We used inverse modeling to reconstruct major planktonic food web carbon flows in theAtlantic Water inflow, east and north of Svalbard during spring (18–25 May) and summer(9–13 August), 2014. The model was based on three intensively sampled stations duringboth periods, corresponding to early, peak, and decline phases of a Phaeocystis anddiatom dominated bloom (May), and flagellates dominated post bloom stages (August).The food web carbon flows were driven by primary production (290–2,850 mg Cm−2 d−1), which was channeled through a network of planktonic compartments, andultimately respired (180–1200 mg C m2 d−1), settled out of the euphotic zone asorganic particles (145–530 mg C m−2 d−1), or accumulated in the water columnin various organic pools. The accumulation of dissolved organic carbon was intense(1070 mg C m−2 d−1) during the early bloom stage, slowed down during the bloompeak (400 mg C m−2 d−1), and remained low during the rest of the season. Theheterotrophic bacteria responded swiftly to the massive release of new DOC by high butdecreasing carbon assimilation rates (from 534 to 330 mg C m−2 d−1) in May. The netbacterial production was low during the early and peak bloom (26–31 mg C m−2 d−1)but increased in the late and post bloom phases (>50 mg C m−2 d−1). Theheterotrophic nanoflagellates did not respond predictably to the different bloomphases, with relatively modest carbon uptake, 30–170 mg C m2 d−1. In contrast,microzooplankton increased food intake from 160 to 380 mg C m2 d−1 during thebuildup and decline phases, and highly variable carbon intake 46–624 mg C m2 d−1,during post bloom phases. Mesozooplankton had an initially high but decreasingcarbon uptake in May (220–48 mg C m−2 d−1), followed by highly variable carbon consumption during the post bloom stages (40–190 mg C m−2 d−1). Both, micro- andmesozooplankton shifted from almost pure herbivory (92–97% of total food intake)during the early bloom phase to an herbivorous, detritovorous and carnivorous mixeddiet as the season progressed. Our results indicate a temporal decoupling between themicrobial and zooplankton dominated heterotrophic carbon flows during the course ofthe bloom in a highly productive Atlantic gateway to the Arctic Ocean. | This work was funded by the Estonian Research Council (Grant1574P), and the Norwegian Research Council through the projectCarbonBridge (Project Number 226415).

The water&ndash:energy&ndash:food (WEF) nexus attracts much attention due to the elevated public concern regarding environmental conservation and sustainability. As we head into a new era of civilization, population increase and modernized lifestyles have led to an increasing need for water, energy, and food. However, severe hydrological precipitation significantly impacts agricultural harvest, and such influence becomes more apparent under the influence of climate change. Meanwhile, the major method of electricity generation (i.e., fossil fuel burning) has a negative impact on the environment. These inevitable threats are crucial and have to be dealt with for a society on the road towards sustainability. In the present study, an integrated evaluation of the WEF nexus was conducted for two areas with different levels of urbanization using empirical multiple linear regression in a simultaneous equation model (SEM). By incorporating the collected data into the SEM, the weighting coefficient of each identified variable was obtained, and the nexus implication was assessed in model simulation at different scenarios considering the population growth, agro-technology advancement, energy structure improvement, and available water resources. In the simulated results, three observations were found: (1) the rural area is more sustainable than the urban one: (2) the sustainability for both the investigated areas is significantly subject to their water supply and demand: and (3) food production was found to have a less important effect on the sustainable development of the urban area. This study identified the key factors in the WEF nexus exploration, which are economically and environmentally important for resource allocation. An empirical model was developed to correlate sustainable achievement with WEF management, as well as strategic policies that should be implemented under the pressure of urbanization.

Secure and efficient supply for the food, energy and water resources is essential for sustainable urban development. Due to the close interaction of food, energy and water systems, it is necessary to analyze food-energy-water nexus from an integrated perspective. Taking the Detroit Metropolitan Area as a case, this study first constructs a food-energy-water physical input-output model to quantify food, energy and water flows. Then, structural path analysis is adopted to identify critical supply chain paths driven by the final demand of key sectors. Quantitative results of food-energy-water flows show that major inputs of food and energy in the Detroit Metropolitan Area are from outside through imports, while water use is predominately extracted from local sources. Local consumption activities for the food, energy, and water systems are mainly concentrated downstream of the supply chain. Structural path analysis results show that intermediate processes use relatively large amounts of food, energy and water, and should be more concerned. Also, identifying sectors involving multiple systems, such as Food Processing, Domestic Consumption, Solid Waste Management, Wastewater Treatment, and Residual Processing, can promote co-benefit opportunities. This holistic view on urban FEW nexus presented in this study can facilitate better decisions and help avoid unintended consequences.

