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81-401: In modern times the lake has been reported to have a surface area of 130 km (50 sq mi), although it dries out periodically. It is very shallow, not exceeding 3.7 m (12 ft) in depth. There are two small islands near the lake's southeastern shore, Loya ghundai (2,500 m [27,000 sq ft]) and Kuchney ghundai (500 m [5,400 sq ft]). The water

162-736: A body of water leads to oxygen depletion as microorganisms use up available oxygen in the process of breaking down organic matter . For example, a 10 miles (16 km) fish kill in September, 2010, in the Sangamon River in Illinois was traced to discharge of animal waste into the river from a large dairy operation. The illegal discharge resulted in a complete kill of fish, frogs, mussels and mudpuppies . Excessive anthropogenic nutrient enrichment of phosphorus and nitrogen allow for rapid growth and multiplication of phytoplankton in

243-456: A breakdown or design fault in the sanitation system, or by chemical contaminants. Further examples of contamination include: Examples of chemical contamination include: Most water requires some treatment before use; even water from deep wells or springs. The extent of treatment depends on the source of the water. Appropriate technology options in water treatment include both community-scale and household-scale point-of-use (POU) designs. Only

324-452: A chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens. Pesticides are also potential drinking water contaminants of the category chemical contaminants . Pesticides may be present in drinking water in low concentrations, but

405-566: A component of effective policy for health protection." In 1990, only 76 percent of the global population had access to drinking water. By 2015 that number had increased to 91 percent. In 1990, most countries in Latin America, East and South Asia, and Sub-Saharan Africa were well below 90%. In Sub-Saharan Africa, where the rates are lowest, household access ranges from 40 to 80 percent. Countries that experience violent conflict can have reductions in drinking water access: One study found that

486-523: A conflict with about 2,500 battle deaths deprives 1.8% of the population of potable water. Typically in developed countries , tap water meets drinking water quality standards , even though only a small proportion is actually consumed or used in food preparation. Other typical uses for tap water include washing, toilets, and irrigation . Greywater may also be used for toilets or irrigation. Its use for irrigation however may be associated with risks. Globally, by 2015, 89% of people had access to water from

567-586: A farmer might plan for 35 U.S. gallons (130 L) per day for a dairy cow , a third of that for a horse , and a tenth of that for a hog . However, relatively few studies have been focused on the drinking behavior of wild animals. According to the World Health Organization's 2017 report, safe drinking water is water that "does not represent any significant risk to health over a lifetime of consumption, including different sensitivities that may occur between life stages". According to

648-421: A few large urban areas such as Christchurch , New Zealand have access to sufficiently pure water of sufficient volume that no treatment of the raw water is required. In emergency situations when conventional treatment systems have been compromised, waterborne pathogens may be killed or inactivated by boiling but this requires abundant sources of fuel, and can be very onerous on consumers, especially where it

729-469: A fish native to a more tropical region has been introduced to cooler waters, such as the introduction of the tilapia to bodies of water in Florida. Native to Africa's Nile River , the tilapia stop feeding when water temperatures drop below 60 °F (16 °C) and die when it reaches 45 °F (7 °C). Thus, tilapia that have survived and successfully reproduced in Florida are occasionally killed by

810-486: A generally illegal practice known as blast fishing . Underwater explosions may be accidental or planned, such as for construction, seismic testing , mining or blast testing of structures under water. In many places, an assessment of potential effects of underwater explosions on marine life must be completed and preventive measures taken before blasting. Droughts and overstocking can also result in inland fish kills. A drought can lead to lower water volumes so that even if

891-400: A localized mass die-off of fish populations which may also be associated with more generalized mortality of aquatic life. The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought , harmful algal bloom , overpopulation , or a sustained increase in water temperature. Infectious diseases and parasites can also lead to fish kill. Toxicity is

