publishedVersion

Cold-water corals (CWCs) are important ecosystem engineers in the deep sea that provide habitat for numerous species and can form large coral mounds. These mounds influence surrounding currents and induce distinct hy- drodynamic features, such as internal waves and episodic downwelling events that accelerate transport of organic matter towards the mounds, supplying the corals with food. To date, research on organic matter distribution at coral mounds has focussed either on seasonal timescales or has provided single point snapshots. Data on food distribution at the timescale of a diurnal tidal cycle is currently limited. Here, we integrate physical, biogeochemical, and biological data throughout the water column and along a transect on the south-eastern slope of Rockall Bank, Northeast Atlantic Ocean. This transect consisted of 24-h sampling stations at four locations: Bank, Upper slope, Lower slope, and the Oreo coral mound. We investigated how the organic matter distribution in the water column along the transect is affected by tidal activity. Repeated CTD casts indicated that the water column above Oreo mound was more dynamic than above other stations in multiple ways. First, the bottom water showed high vari- ability in physical parameters and nutrient concentrations, possibly due to the interaction of the tide with the mound topography. Second, in the surface water a diurnal tidal wave replenished nutrients in the photic zone, supporting new primary production. Third, above the coral mound an internal wave (200 m amplitude) was recorded at 400 m depth after the turning of the barotropic tide. After this wave passed, high quality organic matter was recorded in bottom waters on the mound coinciding with shallow water physical characteristics such as high oxygen concentration and high temperature. Trophic markers in the benthic community suggest feeding on a va- riety of food sources, including phytodetritus and zooplankton. We suggest that there are three transport mecha- nisms that supply food to the CWC ecosystem. First, small phytodetritus particles are transported downwards to the seafloor by advection from internal waves, supplying high quality organic matter to the CWC reef community. Second, the shoaling of deeper nutrient-rich water into the surface water layer above the coral mound could stimulate diatom growth, which form fast-sinking aggregates. Third, evidence from lipid analysis indicates that zooplankton faecal pellets also enhance supply of organic matter to the reef communities. This study is the first to report organic matter quality and composition over a tidal cycle at a coral mound and provides evidence that fresh high-quality organic matter is transported towards a coral reef during a tidal cycle. | publishedVersion

To achieve climate neutrality in the food sector, there is an urgent need for eco-friendly steam boilers. The absorption-compression heat pumps (ACHP) using an ammonia-water mixture as working fluid can provide a high heat sink temperature at low discharge pressure levels and with temperature glides in absorption and desorption. The present study aims to investigate the performance of the ACHP for hot water and steam production. The simulation model was established based on an ACHP prototype in a NTNU lab. A case of 150 kW heating capacity was simulated with a high pressure of 23.65 bar and a low pressure of 4 bar. The system COP was 2.85 for a pressurized hot water supply temperature of 105 °C. The system performance at different temperature lifts with different heat source inlet temperatures was investigated. In addition, the effects of rich solution composition and compressor intercooling on the system performance were also analyzed. | publishedVersion

The deep sea is amongst the most food-limited habitats on Earth, as only a small fraction (<4%) of the surface primary production is exported below 200 m water depth. Here, cold-water coral (CWC) reefs form oases of life: their biodiversity compares with tropical coral reefs, their biomass and metabolic activity exceed other deep-sea ecosystems by far. We critically assess the paradox of thriving CWC reefs in the food-limited deep sea, by reviewing the literature and open-access data on CWC habitats. This review shows firstly that CWCs typically occur in areas where the food supply is not constantly low, but undergoes pronounced temporal variation. High currents, downwelling and/or vertically migrating zooplankton temporally boost the export of surface organic matter to the seabed, creating ‘feast’ conditions, interspersed with ‘famine’ periods during the non-productive season. Secondly, CWCs, particularly the most common reef-builder Desmophyllum pertusum (formerly known as Lophelia pertusa), are well adapted to these fluctuations in food availability. Laboratory and in situ measurements revealed their dietary flexibility, tissue reserves, and temporal variation in growth and energy allocation. Thirdly, the high structural and functional diversity of CWC reefs increases resource retention: acting as giant filters and sustaining complex food webs with diverse recycling pathways, the reefs optimise resource gains over losses. Anthropogenic pressures, including climate change and ocean acidification, threaten this fragile equilibrium through decreased resource supply, increased energy costs, and dissolution of the calcium-carbonate reef framework. Based on this review, we suggest additional criteria to judge the health of CWC reefs and their chance to persist in the future. | publishedVersion

Cold-water lakes situated in high latitudes and altitudes have pivotal socio-ecological importance both globally and locally. However, they are increasingly threatened by multiple anthropogenic stressors, such as climate change, hydropower and invasive species. The development of efficient management strategies is therefore urgently needed and requires a comprehensive understanding of the factors influencing the biodiversity and ecological processes of these ecosystems. We provide a holistic knowledge base for informed future research and management by addressing the interplay between local and global environmental drivers of food webs in Arctic charr (Salvelinus alpinus, Salmonidae) and brown trout (Salmo trutta, Salmonidae) dominated cold-water lakes in Fennoscandia. The trophic niche and population dynamics of these generalist top consumers provide extensive insights into the effects of natural and anthropogenic drivers on food webs in intensively studied Fennoscandian cold-water lakes, covering marked biogeographical gradients in abiotic and biotic conditions. Drawing on a synthesis of existing literature, our focus is on three pivotal drivers: (1) lake location and connectivity, (2) lake area and morphometry and (3) fish community composition. These drivers significantly influence the complexity and the origin and flow of energy in lake food webs, and ultimately the size structure of the charr and trout populations. Furthermore, we highlight ongoing environmental changes in Fennoscandian cold-water lakes caused by hydropower and invasive species. Finally, we identify crucial knowledge gaps and propose management actions for improving the future state of Fennoscandian cold-water lake ecosystems and their charr and trout populations.

