The Silent Bell of Doom--The Sixth Mass Extinction and Amphibian Tragedy (2020s)

The Silent Bell of Doom--The Sixth Mass Extinction and Amphibian Tragedy (2020s)

The reason why the present era is called the "New Great Extinction Era (the Sixth Mass Extinction)" is because of the rapid loss of biodiversity on the planet due to human activities.

Normally, extinction of species in nature proceeds very slowly. Today, however, the rate of extinction is tens to hundreds of times faster than the natural background rate, and organisms are disappearing at an alarming rate. Deforestation, agricultural development, urbanization, climate change, overhunting, invasive alien species, environmental pollution - human activities are destroying ecosystems on all fronts, with serious consequences for the entire planet. In the past, the earth has experienced mass extinctions on five occasions. The famous extinction of the dinosaurs 66 million years ago (the mass extinction at the end of the Cretaceous Period) was caused by natural phenomena such as meteorite impacts and massive volcanic eruptions. In contrast, the sixth mass extinction, which is currently underway, is decidedly different in that it is the result of mankind's own handiwork.

The sixth mass extinction is characterized by more than just a reduction in the number of species. It is in the fact that all life forms are being affected simultaneously in all areas of the world, on land, in the oceans, and in the air.

In amphibians, for example, about 40 percent or more of the world's species, including frogs and salamanders, are threatened with extinction. In Latin America and Australia, the spread of an exotic chytrid fungus (Batrachochytrium dendrobatidis) has decimated many species. Amphibians are on the front lines of extinction because they are skin breathers and extremely sensitive to environmental changes.

Among large mammals, African elephants and black rhinoceroses have been drastically reduced due to poaching and habitat destruction. The black rhino population was approximately 200,000 at the beginning of the 20th century, but has now declined to less than about 5,500.

A similar tragedy is underway in birds. Island birds in particular, such as the honeycreeper in Hawaii, are undergoing mass extinction due to exotic species and disease. About 14% of the world's bird species are in danger of extinction.

In addition, studies in Germany and Puerto Rico have shown that wild insect populations have declined by more than 70 percent in the past few decades. Habitat loss due to pesticide use, climate change, and urban development are the main causes. The collapse of insects has serious consequences for pollination, soil fertility, and the food chain, with ripple effects throughout the ecosystem.

Turning to the ocean, large-scale mortality has been observed in Australia's Great Barrier Reef, where coral bleaching is progressing as a result of rising sea temperatures. Coral reefs are ecosystems on which a quarter of all marine life depends, and the loss of coral reefs will fundamentally shake the biodiversity of the ocean.

Among the most serious reasons why amphibians are particularly at risk. Because they absorb water and oxygen directly through their skin, even the slightest environmental degradation, such as air and water pollution or increased ultraviolet radiation, can be fatal. Because of their role as ecological alarmists (bioindicators), amphibians are among the first to suffer.

Furthermore, because amphibians raise their eggs and larvae in water and live on land after growth, they require the health of both the aquatic and terrestrial environments. If the environment is compromised in one or the other, populations are rapidly decimated. This dual dependence of amphibians has become a critical vulnerability in today's rapidly changing environment.

In addition, new infectious diseases, such as chytrid fungus, have spread around the world through international human trade and pet transport. Immune-less amphibians were left helpless against these pathogens and were pushed to the brink of extinction.

Amphibian habitats are rapidly disappearing. Wetlands, forests, ponds, and other natural environments they need are being destroyed one by one by development and agricultural expansion. In particular, the rate of loss of wetlands has exceeded that of deforestation in some areas.

Thus, amphibians are inherently vulnerable to environmental change and are the group of organisms most acutely affected by the rapid pace of human activity today. Their extinction would not be limited to the loss of a single biome, but would threaten to disrupt the balance of the food chain and disrupt the entire ecosystem in a chain reaction.

The sixth mass extinction - the one we are living in at this very moment - is quietly but surely underway.