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972-596: A maximum of 8 mg/L of oxygen can dissolve in sea water (35 mg/L salinity ) while a maximum of 9 mg/L of oxygen can dissolve in fresh water. The amount of oxygen that can be dissolved in the water decreases by about 1 mg/L for each 10 °C increase in water temperature above 20 °C. Many cold water fish that live in clean cold waters become stressed when oxygen concentrations fall below 8 mg/L while warm water fish generally need at least 5 ppm (5 mg/L) of dissolved oxygen. Fish can endure short periods of reduced oxygen. Depleted oxygen levels are

1053-777: A negative effect on child development (both physical and cognitive). Sixty million people are estimated to have been poisoned by well water contaminated by excessive fluoride , which dissolved from granite rocks. The effects are particularly evident in the bone deformations of children. Similar or larger problems are anticipated in other countries including China, Uzbekistan, and Ethiopia. Although helpful for dental health in low dosage, fluoride in large amounts interferes with bone formation. Long-term consumption of water with high fluoride concentration (> 1.5 ppm F) can have serious undesirable consequences such as dental fluorosis , enamel mottle and skeletal fluorosis , bone deformities in children. Fluorosis severity depends on how much fluoride

1134-452: A normally stable aquatic population. Because of the difficulty and lack of standard protocol to investigate fish kills, many fish kill cases are designated as having an unknown cause. Oxygen enters the water through diffusion . The amount of oxygen that can be dissolved in water depends on the atmospheric pressure , the water temperature and whether the water is salty. For example, at 20 °C (68 °F) and one atmosphere of pressure,

1215-399: A real but far less common cause of fish kill, and is often associated with man-made water pollution . Fish kills are often the first visible signs of environmental stress and are usually investigated as a matter of urgency by environmental agencies to determine the cause of the kill. Many fish species have a relatively low tolerance of variations in environmental conditions and their death

1296-451: A report by UNICEF and UNESCO , Finland has the best drinking water quality in the world. Parameters for drinking water quality typically fall within three categories: microbiological, chemical, physical. Microbiological parameters include coliform bacteria , E. coli , and specific pathogenic species of bacteria (such as cholera -causing Vibrio cholerae ), viruses , and protozoan parasites . Originally, fecal contamination

1377-578: A source that is suitable for drinking – called improved water source  – and 71% of the world could access safely managed drinking water that is clean and available on-demand. Estimates suggest that at least 25% of improved sources contain fecal contamination. 1.8 billion people still use an unsafe drinking water source which may be contaminated by feces . This can result in infectious diseases , such as gastroenteritis , cholera , and typhoid , among others. Reduction of waterborne diseases and development of safe water resources

1458-481: A source that is suitable for drinking – called improved water sources . In sub-Saharan Africa , access to potable water ranged from 40% to 80% of the population. Nearly 4.2 billion people worldwide had access to tap water, while another 2.4 billion had access to wells or public taps. By 2015, 5.2 billion people representing 71% of the global population used safely managed drinking water services. As of 2017, 90% of people having access to water from

1539-458: A spilled substance causes direct toxicity or a shift in water temperature or pH that can lead to fish kill. For example, in 1997 a phosphate plant in Mulberry, Florida , accidentally dumped 60 million US gal (0.23 million kl) of acidic process water into Skinned Sapling Creek, reducing the pH from about 8 to less than 4 along 36 miles (58 km) of creek, resulting in

1620-592: A winter cold front. In January, 2011, a selective fish kill affecting an estimated 2 million juvenile spot fish was attributed to a combination of cold stress and overpopulation after a particularly large spawn. "Hundreds of thousands" of fish were found dead in Texas in June 2023 due to warming water. Underwater explosions can lead to fish kill, and fish with swim bladders are more susceptible. Sometimes underwater explosions are used on purpose to induce fish kills,

1701-493: A year. Leakage of untreated and treated water from pipes reduces access to water. Leakage rates of 50% are not uncommon in urban systems. Tap water , delivered by domestic water systems refers to water piped to homes and delivered to a tap or spigot. In the United States, the typical water consumption per capita, at home, is 69.3 US gallons (262 L; 57.7 imp gal) of water per day. Of this, only 1% of

