My Science School

The planet is home to billions of organisms and none of them (including humans) exists on its own. We are all dependent on each other for our survival. Symbiosis is the umbrella term used to refer to such interactions among animals, birds and plants of different species living together. There are five main symbiotic relationships: mutualism, commensalism, predation, parasitism, and competition Mutualism is the relationship where both the species benefit from each other, in commensalism one species benefits from another, while the other remains unaffected in predation and parasitism, one benefits by harming the other while a predator kills its prey immediately, a parasite lives at the expense of the host species and may kill it over time Competition is the struggle between different species to utilise the same limited resources Today, let’s take a look at some of the species that share mutualistic relationship with each other.

Zebra and Ostrich

Zebras and ostriches are perfect examples of friends having each others' back. Herds of zebras and of ostriches often travel across the open African plains together and they warn each other of danger. Ostriches have a poor sense of hearing and smell, while zebras have a poor eyesight. Zebras look out for potential threats to the ostriches by using their exceptional hearing skills, while the far-sighted ostriches stay vigilant towards the zebras predators by scanning the grassland and spotting threat from afar.

Clownfish and Anemone

There are 30 species of clownfish and all of them form a mutual relationship with anemones. They are even called anemonefish. A sea anemone is a predatory marine animal that lives attached to rocks and catches prey by injecting venom from its tentacles. Clownfish are immune to the anemones venom and actually live within their tentacles. While sea anemones provide protection to the clownfish, the fish clean the anemones tentacles, keeping them free from parasites. Clownfish also lure anemones prey towards the tentacles by acting like baits.

 Humans and Honeyguide bird

An African bird called the greater honeyguide is famous for sharing a friendship with hunters. It helps humans locate bees’ nests to harvest honey. Honeyguides give a special call to attract people's attention, then fly from tree to tree to indicate the direction of a bees' nest. While humans get honey, the birds get to feast on bee larvae and wax. Honeyguide perhaps consider humans useful collaborators because of our ability to control stinging bees with smoke and use tools to open the honeycomb, which the bird cannot do on its own.

Ants and Aphid

Several species of ants and aphids share a well-documented mutualistic relationship. Aphids are small insects that feed on the sap from plants and secret a sugary-liquid called honeydew. This secretion is quite enjoyed by some species of ants. The ants milk the aphids by stroking them with their antennae and in return, the ants protect the aphids, pretty rigorously, from predators and parasites.

The ants ensure the aphids are well-fed. They move the insects to a new plant when the nutrients from the host plant are exhausted. Some species of ants go to the extent of destroying aphid predators' eggs. Some species of ants care for the eggs of aphids by transfering them to their own nest during winter. When the eggs hatch, the ants carry the newborns to host plants to feed. They secret the sugary meal for the ants and the cycle continues.

Bat and Pitcher plant

Pitcher plants are carnivorous plants that trap their insect preys by luring them with nectar. The unassuming insects fall down the slippery slope and eventually drown in the digestive liquid of the plant. While we might think it would be prudent for animals to avoid these plants, woolly bats voluntarily clamber inside the plants - to roost. They share a mutually beneficial relationship with the plants. So what does the plant get in return for subletting its comfy room to the mammal? Poop. The bat guano (waste) is rich in nitrogen, a crucial plant nutrient, you see!

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Places where the land meets the sea are crucial for our planet to function. They support biodiversity and the livelihoods of billions of people. But due to pressure caused by human activity, only 16% of coastal areas around the world remain intact, according to a study. The research, involving an international team of experts, revealed an alarming story.

An international team led by researchers at the University of Queensland in Australia has mapped the impact of human-caused pressures on coastal regions to identify those that have been already highly degraded, and those that remain intact. The findings, published in the journal Conservation Biology, provide insights into the widespread impacts of human activity on Earth's precious coastal ecosystems.

What did the study find?

The research looked at two datasets - one focussed on human impacts on land, and the other observed human impacts from a marine perspective. Both maps use data up to the year 2013 - the most recent year for which cohesive data is available.

• Coastal regions containing seagrasses, savannah, and coral reefs had the highest levels of human pressure compared to other coastal ecosystems.
• More than half the coastal regions have degraded in 84% of countries.
• Earth's 47.9% of coastal regions have been exposed to very high levels of human pressure.
• Human pressures were high in about 43% of protected coastal regions.
• Scientists believe that some coastal regions have been so degraded that they cannot be restored.

Where are the highly damaged coastal regions located?

High levels of degradation are found in island nations, much of Europe, and in countries including Vietnam, India and Singapore.

Which are the intact regions?

Many of the intact coastal regions are in Canada, followed by Russia and Greenland. Large expanses of intact coast are also found elsewhere including Australia, Indonesia, Papua New Guinea, Chile, Brazil and the United States.

Why are coasts vital?

• Coastal regions encompass some of the most diverse and unique ecosystems on Earth. They include coral reefs, kelp forests, seagrass, tidal flats, mangroves, estuaries, salt marshes, wetlands and coastal wooded habitats.
• Many animal species, including those that migrate, rely on coastlines for breeding, foraging and protection.
• Coastal sites are also where rivers discharge, mangrove forests exchange nutrients with the ocean, and tidal flows are maintained.
• Humans also need coastlines. Among other functions, they support our fisheries, protect us from storms and, importantly, store carbon to help mitigate climate change.

How is human activity impacting the coasts?

As much as 74% of the human population live within 50km of the coast, and humans put pressure on coastal environments in myriad ways. In marine environments, these pressures include:

• Fishing at various intensities
• Water and light pollution
• Recreation and tourism
• Shipping
• Climate change and associated issues such as ocean acidification, sea-level rise and increased sea surface temperatures.

