Food webs as representations of who eats whom are at the core of community ecology. Incorporation of tools from network theory enables assessment of how complex systems respond to natural and human-induced stressors, revealing how harvesting may degrade the properties and resilience of food webs. We present a comprehensive, coastal marine food web that includes 147 taxa cooccurring on shallow subtidal reefs along the highly productive and exploited Humboldt Current System of central Chile. This food web has connectance of 0.06, link density of 1204 and mean chain length of 4.3. The fractions of intermediate (76%), omnivorous (49%) and cannibalistic (8%) nodes are slightly lower than those observed in other marine food webs. Of the 147 nodes, 34 are harvested. Links to harvested nodes represented 50 to 100% of all trophic links of non-harvested nodes, illustrating the great impact that fishery pressure can have on the food web. The food web was compartmentalized into 5 sub-webs with high representation of harvested taxa. This structure changes if the fishery node is removed. Similarity analyses identified groups of harvested species with non-harvested nodes, suggesting that these tropho-equivalents could be sentinel species for the community-wide impacts of coastal fisheries. We conclude that fishing effects can be transmitted throughout the food web, with no compartments completely unaffected by harvesting. It is urgent to establish monitoring programs for community-wide effects of fisheries and assess whether resilience of these highly productive subtidal food webs has al - ready been compromised, thereby identifying essential nodes that require stronger fisheries regulation.
As the marine renewable energy industry evolves, in parallel with an increase in the quantity of available data and improvements in validated numerical simulations, it is occasionally appropriate to re-assess the wave and tidal resource of a region. This is particularly true for Scotland - a leading nation that the international community monitors for developments in the marine renewable energy industry, and which has witnessed much progress in the sector over the last decade. With 7 leased wave and 17 leased tidal sites, Scotland is well poised to generate significant levels of electricity from its abundant natural marine resources. In this state-of-the-art review of Scotland's wave and tidal resource, we examine the theoretical and technical resource, and provide an overview of commercial progress. We also discuss issues that affect future development of the marine energy seascape in Scotland, applicable to other regions of the world, including the potential for developing lower energy sites, and grid connectivity.
Marine litter is a growing environmental problem, especially plastic material is accumulated in the seas where it will fragment to smaller pieces. Marine litter has severe consequences for the marine life, as well as for economy and social development. Marine litter is high on the political agenda, and legislations, amongst all the Marine Strategy Framework Directive's descriptor 10 for determining good environmental status, aims at preventing waste to become marine litter. The purpose of the pilot study presented in this report is to raise awareness amongst officials at municipalities and authorities about the need to reduce the presence of litter in the marine environment and to give ideas/suggestions on how this can be done. The project has therefore developed a “Plug the Marine Litter Tap”-approach, which together with local knowledge and experience, can be used to identify sources of marine debris by using existing statistics. Södertälje is used as a pilot area where we give examples on indicators for marine litter in the urban environment and proposed measures for each indicator. We hope that this will encourage municipalities to reflect on how preventive measures against marine litter can be incorporated in local waste management plans and become part of their regular routine.
The distribution of oceanic cephalopod species is not fully understood but seabirds, which feed on cephalopods and cover vast oceanic areas, might work as samplers and mappers of the occurrence of this elusive group. We tracked 17 wandering albatrosses Diomedea exulans at Bird Island, South Georgia (54° S, 38° W) over the austral winter (breeding period) with GPS-loggers, activity recorders and stomach temperature probes. At logger retrieval, diet composition was accessed via stomach flushings of the tagged individuals. Wandering albatrosses captured circumpolar and rarer oceanic squid in all water masses of the Southern Ocean (i.e. Antarctic, sub-Antarctic and subtropical waters), complementing much of the knowledge about the cephalopod distribution in the Atlantic sector of the Southern Ocean. Some cephalopod species showed a distribution range wider than expected, with oceanic fronts not functioning as ecological barriers as previously thought. This suggests they might be capable of overcoming these frontal regimes and even take advantage of their dynamics as migration pathways.
