The imbalance of ecosystems and their impact on public health and animal
Dr. Kedar Karki MV S. (Preventive Veterinary Medicine)
Central Veterinary Laboratory Tripureshwor
The health of humans, like all living organisms depends on an ecosystem that sustains life. Healthy ecosystems are the sine qua non for healthy organisms. However, there is ample evidence that the lives of many support systems are far from healthy, placing a heavier burden on human health. In some areas of the world, gains in life expectancy and quality of life during the twentieth century are in danger of being reversed in the XXI century. The consequences of ecosystem degradation to human health are numerous, including the health risks of drinking water at risk, air pollution, climate change, emerging new diseases and resurgence of old diseases owing to ecological imbalances . Reversing this damage is possible in some cases but not others. Prevention of ecological damage is by far the most effective strategy.
DEFINITION OF THE ECOSYSTEM
An ecological system can be defined as a community of plants and animals that interact among themselves and with their abiotic, or natural environment. Typically, ecosystems are distinguished on the basis of dominant vegetation, topography, climate, or other criteria. Boreal forests, for example, are characterized by the predominance of conifers, grasslands are characterized by the predominance of grasses, Arctic tundra is determined in part by extreme climatic zones. In many parts of the world, the human community is an important and often dominant ecosystem. Ecosystems are not only natural areas (eg forests, lakes, coastal marine systems), but also the systems built by humans (eg, urban ecosystems, agro-ecosystems, dams). Human populations are increasingly concentrated in urban ecosystems, and it is estimated that by the year 2010, 50 percent of the world's population live in urban areas.
A landscape is a mosaic of ecosystems, including cities, rivers, lakes, agricultural systems, and so on. Precise boundaries between ecosystems are often difficult to establish. Often, the slide between regions gradually over a long transition, "the area, for example between the boreal and taiga regions of Canada.
Ecosystem health
It is important to recognize the difficulties inherent in the definition of "health", both at the individual, population, or ecosystem. The concept of health is a bit 'of an enigma, it is easier to define in its absence (illness) and in his presence. Perhaps partly for this reason, ecologists have resisted applying the concept of "health" to ecosystems. However, ecosystems can become dysfunctional, particularly under conditions of chronic stress from human activities. Examples of this can be cited the discharge of nutrients from sewage, industrial waste, agricultural waste into lakes or rivers affects the normal functioning of ecosystems, and may cause kidney failure. Excessive nutrient inputs from human activities has been one of the main factors that seriously endangers the health of children Laurentian Great Lakes (Lakes Erie and Ontario) and Great Lakes regions of higher (Lake Michigan). Lamentablemente, los ecosistemas degradados son cada vez más la regla que la excepción.
The study of the features of degraded systems and comparison with systems that have not been altered by human activity, identifies the characteristics of healthy ecosystems. Healthy ecosystems can be characterized not only by the lack of signs of pathology, but also by the signs of health, including measures of vigor (productivity), organization and resistance.
Force can be assessed in terms of metabolism (activity and productivity) of the system. Very different ecosystems in their normal ranges of productivity. Estuaries are far more productive than open oceans, and marshes have higher productivity than deserts. Health is not valued by the application of a standard for all systems. The organization can be assessed by the structure of the biotic community, an ecosystem and the nature of interactions between species (plants and animals). Invariably, healthy ecosystems have a greater diversity of flora and fauna threatened ecological terms. Resilience is the capacity of an ecosystem to maintain its structure and functions in the face of natural disturbances. Systems with a history of chronic stress are less likely to recover from disturbances such as drought normal systems have been relatively less stressed.
