Invasive Species

Ballast water bringing invasive species to coast: Scientists fear that the expansion of seaports and minor ports could pave the way for the arrival of invasive species in coastal areas. It is because the ballast water carried by ships is providing a vehicle to bring in exotic species. Ballast is a compartment in a ship that provides it stability. It holds water which moves in and out of it to balance the ship. It remains below the water level, to counteract the weight above the water level. Ballast water is discharged when the ship enters a new port, releasing alien organisms into the local waters.

What do you understand by ‘invasive species’? How do they alter local ecology? Illustrate with suitable examples. (200 Words)
Invasive species maybe termed as species, who either naturally or by anthropogenic activities, ‘invade’ habitats which they do not originally belong to. Invasive species have an impact on local ecology in the following ways:
  1. Due to their high reproductive capabilities, most invasive species have the capabilities to displace local counterparts and disrupt ecosystems.
  2. They also disturb the ecological balance, by wiping out prey species which do not see them as a threat, like the pythons in Florida are doing to wood rats and other species.
  3. They also compete for resources against the local species. Alligators and pythons have been competing for food and space in the everglades recently.
  4. Invasive species sometimes adapt by preying on their local cousins, like Asian lionfish when introduced into American markets preys on the local species.
  5. Sometimes, invasive species like snakes and other venomous reptiles can be dangerous to human lives as well.
Some invasive species, like the Himalayan blackberry have positive effects as well in the form of edible fruits eaten by both humans and animals. But most invasive species have detrimental and insidious effects on the local populations and have to be controlled, and in some cases eradicated.
Examples of invasive species:
Three most dangerous invasive species include:
  1. Nile Perch: Introduced in lake Victoria led to extinction of Lake Victoria in east Africa led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake.
  2. African Catfish: It was introduced to improve aquaculture but currently it is posing threat to indigenous catfishes.
  3. Lantana: They came from Central and South America and are spread in South Africa . They competes and replaces indigenous species.
Measures to address threat:
  1. There should be effective mechanisms to prevent their introduction in first instance.
  2. There should be monitoring of pathways from where these species enter . For example Canada is suffering from aquatic invasive species problem . The pathway through which they enter Canada is shipping, boats; the best example being zebra mussels which is an invasive species in Great Banks.
  3. Newly detected invaders should be removed quickly as these species have a tendency to multiply because they have no predators in new environment .
  4. There are certain sites that are vulnerable or potential sites for invasion , a careful assessment of such sites needs to be done.
  5. Biological control is another method in which invaded species are eaten up by another species ,it works well for invertebrates.



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