Let’s discuss different kinds of threats to our biodiversity

Hyderabad: This article is in continuation to the previous articles that deal with various topics categorised as biological sciences. These series of articles will help you understand each of the topics under ‘Biodiversity’.

Broadly utilitarian argument:

It explains that biodiversity plays a major role in many  ecosystem series the nature provides, for which we cannot put a price tag (we cannot fix its prices) to exemplify this, consider the following.

Example-1: Forests of Amazon produce 20% of the total oxygen in the earth’s atmosphere.

Example-2: Pollination by pollinating agents (bees, birds, bats etc.,) without which plants do not produce fruits and seeds. There are other benefits also the ones which cannot be measured in terms of money, like aesthetic pleasure derived by taking a walk in the woods.

Ethical argument:

It relates to what we owe to plants, animals and microbe species with which we co-exist on the planet. The moral duty to care and pass on biological legacy to future generations is the need of the hour as every species has an intrinsic value.

Threats to Biodiversity:

The following are the four major causes (The evil quartet) for accelerated rates of species extinction in the world.

* Habitat loss and fragmentation

* Over exploitation

* Invasion of alien species

* Co-extinctions

Habitat loss and Fragmentation:

Following are the most important reasons, for the loss of biodiversity.

* Deforestation-leads to species extinction in forests

Example: Tropical rain forest once covering 14% of the earth’s land surface is now not more than 4%

* Conversion of forest land to agricultural land

Example: Amazon Rain forest, called “Lungs of our planet” harbouring innumerable species is cut and cleared to cultivate soya beans/conversion to grass lands for raising beef cattle.

* Pollution enhances degradation of habitats and threatens the survival of species as pollutants change the quality of the environment.

* Fragmentation of habitat leads to population decline.

Example: mammals and birds requiring large territories and certain animals with migratory habits are badly affected.

Over exploitation: When need turns to greed it leads to overexploitation.

Example: Staller’s sea cow, passenger pigeon are extent due to over exploitation by humans. The existences of many commercially important marine fishes are endangered as they are over harvested.

Invasion of Alien species:

When alien species are introduced into a habitat, they turn invasive and establish themselves at the cost of the indigenous species, consider the following–

Example-1: Nile perch introduced into Lake Victoria, in East Africa led to the extinction of 200 species of Cichlid fish In the lake.

Example-2: Illegal introduction of exotic African catfish, clarias garie pinus, for aquaculture purpose is posing a threat to the indigenous cat fishes.

Example-3: when exotic and invasive weeds like the carrot grass (Parthenium), Spanish flag (Lantana), water hyacinth (Eichhornia) are introduced in to our ecosystems, they not only damaged the environment but also threatened the very existence of native species.

Co-extinctions:

In an obligate association between a plant and animals, if a plant becomes extinct, the animal also becomes extinct as seen in a parasite and host association if the host becomes extinct, parasite meets the same fate.

Another association which explains co-extinctions in plant-pollinator mutualism where extinction of one invariably leads to the extinction of other.