Healthy ecosystems can also be characterized in terms of health, economic, social and human. Healthy ecosystems support a certain level of economic activity. This does not mean that the ecosystem is necessarily self-sufficient, but supports economic productivity to the human community to meet reasonable needs. Inevitably, ecosystem degradation affects the long-term sustainability of the human economy that is associated with it, although in the short term this may not be obvious, natural capital (eg, soil, non-renewable resources) can be exploited and temporarily improve economic performance. Similarly, social welfare, healthy ecosystems provide a basis for promoting integration and community. Historically, for example, native Hawaiian groups managed their ecosystem through a well developed social cohesion, which provides a high level of cooperation in fisheries and agriculture.
Another reflection of ecosystem health is directly in the field of public health. In the spring of 2000, a deadly strain of the bacteria E-coli (0157: H7) entered the public water supply in Walkerton, Ontario, Canada, causing seven deaths and making thousands sick. This small town with a population of five thousand, is located in an agricultural community. Improper management of manure from livestock operations was the likely source of this tragedy.
How healthy ecosystems are pathological
The stress from human activities is an important factor in transforming healthy ecosystems to sick ecosystems. Chronic stress from human activity differs from natural disturbances. Natural disturbances (fires, floods, periodic insect) are part of the ecosystem dynamics. These processes help to "reset" the ecosystem by recycling nutrients and clearing space for recolonization by biota that can better adapt to changing environments. Therefore, natural disturbances help maintain healthy ecosystems. In contrast, acute and chronic stress on ecosystems resulting from human activities (eg, construction of large dams, the release of nutrients and toxic substances in air, water and earth) usually results in long-term disturbance ecological.
From five main sources of human origin (anthropogenic) stresses have been identified by DJ Rapport and Friend (1979): physical restructuring, overfishing, waste, waste, introduction of alien species and global change.
The restructuring of concrete. Activities such as restoration of wetlands, removal of the banks in lakes, damming of rivers, and the piece of road construction and alter the landscape and damage critical habitat. These activities also disrupt nutrient cycling, and cause loss of biodiversity.
Excessive logging. Overexploitation usual when it comes to collection of wildlife, fisheries and forests. For long periods of time, reducing the populations of the preferred species. For example, the giant redwoods that once thrived along the California coast, and exist only in patches of rest due to overexploitation. When the dominant species, including giant sequoias tallest tree (perhaps in the world, a specimen was recorded at 110 meters high with a circumference of 13. 4 meters) are lost, the whole ecosystem changes. Excessive logging often results in reduced biodiversity of endemic species and facilitates the invasion of opportunistic species.
Waste residue. Discharges from municipal sources, industrial, agricultural and air, water, soil and have seriously compromised many of Earth's ecosystems. The effects are particularly apparent in aquatic ecosystems. In some lakes that lack a natural buffering capacity, acid precipitation has eliminated most of the fish and other organisms. While the visual effect is positive (water clarity goes up) the impact on ecosystem health are devastating. Systems that once contained a variety of organisms and have been very productive (biological) is devoid of life forms except for a few acid-tolerant bacteria and sediment dwelling organisms.
Introduction of exotic species. The spread of alien species has become a problem in almost all ecosystems in the world. The transport of species in their native habitats entirely new ecosystems can wreak havoc, such as new environments are often without natural checks and balances of new species. In the Great Lakes basin, the accidental introduction of two small pelagic fish, tarpon, and the smell of the rainbow, along with the simultaneous exploitation of natural predators such as lake trout has led to a significant decrease in species native fish. The introduction of the sea lamprey, eels, and large predatory fish that attacks fish in Lake Erie and the upper Great Lakes further destabilized the native fish community. The sea lamprey contributed to the disappearance of benthic communities of deep sea fish prey on lake trout, whitefish and turbot. This contributed to a change in the fish community from one that was dominated by large benthics to one dominated by small pelagics (fish found in the upper layers of the profile of the lake). This change in housing bottom fish (benthic) to surface-dwelling fish (pelagic) has been partially revoked by another accidental introduction of exotic: the zebra mussel. Like the zebra mussel is a filter phtyoplankton is very efficient and zooplankton, its presence has reduced food availability in surface waters of pelagic fish. However, while the benthic fish community has gained back its dominance, the preferred benthic fish species have not recovered to the level of initial degradation. In general, not the increasing dominance by exotics only altered the ecology, but also significantly reduced the commercial value of fisheries.