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1782-517: Is WASH - standing for water, sanitation and hygiene . The WHO has investigated which proportion of death and disease worldwide can be attributed to insufficient WASH services. In their analysis they focus on the following four health outcomes: diarrhea , acute respiratory infections , malnutrition , and soil-transmitted Helminthiasis (STHs). These health outcomes are also included as an indicator for achieving Sustainable Development Goal 3 ("Good Health and Well-being"): Indicator 3.9.2 reports on

1863-419: Is atmospheric water generators . Springs are often used as sources for bottled waters . The most efficient and convenient way to transport and deliver potable water is through pipes. Plumbing can require significant capital investment. Some systems suffer high operating costs. The cost to replace the deteriorating water and sanitation infrastructure of industrialized countries may be as high as $ 200 billion

1944-436: Is a major public health goal in developing countries. In 2017, almost 22 million Americans drank from water systems that were in violation of public health standards, which could contribute to citizens developing water-borne illnesses . Safe drinking water is an environmental health concern. Bottled water is sold for public consumption in most parts of the world. Improved sources are also monitored based on whether water

2025-793: Is a matching pH rhythm as bicarbonate ion is metabolised by plant cells. This can lead to pH stress even when oxygen levels are high. Additional dissolved organic loads are the most common cause of oxygen depletion and such organic loads may come from sewage, farm waste, tip/landfill leachate and many other sources. Fish are subject to various viruses , bacteria and fungi in addition to parasites such as protozoans , flukes and worms, or crustaceans. These are naturally occurring in many bodies of water, and fish that are stressed for other reasons, such as spawning or suboptimal water quality, are more susceptible. Signs of disease include sores, missing scales or lack of slime, strange growths or visible parasites, and abnormal behavior–lazy, erratic, gasping at

2106-526: Is available in almost all populated areas of the world, although it may be expensive, and the supply may not always be sustainable. Sources where drinking water is commonly obtained include springs , hyporheic zones and aquifers ( groundwater ), from rainwater harvesting , surface water (from rivers, streams, glaciers ), or desalinated seawater . For these water sources to be consumed safely, they must receive adequate water treatment and meet drinking water quality standards . An experimental source

2187-658: Is available when needed (5.8 billion people), located on premises (5.4 billion), free from contamination (5.4 billion), and within a 30-minute round trip. While improved water sources such as protected piped water are more likely to provide safe and adequate water as they may prevent contact with human excreta, for example, this is not always the case. According to a 2014 study, approximately 25% of improved sources contained fecal contamination. The population in Australia, New Zealand, North America and Europe have achieved nearly universal basic drinking water services. Because of

2268-647: Is called desalination and is used mainly in dry areas with access to large bodies of saltwater. Publicly available treated water has historically been associated with major increases in life expectancy and improved public health . Water disinfection can greatly reduce the risks of waterborne diseases such as typhoid and cholera . Chlorination is currently the most widely used water disinfection method, although chlorine compounds can react with substances in water and produce disinfection by-products (DBP) that pose problems to human health. Local geological conditions affecting groundwater are determining factors for

2349-449: Is defined as the measure of water clarity by how much the suspended material, such as algae and phytoplankton, constrict the passage of sunlight through water. Hence, as phytoplankton begin to multiply more rapidly, turbidity in the river and gulf increases. The increasing turbidity blocks plants from absorbing sunlight. The process of turbidity results in limited photosynthesis production, and sometimes even death from sunlight deprivation of

2430-427: Is difficult to store boiled water in sterile conditions. Other techniques, such as filtration, chemical disinfection, and exposure to ultraviolet radiation (including solar UV) have been demonstrated in an array of randomized control trials to significantly reduce levels of water-borne disease among users in low-income countries, but these suffer from the same problems as boiling methods. Another type of water treatment

