seagrass ecosystem in each fishing location to represent the current value, which varied significantly, ranging from near-zero in some locations to AU $87.47 per trip in other location. Over the past several decades, the bay-wide seagrass ecosystem has dropped by 36.7% in Western Port, resulting in potential welfare loss of an estimated AU $ 86.7 million per annum. Our analyses provide insightful spatial policy implications for coastal and marine ecosystem rehabilitation in the region.
The aim of the present study was to risk screen 45 jellyfish species (30 hydromedusae, 14 scyphomedusae, one cubomedusa) for their potential invasiveness in the Mediterranean Sea to aid managers in making informed decisions on targeting appropriate species for management. Using the Aquatic Species Invasiveness Screening Kit (AS-ISK), calibrated basic and climate-change threshold assessment scores of 6.5 and 12.5, respectively, were identified for distinguishing reliably between species that pose ‘low-to-medium’ and ‘high’ risk of becoming invasive in the risk assessment area. Using these thresholds, 16 species were classified as high risk, 23 as medium risk and six as low risk under current climate conditions. Whereas, under future climate conditions, 13, 30 and two species, respectively, were classified as high, medium and low risk, respectively. Upside-down jellyfish Cassiopea andromeda, Australian spotted jellyfish Phyllorhiza punctata, sea nettle Chrysaora quinquecirrha and Rhopilema nomadica were the highest-scoring species, with the maximum increase in risk score under predicted climate change conditions being achieved by C. andromeda.
This paper examines the potential for improved environmental performance of smallholder aquaculture production through ‘beyond-farm’ governance. Smallholder aquaculture farmers face a range of systemic environmental risks related to disease and water quality that extend beyond the boundary of their farms. Yet most governance arrangements aimed at mitigating risks, such as certification, finance and insurance, are focused on the farm-level rather than the wider landscape within which farming takes place. In this paper we propose an integrated approach to area-based management of aquaculture risks that integrates collective action, risk assurance and transfer, and inclusive value chains. In doing so, we set a new research agenda for the integrated governance of mitigating production risks and producer vulnerability in global food production.
Marine biodiversity is under extreme pressure from anthropogenic activity globally, leading to calls to protect at least 10% of the world’s oceans within marine protected areas (MPAs) and other effective area-based conservation measures. Fulfilling such commitments, however, requires a detailed understanding of the distribution of potentially detrimental human activities, and their predicted impacts. One such approach that is being increasingly used to strengthen our understanding of human impacts is cumulative impact mapping; as it can help identify economic sectors with the greatest potential impact on species and ecosystems in order to prioritize conservation management strategies, providing clear direction for intervention. In this paper, we present the first local cumulative utilization impact mapping exercise for the Bioko-Corisco-Continental area of Equatorial Guinea’s Exclusive Economic Zone – situated in the Gulf of Guinea, one of the most important and least studied marine regions in the Eastern Central Atlantic. This study examines the potential impact of ten direct anthropogenic activities on a suite of key marine megafauna species and reveals that the most suitable habitats for these species, located on the continental shelf, are subject to the highest threat scores. However, in some coastal areas, the persistence of highly suitable habitat subject to lower threat scores suggests that there are still several strategic areas that are less impacted by human activity that may be suitable sites for protected area expansion. Highlighting both the areas with potentially the highest impact, and those with lower impact levels, as well as particularly damaging activities can inform the direction of future conservation initiatives in the region.