Fishermen of Pulicat and Ennore are raised concerns over the spread of an invasive species of mussel that is a threat to the prawns of both waterbodies.

 

What is a ‘mussel’?

  • Mussel is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.
  • The word “mussel” is frequently used to mean the bivalves of the marine family Mytilidae, most of which live on exposed shores in the intertidal zone, attached by means of their strong byssal threads (“beard”) to a firm substrate.  A few species (in the genus Bathymodiolus) have colonised hydrothermal vents associated with deep ocean ridges.
  • In most marine mussels the shell is longer than it is wide, being wedge-shaped or asymmetrical. The external colour of the shell is often dark blue, blackish, or brown, while the interior is silvery and somewhat nacreous.
  • The common name “mussel” is also used for many freshwater bivalves, including the freshwater pearl mussels. Freshwater mussel species inhabit lakes, ponds, rivers, creeks, canals, and they are classified in a different subclass of bivalves, despite some very superficial similarities in appearance.

 

Details

  • The marine biologists identified these species as Mytella strigata or Charru mussels which are Native to South America.
  • These mussels have invaded tidal wetlands in several parts of the world, including Vembanad in Kerala. This is spreading due to the discharge of ballast waters from ships visiting the ports of Kattupalli.
  • After Cyclone Vardah in December 2016, the mussels began to intensify and spread far north towards the Pulicat waters.
  • Human interference in the wetlands, pollution and nature’s actions have triggered the rapid spread of the species.
  • Threats — These mussels spread like a carpet over the river bottoms and thus preventing prawns from grazing or burying themselves in the sediment.
  • Its spread is wiping out the locally prevalent yellow clams and green mussels.