My Science School

Blue tide and algal bloom

You may have often come across news about beach visitors witnessing glowing blue waves. This phenomenon is called blue tide and is caused when an abundance of marine noctilucent algae emit light in a chemical process called bioluminescence. The algae emit light when disturbed (by the waves in this case). It is an antipredatory response and is assumed to startle predators.

Though it may look magical, it is an ecological indicator of degraded water quality. Factors such as the pattern of the wind and higher sea temperature also determine the occurrence of algal bloom and bioluminescent waves.

What causes this algal bloom? When humans channel agricultural runoff, sewage and industrial effluents into waterways, the amount of nutrients in the water increases. The excess nutrients, especially nitrogen and phosphorous, lead to a spurt in the growth of microscopic algae. This is called algal bloom. Some of these can be bioluminescent. Not all algal blooms are harmful, but some are deadly. The presence of so many algae may suffocate fish by clogging or irritating the gills. Some algal species produce deadly toxins which either kill the animals or accumulate in the body of animals and spread through the food web.

Sea snot

Recently, there has been growing environmental concern in Turkey over the accumulation of 'sea snot, in the country's seas, which can cause considerable damage to the marine ecosystem.

"Sea snot", or marine mucilage, is a naturally occurring green sludge that forms when algae is overloaded with nutrients as a result of hot weather and water pollution. Most marine organisms produce mucus. But in unpolluted waters, mucus doesn't amass to large proportions. The current sea-snot outbreak can be blamed on phytoplankton, a type of algae that produces the small bits of mucus that turn into flakes of marine snow. During an algal bloom, they make an overabundance of mucus. Beads of that mucus can accumulate into sheets and wash up shore.

Sea snot affect marine and coastal ecosystem. It could poison the mussels and creatures such as crabs. It also affects fishing and tourism.

Sea foam

Sea foam is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter derived from sources such as the decay of offshore algal blooms. Sea foam forms when the ocean is churned by wind and waves. As a result, great amounts of decaying algal matter wash ashore.

Most sea foam is not harmful to humans, but when large harmful algal blooms decay near shore, there are potential for impacts to human health and the environment. The resulting aerosol can irritate the eyes and pose a health risk for those with respiratory conditions.

Sargassum

In the centre of the North Atlantic ocean, amidst the vast blue expanse, is a huge floating mat of brown seaweed called sargassum. These mats are quite common in the Sargasso Sea, a region around Bermuda. But since 2011, the Atlantic Ocean has been witnessing massive sargassum blooms every year. It stretches nearly 9000 km from West Africa to the Gulf of Mexico. Scientists call this the Great Atlantic Sargassum Belt. The seaweed band has been getting bigger every year, posing a serious threat to marine life, coastal ecosystem and the fishing communities dependent on it. The seaweeds often wash up ashore en masse and choke coastal ecosystems. As the seaweed rots, it releases foul-smelling hydrogen sulphide gas, causing respiratory illness in local populations. It also affects coastal tourism.

Removal is time-consuming, expensive, and not always effective. Scientists attribute it various factors such as warming of the ocean due to climate change, discharge of nutrients from agricultural runoff.

Ghost forests

Grey and barren dead trees are dotting coastal regions across many parts of the world. Called ghost forests, these are leafless, limbless trees that can last decades in this dried-up barren state. Scientists believe they are the immediate consequences of sea-level rise. Sea-level rise increases the risk of saltwater intrusion. It is the flow of seawater into wetlands and rivers. As sea level rises, more and more saltwater encroaches on the land and overtakes freshwater that trees rely upon for sustenance. The salty water slowly poisons trees and eventually kills them. (Dead trees with pale trunks are a telltale sign of high salt levels in the soil.) The rising salt water also leaves soil unhealthy and forests unsuitable for new growth. Scientists note that extreme weather events, fuelled by climate change, are causing further damage to vegetation in the form of heavy storms, more frequent hurricanes and drought. This is causing mass tree die-offs across coastal regions.

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The Great Indian Bustard, a bird species once found in abundance across the grasslands of India, is facing the risk of extinction.

The 2011 Red List of birds, released by the International Union for Conservation of Nature (IUCN), has enlisted the bird in the Critically Endangered category, the highest level of threat. The population of the species is estimated to be just 250.

Besides the Bustard, the list has enumerated 15 species from India as critically endangered and 16 as endangered ones. There are 55 vulnerable ones and 65 near-threatened bird species in the country. Some of the critically endangered Indian varieties include the Himalayan Quail, Pink-headed Duck, White-bellied Heron and Christmas Island Frigatebird. The vulture species found in India namely the White-backed, the Indian, the Slender-billed and the Red-headed are also in the critical list, says Dr. Nameer.