2511-658: Is highly alkaline and mass die-offs of freshwater fish from the Ghazni River sometimes occur. The main inflows into Ab-i Istada are the Ghazni, Sardeh and Nahara Rivers, which drain into it from the northeast. The watershed draining into the lake covers 17,252 km (6,661 sq mi) and was home to over 1.8 million people in 2003. Three sets of raised beaches surrounding the lake have been noted at 2–3 m (6 ft 7 in – 9 ft 10 in), 6–7 m (20–23 ft) and 9–10 m (30–33 ft) above

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2592-752: Is in full motion, a dead zone has been created. As a result of the excess nutrient enrichment in the Mississippi River, dead zones appear in the Gulf of Mexico, created from the process of eutrophication. The dead zones in the gulf are mainly created by the nitrogen and phosphorus enrichment of the Lower Mississippi River. Some species of fish exhibit mass simultaneous mortality as part of their natural life cycle. Fish kill due to spawning fatalities can occur when fish are exhausted from spawning activities such as courtship, nest building, and

2673-650: Is often (but not always) supplied through taps, in which case it is also called tap water . The amount of drinking water required to maintain good health varies, and depends on physical activity level, age, health-related issues, and environmental conditions. For those who work in a hot climate, up to 16 litres (4.2 US gal) a day may be required. About 1 to 2 billion people lack safe drinking water. Water can carry vectors of disease . More people die from unsafe water than from war, then- U.N. secretary-general Ban Ki-moon said in 2010. Developing countries are most affected by unsafe drinking water. Potable water

2754-418: Is often a potent indicator of problems in their environment that may be affecting other animals and plants and may have a direct impact on other uses of the water such as for drinking water production. Pollution events may affect fish species and fish age classes in different ways. If it is a cold-related fish kill, juvenile fish or species that are not cold-tolerant may be selectively affected. If toxicity

2835-496: Is one of the most common natural causes of fish kills. The suffocating event may be brought on by factors such as algae blooms , droughts, high temperatures and thermal pollution . Fish kills may also occur due to the presence of disease, agricultural runoff , sewage discharges, oil or hazardous waste spills, hydraulic fracturing wastewater, sea-quakes , inappropriate re-stocking of fish, poaching with chemicals, underwater explosions , and other catastrophic events that upset

2916-513: Is present in the water, as well as people's diet and physical activity. Defluoridation methods include membrane-based methods, precipitation, absorption, and electrocoagulation. Natural arsenic contamination of groundwater is a global threat with 140 million people affected in 70 countries globally. Some well-known examples of water quality problems with drinking water supplies include: Water supply can get contaminated by pathogens which may originate from human excreta , for example due to

2997-416: Is the appearance of a large amount of algae or scum floating on the surface of a body of water. Algae blooms are a natural occurrence in nutrient-rich lakes and rivers, though sometimes increased nutrient levels leading to algae blooms are due to fertilizer or animal waste runoff . A few species of algae produce toxins , but most fish kills due to algae bloom are a result of decreased oxygen levels. When

3078-485: Is the cause, species are more generally affected and the event may include amphibians and shellfish as well. A reduction in dissolved oxygen may affect larger specimens more than smaller fish as these may be able to access oxygen richer water at the surface, at least for a short time. Fish kills may result from a variety of causes. Of known causes, fish kills are most frequently caused by pollution from agricultural runoff or biotoxins. Ecological hypoxia (oxygen depletion)

3159-458: Is to reach large numbers of low-income households on a sustainable basis. Few POU measures have reached significant scale thus far, but efforts to promote and commercially distribute these products to the world's poor have only been under way for a few years. Solar water disinfection is a low-cost method of purifying water that can often be implemented with locally available materials. Unlike methods that rely on firewood , it has low impact on

