SciCombinator

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Concept: Freshwater

168

Poyang Lake, the largest fresh water lake in China, is the major transmission site of Schistosoma japonicum in China. Epidemics of schistosomiasis japonica have threatened the health of residents and stunted social-economic development there.

Concepts: Epidemiology, Mathematics, Physics, Schistosomiasis, Schistosoma, Digenea, Freshwater, Schistosoma japonicum

71

Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems-the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services.

Concepts: Biodiversity, Hydrology, River, Drainage basin, Stream, Amazon River, Freshwater, Geomorphology

35

Wildland fire impacts on surface freshwater resources have not previously been measured, nor factored into regional water management strategies. But, large wildland fires are increasing and raise concerns about fire impacts on potable water. Here we synthesize long-term records of wildland fire, climate, and river flow for 168 locations across the United States. We show that annual river flow changed in 32 locations, where more than 19% of the basin area was burned. Wildland fires enhanced annual river flow in the western regions with a warm temperate or humid continental climate. Wildland fires increased annual river flow most in the semi-arid Lower Colorado region, in spite of frequent droughts in this region. In contrast, prescribed burns in the subtropical Southeast did not significantly alter river flow. These extremely variable outcomes offer new insights into the potential role of wildfire and prescribed fire in regional water resource management, under a changing climate.

Concepts: United States, Precipitation, Climate, Freshwater, Water resources, Oceanic climate, Water crisis, Wildfire

28

In the last decade, more than 22 million ha of land have been contracted to large-scale land acquisitions in Africa, leading to increased pressures, competition, and conflicts over freshwater resources. Currently, 3% of contracted land is in production, for which we model site-specific water demands to indicate where freshwater appropriation might pose high socioenvironmental challenges. We use the dynamic global vegetation model Lund-Potsdam-Jena managed Land to simulate green (precipitation stored in soils and consumed by plants through evapotranspiration) and blue (extracted from rivers, lakes, aquifers, and dams) water demand and crop yields for seven irrigation scenarios, and compare these data with two baseline scenarios of staple crops representing previous water demand. We find that most land acquisitions are planted with crops that demand large volumes of water (>9,000 m(3)⋅ha(-1)) like sugarcane, jatropha, and eucalyptus, and that staple crops have lower water requirements (<7,000 m(3)⋅ha(-1)). Blue water demand varies with irrigation system, crop choice, and climate. Even if the most efficient irrigation systems were implemented, 18% of the land acquisitions, totaling 91,000 ha, would still require more than 50% of water from blue water sources. These hotspots indicate areas at risk for transgressing regional constraints for freshwater use as a result of overconsumption of blue water, where socioenvironmental systems might face increased conflicts and tensions over water resources.

Concepts: Agriculture, Water, Aquifer, Groundwater, Irrigation, Freshwater, Water resources, Deficit irrigation

24

Furunculosis, a septicaemic infection caused by the bacterium Aeromonas salmonicida subsp. salmonicida, currently causes problems in Danish seawater rainbow trout production. Detection has mainly been achieved by bacterial culture, but more rapid and sensitive methods are needed. A previously developed real-time PCR assay targeting the plasmid encoded aopP gene of A. salmonicida was, in parallel with culturing, used for the examination of five organs of 40 fish from Danish freshwater and seawater farms. Real-time PCR showed overall a higher frequency of positives than culturing (65% of positive fish by real-time PCR compared to 30% by a culture approach). Also, no real-time PCR-negative samples were found positive by culturing. A. salmonicida was detected by real-time PCR, though not by culturing, in freshwater fish showing no signs of furunculosis, indicating possible presence of carrier fish. In seawater fish examined after an outbreak and antibiotics treatment, real-time PCR showed the presence of the bacterium in all examined organs (1-482 genomic units mg(-1) ). With a limit of detection of 40 target copies (1-2 genomic units) per reaction, a high reproducibility and an excellent efficiency, the present real-time PCR assay provides a sensitive tool for the detection of A. salmonicida.

Concepts: DNA, Gene, Bacteria, Polymerase chain reaction, Molecular biology, Genome, Freshwater, Aeromonas salmonicida

24

The main goal of the present study was to investigate the effects of acute exposure to copper (Cu) using a Neotropical freshwater fish as sentinel species through multi biomarkers analysis at different biological levels. Juveniles of Prochilodus lineatus were kept under control condition (no Cu addition in the water) or exposed to environmentally relevant concentrations of waterborne Cu (5, 9 and 20μgL(-1)) for 96h. These concentrations were selected to bracket the current Brazilian water quality criteria for Cu in fresh water (9 and 13μgL(-1) dissolved copper). Endpoints analyzed included ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity, reduced glutathione (GSH) and metallothionein-like protein (MT) concentration, lipid peroxidation (LPO) level, tissue damage index, and incidence of free melano-macrophages (FMM) and melano-macrophage centers (MMC) in the liver. They also included DNA damage (frequency of nucleoids per comet class, number of damaged nucleoids per fish and DNA damage score) in erythrocytes, as well as muscle and brain acetylcholinesterase (AChE) activity and behavioral parameters (swimming distance and velocity, time spent swimming and swimming activity in the upper and lower layers of the water column). Fish exposed to any of the Cu concentrations tested showed increased liver MT concentration and LPO level, higher number of damaged nucleoids in erythrocytes per fish, and inhibited muscle AChE activity. Also, increased liver SOD activity was observed in fish exposed to 9 and 20μgL(-1) Cu. Fish exposed to 5 and 9μgL(-1) Cu spent lower amount of time swimming. Fish exposed to 9μgL(-1) Cu showed increased swimming distance and velocity while those exposed to 20μgL(-1) Cu had lower swimming distance and velocity, as well as, spent less time swimming in the lower layer of the water column when compared to those kept under control condition. These findings indicate that Cu exposure at environmentally relevant concentrations (below or close to the current Brazilian water quality criteria) induced significant biological (histological, biochemical and genetic) and ecological (swimming and exploratory abilities) damages in the Neotropical fish P. lineatus. They also suggest that MT concentration, DNA damage (comet assay), LPO (TBARS method), SOD and AChE activity, together with swimming behavior analyses are potential biomarkers to assess and monitor areas impacted by Cu in fresh water.

