Search

Aim: We aimed to enhance our understanding of the distribution of mesopelagic mesozooplankton (MM) using species distribution models, assess the performance of various modelling techniques, identify key environmental predictors for MM distribution and compute their habitat suitability indices. Location: Our study focused on the mesopelagic zone globally, with data analysed from different oceans. Taxon: Our focus was primarily on mesopelagic mesozooplankton, gathering data on 861 different species from the Mesopelagic Mesozooplankton and Micronekton (MMM) Database. Methods: We used an ensemble of species distribution models, applying 10 different modelling algorithms and three multi‐model ensemble approaches. We explored two important factors that can affect model performance: subsampling and the choice of background points. We also estimated the relative importance of various environmental conditions such as mixed layer depth, temperature, salinity, net primary productivity, euphotic zone depth and dissolved nitrate concentration on the distribution of these species. Results: Euphotic zone depth, salinity and dissolved nitrate concentration were identified as the most important variables for explaining the distribution of mesopelagic mesozooplankton. The ensemble modelling results were robust in areas with abundant observational records, but high uncertainty was observed in data‐limited regions. We found a patchy habitat suitability map for zooplankton when modelled within their native range, largely due to uneven sampling. Unrestricted range models yielded smoother patterns but could inaccurately project species in areas where they do not occur. Main Conclusions: Our study highlights the need for increased sampling effort in data‐limited regions to improve the accuracy of mesopelagic species distribution models. Despite some inaccuracies, unrestricted range models, assuming ecological equivalence (where different species occupying a similar ecological niche in different geographical regions or different ecosystems exhibit similar adaptations and behaviours), provide a reasonable comparison for habitat suitability maps and model performance. It also confirms the significant impact of certain environmental conditions on mesozooplankton distribution. [ABSTRACT FROM AUTHOR]

ABSTRACT Marine fisheries are crucial to the economy, livelihood, food security and culture of coastal nations and communities, significantly contributing to the United Nations Sustainable Development Goals. A decade ago, T. J. Pitcher and W. W. L. Cheung highlighted the dichotomy in the perception of fisheries' status, concluding that long‐term sustainability and benefits to people were threatened by overexploitation, climate change, pollution, habitat change and other human stressors. They advocated for a fundamental shift towards ecosystem‐based management, better enforcement of existing regulations and more inclusive and equitable management practices. In this paper, we provide an updated review of the status of global fisheries, reflecting on policy actions, key assessments and research findings over the past decade. While there is a growing recognition of the need for sustainable fisheries management and ocean protection, the overall status of fisheries has not improved. Despite progress in international and national policies addressing direct and indirect drivers such as climate change and harmful practices, these trends have not been reversed. Many challenges identified by Pitcher and Cheung and others persist. Additionally, new and emerging issues such as deep‐sea mining, plastic pollution, unhealthy aquaculture development, increasing social inequity and the rapidly increasing push for the acceleration of the blue economy exacerbate the complexity of achieving fisheries and other ocean management goals. Debating whether there is more hope or despair in global fisheries has become irrelevant. Pathways to ‘bend the curve’ for fisheries are clear, and effective actions are now urgently needed to achieve desirable and sustainable fisheries. [ABSTRACT FROM AUTHOR]

Global pollution has exacerbated accumulation of toxicants like methylmercury (MeHg) in seafood. Human exposure to MeHg has been associated with long-term neurodevelopmental delays and impaired cardiovascular health, while many micronutrients in seafood are beneficial to health. The largest MeHg exposure source for many general populations originates from marine fish that are harvested from the global ocean and sold in the commercial seafood market. Here, we use high-resolution catch data for global fisheries and an empirically constrained spatial model for seafood MeHg to examine the spatial origins and magnitudes of MeHg extracted from the ocean. Results suggest that tropical and subtropical fisheries account for >70% of the MeHg extracted from the ocean because they are the major fishing grounds for large pelagic fishes and the natural biogeochemistry in this region facilitates seawater MeHg production. Compounding this issue, micronutrients (selenium and omega-3 fatty acids) are lowest in seafood harvested from warm, low-latitude regions and may be further depleted by future ocean warming. Our results imply that extensive harvests of large pelagic species by industrial fisheries, particularly in the tropics, drive global public health concerns related to MeHg exposure. We estimate that 84 to 99% of subsistence fishing entities globally likely exceed MeHg exposure thresholds based on typical rates of subsistence fish consumption. Results highlight the need for both stringent controls on global pollution and better accounting for human nutrition in fishing choices. [ABSTRACT FROM AUTHOR]

Are there limits to our ability to adapt food systems to climate change? This overview paper for the special issue highlights results of research on potential limits and responses by food system actors. Responses are shaped by the critical interactions among the physical, chemical, biological, and social impacts in food systems arising from climate change. Food grains, temperate perennials, livestock, and oceanic capture fisheries and farming are covered. Climate change impacts on the biology of plants, animals, and humans, as well as the options for societal responses are explored. The results show where and how possible adaptations will be limited. [ABSTRACT FROM AUTHOR]