3240-671: The European Drinking Water Directive and in the United States, the United States Environmental Protection Agency (EPA) establishes standards as required by the Safe Drinking Water Act . China adopted its own drinking water standard GB3838-2002 (Type II) enacted by Ministry of Environmental Protection in 2002. For countries without a legislative or administrative framework for such standards,

3321-593: The Mississippi River . As phytoplankton continue to rapidly grow under optimal conditions, their biomass is almost doubled every 24 hours. In the water, higher concentrations of organic matter are present because of the high reproductive rate of the phytoplankton over a short period of time. The rapid growth of phytoplankton causes turbidity in the waters of the Mississippi and the Gulf of Mexico . Turbidity

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3402-598: The Soviet invasion in 1979 and have not been restarted since. A 27,000 ha area, encompassing the lake and its immediate surrounds, has been designated an Important Bird Area (IBA) by BirdLife International because it supports populations of greylag geese , common pochards , greater flamingos , Siberian cranes , grey herons , great white pelicans , black-winged stilts , Kentish plovers , slender-billed gulls and gull-billed terns . Fish kill The term fish kill , known also as fish die-off , refers to

3483-528: The World Health Organization publishes guidelines on the standards that should be achieved. The World Health Organization considers access to safe drinking-water a basic human right. Contaminated water is estimated to result in more than half a million deaths per year. Contaminated water together with the lack of sanitation was estimated to cause about one percent of disability adjusted life years worldwide in 2010. According to

3564-442: The layers can mix . If the volume of low oxygen water is much greater than the volume in the warm surface layer, this mixing can reduce oxygen levels throughout the water column and lead to fish kill. Fish kills can also result from a dramatic or prolonged drop in air (and thus, water) temperature. This kind of fish kill is selective – usually the dead fish are species that cannot tolerate cold. This has been observed in cases where

3645-692: The toxicity of the chemical and the extent of human exposure are factors that are used to determine the specific health risk. Perfluorinated alkylated substances (PFAS) are a group of synthetic compounds used in a large variety of consumer products, such as food packaging , waterproof fabrics, carpeting and cookware. PFAS are known to persist in the environment and are commonly described as persistent organic pollutants . PFAS chemicals have been detected in blood, both humans and animals, worldwide, as well as in food products, water, air and soil. Animal testing studies with PFAS have shown effects on growth and development, and possibly effects on reproduction, thyroid,

3726-567: The "mortality rate attributed to unsafe water, sanitation, and lack of hygiene". Diarrhea is primarily transmitted through fecal–oral routes . In 2011, infectious diarrhea resulted in about 0.7 million deaths in children under five years old and 250 million lost school days. This equates to about 2000 child deaths per day. Children suffering from diarrhea are more vulnerable to become underweight (due to stunted growth ). This makes them more vulnerable to other diseases such as acute respiratory infections and malaria . Chronic diarrhea can have

3807-414: The 1950s were due to a pesticide called endrin . Natural instances of toxic conditions can occur, especially in poorly buffered water. Aluminium compounds can cause complete fish kills, sometimes associated with autumn turn-over of lakes leading to complex chemical interactions between pH, calcium ions and complex polymeric salts of aluminium. Human-induced fish kills are unusual, but occasionally

3888-427: The United States, particularly in the Gulf of Maine . This type of bloom is caused by another species of dinoflagellate known as Alexandrium fundyense . These blooms are natural phenomena, but the exact combination of factors that result in red tide outbreaks is not fully understood. Just as an algae bloom can lead to oxygen depletion, introduction of a large amount of decaying biological material in general to

3969-510: The WHO, the most common diseases linked with poor water quality are cholera , diarrhea , dysentery , hepatitis A , typhoid , and polio . One of the main causes for contaminated drinking water in developing countries is lack of sanitation and poor hygiene. For this reason, the quantification of the burden of disease from consuming contaminated drinking water usually looks at water, sanitation and hygiene aspects together. The acronym for this

