Environment, GS-3, Uncategorized

Environment Digest – 27 March – 2 April 2016

Invasive catfish rules Kerala’s reservoirs


Indigenous species are being edged out, putting aquatic biodiversity in peril


Kundala, Mattupetti, Anayirankal, Munnar head works, Shengulam, Ponmudi, Kallarkutty and Lower Periyar dams and in all the tributaries of the Periyar river.

What is a catfish

  • Native to Africa and the Middle East( Clarias gariepinus ), where it inhabits freshwater lakes, rivers, swamps and urban sewage systems,
  • the African catfish was introduced all over the world in the early 1980s for aquaculture purposes.
  • nocturnal predatory fish feeds primarily on living as well as dead animal matter, including fish, invertebrates, and small birds.
  • Its ability to survive in shallow mud for long periods of time and its high tolerance for poorly oxygenated water give it an edge over other native species.
  • It is also capable of hybridising with other catfish, though there is no evidence of that in India.
  • Juveniles weighing 150 grams and adults weighing 2 kg to 7 kg

Why is catfish a threat

  • The presence of the fish in large numbers has led to the disappearance of many of the indigenous species, posing a threat to the aquatic biodiversity.
  • Farmed illegally and revered as sacred, the invasive North African catfish is proliferating in water bodies across Kerala, edging out native aquatic species.

Interestingly, the African catfish are considered sacred in many temple ponds like the Thiruvachira Sreekrishna Temple, Kozhikode, where they are fed by the temple authorities.

Did climate change cause those floods?

“Determining whether extreme weather events are caused by climate change is crucial in planning for risks. Else, we will reach a situation in which corrective action may not be enough to protect us.”

How extreme natural events affect lives

  • Such events typically destroy lives, property and ecosystems while stretching the capacities of disaster management departments and coffers for emergency funds in various parts of the world.
  • There are generally nine kinds of extreme events that are considered: heat and cold waves, droughts, wildfires, extreme rainfall, tropical and other cyclones, extreme snow and ice events, and severe convective storms.

How these events are ‘attributed’

  • After an extreme event there is an interest among people that whether the event was due to global warming
  • Scientists answer these question as to what attributed to the extreme event and whether it was the climate change that triggered the event
  • In order to determine attribution, scientists run climate models to simulate an event or they rely on the observational record from which they may estimate the statistical chance and magnitude of an extreme event

How are they related to climate change

Most such events have one or more components that are not related to climate change.

  • Incompetent forest management practices contribute to fires.
  • Poor land use planning contributed to heavy downpours and floods in Chennai last year.


How scientific studies of extreme events would help

  • Planners, emergency responders, policymakers and insurance companies will have better chance of making a better decision
  • Better knowledge of the risk contributes to how communities, governments, investors and others prepare for the future, with regard to planning cities, proposed infrastructure, natural resources or food security.

International agreements such as the recent Paris climate pact and the global targets for sustainable development set goals for governments and political parties to enable nations and communities to address the risks the world faces in the medium and longer terms.


On the margins in a city of dreams


People are migrating from villages into the cities for a better prospect of life, instead they settle in an area where all the city garbage is collected leading them to a life where they get detached from the basic necessities which are needed to sustain oneself

Why people migrate

They migrate to the city because of distress conditions back home and in expecting a better life in the city

What happens to their life

  • they are uprooted from their social, economic, and environmental context
  • They may put up/rent a hut in the ward, but lose access to workplaces, schooling, water and sanitation, and social capital
  • relocated close to the dumping ground is devastating particularly for children, women, the elderly, and persons with disability or illness.

Why slums unfit for human habitation

  • lack of decent housing
  • lack of potable water
  • no adequate drainage, electricity
  • no welfare services such as public health facilities and government secondary schools

Problems people face while living in the slums

  • With open defecation, acute air and water pollution, and decaying garbage
  • low life expectancy rate, high infant mortality rate
  • Every second child is underweight. Over 90 per cent of pregnant women in 2014-15 were anaemic
  • high instance of maternal mortality.
  • high threat of contracting diseases such as tuberculosis
  • Health Care is inadequate Education is poor


Rare frogs and the circle of life


Frogs are vital to the biodiversity, lesser known species are being ignored because less research and data about them has been compiled.

Western Ghats

  • As a biodiversity-rich mountainous realm of plants and animals, many of which are endemic to the region, the Western Ghats are an acknowledged hotspot.
  • In the Western Ghats the threat level is high for an estimated 40 per cent of amphibian species, even as more are being discovered.
  • The new insights on the life stages of a species of dancing frog in the Western Ghats reported in the journal PLoS

Factors responsible for frog populations

If amphibians are considered indicators of the health of ecosystems, their fate around the world is cause for worry. Of about 7,300 known species, a third are threatened and their populations are declining owing to

  • habitat destruction
  • chemical pollution
  • climate change
  • Disease
  • invasive species
  • other factors.

Various Frogs which are threatened

1.Dancing frog (Micrixalus herrei )

They complete their life cycle only if critical features of the natural landscape are preserved, and human pressure on habitats is consciously reduced.

2.Indian dancing frog

The availability of shallow streams with sandy depressions enables the laying of eggs and development of tadpoles, that then spend some time under the sand.

3.Ancient Purple Frog

From the same region, which surprised the world with its unusual appearance, colour and small size when it was described a dozen years ago, there is a persistent threat in the form of excessive hunting of tadpoles by tribals for food.

Some shortfalls in researching about frogs

  • Since there is less data, there is an urgent to do research about the dwindling population about the frogs who are threatened by various factors
  • Some frogs have hidden phases of life like living in sand like Indian dancing frog mentioned above, so they are not known and not widely discussed and therefore do not find place in rapid environment impact assessments when a project is proposed

What needs to be done

  • Sufficient documentation by newer methods such as DNA barcoding
  • It’s vital that the habitat of amphibians in the Western Ghats, a unique part of the world that has landscapes ranging from scrub to evergreen forests, be given utmost protection as scientists document its richness.
  • Already efforts of scientists are yielding results and tribals are looking for alternatives to mass capturing during the breeding seasons

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