Fish occurring in the outlets of water basins reduce the abundance of zooplankton. The study was performed at the outlet sections of the lake and waste stabilization pond of a sewage treatment plant. The aim of the study was to determine which zooplankton is chosen more often by the roach (Rutilus rutilus), those drifting from the waste stabilization pond or from the lake. The zooplankton from the pond was dominated by Daphnia pulex while zooplankton from the lake was dominated by small planktonic rotifers. We observed that the larger the plankter-victim’s size, the faster the reduction of its number. The fish were more likely to feed on zooplankton drifting from the waste stabilization pond than from the lake. It was influenced by D. pulex individuals, attractive for fish due to their largest body size among the analyzed zooplankton. The significance of riverine zooplankton in the downstream food web may render this data even more important.

Since the 21st century, the natural runoff from the headwater region of the Yellow River has generally been decreasing, resulting in a particularly prominent contradiction in utilization of water resources. In this study, key components were identified from the perspective of water-energy-food (WEF) nexus, and a WEF nexus model was established for the Upper Yellow River Basin (UYRB), taking into consideration the benefits of water supply to the middle and lower reaches of Yellow River, food growth in major food-producing areas in the UYRB and hydropower utilization of the UYR reservoir system. The Multi-start Solver of LINGO and the ε constraint method were used to carry out multi-objective optimization, revealing the trade-off between the WEF benefits. 1) The model computed the Pareto non-inferior set of solutions for the electricity generated by the UYR reservoir system and the degree to which the water demands of the main intake areas (Ningxia and Inner Mongolia irrigated areas, and Toudaoguai section) are satisfied, quantifying the improvement room for the overall benefits brought about by the jointly optimal operation of the WEF sectors. 2) The historical operation of Longyangxia Reservoir, a multi-year storage reservoir, was evaluated, the results of which show that the realization of the WEF benefits is determined by the proper operation of Longyangxia Reservoir. To guarantee the overall benefits in the long term, Longyangxia Reservoir should maintain a high water level. 3) The trade-offs between the WEF benefits under different boundary conditions were discussed, including various initial/final fore-bay water levels of Longyangxia Reservoir and inflows of various total water amounts from the headwater region of the UYRB. The research reveals the WEF nexus in the UYRB under different scenarios, and moreover, the formulated multi-objective optimization model is a good example that can be extended to other similar WEF nexus systems worldwide.

Following intense debates about a new global development agenda, in 2015 the Sustainable Development Goals (SDGs) were introduced based on the commitment for international collaboration to promote sustained and inclusive economic growth, social development, and environmental protection. In accordance with these objectives, the ‘food–energy–water’ (FEW) nexus developed as an integrative concept to optimize the interdependent uses of the different nexus resources in order to achieve a sustainable, fair allocation of these resources while enabling economic growth. Addressing this challenge, various FEW nexus indices have been published to allow the global comparison of countries’ nexus statuses. Given the complexity of nexus thinking, measuring the state of the nexus is a challenging task in need of a clear methodology. Based on the comparative analysis of selected nexus indices – including our own nexus index (the STE FEW Security Index) – and their underlying methodical approaches, in this paper we discuss the consistency and inconsistencies among these indices as well as their resulting implications.

Climate-stressed groundwater resources present a growing challenge for protecting food security and economic sustainability, notably in Small Island Developing States (SIDS). These states are some of the most vulnerable to climate stress because of their large coastlines, vulnerability to rising sea levels, weak access to reliable surface water, and limited food production capacity for handling increased groundwater scarcity. Impacts of climate stressed groundwater resources brought on by irrigation and growing urban demand in SIDS continue to receive widespread attention by both scientists and policymakers. Policies that limit pumping to protect aquifer sustainability reduce short-term economic welfare by unknown amounts that would otherwise be secured by both urban and irrigation water users. Yet, little scholarly research has addressed economic impacts of climate-water stress for the special needs of SIDS for which urban and irrigation pumping compete hydrologically and economically over long time periods. The original contribution of this work is to address that gap by employing downscaled data on precipitation from Representative Concentration Pathways (RCP) climate scenarios. Its novel contribution is to conceptualize, develop, apply, and interpret an integrated hydro-economic framework to understand interconnected physical and economic linkages from managing an unconfined regional aquifer system under each of three climate and two policy scenarios. The application is to Barbados, a SIDS, for which current and future irrigation and urban demands compete for water. The framework integrates groundwater hydrology, climate scenarios, economics, land use, and groundwater management, with the intent to mitigate impacts of climate stress on current economic values of water as well as protecting future aquifer sustainability. Results provide a framework to guide water management for SIDS vulnerable to climate stress for which water of the right quantity, quality, timing, location, and price are essential elements of economic development.