The Mediterranean is an area where the balance between water demand and abstractions vs. water availability is often under stress already, as demonstrated here with the Water Exploitation Index. In this work, model estimates on how different proposed measures for water resources management would affect different indicators. After a review of the current water resources status in the Mediterranean and the definition of indicators used in this study, aspects interlinked with water in the Water-Energy-Food-Ecosystems Nexus are briefly discussed, focusing on problems linked with water scarcity and depletion of groundwater resources as well as with climate change projections. Subsequently, the proposed measures for water efficiency are detailed—irrigation efficiency, urban water efficiency, water reuse and desalination—that might be effective to reduce the growing water scarcity problems in the Mediterranean. Their effects that result from the LISFLOOD model, show that wastewater reuse, desalination and water supply leakage reduction lead to decreased abstractions, but do not affect net water consumption. Increased irrigation efficiency does decrease consumption and reduces abstractions as well. We deduct however that the current envisaged water efficiency measures might not be sufficient to keep up with the pace of diminishing water availability due to climate change. More ambition is needed on water efficiency in the Mediterranean to keep water scarcity at bay.

Water-Energy-Food (WEF) Nexus and CO2 emissions for a farm in northwest Iran were analyzed to provide data support for decision-makers formulating national strategies in response to climate change. In the analysis, input–output energy in the production of seven crop species (alfalfa, barley, silage corn, potato, rapeseed, sugar beet, and wheat) was determined using six indicators, water, and energy consumption, mass productivity, and economic productivity. WEF Nexus index (WEFNI), calculated based on these indicators, showed the highest (best) value for silage corn and the lowest for potato. Nitrogen fertilizer and diesel fuel with an average of 36.8% and 30.6% of total input energy were the greatest contributors to energy demand. Because of the direct relationship between energy consumption and CO2 emissions, potato cropping, with the highest energy consumption, had the highest CO2 emissions with a value of 5166 kg CO2eq ha−1. A comparison of energy inputs and CO2 emissions revealed a direct relationship between input energy and global warming potential. A 1 MJ increase in input energy increased CO2 emissions by 0.047, 0.049, 0.047, 0.054, 0.046, 0.046, and 0.047 kg ha−1 for alfalfa, barley, silage corn, potato, rapeseed, sugar beet, and wheat, respectively. Optimization assessments to identify the optimal cultivation pattern, with emphasis on maximized WEFNI and minimized CO2 emissions, showed that barley, rapeseed, silage corn, and wheat performed best under the conditions studied. | publishedVersion

A large amount of fossil fuels is consumed for hot water and steam generation in food processes such as smoking, scalding, drying, pasteurization, sterilization, cleaning, and cooking, which currently rises both economic- and environmental concerns. At the same time, there is a considerable number of low-grade waste heat available, often from associated cooling processes. High-temperature heat pumps (HTHPs) are considered as a promising solution for steam boilers replacement and waste heat recovery owing to their high energy efficiency and sustainability. In the present study, the performance of three heat pump systems — a trans-critical CO2 heat pump system, a cascade propane-butane heat pump system and an ammonia-water absorption-compression heat pump (ACHP) system, for hot water and steam production in food processing is evaluated based on different application scenarios. In all the scenarios and temperature lift levels, the ACHP exhibits the best thermal performance with moderate pressure levels and low-pressure ratios. When applying the ACHP for both the cleaning and cooking processes, the achievable energy saving rate can reach 79%. Further, the optimal HTHP system architectures for different application scenarios are discussed. | acceptedVersion

The scarcity of grazing and water for an animal has a negative effect on household welfare and food security either by affecting livestock production directly, affecting crop or off-farm income due to labor reallocation or through its direct impact on time leisure consumption. The economic impacts of resource (grazing and water) scarcity on welfare are undermined. Thus, a better understanding that is derived from the factual evidence is required. The first objective of this paper is to explore the link between natural resource scarcity and per capita food consumption expenditure (PCFE) as proxy for welfare and food security followed by the second objective of analyzing whether this effect is uniform across all quantile groups and there is gender differential effect using distance and shadow price as resource scarcity indicators. The paper used a relatively unique data set from a randomly drawn 518 sample farmers in Northern Ethiopia. To address our first objective, we employ the IV two-stage least square estimation for welfare and probit model for food security drawing on non-separable farm household model. Our estimates show that about 48% of the households were food secure while 52% were food insecure. Our results confirmed the theoretical prediction that resource scarcity affects household PCFE and food security adversely as predicted by the downward spiral hypothesis. The results indicate that animal feed and water scarcity have an important impact on welfare and food security. As expected, in aggregate, reducing time spent searching for water per day leads to an increase in PCFE and food security. Similarly, a decrease in time wastage for searching grazing increase PCFE and food security respectively, and an increment of PCFE and food security is achieved by a reduction in crop residue transporting time per day. The gender differential analysis signals that increasing resource scarcity results in low PCFE and food security, with the male are considerably likely to have less food consumption expenditure and being food insecure more as compared to female households. The total impact of time spent searching for water, grazing, and transporting straw on per PCFE is − 0.142%, − 0.102%, and − 0.092%, respectively, and decreasing reaching time to a water, grazing, and straw source by 0.6 min will increase PCFE by 354 ETB, 254 ETB, and 229 ETB for the median household. Depending on results from the quantile regression, the effect of water and feed scarcity is not uniform across the food consumption distribution.