Bleaching events are becoming more frequent and are projected to become annual in Micronesia by 2040. To prepare for this threat, the Government of Palau is reviewing its marine protected area network to increase the resilience of the reefs by integrating connectivity into the network design. To support their effort, we used high-throughput sequencing of microsatellites to create genotypes of colonies of the coral Acropora hyacinthus to characterize population genetic structure and dispersal patterns that led to the recovery of Palau’s reefs from a 1998 bleaching event. We found no evidence of a founder effect or refugium where colonies may have survived to recolonize the reef. Instead, we found significant pairwise F′stvalues, indicating population structure and low connectivity among most of the 25 sites around Palau. We used kinship to measure genetic differences at the individual level among sites and found that differences were best explained by the degree of exposure to the ocean [F1,20 = 3.015, Pr(>F) = 0.01], but with little of the total variation explained. A permutation test of the pairwise kinship coefficients revealed that there was self-seeding within sites. Overall, the data point to the population of A. hyacinthus in Palau recovering from a handful of surviving colonies with population growth primarily from self-seeding and little exchange among sites. This finding has significant implications for the management strategies for the reefs of Palau, and we recommend increasing the number and distribution of management areas around Palau to capture the genetic architecture and increase the chances of protecting potential refuges in the future.
The Mediterranean Sea has been defined “under siege” because of intense pressures from multiple human activities; yet there is still insufficient information on the cumulative impact of these stressors on the ecosystem and its resources. We evaluate how the historical (1950–2011) trends of various ecosystems groups/species have been impacted by changes in primary productivity (PP) combined with fishing pressure. We investigate the whole Mediterranean Sea using a food web modelling approach. Results indicate that both changes in PP and fishing pressure played an important role in driving species dynamics. Yet, PP was the strongest driver upon the Mediterranean Sea ecosystem. This highlights the importance of bottom-up processes in controlling the biological characteristics of the region. We observe a reduction in abundance of important fish species (~34%, including commercial and non-commercial) and top predators (~41%), and increases of the organisms at the bottom of the food web (~23%). Ecological indicators, such as community biomass, trophic levels, catch and diversity indicators, reflect such changes and show overall ecosystem degradation over time. Since climate change and fishing pressure are expected to intensify in the Mediterranean Sea, this study constitutes a baseline reference for stepping forward in assessing the future management of the basin.
Marine ecosystems are subject to anthropogenic change at global, regional and local scales. Global drivers interact with regional- and local-scale impacts of both a chronic and acute nature. Natural fluctuations and those driven by climate change need to be understood to diagnose local- and regional-scale impacts, and to inform assessments of recovery. Three case studies are used to illustrate the need for long-term studies: (i) separation of the influence of fishing pressure from climate change on bottom fish in the English Channel; (ii) recovery of rocky shore assemblages from the Torrey Canyon oil spill in the southwest of England; (iii) interaction of climate change and chronic Tributyltin pollution affecting recovery of rocky shore populations following the Torrey Canyon oil spill. We emphasize that “baselines” or “reference states” are better viewed as envelopes that are dependent on the time window of observation. Recommendations are made for adaptive management in a rapidly changing world.
In 2004, the UN General Assembly resolved to establish a working group to consider issues pertaining to the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction (BBNJ). The group met nine times between 2006 and 2015 before concluding its mandate by recommending the development of an international legally binding instrument on BBNJ under the United Nations Convention on the Law of the Sea. Based on in-depth interviews with working group participants, this research examines how NGOs contributed to the working group process. Respondents from government delegations highlighted the usefulness of workshops and side events convened by NGOs, and the role of NGOs in bringing experts on technical issues – particularly marine genetic resources and the sharing of benefits – into the BBNJ negotiations. Respondents from both NGOs and government delegations emphasized the importance of fostering personal relationships in order to ensure a steady and constructive information flow. Social media efforts by NGOs were considered by some government representatives to have occasionally hampered open discussion, although they noted that conditions have improved. The lengthy working group process was marked by substantial fluctuation in participation, particularly within government delegations from developing states. Of 1523 individuals who participated in at least one of the working group meetings, only 45 attended more than half of the meetings, and 80% of these were representing NGOs or highly industrialized countries. Respondents felt that this comparatively small number of individuals provided a source of continuity that was crucial for moving the discussions forward.