4050-491: The algae die, decomposition uses oxygen in the water that would be available to fish. A fish kill in a lake in Estonia in 2002 was attributed to a combination of algae bloom and high temperatures. When people manage algae blooms in fish ponds , it is recommended that treatments be staggered to avoid too much algae dying at once, which may result in a large drop in oxygen content. Some diseases result in mass die-offs. One of

4131-409: The area and its problems. The counts given below are all estimates. They tend to be underestimates, and may omit, for example, small fish, those removed by scavengers and those that settle to the bottom. Drinking water Drinking water or potable water is water that is safe for ingestion , either when drunk directly in liquid form or consumed indirectly through food preparation . It

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4212-850: The available resources, parasites or disease can spread quickly. In channel catfish aquaculture ponds , for example, the "hamburger gill disease" is caused by a protozoan called Aurantiactinomyxon and can kill all the fish in an affected pond. In addition to altered behavior, affected fish have swollen gills that are mottled and have the appearance of ground hamburger meat. Some early warning signs of fish suffering from disease or parasite infections include: Agricultural runoff , sewage , surface runoff , chemical spills and hazardous waste spills can all potentially lead to water toxicity and fish kill. Some algae species also produce toxins. In Florida, these include Aphanizomenon , Anabaena and Microcystis . Some notable fish kills in Louisiana in

4293-534: The dead phytoplankton accumulate, detritus, or organic matter waste, forms at the surface along with other bacteria and algae. As more phytoplankton die, the higher the concentration of organic matter becomes; and with a higher concentration of organic matter, more bacteria will reproduce. Consequently, as more bacteria, phytoplankton, and algae exponentially grow and multiply, the more submerged aquatic vegetation die, because they do not have access to sunlight due to eutrophication. Once this snowball-like course of action

4374-546: The death of about 1.3 million fish. It is often difficult or impossible to determine whether a potential toxin is the direct cause of a fish kill. For example, hundreds of thousands of fish died after an accidental spill of bourbon whiskey into the Kentucky River near Lawrenceburg . However, officials could not determine whether the fish kill was due to the bourbon directly or to oxygen depletion that resulted when aquatic microbes rapidly began to consume and digest

4455-410: The developed world have specific provisions in place to encourage the public to report fish kills so that a proper investigation can take place. Investigation of the cause of a kill requires a multi-disciplinary approach including on-site environmental measurements , investigation of inputs, review of meteorology and past history, toxicology, fish autopsy, invertebrate analysis and a robust knowledge of

4536-404: The environment. In many areas, low concentration of fluoride (< 1.0 ppm F) is intentionally added to tap water to improve dental health , although in some communities water fluoridation remains a controversial issue. (See water fluoridation controversy ). According to the World Health Organization (WHO), "access to safe drinking-water is essential to health, a basic human right and

4617-403: The fish remain in the area, continuing to provide nourishment, then the zoospores start secreting a neurotoxin . This toxin results in the fish developing bleeding lesions, and their skin flakes off in the water. The dinoflagellates then eat the blood and flakes of tissue while the affected fish die. Fish kills by this dinoflagellate are common, and they may also have been responsible for kills in

4698-535: The high initial investments, many less wealthy nations cannot afford to develop or sustain appropriate infrastructure, and as a consequence people in these areas may spend a correspondingly higher fraction of their income on water. 2003 statistics from El Salvador, for example, indicate that the poorest 20% of households spend more than 10% of their total income on water. In the United Kingdom, authorities define spending of more than 3% of one's income on water as

4779-402: The immune system and liver. As of 2022 the health impacts of many PFAS compounds are not understood. Scientists are conducting research to determine the extent and severity of impacts from PFAS on human health. PFAS have been widely detected in drinking water worldwide and regulations have been developed, or are under development, in many countries. Drinking water quality standards describes

4860-461: The lake; their numbers in recent years have varied between 0 and 9000. The wetlands were once a critical stopover for the central migratory population of Siberian cranes , but these have not been sighted at the lake since 1986. In 1974, the Afghani government proclaimed a Waterfowl and Flamingo Sanctuary around the lake, causing considerable resentment among the locals; conservation efforts ended with