The effects of climate change on marine ecosystems are causing cascading impacts on livelihood, food security, and culture through fisheries. Such impacts interact and exacerbate the effects of overfishing on marine social‐ecological systems, complicating the rebuilding of ecosystems to achieve desirable and sustainable ocean futures. Developing effective pathways for ecosystem rebuilding requires consideration of the co‐benefits and trade‐offs between ecological and social dimensions and between fishing sectors. However, the effects of intensifying climate change on such co‐benefits or trade‐offs are yet to be well understood, particularly in regions where ecosystem rebuilding is urgently needed. We applied a numerical optimization routine to define the scope for improvement toward the Pareto‐frontier for ecological robustness and economic benefits of the northern South China Sea (NSCS) and the East China Sea (ECS) ecosystems. These two ecosystems were used to represent over‐exploited low‐ and mid‐latitude systems, respectively, and the optimization aimed to improve their status through fisheries management. We find that the ECS ecosystem has the possibility of increasing the economic benefits generated by the fisheries it supports under climate change by 2050 while increasing the uncertainty of achieving biodiversity objectives. Nevertheless, climate change is projected to reduce the scope to restore ecosystem structures and the potential economic benefits in the NSCS ecosystem. This study highlights the contrasting impacts of climate change on the co‐benefits/trade‐offs in ecosystem rebuilding and the benefits obtainable by different fishing sectors even in neighboring ecosystems. We conclude that consideration at the nexus of climate–biodiversity‐fisheries is a key to developing effective ecosystem rebuilding plan. [ABSTRACT FROM AUTHOR]

The future of the global ocean economy is currently envisioned as advancing towards a 'blue economy'--socially equitable, environmentally sustainable and economically viable ocean industries.sup.1,2. However, tensions exist within sustainable development approaches, arising from differing perspectives framed around natural capital or social equity. Here we show that there are stark differences in outlook on the capacity for establishing a blue economy, and on its potential outcomes, when social conditions and governance capacity--not just resource availability--are considered, and we highlight limits to establishing multiple overlapping industries. This is reflected by an analysis using a fuzzy logic model to integrate indicators from multiple disciplines and to evaluate their current capacity to contribute to establishing equitable, sustainable and viable ocean sectors consistent with a blue economy approach. We find that the key differences in the capacity of regions to achieve a blue economy are not due to available natural resources, but include factors such as national stability, corruption and infrastructure, which can be improved through targeted investments and cross-scale cooperation. Knowledge gaps can be addressed by integrating historical natural and social science information on the drivers and outcomes of resource use and management, thus identifying equitable pathways to establishing or transforming ocean sectors.sup.1,3,4. Our results suggest that policymakers must engage researchers and stakeholders to promote evidence-based, collaborative planning that ensures that sectors are chosen carefully, that local benefits are prioritized, and that the blue economy delivers on its social, environmental and economic goals. The capacity to create an equitable and sustainable 'blue economy' from ocean resources will be determined by addressing social conditions, governance and infrastructure, not just resource availability, as shown by a fuzzy logic model incorporating multidisciplinary criteria., Author(s): Andrés M. Cisneros-Montemayor [sup.1] , Marcia Moreno-Báez [sup.2] , Gabriel Reygondeau [sup.3] , William W. L. Cheung [sup.3] , Katherine M. Crosman [sup.4] , Pedro C. González-Espinosa [sup.5] , [...]

Ocean warming is driving significant changes in the structure and functioning of marine ecosystems, shifting species' biogeography and phenology, changing body size and biomass and altering the trophodynamics of the system. Particularly, extreme temperature events such as marine heatwaves (MHWs) have been increasing in intensity, duration and frequency. MHWs are causing large‐scale impacts on marine ecosystems, such as coral bleaching, mass mortality of seagrass meadows and declines in fish stocks and other marine organisms in recent decades. In this study, we developed and applied a dynamic version of the EcoTroph trophodynamic modelling approach to study the cascading effects of individual MHW on marine ecosystem functioning. We simulated theoretical user‐controlled ecosystems and explored the consequences of various assumptions of marine species mortality along the food web, associated with different MHW intensities. We show that an MHW can lead to a significant biomass reduction of all consumers, with the severity of the declines being dependent on species trophic levels (TLs) and biomes, in addition to the characteristics of MHWs. Biomass of higher TLs declines more than lower TLs under an MHW, leading to changes in ecosystem structure. While tropical ecosystems are projected to be sensitive to low‐intensity MHWs, polar and temperate ecosystems are expected to be impacted by more intense MHWs. The estimated time to recover from MHW impacts is twice as long for polar ecosystems and one‐third longer for temperate biomes compared with tropical biomes. This study highlights the importance of considering extreme weather events in assessing the effects of climate change on the structures and functions of marine ecosystems. [ABSTRACT FROM AUTHOR]