Global Change. Rapid climate change (or warming) is a potential new global effort in all ecosystems on earth. Over evolutionary time, there has naturally been considerable fluctuations in climate. However, for most of these fluctuations have occurred gradually over long periods of time. Fast cambiamento è una questione climate totally different. Changing both the means and extremes of precipitation, temperature and storms, and by destabilizing the El Niño-Southern Oscillation (ENSO), which controls weather patterns in most of the South Pacific region, many processes ecosystems may become a significant alteration. Too long periods of drought or unusually heavy rains and floods exceeding the tolerance of many species, thus changing the biotic composition. Flooding and unusually high winds contribute to soil erosion, and at the same time add to nutrient loads in rivers and coastal waters.
These impacts of human activities have impaired the function of ecosystems in many regions, resulting in distress syndrome of ecosystems (EDS). EDS is characterized by a set of signs, including nutrient cycling, productivity, species diversity and richness, biotic structure, disease prevalence, soil fertility, and so on. The consequences of these changes on human health are negligible. Impoverished biotic communities are natural harbors for pathogens that affect humans and other species.
ECOSYSTEM HEALTH AND HUMAN HEALTH
An important aspect of ecosystem degradation is associated with an increased risk to human health. Traditionally, concern has been that of the contaminants, particularly industrial chemicals that can have negative impacts on human development, neurological functions, reproductive functions, and appear to be the etiologic agents in a variety of cancers. In addition to these serious environmental concerns (where resources are often technological, including engineering solutions to reduce emissions of pollutants), there are many other risks to human health from ecological imbalance.
The Ecosystem syndrome risk in the loss of value of ecosystem services including flood control, water quality, air quality, fish and wildlife diversity and recreation. One of the most important signs of EDS increased the incidence of disease in humans and other species. The human population health should be evaluated in an ecological context, as an expression of integrity and health of life, load capacity of the environment.
Ecological imbalances caused by climate change and other causes are responsible for increased risk to human health.
Climate change and vector-borne diseases. The global burden of infectious diseases is the order of several hundred million cases annually. Many carry climate-sensitive diseases. Fever, malaria, dengue, hantavirus pulmonary syndrome, and various forms of viral encephalitis are all in this category. All these diseases are the result of viruses of arthropods (arboviruses), transmitted to humans through bites from blood-sucking arthropods.
Global climate change, rather than the impact of temperature and rainfall, is strongly correlated with the prevalence of disease vectors. For example, viruses carried by mosquitoes, ticks and other bloodsucking arthropods generally have increased transmission speed, with increasing temperatures. St. Louis encefalite (SLE) come un esempio serve. The mosquito Culex tarsalis carries this virus. The percentage of bites that results in transmission of SLE is dependent on temperature, with greater transmission at high temperatures.
The temperature dependence of vectors is well illustrated with malaria. Malaria is endemic in the tropics, with a high prevalence in Africa, the Indian subcontinent, Southeast Asia, and parts of South and Central America and Mexico. Approximately 2. 4 billion people living in areas at risk, with almost 350 million new infections each year, an increase of approximately 2 million deaths, mostly children. Untreated malaria can become life-long pain, general symptoms include fever, headache and malaise.
The climate sensitivity of malaria arises from the nature of the interactions of pests, vectors and hosts, all types of the final impact of transmission to humans. El tiempo de gestación necesario para que el parásito llegue a ser plenamente desarrollado dentro del mosquito-huésped (un proceso denominado esporogonia) se produce a partir de ocho a treinta y cinco días. When temperatures are in the range of 20 ° C to 27 ° C, the gestation time is reduced. The rain and humidity also play a role. Both droughts and rains tend to reduce the mosquito population that act as vectors of malaria. The more arid regions of the tropics, low rainfall and humidity limits the survival of mosquitoes. It can cause severe flooding in the river wash and destruction of habitats for the reproduction of the mosquito vector, while rain increases the production of intermediate vectors.