4941-421: The liquor. Cyanide is a particular toxic compound that has been used to poach fish . In cyanide poisoning the gills turn a distinctive cherry red. Chlorine introduced as alkaline hypochlorite solution is also extremely toxic, leaving pale mucilaginous gills and an over-production of mucilage across the whole body. Lime produces similar symptoms but is also often associated with milk eyes. An algae bloom

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5022-556: The magnitude of a kill presents a number of problems. Some very large fish kills may never be estimated because of these factors. The discharge of red aluminium sludge from a reservoir in Hungary into the Marcai River is acknowledged as causing environmental devastation, The loss of adult fish also can have long-term impacts on the success of the fishery as the following year's spawning stock may have been lost and recovery of

5103-420: The matter is resolved. The ability of point of use (POU) options to reduce disease is a function of both their ability to remove microbial pathogens if properly applied and such social factors as ease of use and cultural appropriateness. Technologies may generate more (or less) health benefit than their lab-based microbial removal performance would suggest. The current priority of the proponents of POU treatment

5184-419: The more bizarre and recently discovered diseases produces huge fish kills in shallow marine waters. It is caused by the ambush predator dinoflagellate Pfiesteria piscicida . When large numbers of fish, like shoaling forage fish , are in confined situations such as shallow bays, the excretions from the fish encourage this dinoflagellate, which is not normally toxic, to produce free-swimming zoospores . If

5265-518: The most common cause of fish kills. Oxygen levels normally fluctuate even over the course of a day and are affected by weather, temperature, the amount of sunlight available, and the amount of living and dead plant and animal matter in the water. In temperate zones oxygen levels in eutrophic rivers in summertime can exhibit very large diurnal fluctuations with many hours of oxygen supersaturation during daylight followed by oxygen depletion at night. Associated with these photosynthetic rhythms there

5346-582: The normal lake level. At high water levels, the lake is known to overflow into the Lora River , a tributary of the Arghistan River , through two channels on the south side of the lake, Akasi Mandeh and Sekva Mandeh. A groundwater connection between the lake and the Lora drainage has been suggested. Historically the area around the lake was unpopulated, although nomads from nearby regions visited it in

5427-443: The oxygen concentration available to fish Overstocking of fish (or an unusually large spawn ) can also result in inland fish kills. Fish kill due to insufficient oxygen is really a matter of too much demand and too little supply for whatever reason(s). Recommended stocking densities are available from many sources for bodies of water ranging from a home aquarium or backyard pond to commercial aquaculture facilities. Estimating

5508-460: The past which were thought to have had other causes. Kills like these can be viewed as natural mechanisms for regulating the population of exceptionally abundant fish. The rate at which the kills occur increases as organically polluted land runoff increases. Red tide is the name commonly given to an algal bloom of Karenia brevis , a microscopic marine dinoflagellate which is common in Gulf of Mexico waters. In high concentrations it discolors

5589-632: The potential to hold more oxygen, so a period of sustained high temperatures can lead to decreased dissolved oxygen in a body of water. An August 2010 fish kill in Delaware Bay was attributed to low oxygen as a result of high temperatures. A massive (hundreds of thousands) fish kill at the mouth of the Mississippi River in Louisiana , September, 2010, was attributed to a combination of high temperatures and low tide. Such kills are known to happen in this region in late summer and early fall, but this one

5670-533: The pre-kill population may take years. The loss of food supplies or recreational income may be very significant to the local economy. Fish kills are difficult to predict. Even when conditions that contribute to fish kill are known to exist, prevention is hard because often conditions cannot be improved and fish cannot be safely removed in time. In small ponds, mechanical aeration and/or removal of decaying matter (such as fallen leaves or dead algae) may be reasonable and effective preventive measures. Many countries in