Marine phytoplankton inhabit a dynamic environment where turbulence, together with nutrient and light availability, shapes species fitness, succession and selection1, 2. Many species of phytoplankton are motile and undertake diel vertical migrations to gain access to nutrient-rich deeper layers at night and well-lit surface waters during the day3, 4. Disruption of this migratory strategy by turbulence is considered to be an important cause of the succession between motile and non-motile species when conditions turn turbulent1, 5, 6. However, this classical view neglects the possibility that motile species may actively respond to turbulent cues to avoid layers of strong turbulence7. Here we report that phytoplankton, including raphidophytes and dinoflagellates, can actively diversify their migratory strategy in response to hydrodynamic cues characteristic of overturning by Kolmogorov-scale eddies. Upon experiencing repeated overturning with timescales and statistics representative of ocean turbulence, an upward-swimming population rapidly (5–60 min) splits into two subpopulations, one swimming upward and one swimming downward. Quantitative morphological analysis of the harmful-algal-bloom-forming raphidophyte Heterosigma akashiwo together with a model of cell mechanics revealed that this behaviour was accompanied by a modulation of the cells’ fore–aft asymmetry. The minute magnitude of the required modulation, sufficient to invert the preferential swimming direction of the cells, highlights the advanced level of control that phytoplankton can exert on their migratory behaviour. Together with observations of enhanced cellular stress after overturning and the typically deleterious effects of strong turbulence on motile phytoplankton5, 8, these results point to an active adaptation of H. akashiwo to increase the chance of evading turbulent layers by diversifying the direction of migration within the population, in a manner suggestive of evolutionary bet-hedging. This migratory behaviour relaxes the boundaries between the fluid dynamic niches of motile and non-motile phytoplankton, and highlights that rapid responses to hydrodynamic cues are important survival strategies for phytoplankton in the ocean.
- The conservation of many wildlife species requires understanding the demographic effects of climate change, including interactions between climate change and harvest, which can provide cultural, nutritional or economic value to humans.
- We present a demographic model that is based on the polar bear Ursus maritimus life cycle and includes density-dependent relationships linking vital rates to environmental carrying capacity (K). Using this model, we develop a state-dependent management framework to calculate a harvest level that (i) maintains a population above its maximum net productivity level (MNPL; the population size that produces the greatest net increment in abundance) relative to a changing K, and (ii) has a limited negative effect on population persistence.
- Our density-dependent relationships suggest that MNPL for polar bears occurs at approximately 0·69 (95% CI = 0·63–0·74) of K. Population growth rate at MNPL was approximately 0·82 (95% CI = 0·79–0·84) of the maximum intrinsic growth rate, suggesting relatively strong compensation for human-caused mortality.
- Our findings indicate that it is possible to minimize the demographic risks of harvest under climate change, including the risk that harvest will accelerate population declines driven by loss of the polar bear's sea-ice habitat. This requires that (i) the harvest rate – which could be 0 in some situations – accounts for a population's intrinsic growth rate, (ii) the harvest rate accounts for the quality of population data (e.g. lower harvest when uncertainty is large), and (iii) the harvest level is obtained by multiplying the harvest rate by an updated estimate of population size. Environmental variability, the sex and age of removed animals and risk tolerance can also affect the harvest rate.
- Synthesis and applications. We present a coupled modelling and management approach for wildlife that accounts for climate change and can be used to balance trade-offs among multiple conservation goals. In our example application to polar bears experiencing sea-ice loss, the goals are to maintain population viability while providing continued opportunities for subsistence harvest. Our approach may be relevant to other species for which near-term management is focused on human factors that directly influence population dynamics within the broader context of climate-induced habitat degradation.
Guatemala's rich coastal and marine biodiversity provides essential ecosystem goods and services to local residents and the national economy through artisanal and commercial fisheries, aquaculture, port exports and, to a lesser extent, tourism. As in many other countries, national policies emphasise the significance of marine conservation and marine resources, primarily through implementing marine protected areas (MPAs). However, this assumes that governance, as reflected in legal, institutional and organizational frameworks, political capacity and human resources is sufficiently developed to ensure MPAs meet these goals. These issues are explored through presenting the first detailed analysis of coastal and marine governance in Guatemala. The research highlights a range of barriers to good governance which restrict the extent to which MPAs can function effectively. Recommendations are made which can capitalise upon the potential for locally managed marine areas as a means to facilitate the improved governance of coastal and marine resources in Guatemala.
Top-down conservation projects, (Eco-)tourism, large-scale aquaculture and the expansion of industrial infrastructure are transforming Myanmar. Myanmar's coastal and inland aquatic resources are vast, but these evolving processes and dynamics raise important questions about who benefits from using these resources, who gets to access them and where control lies.