Ecological imbalances. Cholera is a severe and potentially fatal disease that is caused by the bacterium Vibrio cholerae. Although not as common as malaria, cases are still numerous. In 1993, there were 296,206 new cases of cholera in South America, 9280 cases were reported in Mexico, 62,964 cases in Africa, and 64,599 cases in Asia. Most of the outbreaks in Asia, Africa and South America have their origin in coastal areas. The symptoms of cholera are explosive watery diarrhea, vomiting and abdominal pain. The most recent pandemic of cholera-affected areas more than in any previous time in the twentieth century. The disease remains endemic in India, Bangladesh and Africa. Vibrio cholerae is in the United States in the region of the Gulf Coast of Texas, Louisiana and Florida, the area of the Chesapeake Bay and the coast of California.
The increasing prevalence of Vibrio cholerae has been closely linked to the degradation of marine and coastal environments. The warm nutrient rich coastal waters as a result of a combination of climate change and the use of fertilizers, provides an ideal environment for reproduction and distribution of Vibrio cholerae. The recent outbreak of cholera in Bangladesh, for example, are closely correlated with the temperature of the upper surface of the sea. V. cholerae attach to the surface freshwater and marine copepods (crustaceans), and the roots and exposed surfaces of macrophytes (aquatic plants) such as water hyacinth, the most abundant aquatic plant in Bangladesh. Nutrient enrichment and warmer temperatures lead to algae blooms and abundance of macrophytes. Algal blooms provide abundant food for copepods, and copepod and macrophyte populations provide V. growing cholerae with habitat. After the dispersal of V. cholerae into estuaries and fresh water bodies allows contact with humans who use these waters for drinking and bathing. The global distribution of marine pathogens such as V. cholerae is facilitated by ballast water of ships. Ballast water contains a virtual cocktail of pathogens, including V. cholerae.
Two other examples of ecological imbalances that rates how to relate to human health, the increased prevalence of Lyme disease and hantavirus pulmonary disease. Lyme disease, Sonam because it was first identified in Lyme, Conn., is the paralysis of a type of arthritis disease that is transmitted by spirochete-infected Ixodes ticks (deer ticks). Ticks acquire the infection by rodents, and spend part of their life cycle of deer. Three factors have combined to increase the risk to humans of contracting Lyme disease, especially in North America: (1) the elimination of natural deer predators, particularly wolves, (2) reforestation of abandoned farmland has created the most favorable habitat for deer, and (3) the creation of businesses in the suburbs, which are ideal habitats for deer browsing. The net result is an increase in the deer population, which increases the chances of humans coming into closer contact with ticks.
Since 1995, in the southwestern United States, hantavirus infection was confirmed in ninety-four persons in twenty states, with 48 percent mortality. Variants of the strain that causes hantavirus pulmonary syndrome have been found in other parts of the country and in Asia and Europe. The virus is apparently asymptomatic in rodents, and transmitted in their saliva and feces. Humans have a flu-like presentation, which is followed by respiratory distress syndrome. El tanque principal de las cuatro esquinas del suroeste de Estados Unidos es el ratón venado. Climate change, which in recent years are believed to be exacerbated by human activities (eg global warming), appear to be the conditions that trigger outbreaks. In the 1990s, ENSO events initially caused drought conditions to develop in the southwestern United States. This has led to a decline in populations of plants and animals, including natural predators of the deer mouse. Heavy rains after the drought of 1993, resulting in a bumper crop of pine nuts, an important source of food for the deer mouse. Subsequently, the deer mouse population greatly increased, resulting in greater contact with humans and causing the outbreak of the hantavirus.
