People take fresh water for granted, so concern for its conservation goes awayinto the background.
The quality of fresh water should be of concern to people as much as its scarcity.According to the Nature Conservancy, more than half of the world's 500 most important rivers are already polluted.The water from these reservoirs could be a resource for millions of people, but due to the level of waste, it cannot be used.
One-sixth of the world's population does not have direct access to water, and the U.S. Agency for International Development predicts that by 2025 the situation will worsen: water will beThis is a future catastrophe for all of humanity, but the cataclysm for other life forms has already begun.17.4 thousand species live in different types of freshwater reservoirs, and water quality is no less important for them than for people.
The paradox of diversity: most aquatic organisms live in fresh water. The volume of oceans, while almost 1000 times greater than the volume of rivers and freshwater lakes. If to describe in numbers - 50.7% of aquatic organisms live in 0.009% of water.
The Cretaceous biocenotic crisis in the diversity of living organisms began about 135 million years agoThis was the last major period of extinction of living organisms on Earth, and there has not been a new one until the present day.Some researchers believe that the next such crisis will begin in the Anthropocene epoch due to global climate change and humans in particular.It's too early to make pessimistic predictions, but scientists have reason to be alarmed.
Colorful bland world: a variety of species
The biodiversity fund is made up of organisms living in all types of freshwater bodies.Classification of reservoirs divided into rivers, lakes, ponds, small ponds and artificial reservoirs.The type of water varies depending on whether it stagnates in bodies of water or is constantly overflowingfrom one place to another.
The inhabitants of water bodies are also divided into several groups: periphytons, benthos, nectons, plankton and neistons.Periphytons parasitize dead and living bottom dwellers, finding shelter in silt or among algae.Actively swimming and mostly large creatures are nektons, which include most fish, amphibians and insects.Representatives of benthos live in the depths: worms, mollusks, some fish - gudgeon, sterlet and burbot, which preferPlankton, unable to resist the current, drift in the water, and neistons, sliding on the surface, are water striders, bugs and whirling beetles.
Bioindication– assessment of the human impact on the water body by the reaction of its inhabitants to the external environment.The bioindicators are the inhabitants of the reservoirs under study, which replace each other depending on theIn polluted water bodies, for example, leeches and pond flakes live, while in clean waters they are replacedHanging flies and mayflies.
The presence of leeches in reservoirs indicates the degree of contamination. Leeches live in polluted water bodies. In the net, they are replaced by visokrylki and polenki.
Not all bodies of water are tested, but the state of the water can also be judged by external signs: blooming, water color and its viscosity.Another good indicator is endangered species and dead fish.Over the past decade, more than 20% of the 10,000 known freshwater fish species have either gone extinct or are on the verge of extinction.Marguerite Xenopoulos, a biologist at Trent University in Ontario, said: "The numbers are a wake-up call, and we urgently need to take action to preserve freshwater ecosystems."
The global index of a living planet is formed from data on vertebrate populations and population dynamics. The fluids for freshwater populations have decreased by 81% since 1970: danger levels are measurable.
The study, published in the journal Scientific Reports, reports the gradual extinction of the European river mollusk.This bivalve has a lifespan of about 200 yearsEcologists have noted a sharp decline in the population of shells in their habitual habitats.In order to study the causes of extinction, scientists collected samples from fifty rivers in Europe, and also studied shell specimens from natural history museums - collections were collected in the 19th century.The reason for the decline in the population turned out to be trivial, but no less dramatic.
Global Warming and Intrusive People
The factors that change freshwater ecosystems are interrelated and come down to the essence of the Anthropocene.Without human impact, the rate of extinction might not have been as rapid.Nevertheless, today the inhabitants of rivers and lakes are forced to adapt to the gradual increase in water temperature and the constant change in its chemical composition.
In the case of the European mollusk, the increase in ambient temperature turned out to be critical.This species is characterized by a geographical change in the ratio of width to length, i.e. convexity.Scientists have found that this indicator used to be the same for all, southern and northern, mollusks.Today, the situation is as follows: the colder the water in the river, the smaller the bulge on the sink.The cold beginning of the 20th century was far more comfortable than the current trend towards global warming.Warm water accelerates metabolism and growth, so the mortality of larvae and juveniles reducesthe total lifespan of the population.