The list has classified 189 species worldwide as critically endangered, 381 as endangered with very high risk of extinction and 683 as vulnerable with high risk of extinction. It has also listed 843 species as near-threatened. A total of 2,096 species were treated as global conservation priorities. The threat status of 62 species could not be properly assessed following deficiency of data.

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The Amur leopard is a leopard subspecies native to the Primorye region of southeastern Russia and northern China. It is listed as Critically Endangered on the IUCN Red List. In 2007, only 19–26 wild leopards were estimated to survive in southeastern Russia and northeastern China. It was considered as one of the rarest cats on Earth.

Amur leopards are solitary, unless females have offspring. Records from camera-traps indicate that they are more active during the day than at night and during twilight, both in the summer and winter seasons. This activity pattern coincides with activity of prey species such as Siberian roe deer, sika deer and wild boar.

The Amur leopard is threatened by poaching, poaching of prey species, habitat loss and deforestation or exploitation of forests. Its natural habitat is threatened by forest fires and construction of new roads. Due to the small number of reproducing Amur leopards in the wild, the gene pool is so reduced that the population is at risk from inbreeding depression. In 2015, a wild Amur leopard was found with canine distemper virus in Primorskii Krai. The small population is possibly exposed to domestic or wild disease carriers and transmitters.

Tigers can eliminate leopards if densities of large and medium-sized prey species are low. Competition between these predators supposedly decreases in summer, when small prey species are more available. In winter, conditions are less favorable for tigers and the extent of trophic niche overlap with that of leopards probably reaches its peak.

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The vaquita is a species of porpoise endemic to the northern end of the Gulf of California in Baja California, Mexico. Averaging 150 cm (4.9 ft) (females) or 140 cm (4.6 ft) (males) in length, it is the smallest of all living cetaceans.

Vaquitas are generally seen alone or in pairs, often with a calf, but have been observed in small groups of up to 10 individuals.

Little is known about the life history of this species. Life expectancy is estimated at about 20 years and age of sexual maturity is somewhere between 3 and 6 years of age. While an initial analysis of stranded vaquitas estimated a two-year calving interval, recent sightings data suggest that vaquitas can reproduce annually. It is thought that vaquitas have a polygynous mating system in which males compete for females. This competition is evidenced by the presence of sexual dimorphism (females are larger than males), small group sizes, and large testes (accounting for nearly 3% of body mass).

This species inhabits shallow, murky lagoons along the shoreline where there is strong tidal mixing, convection processes and high food availability. Individuals are generally seen traveling alone or in small groups of 1-3 individuals, although they are sometimes observed swimming in groups as large as ten. They feed primarily on bony fish and squid which are found at or near the bottom of the sea.

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The sangai is an endemic and endangered subspecies of brow-antlered deer found only in Manipur, India. It is also the state animal of Manipur. The brow-antlered deer is a medium-sized deer, with uniquely distinctive antlers, measuring 100–110 cm. in length with extremely long brow tine, which form the main beam. The two tines form a continuous curve at right angles to the closely set pedicels. This signifies its name, brow-antlered deer, the forward protruding beam appears to come out from the eyebrow. The antlers of the opposite sides are unsymmetrical with respect to each other. The beams are unbranched initially whereas curvature increases as length increases and they get forked also. The sexes are moderately dimorphic in body size and weight. The height and weight of a fully grown stag may be approximately 115–125 cm at shoulder and 95 to 110 kg (210 to 230 lb) respectively. The height and weight of the female are shorter and less as compared to the male counterpart. The length of the body from the base to the ear up to the tail is about 145 to 155 cm in both sexes. The tail is short and rump patch is not pronounced.

Culturally, the sangai finds itself imbedded deep into the legends and folklore of the Manipuris. Based on a popular folk legend, the sangai is interpreted as the binding soul between humans and the nature. The slaying of the sangai, an unpardonable sin, is conceived as the rude breaking up of the cordial relationship between humans and the nature. When humans love and respect the sangai, it is respecting nature. In the sangai, therefore, humans find a way of expressing their love for the nature. Socially, the sangai is the symbol of a prized possession of the state.

It is believed that the name sangai (sa "animal" and ngai "in awaiting") was coined from its peculiar posture and behaviour while running. By nature, the deer, particularly the males, even when running for its life stops occasionally and looks back as if he is waiting for someone and hence the name.

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Ozone is an elemental molecule with formula O3. Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere).  Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways.

Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidizing potential, however, causes ozone to damage mucous and respiratory tissues in animals, and also tissues in plants, and above concentrations of about 0.1 ppm. While this makes ozone a potent respiratory hazard and pollutant near ground level, a higher concentration in the ozone layer (from two to eight ppm) is beneficial, preventing damaging UV light from reaching the Earth's surface.

Ozone occurs naturally in the troposphere, mainly due to the release of hydrocarbons from plants and soil that break down in sunlight to nitric acid and oxygen radicals. Natural levels are seldom high enough to cause problems for humans, but the extra ozone from industrial processes and automobiles can cause a number of them. The highly reactive gas damages forests and crops, damages living tissue and causes respiratory ailments in sensitive individuals. Ozone levels in the troposphere aren't constant -- they increase on hot sunny days in metropolitan and other areas of high industrial activity. Ozone is a primary component of smog.

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Greta Tintin Eleonora Ernman Thunberg is a Swedish environmental activist who is internationally known for challenging world leaders to take immediate action for climate change mitigation. Thunberg initially gained notice for her youth and her straightforward speaking manner, both in public and to political leaders and assemblies, in which she criticises world leaders for their failure to take what she considers sufficient action to address the climate crisis.

Seeking to make a greater impact, Thunberg attempted to spur lawmakers into addressing climate change. For almost three weeks prior to the Swedish election in September 2018, she missed school to sit outside the country’s parliament with a sign that stated “Skolstrejk för Klimatet” (School Strike for Climate). Although alone for the first day of the strike, she was joined each subsequent day by more and more people, and her story garnered international attention. After the election Thunberg returned to school but continued to skip classes on Fridays to strike, and these days were called Fridays for Future. Her action inspired hundreds of thousands of students around the world to participate in their own Fridays for Future. Strikes were held in such countries as Belgium, Canada, the United States, the United Kingdom, Finland, Denmark, France, and the Netherlands.

Her sudden rise to world fame has made her both a leader and a target for critics, especially due to her age. Her influence on the world stage has been described by The Guardian and other newspapers as the "Greta effect". She received numerous honours and awards, including an honorary Fellowship of the Royal Scottish Geographical Society, inclusion in Time's 100 most influential people, being the youngest Time Person of the Year, inclusion in the Forbes list of The World's 100 Most Powerful Women (2019), and three consecutive nominations for the Nobel Peace Prize (2019–2021).

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Heat wave, also called heatwave, period of prolonged abnormally high surface temperatures relative to those normally expected. Heat waves may span several days to several weeks and are significant causes of weather-related mortality, affecting developed and developing countries alike.

The term is applied both to hot weather variations and too extraordinary spells of hot which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning. A heat wave is considered extreme weather that can be a natural disaster, and a danger because heat and sunlight may overheat the human body. Heat waves can usually be detected using forecasting instruments so that a warning call can be issued.

Heat waves form when high pressure aloft (from 10,000–25,000 feet (3,000–7,600 metres)) strengthens and remains over a region for several days up to several weeks. This is common in summer (in both Northern and Southern Hemispheres) as the jet stream 'follows the sun'. On the equator side of the jet stream, in the upper layers of the atmosphere, is the high pressure area.

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Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2ml of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 ml O2/liter in a body of water, mass mortality occurs. With such low concentration of DO, these bodies of water fail to support the aquatic life living there. Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated.

Dead zones can be caused by natural and by anthropogenic factors. Natural causes include coastal upwelling, changes in wind, and water circulation patterns. Other environmental factors that determine the occurrence or intensity of a dead zone include long water residence times, high temperatures, and high levels of sunlight penetration through the water column.

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The 2019 Amazon rainforest wildfires season saw a year-to-year surge in fires occurring in the Amazon rainforest and Amazon biome within Brazil, Bolivia, Paraguay, and Peru during that year's Amazonian tropical dry season. Fires normally occur around the dry season as slash-and-burn methods are used to clear the forest to make way for agriculture, livestock, logging, and mining, leading to deforestation of the Amazon rainforest. Such activity is generally illegal within these nations, but enforcement of environmental protection can be lax. The increased rates of fire counts in 2019 led to international concern about the fate of the Amazon rainforest, which is the world's largest terrestrial carbon dioxide sink and plays a significant role in mitigating global warming.

The increased rate of fires in Brazil has raised the most concerns as international leaders, particularly French president Emmanuel Macron, and environmental non-government organizations (ENGOs) attributed these to Brazilian president Jair Bolsonaro's pro-business policies that had weakened environmental protections and have encouraged deforestation of the Amazon after he took office in January 2019.