Concepts: DNA, Antioxidant, Reactive oxygen species, Superoxide dismutase, Liver, Glutathione, Glutathione peroxidase, Freshwater

23

The aim of the study was to monitor seasonal changes in stable isotopes of pool freshwater, and harp seal (Phoca groenlandica) body water, and to study if these potential seasonal changes might bias results of using the doubly labeled water (DLW) method when measuring energy expenditure in animals with access to fresh water. Seasonal changes in the background levels of deuterium and oxygen-18 in the body water of four captive harp seals and in the freshwater pool in which they were kept, were measured over a time period of one year. The seals were offered daily amounts of capelin and kept under a seasonal photoperiod of 69° N. Large seasonal variations of deuterium and oxygen-18 in the pool water was measured, and the isotope abundance in body water showed similar seasonal changes as the pool water. This shows that the seals were continuously equilibrating with surrounding water due to significant daily water drinking.Variations in background levels of deuterium and oxygen-18 in freshwater sources may be due to seasonal changes in physical processes such as precipitation and evaporation that may cause fractionation of isotopes. Rapid and abrupt changes in the background levels of deuterium and oxygen-18 may complicate calculation of energy expenditure by use of the DLW method. It is therefore strongly recommended to perform analysis of seasonal changes in background levels of isotopes before the DLW method is applied on (free-ranging) animals, and to use a control group in order to correct for changes in background levels.

Concepts: Oxygen, Water, Atom, Seawater, Freshwater, Water resources, Isotopes, Harp Seal

22

Mosses are well known as biomonitors of fresh water for metal pollutants, but no studies were reported so far about their ability to intercept plastic particles, although this kind of pollution has become an urgent issue worldwide. In the present work, the interaction between the moss Sphagnum palustre L. cultured in vitro and polystyrene nanoparticles (NPs) was studied for the first time in a laboratory experiment, in the view of using moss transplants for detecting microplastics in fresh water environments. The ability of S. palustre to intercept and retain polystyrene, and the effects of vitality and post-exposure washing on NP retention by moss were tested. Fluorescence microscope observations showed that polystyrene NPs were retained by moss leaves in form of small (the most abundant fraction) and large aggregates. Particle count analysis highlighted that the number of particles increased while increasing the exposure time. Moreover, moss devitalization favored NP accumulation, likely because of cell membrane damages occurred in dead moss material. Post-exposure washing induced a loss of larger aggregates, suggesting that exposure time is a key point to be carefully evaluated in field conditions. These results encourage the use of S. palustre transplants for monitoring microplastics contamination of fresh water environments.

Concepts: Environment, Plant, Freshwater, Moss, Shutter speed, Sphagnum, Sphagnopsida, Fresh Water

22

The growing geographic disconnect between consumption of goods, the extraction and processing of resources, and the environmental impacts associated with production activities makes it crucial to factor global trade into sustainability assessments. Using an empirically validated environmentally extended global trade model, we examine the relationship between two key resources underpinning economies and human well-being-energy and freshwater. A comparison of three energy sectors (petroleum, gas, and electricity) reveals that freshwater consumption associated with gas and electricity production is largely confined within the territorial boundaries where demand originates. This finding contrasts with petroleum, which exhibits a varying ratio of territorial to international freshwater consumption, depending on the origin of demand. For example, although the United States and China have similar demand associated with the petroleum sector, international freshwater consumption is three times higher for the former than the latter. Based on mapping patterns of freshwater consumption associated with energy sectors at subnational scales, our analysis also reveals concordance between pressure on freshwater resources associated with energy production and freshwater scarcity in a number of river basins globally. These energy-driven pressures on freshwater resources in areas distant from the origin of energy demand complicate the design of policy to ensure security of fresh water and energy supply. Although much of the debate around energy is focused on greenhouse gas emissions, our findings highlight the need to consider the full range of consequences of energy production when designing policy.

Concepts: Natural gas, Freshwater, Coal, Peak oil, Nuclear power, Globalization, Greenhouse gas, World energy resources and consumption

11

Societal pressure on the global land and freshwater resources is increasing as a result of the rising food demand by the growing human population, dietary changes, and the enhancement of biofuel production induced by the rising oil prices and recent changes in United States and European Union bioethanol policies. Many countries and corporations have started to acquire relatively inexpensive and productive agricultural land located in foreign countries, as evidenced by the dramatic increase in the number of transnational land deals between 2005 and 2009. Often known as “land grabbing,” this phenomenon is associated with an appropriation of freshwater resources that has never been assessed before. Here we gather land-grabbing data from multiple sources and use a hydrological model to determine the associated rates of freshwater grabbing. We find that land and water grabbing are occurring at alarming rates in all continents except Antarctica. The per capita volume of grabbed water often exceeds the water requirements for a balanced diet and would be sufficient to improve food security and abate malnourishment in the grabbed countries. It is found that about 0.31 × 10(12) m(3)⋅y(-1) of green water (i.e., rainwater) and up to 0.14 × 10(12) m(3)⋅y(-1) of blue water (i.e., irrigation water) are appropriated globally for crop and livestock production in 47 × 10(6) ha of grabbed land worldwide (i.e., in 90% of the reported global grabbed land).

Concepts: Agriculture, Water, Hydrology, Water cycle, Irrigation, Freshwater, Water resources, World population