Territorial use rights in fisheries (TURFs) paired with marine reserves (henceforth called "TURF-reserves") have been proposed as a viable management strategy to combat overfishing in many small-scale fisheries by combining the TURF benefits of exclusive access with the conservation, spillover, and resilience benefits of reserves. When appropriately designed and implemented, TURF- reserves can encourage stewardship and empower fishers to better manage their resources. While tools that assist spatial design in marine nearshore contexts exist, they are data intensive, require expertise in software operation, and often need Internet connection. We developed the TURF-Reserve Design Tool to assist spatial design in settings where these elements are not present by providing an easy-to-use decision support tool for small-scale fisheries contexts. This tool consists of a spatial bioeconomic model that allows managers to analyze the relative performance of TURF-reserve designs for a specific setting by assessing the relative ecological and economic outcomes of each design.
Do fishers know best when it comes to identifying areas with rare and depleted fish species? The global conservation crisis demands that managers marshal all available datasets to inform conservation management plans for depleted species, yet the level of trust placed in local knowledge remains uncertain. This study compares four methods for inferring species distributions of an internationally traded, rare and depleted genus of marine fishes (Hippocampus spp.): the use of (i) fisher interviews; (ii) government research trawls, (iii) scientific diving surveys, and (iv) citizen science contributions. We analyzed these four datasets at the genus and individual species levels to evaluate our conclusions about seahorse spatial occurrence, diversity of species present and the cost effectiveness of sampling effort. We found that fisher knowledge provided more information on our data-poor fish genus at larger spatial scales, with less effort, and for a cheaper price than all other datasets. One drawback was that fishers were unable to provide data down to the species level. People embarking on conservation endeavors for data-poor species may wish to begin with fisher interviews and use these to inform the application of government research, scientific diving, or citizen science programs.
Territorial use rights in fisheries (TURFs) are becoming a widely promoted tool to enhance the sustainability of small-scale fisheries. In 1991, Chile established a national coastal TURF policy that gave legal authority to assign exclusive access rights to artisanal fisher organizations. In 2014, there were several hundred TURFs decreed to fisher organizations in different biophysical and socioeconomic settings. To date, research assessing TURF implementation has generally been based on a few case studies and have had mixed results. Here, we present results from a survey of 535 fishers from 55 different artisanal fisher organizations. The survey consisted of three open-ended questions that explore users' perceptions of the main problems, benefits, and improvements concerning assigned TURFs. We also sampled 55 presidents of artisanal fisher organizations to explore how they perceived the accomplishments of TURFs. Main key problems, as perceived by fishers, include increased costs associated with surveillance and poaching, and the variability and sometimes lack of financial returns. Despite strong price drops in exported species, TURFs have provided incentives for innovation and stewardship, and fishers are generally unwilling to relinquish them. In fact, fishers define TURF benefits in multiple dimensions, which include conservation/ ecological and territorial empowerment. Fisher presidents stress that although expectations of economic benefits have not been fully realized, territorial empowerment is a critical benefit. Through the analysis of fishers' perceptions on solutions to TURFs' problems, we highlight the development of stocking activities, combining TURFs with marine reserves, food traceability, and what we call BIO+ seafood— products that have associated biodiversity benefits.
Mean trophic level of fishery landings (MTL) is one of the most widely used biodiversity indicators to assess the impacts of fishing. Based on the landing data compiled by Food and Agriculture Organization combined with trophic information of relevant species in FishBase, we evaluated the status of marine fisheries from 1950 to 2010 for different coastal states in Pacific, Atlantic and Indian Oceans. We found that the phenomenon of “fishing down marine food webs” occurred in 43 states. Specifically, 27 states belonged to “fishing-through” pattern, and 16 states resulted from “fishing-down” scenario. The sign of recovery in MTL was common in the Pacific, Atlantic and Indian Oceans (occurred in 20 states), but was generally accompanied by significantly decreased catches of traditional low trophic level species. In particular, 11 states showed significant declining catches of lower trophic levels. The MTL-based assessment of “fishing down marine food webs” needs to be interpreted cautiously.