The antibiotic resistance and resistance to agricultural practices to antibiotics is a growing threat to public health. Antibiotic resistant strains of Streptococcus pneumoniae, a common bacterial pathogen in humans and a major cause of infections, including chronic bronchitis, pneumonia and meningitis, have greatly increased in prevalence since the 1970s. In some regions, up to 70 percent of bacterial isolates taken from patients proved resistant to penicillin and other b-lactams. The use of large quantities of antibiotics in agriculture and aquaculture seem to have been a key factor for the development of antibiotic resistance of pathogens in farm animals, which subsequently may also infect humans. One of the most serious risks to human health from such practices is vancomycin-resistant enterococci. The use of avoparcin, a growth promoter in animals, appears to have diminished the usefulness of vancomycin, the antibiotic effective against the latest of several drug-resistant bacteria. It was in areas where avoparcin was used, as on farms in Denmark and Germany, vancomycin-resistant bacteria were detected in meat sold in supermarkets. Avoparcin was subsequently banned by the EU. Another example is the use of ofloxacin to protect chickens from infection and thereby enhance their growth. This drug is closely related to ciprofloxacin, one of the most commonly used antibiotics in 2000. There have been cases of resistance to ciprofloxacin directly related to veterinary use. In the UK, has developed resistance to ciprofloxacin in strains of Campylobacter, a common cause of diarrhea. Multi-resistant strains of salmonella have been linked to egg production in Europe.
Food security and water. Agricultural practices are also responsible for a growing number of threats to public health. Some of these are related to inadequate waste management, leading to parasites and bacteria that enter the water supply. Other origins are completely different and involve the transfer is between species of pathogens that affect both animals and humans. The latest example is spectacular and the mad cow disease, called Creutzfeldt-Jakob disease in humans, a neuro-degenerative, in humans, is ultimately fatal. The first case of bovine spongiform encephalopathy (BSE), the animal form of the disease was identified in southern England, in November 1981. With the fall of 2000, an outbreak in France, and isolated cases appeared in Germany, Switzerland and Spain. More than a hundred deaths in Europe were attributed to what has become commonly known as mad cow disease.
Improper handling of manure is the likely source of the outbreak of Escherichia coli 0157: H7 in Walkerton, Ontario, Canada. The health risks associated with agroecosystems failures can be periodic epidemics of cryptosporidiosis, a parasitic disease spread by surface runoff contaminated with feces of infected animals. This parasite causes fever and diarrhea in immunocompetent individuals and severe diarrhea and even death in immunocompromised individuals.
Ecosystem Restoration
Ecosystem Pathology, in some cases can be reversed simply remove the source of stress. En estos casos, por ejemplo, donde la degradación de los ecosistemas, son el resultado del punto adiciones fuente de nutrientes o de sustancias químicas tóxicas, la eliminación de estas tensiones pueden dar lugar a una considerable recuperación de la salud de los ecosistemas. A classic case is Lake Washington (near Seattle, Washington). This lake had become highly anoxic (oxygen is depleted) due to a sewage discharge entering the lake. Redirect the output of waste water from the lake reversed many of the signs of the disease.
When you can not eliminate the source of stress, more innovative engineering solutions have been tried. For example, Lestijoki Kyrönjoki and rivers in western Finland, spring and autumn brings a net outflow of pulses of acidity. Runoff from spring melt, which releases acid or dug culture, was particularly damaging to fish during the critical period of the year for spawning. Fish reproduction has been drastically reduced if not eliminated all together in highly acidic waters. There were large fish kills resulting from the highly acidic waters. One possible solution is to replace the original drains which take runoff from land to rivers with new limed drains that can neutralize the acidity. This solution has been used experimentally and appears to substantially reduce acidic runoff.
The more radical treatments for damaged ecosystems involve "ecosystem surgery." In some cases, invasive exotic vegetation (such as mangroves in Hawaii) were removed from the region and the native vegetation has been replanted. In areas of North America, where wetlands have been severely depleted due to agriculture, urbanization and industrial activity, efforts were made to create new wetlands.