On land, human pressures include:

• Coastal development
• Infrastructure development
• Agriculture and pasture lands
• Clearing of land for settlement
• Plastic and other forms of land pollution

What should governments do?

Governments should take steps to conserve the coastal regions that remain in good condition, while restoring those that have been degraded but can still be fixed.

Other actions should include improving environmental governance and laws related to encroachments, increasing well-resourced protected areas, mitigating land-use change to prevent increased pollution run-off, better community and local engagement, strengthening indigenous involvement in managing coastal regions, effective management of fishing resources, addressing climate change and tackling geopolitical and socioeconomic drivers of damage to coastal environments.

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Greta Thunberg, the young climate activist, in her famous speech "Blah, Blah, Blah..." made at COP26 conference at Glasgow in November last year spoke about how climate summits are becoming 'greenwashing' festivals. She attacked CO2 offset commitments by corporates as just a greenwash. We have all heard of brainwash" and whitewash". Now what is greenwash?

When companies and organisations mislead their consumers by claiming that a product or service they provide, or that their organisation itself is environmentally friendly or sustainable, when it actually is not, it is called greenwashing. Greenwashing is not a new concept. The term was originally coined by environmental activist Jay Westerveld in the mid-1980s.

How does this happen?

From high-end cars to toilet papers, everything these days carries a label claiming that it is green or eco-friendly. But more often than not, they are half truths. Sometimes labels are vague, poorly defined, or so broad that their real meaning is likely to be misunderstood by the consumer. Some products are simply labelled 'green' without any proof or certification by authorities concerned.

As for CO2 offset" commitments, environmentalists are of the view that offsets are a way for companies to continue polluting while funding projects to adopt climate-friendly behaviours elsewhere.

It's a matter of concern

Why are corporations falling all over themselves to demonstrate that they are environmentally conscious? While some of the claims may be genuine, most are just marketing tools to drive profit, rather than to take environmental responsibility. In the face of climate crisis, consumers are more cautious of buying environment-friendly products. They're also likely to spend the extra amount it takes to acquire the so-called eco-friendly goods. It is essentially exploitation as companies prioritise financial gain over being eco-conscious.

• Brainwash is to make someone believe something by repeatedly telling them that it is true.
• Whitewash is to make something bad seem acceptable by hiding the truth.
• Carbon offset refers to the measures taken by a company or organisation to reduce or remove emissions of carbon dioxide or other greenhouse gases elsewhere to compensate for the emissions made by it for its business.

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Starlings are medium-sized passerine birds that are famous for gathering in huge flocks and moving across the sky in sync to form startling ‘murmurations’. Between October and February every year, millions of starlings migrate from northern Europe to Central and Southern Europe to escape the cold. But scientists have lately observed that warmer temperatures in northern European caused by climate change have shortened the starlings' stay in Southern parts. Studies have predicted that warmer temperatures could also make starlings advance their breeding period.

Though one would be fascinated by the sheer number of the birds in the flock (pre-roost murmurations have been known to number as many as 1,00,000 birds), many roosts are significantly smaller than they used to be due to population decline. Lack of food and habitat loss, partly driven by climate change, have put some of the starling species on the IUCN red list in various Europe countries. (IUCN- International Union for Conservation of Nature). Starlings are not alone in this struggle. Many birds around the world are impacted by climate change. The timing of bird’s migration, nesting, hatching, and feeding are adapted to specific conditions, such as the availability of suitable habitat and adequate food sources. These factors make birds particularly vulnerable.

Here is a closer look at the threats faced by birds due to a warming planet.

Migration pattern

The impact of climate change on birds migration patterns has been noticed in the last few decades. Scientists have documented that fewer birds show up in breeding and wintering grounds and they attribute it to the increasing temperatures, changing vegetation, and extreme weather conditions.

Birds synchronise their migratory movements with seasonal changes. The start of their journey and their speed must match the life cycle (before caterpillars pupate) of food sources at the stopover and destination sites. But these environmental cues go for a toss with changing climate.

Habitat loss

One of the major effects of climate change is the loss of habitats. While some species face shrinking ranges, others face habitat destruction. For migrating birds, flooding or desertification could spell doom. Flocks might fly thousands of kilometres only to find their destination submerged or barren. Many goose species use the Siberian tundra's rocky bedrock to raise their offspring. But increasing temperatures make the permafrost soil to thaw and change the habitat completely, making it impossible for the geese to breed.

Lack of food

A number of birds has adjusted breeding times to match early Spring. They arrive at the breeding site earlier than before.

Meanwhile, increasing temperatures also make the vegetation bloom and insects hatch earlier at the site. But sometimes these shifts are not in line with each other. As a result, the chicks hatch way after the caterpillars are gone. And so, they starve. (On average, the window of time when birds lay their eggs has gotten earlier by almost two weeks over half-a-century. Since many small songbirds can raise their young in roughly one month, two weeks is a big shift in their timing.)

Sea-level rise

Sea-level rise and erosion alter coastal wetlands. Many birds, such as piping plovers, that inhabit coastal areas lay their eggs directly on the sand of the beach in a shallow depression. The erosion of beaches and storm surges can cause nests to be lost to the ocean.

Smaller body, larger wings

A study published in December 2019 found that global warming was causing birds to shrink and their wingspans to grow in size. Scientists explained that it could be an adaptation of birds as smaller birds are better at cooling off, losing, body heat more quickly due to their larger surface-area-to-volume ratios. But smaller body size means less energy available for the birds to complete long journeys. Scientists say that birds would have evolved to grow long wings to compensate for their smaller bodies as it helps them survive migration.

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