Other Amazonian countries have been affected by the wildfires in higher or lesser degree. The number of hectares of Bolivian rainforest affected by the wildfires were roughly equal to those of Brazil, being the area of Bolivia only about one-eighth of Brazil's. Bolivian president Evo Morales was similarly blamed for past policies that encouraged deforestation, Morales has also taken proactive measures to fight the fires and seek aid from other countries.

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Microbeads are small, solid, manufactured plastic particles that are less than 5mm in diameter and do not degrade or dissolve in water. They may be added to a range of products, including rinse-off cosmetic, personal care and cleaning products. Microbeads are a relatively cheap ingredient and are used in these products for a variety of purposes. This includes as an abrasive or exfoliant, a bulking agent, to prolong shelf-life, or for the controlled release of active ingredients.

Microbeads are not captured by most wastewater treatment systems. If washed down the drain after use, they can end up in our rivers, lakes, and oceans. These tiny plastics persist in the environment and have a damaging effect on marine life, the environment and human health. This is due to their composition, ability to adsorb toxins and potential to transfer up the marine food chain. The best way to reduce the impact of microbeads is to prevent them from entering the environment in the first place.

Further research needs to be conducted to determine how damaging the beads are for marine life, but current evidence suggests that sea-dwelling creatures at the bottom of the food chain are ingesting the plastic. It is possible that this has wider implications across our food chain as a whole. The fear surrounding marine microplastic pollution has led to a cross-party Environmental Audit Committee warning that increasing amounts of damage to sealife can lead to potential harm to human health, as a result of plastic being ingested and accumulating in marine life such as mussels and oysters.

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Methane (CH4) is the second most important greenhouse gas. It is more potent than CO2, but exists in far lower concentrations in the atmosphere. CH4 also hangs around in the atmosphere for a shorter time than CO2—the residence time for CH4 is roughly 10 years, compared with hundreds of years for CO2. Natural sources of methane include many wetlands, methane-oxidizing bacteria that feed on organic material consumed by termites, volcanoes, seepage vents of the seafloor in regions rich with organic sediment, and methane hydrates trapped along the continental shelves of the oceans and in polar permafrost. The primary natural sink for methane is the atmosphere itself; another natural sink is soil, where methane is oxidized by bacteria.
As with CO2, human activity is increasing the CH4 concentration faster than it can be offset by natural sinks. Human sources (rice cultivation, livestock farming, the burning of coal and natural gas, biomass combustion, and decomposition in landfills) currently account for approximately 70 percent of total annual emissions, leading to substantial increases in concentration over time.

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When we talk about greenhouse gases, we often think of carbon-dioxide (CO2). But did you know nitrous oxide (N2O), also called laughing gas, is a potent greenhouse gas, with ozone-depleting property?

You must be aware that a greenhouse gas is a gas that traps heat in the atmosphere and keeps the planet warm. This process called the greenhouse effect is a good thing. Without it the world would be a frozen, uninhabitable place. However, too much greenhouse gases in the atmosphere can cause the temperature to increase out of control. The more greenhouse gases in the atmosphere, the hotter the earth will become. It changes the Earth's climate system and affect all forms of life.

The main gases responsible for the greenhouse effect include carbon dioxide, methane, nitrous oxide, and water vapour. While carbon dioxide and to some extent methane have gained the recognition as climate change villains, N20 emission has largely been ignored in climate policies, despite its significant contribution to climate change.

A 2020 review of nitrous oxide sources and sinks found that emissions rose 30% in the last four decades. Nitrous oxide is responsible for roughly 7% of global warming since preindustrial times. Most N20 emissions have come from emerging countries like India, China and Brazil.

What are the sources of N20?

Nitrous oxide in the atmosphere comes from both natural and anthropogenic sources. The largest source of nitrous oxide is agriculture (73%), and the majority of agricultural emissions result from usage of nitrogen fertilizers and ill-management of animals waste.

Fossil fuel combustion and industrial processes are the other important source of nitrous oxide emissions. Biomass burning, atmospheric deposition and wastewater treatment are the other sources.

Why is N20 a cause for concern?

Like other greenhouse gases, nitrous oxide absorbs radiation and traps heat in the atmosphere. N20 has a long lifespan in the atmosphere-about 114 years.

N20 is nearly 300 times more potent at warming the planet than carbon dioxide, which means that even small sources of emissions can have a significant impact on the climate.

N20 has emerged as the most critical ozone depleting substance. It is stable in the lowest level of the atmosphere, the troposphere and acts like a greenhouse gas. When it migrates up to the stratosphere, it reacts with ozone and depletes it.

The growing demand for food and feed for animals and increased usage of fertilizers will further increase global nitrous oxide emissions.

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