5751-487: The presence of various metal ions , often rendering the water " soft " or " hard ". In the event of contamination of drinking water, government officials typically issue an advisory regarding water consumption. In the case of biological contamination , residents are usually advised to boil their water before consumption or to use bottled water as an alternative. In the case of chemical contamination , residents may be advised to refrain from consuming tap water entirely until

5832-443: The quality parameters set for drinking water. Water may contain many harmful constituents , yet there are no universally recognized and accepted international standards for drinking water. Even where standards do exist, the permitted concentration of individual constituents may vary by as much as ten times from one set of standards to another. Many countries specify standards to be applied in their own country. In Europe, this includes

5913-517: The release of eggs or milt (sperm). Fish are generally weaker after spawning and are less resilient than usual to smaller changes in the environment. Examples include the Atlantic salmon and the Sockeye salmon where many of the females routinely die immediately after spawning. A fish kill can occur with rapid fluctuations in temperature or sustained high temperatures. Generally, cooler water has

5994-449: The submerged aquatic vegetation that are affected by the opaque turbid water accumulating at the surface. Furthermore, a significant detrimental outcome caused by eutrophication in the Mississippi River is the increased uptake of dissolved oxygen by bacteria, in response to higher concentrations of organic matter. After eutrophication starts and is in progress, the phytoplankton reach their maximum population density and begin to die. As

6075-547: The summer. More recently, the Tarakai have settled near the lake: in 2003 there were eight villages within 10 km (6.2 mi) with a total population of approximately 5000. Economic activities around the lake include trapping of saker and peregrine falcons , grazing and collection of fuel wood. The wetlands around Ab-i Istada attract a variety of migratory birds, over 120 species having previously been recorded. Babur observed enormous flocks of greater flamingoes at

6156-442: The water contains a high level of dissolved oxygen, the reduced volume may not be enough for the fish population. Droughts often occur in conjunction with high temperatures so that the oxygen carrying capacity of the water may also be reduced. Low river flows also reduce the available dilution for permitted discharges of treated sewage or industrial waste . The reduced dilution increases the organic demand for oxygen further reducing

6237-437: The water provided by public water suppliers is for drinking and cooking. Uses include (in decreasing order) toilets, washing machines, showers, baths, faucets, and leaks. As of 2015, American households use an average of 300 gallons of water a day. The qualitative and quantitative aspects of drinking water requirements on domesticated animals are studied and described within the context of animal husbandry . For example,

6318-498: The water surface or floating head, tail or belly up. For example, since 2004 fish kills have been observed in the Shenandoah River basin in the spring, from the time water temperatures are in the 50s (°F) until they reach the mid-70s. So far, investigators suspect certain bacteria, along with environmental and contaminant factors that may cause immune suppression . In fish farming , where populations are optimized for

6399-425: The water which often appears reddish-brown in color. It produces a toxin which paralyses the central nervous system of fish so they cannot breathe. Dead fish wash up on beaches around Texas and Florida. Humans can also become seriously ill from eating oysters and other shellfish contaminated with the red tide toxin. The term "red tide" is also commonly used to describe harmful algal blooms on the northern east coast of

6480-658: Was determined with the presence of coliform bacteria , a convenient marker for a class of harmful fecal pathogens . The presence of fecal coliforms (like E. Coli ) serves as an indication of contamination by sewage . Additional contaminants include protozoan oocysts such as Cryptosporidium sp. , Giardia lamblia , Legionella , and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk. Physical and chemical parameters include heavy metals , trace organic compounds , total suspended solids , and turbidity . Chemical parameters tend to pose more of

6561-430: Was unusually large. A short period of hot weather can increase temperatures in the surface layer of water, as the warmer water tends to stay near the surface and be further heated by the air. In this case, the top warmer layer may have more oxygen than the lower, cooler layers because it has constant access to atmospheric oxygen. If a heavy wind or cold rain then occurs (usually during the autumn but sometimes in summer),

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