More often, however, the condition of ecosystems can not be reversed. Efforts to restore native grasslands of the Jornada Experimental Range in south-western United States is an example. Overgrazing by cattle has severely degraded the landscape and led to the replacement of native grasses shrubs largely inedible, dominated by mesquite. The erosion of wind and heavy rain episodes have largely left the area between the bushes naked, and then the underlying sand dunes have developed in fashion as in most of the area. The result of Mesquite dunes have proven highly resistant to efforts to restore native grasslands, although almost all interventions have been tried, including highly toxic defoliants (Agent Orange), fire and demolition.
Although it was possible to restore some ecological functions of degraded ecosystems and, therefore, improve the health of ecosystems, restoration often results in the restoration of the Virgin of the biotic community. The best that can be achieved in many cases, restoration of key ecological functions that constitute the ecosystem services, such as water regulation, primary and secondary productivity, nutrient cycling and pollination. In all these efforts, key indicators of ecosystem health (vigor, productivity and resilience) are essential to monitor progress. Ecological standard indicators can be used for this purpose (for example, measures of productivity, species composition, nutrient flows, soil fertility) along with socio-economic indicators and human health.
Experience in an attempt to restore highly damaged ecosystems suggests that the prevention of ecosystem health is much more effective than restoration. Para los ecosistemas marinos, dejando de lado las zonas de protección que proporcionan un refugio para peces y vida silvestre tiene una promesa considerable. Muchos países están adoptando políticas para establecer dichas zonas, con la posibilidad de que estas regiones saludable puede servir como reservorio para la biota que se han agotado en las zonas no protegidas. Sin embargo, este recurso no es ilimitado. Restaurar la salud del ecosistema no es simplemente una cuestión de la reposición de perdida o dañada la biota. Es también una cuestión de restablecer las complejas interacciones entre las formas de vida del ecosistema. Tener una fuente de la biota saludables que podrían recolonizar los ecosistemas dañados es importante, pero es sólo una parte de la solución.
PREVENCIÓN DE LOS ECOSISTEMAS rompe
Dada la dificultad de revertir la degradación de los ecosistemas, y muchos los riesgos asociados para la salud humana que surgen con la pérdida de la salud de los ecosistemas, el enfoque más efectivo es simplemente la prevención de la alteración del ecosistema. Sin embargo, como muchos planteamientos de sentido común, esto es más fácil decirlo que hacerlo. En los países desarrollados y países en desarrollo existe una fuerte tendencia a continuar el crecimiento económico, aun a costa de graves daños ambientales. Oltre a motivazioni egoistiche, l'argomento è che la crescita economica ha molte evidenti benefici per la salute, quali la fornitura di metodi più efficienti di distribuzione delle forniture alimentari, fornendo più cibo abbondante, e di fornire servizi sanitari migliori e finanziamenti per la ricerca per migliorare il tenore di vita. Questi sono infatti i benefici dello sviluppo economico, e hanno portato ad un sostanziale incremento in tutto il mondo lo stato di salute.
Tuttavia, all'alba del ventunesimo secolo, il passato non è necessariamente la migliore guida per il futuro. La popolazione umana è uno di tutti i tempi alti, e le pressioni associata delle attività umane hanno portato ad aumentare il degrado degli ecosistemi della Terra. Come in ultima analisi ecosistemi sani sono essenziali per la vita di tutti i sistemi viventi, inclusi gli esseri umani, le attuali tendenze globali e regionali sono inquietanti. In queste circostanze, un trade-off tra vantaggi materiali immediati e la sostenibilità a lungo termine degli esseri umani sul pianeta può essere l'unica opzione. In tal caso, la soluzione per sostenere la salute umana e l'ecosistema della salute diventa uno di concepire una nuova politica che pone sostenere i sistemi di supporto vitale come presupposto per il miglioramento della condizione umana.
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