Fish occurring in the outlets of water basins reduce the abundance of zooplankton. The study was performed at the outlet sections of the lake and waste stabilization pond of a sewage treatment plant. The aim of the study was to determine which zooplankton is chosen more often by the roach (<i>Rutilus rutilus</i>), those drifting from the waste stabilization pond or from the lake. The zooplankton from the pond was dominated by <i>Daphnia pulex</i> while zooplankton from the lake was dominated by small planktonic rotifers. We observed that the larger the plankter-victim&#8217;s size, the faster the reduction of its number. The fish were more likely to feed on zooplankton drifting from the waste stabilization pond than from the lake. It was influenced by <i>D. pulex</i> individuals, attractive for fish due to their largest body size among the analyzed zooplankton. The significance of riverine zooplankton in the downstream food web may render this data even more important.

Source at <a href=https://doi.org/10.3389/fmars.2019.00244>https://doi.org/10.3389/fmars.2019.00244</a>. | We used inverse modeling to reconstruct major planktonic food web carbon flows in the Atlantic Water inflow, east and north of Svalbard during spring (18–25 May) and summer (9–13 August), 2014. The model was based on three intensively sampled stations during both periods, corresponding to early, peak, and decline phases of a <i>Phaeocystis</i> and diatom dominated bloom (May), and flagellates dominated post bloom stages (August). The food web carbon flows were driven by primary production (290–2,850 mg C m^-2 d^-1), which was channeled through a network of planktonic compartments, and ultimately respired (180–1200 mg C m² d^-1), settled out of the euphotic zone as organic particles (145–530 mg C m^-2 d^-1), or accumulated in the water column in various organic pools. The accumulation of dissolved organic carbon was intense (1070 mg C m^-2 d^-1) during the early bloom stage, slowed down during the bloom peak (400 mg C m^-2 d^-1), and remained low during the rest of the season. The heterotrophic bacteria responded swiftly to the massive release of new DOC by high but decreasing carbon assimilation rates (from 534 to 330 mg C m^-2 d^-1) in May. The net bacterial production was low during the early and peak bloom (26–31 mg C m^-2 d^-1) but increased in the late and post bloom phases (>50 mg C m^-2 d^-1). The heterotrophic nanoflagellates did not respond predictably to the different bloom phases, with relatively modest carbon uptake, 30–170 mg C m² d^-1. In contrast, microzooplankton increased food intake from 160 to 380 mg C m² d^-1 during the buildup and decline phases, and highly variable carbon intake 46–624 mg C m² d^-1, during post bloom phases. Mesozooplankton had an initially high but decreasing carbon uptake in May (220–48 mg C m^-2 d^-1), followed by highly variable carbon consumption during the post bloom stages (40–190 mg C m^-2 d^-1). Both, micro- and mesozooplankton shifted from almost pure herbivory (92–97% of total food intake) during the early bloom phase to an herbivorous, detritovorous and carnivorous mixed diet as the season progressed. Our results indicate a temporal decoupling between the microbial and zooplankton dominated heterotrophic carbon flows during the course of the bloom in a highly productive Atlantic gateway to the Arctic Ocean.

We used inverse modeling to reconstruct major planktonic food web carbon flows in the Atlantic Water inflow, east and north of Svalbard during spring (18–25 May) and summer (9–13 August), 2014. The model was based on three intensively sampled stations during both periods, corresponding to early, peak, and decline phases of a Phaeocystis and diatom dominated bloom (May), and flagellates dominated post bloom stages (August). The food web carbon flows were driven by primary production (290–2,850 mg C m-2 d-1), which was channeled through a network of planktonic compartments, and ultimately respired (180–1200 mg C m2 d-1), settled out of the euphotic zone as organic particles (145–530 mg C m-2 d-1), or accumulated in the water column in various organic pools. The accumulation of dissolved organic carbon was intense (1070 mg C m-2 d-1) during the early bloom stage, slowed down during the bloom peak (400 mg C m-2 d-1), and remained low during the rest of the season. The heterotrophic bacteria responded swiftly to the massive release of new DOC by high but decreasing carbon assimilation rates (from 534 to 330 mg C m-2 d-1) in May. The net bacterial production was low during the early and peak bloom (26–31 mg C m-2 d-1) but increased in the late and post bloom phases (>50 mg C m-2 d-1). The heterotrophic nanoflagellates did not respond predictably to the different bloom phases, with relatively modest carbon uptake, 30–170 mg C m2 d-1. In contrast, microzooplankton increased food intake from 160 to 380 mg C m2 d-1 during the buildup and decline phases, and highly variable carbon intake 46–624 mg C m2 d-1, during post bloom phases. Mesozooplankton had an initially high but decreasing carbon uptake in May (220–48 mg C m-2 d-1), followed by highly variable carbon consumption during the post bloom stages (40–190 mg C m-2 d-1). Both, micro- and mesozooplankton shifted from almost pure herbivory (92–97% of total food intake) during the early bloom phase to an herbivorous, detritovorous and carnivorous mixed diet as the season progressed. Our results indicate a temporal decoupling between the microbial and zooplankton dominated heterotrophic carbon flows during the course of the bloom in a highly productive Atlantic gateway to the Arctic Ocean. | publishedVersion