Belize recently committed to establishing territorial use rights in fisheries (TURFs), called "managed access" in Belize, throughout its territorial waters. While more remains to be done to ensure that scaling is successful, this national commitment and the design of a national system of managed access areas are important milestones in the expansion of rights-based fishery management in Belize. Theoretical work and empirical studies have yielded principles for scaling conservation innovations, many of which were applied in Belize over 3 yrs to achieve these milestones. Two pilot sites were established in 2011 and encompassed varied ecological and social conditions to maximize learning applicable to scaling to diverse sites. Participatory processes were used to identify fishery management challenges as perceived by fishers, managers, and other stakeholders, and to build consensus on solutions. A scaling team consisting of fishers, scientists, non-governmental organizations, community-based organizations, and government representatives with dedicated resources for scaling was formed. Our case study suggests that scaling principles derived from theoretical considerations and empirical analysis have contributed to the scaling of managed access in Belize, which is expected to result in significant conservation, social, and economic benefits. This in turn suggests that these principles may be relatively robust and perhaps can be applied elsewhere to scale conservation initiatives. Our case study also suggests that careful consideration of new information and changing conditions accompanied by appropriate decisions and changes in tactics and strategy are important for successful scaling.
Territorial use rights in fisheries (TURFs) represent a form of spatial co-management to secure access rights for communities while simultaneously supporting marine conservation. In Ecuador, a TURF system emerged in many mangrove-associated fisheries after the government enacted legislation in 1999 favoring decentralized mangrove conservation. In communities where custodias (mangrove concessions) were implemented, members of local fishing associations have defined access privileges for certain fisheries within the boundaries of their concession. The present study explores the tradeoffs that emerged through the interaction between informal customary norms in fishing and the formal TURF system associated with custodias. Combining fishery data and ethnographic insights about Ecuador's fishery for mangrove cockles Anadara tuberculosa (G. B. Sowerby I, 1833) and Anadara similis (C. B. Adams, 1852), I evaluate outcomes of fisher empowerment, perceptions of success, fishery productivity, and tradeoffs. I argue that empowering fishers with stewardship rights is critical for successful TURFs in Ecuador. Custodias have strengthened access rights and created conditions that promote habitat health with implications for fishery productivity and economic benefits derived from larger catch and shell sizes. On the other hand, custodias limit access and fisher mobility, resulting in the reconfiguration of fishing space and displacement of independent fishers from their customary grounds. Moreover, secure access rights do not necessarily provide incentives for individuals to harvest shells according to the size regulations imposed by current policies. Understanding the benefits and limitations of this integrated approach to coastal management may provide valuable insights for other forms of spatially-explicit marine governance and fisheries co-management.
There is a growing interest in working with customary management (CM) systems to effectively manage benthic resources and small-scale fisheries. The underlying notion is that CM institution as territorial use rights in fisheries (TURFs) can be sufficiently adaptive and dynamic to create the local incentives that are necessary for promoting sustainable fishing practices and marine conservation more generally in a given region. This paper reviews the social opportunities and challenges of working with CM systems as a form of TURF, particularly in Oceania. A key conclusion is that policy makers and managers not only need to recognize natural interconnectivity in any one marine space, but also consider the social interconnectivity of stakeholders that covers customary TURFs. Only by recognizing and working with the existing social networks that overlay any given marine territory can the operational principles of CM (as reviewed in this paper) be effectively deployed for achieving some kind of bioeconomic efficiency and creating an equitable rights-based fisheries management system.
Unsustainable fishing in marine systems creates fisheries management and conservation challenges, with implications for ecosystem health, livelihoods, economies, and seafood supply. Thus there is a need for management approaches that can support productive fisheries and healthy ecosystems. Property rights, and particularly spatial rights or territorial use rights in fisheries (TURFs), are increasingly proposed as a solution. It has been suggested that TURFs may align fishers' incentives with long-term stewardship, resulting in improved yields and positive conservation outcomes. Here we examined this idea by reviewing existing theoretical and empirical evidence for TURF performance in achieving both fisheries and conservation goals, and find equivocal evidence that TURFs can consistently deliver on this promise. We then explored the potential to improve outcomes by implementing no-take marine reserves with TURFs ("TURF-reserves"). We evaluated theoretical and empirical evidence in the literature and develop a simulation model to examine tradeoffs for achieving conservation and fishery objectives. With our model, we examined different management regimes (e.g., open access vs TURFs), harvest controls within the TURF (e.g., selectivity and harvest rate restrictions), and varying reserve sizes. We found that combining reserves with TURFs does not eliminate the tradeoff between fisheries and conservation goals if the TURF already effectively controls fishing pressure. However, given the results from our literature review, many TURFs may not achieve effective fisheries management. Thus, TURF-reserves may be better able to balance fisheries and conservation goals relative to TURF-only systems, but outcomes will depend on target species mobility, TURF size, and fishing intensity outside the TURF-reserve.