Warming changes not only mollusks, but also the environmenttheir habitats. In the rivers there are more algae, they often overflow the banks. Pessimistic forecasts predict the extinction of European mollusks. Pearl oysters can survive only in high-mountain icy rivers, where the temperature remains the same.
The second reason for the gradual extinctionfreshwater organisms - anthropogenic impact, and, in particular, the results of industrialization. The exploitation of water resources of rivers and lakes by industrial enterprises leads to large-scale pollution of nearby waters. Although technology is reducing waste, new treatment facilities are being introduced at a minority of facilities. The annual use of approximately 30 billion cubic meters of water produces 700 million cubic meters of wastewater. The breakdown of chemical waste in water takes years, during which the substances penetrate into groundwater and spread through nearby bodies of water.
It's not just industrial waste that causes harm.The cheapest way to produce electricity is hydropower. It is a source of renewable energy, taking resources from rain and snow. Engineers can easily control the volumes of water transported, and reservoirs are not only strategic, but also of public importance - these are good options for winter skating rinks or artificial reservoirs.
Dams and hydroelectric power stations bring not only benefits,but also cause damage to nature. Artificially changing the flow of rivers, retaining or accelerating water leads to a change in the direction of fish movement. Salmon, for example, swim upstream to spawn using fish ladders, but dams or power plants can be a serious obstacle, literally preventing them from breeding.
Fish ladder— specialized water structures, dams of different heights from 50 to 500 meters. Such rapids allow natural migration of fish up and down the river.
A BioSciences study found thathydroelectric power plants reduce oxygen levels: the amount of methane and carbon dioxide in the water increases. Fish do not always successfully adapt to rising temperatures, and, in addition, suffocate from lack of oxygen.
Oksana Nikitina, project coordinator forconservation of aquatic ecosystems WWF Russia, comments on the massive construction of structures using river energy: “Aquatic inhabitants are evolutionarily adapted to the natural dynamics of the water regime, which determines the time of their reproduction, migration, and feeding. Violation of the regime leads to disruptions in life cycles. If a river is not isolated from the surrounding area by dams and dikes and maintains its natural water regime, it is called free-flowing. The construction of dams has led to a sharp decrease in the number of free-flowing rivers: more than 50,000 large dams have already been built in the world.”
Another “human” threat is poaching.Unregulated fishing of fish and other inhabitants of freshwater bodies destroys ecosystems. The catching quota is usually set by the federal authorities: the calculation takes into account the season, population size, and increasing or decreasing trends. For example, one year you can catch six trout from a pond and only three the next. Of course, poachers' catches rarely meet established standards.
How to cope with the crisis of freshwater?
Today scientists are developing an understanding of the functionseach element of the biological system of each individual reservoir. So far, determining the role of any organism living in a particular lake is complicated by the unique environmental conditions. Unlike large salt water bodies, particular cases of ecosystems of lakes and rivers can differ significantly from each other. The only thing that remains constant is the importance of life living in water. Because of this, species rescue techniques are effective locally, but not on a scale across all freshwater bodies. The situation requires a change in external, not internal conditions.
The freshwater diversity crisis will not end inovernight, but this does not mean that you can give up and end the acute stage. Now people can limit dam construction, create more protected freshwater lands, and reduce industrial and personal water withdrawals. By the way, anyone can find out how much water they spend daily - you need to use a special calculator.
Enterprises can assemble special pumps forpumping out sewage waste. They make it possible to clear sediment from riverbeds using dredging buckets and stirring jets. Settings are created for each reservoir separately: they take into account the nature of bottom sediments, hydraulic resistance of the riverbed, and erosion factors.
It is especially important to reduce the number of builtthe dams. “To preserve aquatic ecosystems, it is important to initially protect particularly valuable parts of river basins from the possible construction of dams. It is necessary to prevent the construction of those dams that are designed without due regard for their impact on ecosystems. If construction is still unavoidable, then we should choose those dams, the location of which has the least impact on the environment compared to other options, ”adds Oksana Nikitina.
Freshwater is not a secondary concern.humanity, but an important component of the overall ecological balance. A man in the street who is aware of the importance of preserving freshwater bodies should follow the necessary minimum recommendations for protecting the environment and preserving water resources. Banal tips: save water, sort garbage, relax in specialized places - not an empty phrase, but the real basis for saving the planet.