Over the last century the term pollution is common and is a concept known to all – a man-made effect that unbalances the environment, having serious consequences for the planet and its inhabitants.
In the vast majority, and what is most notorious and visible, the known pollution tends to be defined by the pollution of the atmosphere (greenhouse gases), soil (contaminants from, for example, agriculture), water pollution ( solid and liquid substances in groundwater, oceans, rivers, among others).
In addition to these types of pollution, there is radioactive pollution (radioactive contaminants such as uranium and plutonium), visual pollution (excessive visual information on posters, poles, electricity wires) and thermal pollution (due to, for example, , electric or nuclear plants, which heat natural waters).
Despite the extreme importance of each of them, there are two other types of pollution whose environmental impacts are enormous and, unfortunately, underestimated – noise pollution and light pollution
Significant events such as the industrial revolution, the implementation of electricity at a global level, the growth of large urban centers and large cities have been responsible for these worrying pollutions.
Noise pollution leaves no residue or traces – only consequences. This is not only defined in decibels of sound, but also in the vibrations that cause this movement of air particles.
Prolonged exposure to this pollutant can cause chronic and irreversible effects. In humans, where this effect is most studied and whose existence is regulated, there is clear evidence of heart problems, high levels of cholesterol and hormones, stress, sleep and memory disorders, propensity to psychic disorders and even a tendency to commit suicide.
The WHO estimates that, in Europe, 10,000 people die prematurely from this form of pollution each year. Transport, industries, urban centers, mining, construction, maritime activity, open-air concerts are examples of forms of noise pollution.
So why will the effect be different on animals?
One of the best known examples is cetaceans (dolphins, sperm whales, whales). These animals use echolocation, which consists of detecting their position through the emission of ultrasonic waves in the water like the sonar of boats that measure depth.
This mechanism is used by some mammals, such as bats and some birds. The ability to maintain vital functions, feeding, communication, migration and reproduction are highly affected by noise.
We don't need to go that far to realize that the peace of marine animals is at risk. The level of stress (measured by the levels of the hormone cortisol) in fish is increasing and affecting the food chain. Another affected animal is the squid, whose ability to float depends on its hearing.
Marine traffic in the Mediterranean produces 30% of the volume of noise. Other events such as oil exploration and military activities are sources of noise that would deaf any human underwater. Given a number of physical and chemical factors, sound travels faster and farther in water – having a greater impact.
Air doesn't seem to be influenced as nefariously as water, however, the consequences are just as worrisome.
The noise and vibration of the air caused, for example, by wind turbine blades and highways disorient animals (mostly birds and bats), reduce their ability to hunt and protect from predators, cause changes in the “home range” ”/live area of animals, as well as reproduction and physiological and behavioral changes and often cause the indirect death of animals by collision
Intra and interspecific competition is affected, directly affecting the adaptation and evolution of species. Birds of prey are an example that use vocal activity for numerous of their activities, being highly impaired. Another example is tree frogs, whose stress and immunosuppression are increased by noise and inadequate vibration of their vocal sac, affecting natural selection and mortality in males – who use this call to attract females.
At least 19% of the area protected by the Natura 2000 network suffers from excessive noise, in other words: noise pollution. Until today, this problem is little studied – especially the environmental impact. Data are scarce and the measures and attempts to implement changes in some of these factors have not yet had a significant improvement that reduces the risks and consequences of this type of pollution.
Light pollution comes not only from the interior lighting of buildings, but above all from the wrong positioning and use of outdoor lamps and spotlights, which are estimated to be around 300 million in the world. These cause excessive lighting and reach, which has harmful effects on plants, animals and humans. This incorrect use significantly increases energy consumption and contributes to the degradation of the environment, consumption of fossil fuels and renewable energies.
Did you know that 2/3 of North Americans and half of Europeans cannot see the Milky Way due to the light emanating from cities?
Unfortunately, this type of pollution affects much more than our ability to see the stars. Although the night is a danger for many animals, it is also often used for migration, reproduction and feeding, in an environment without the heat of the sun and without the competition of several other species.
In addition, there is a vast number of species that use the stars as an orientation. Examples are seals, ants, beetles, birds, bats and moths. About 30% of nocturnal vertebrates are affected by this pollution and about 60% of invertebrates.
What about beyond orienteering? How are animals affected?
Artificial lights from our homes cause 976 million birds to crash into windows at night every year.
Australia's great barrier reef, responsible for recycling a large part of the carbon that causes atmospheric pollution, with more than 400 species of corals on which 65% of fish depend, cannot maintain its normal functioning with the presence of of artificial night light.
The lighting of the beaches leaves the eggs, already very susceptible to predators and traffic, exposed to these dangers. It is estimated that between 1992 and 2013, 3.86 turtle nests were lost for each unit of light added. These specific examples are very common in other species that, because of night light, change their behavior and circadian rhythm, hormonal and reproductive cycle changes, confusion in orientation and migration, predation.
Plants and their pollinators are also involved. The abnormal light supply causes plants not to flower when they should, or to die prematurely – compromising forests and woods and the balance of the ecosystem.
Humans are equally affected.Changes in light cause sleep problems (release of the hormone melatonin is greater in the dark) and can lead to other pathologies related to the alteration of the body's normal rhythm - such as diabetes and other cardiovascular diseases We are also affected by electronic devices before going to sleep, becoming a vicious cycle in everyday life.
Portugal is the worst country in Europe in terms of light pollution.
Are measures for this problem blackouts, blinds and shutters on windows; motion sensors for street lamps, turning off lights and appliances as much as possible, as well as changing the type of bulbs. The NGO WWF created in 2007 a movement against global warming called “Earth Hour”, where every year millions of people are invited to turn off their lights for 1 hour, for the good of nature. The next Earth Hour will be on March 26, 2022 at 8:30 pm.
Written by Teresa Pinho 14ºC.