Invasive species: Its adaptability and harmful effects
- Dr Chetan A Gaonkar
- 12 February 2017
- The Goan
The introduced species which are new to the environment can cause serious problems to the native biota. They can be severely damaging to the local flora and fauna through their over competitive nature. There are over 18 different species of plants and animals that are reported along the Indian coastline that might have got invaded and established 1, 2. This article highlights some of the well-known invasive species in the marine environment, its harmful effects, and points out the adaptability needed in an organism to succeed in a new environment.
Instances of Marine Bioinvasion:
The success of invasion of an organism in a new environment depends on a range of factors such as: its adaptability in terms of resistance to grazers and predators, high tolerance to different abiotic factors, high reproduction potentials and/or fast vegetative growth, capability of organisms to reproduce hermaphroditically, and their ability to hibernate or rejuvenate under unfavourable/favourable environmental settings 2. Many cases of marine bioinvasion have been reported and their harmful effects on the ecosystem have been documented 1,2.
Few examples are as under:
- Mnemiopsis leidyi: It's an opaque comb jellyfish of about 10 cms long. It entered the Black Sea in the early 1980s through ballast water of a ship from the United States. M. Leidyi encountered no predators in the Black Sea but plenty of food. It fed on the eggs and larvae of a wide variety of fishes which ultimately led to a collapse of the fishing industry. The fish catch fell by 90% in six years and the total biomass of M. Leidyi in the Black Sea had reached an estimated 900 million tonnes which was nearly 10 times the total annual fish catch of the entire world's oceans 7.
- Dreissenapolymorpha: Commonly called as zebra mussel, it was first discovered in North America in the year 1988. This species is a native of Europe and is reported to have been introduced in 1984 from ballast water which contained planktonic larvae oryoung adults of this species 3. It has now spread to more than 40% of the United States waters.
- It fouls the cooling water intakes of the industry, and might have costed billions of dollars in its control measures since 1984 5.
- Carcinus meanas: Commonly called as green crab, it is a native of Europe and has now invaded the west coast of North America, South Africa and Australia. It is also found in Sri Lankan waters. It mostly feeds on crustacean and molluscs thus influencing the native biota of the region where it is introduced.
- Mytilopsis sallei: Commonly called the black-stripped mussel, this species has been reported from India (Mumbai and Visakhapatnam) 4,6. This is a native of tropical and subtropical Atlantic waters and is reported to have invaded the Indian waters sometime during the 1960s. This species has also been reported from Hong Kong and Australian waters.
- The International Maritime Organization (IMO), with funding provided by Global Environment Facility (GEF) through the United Nations Development Programme (UNDP) has initiated the Global Ballast Water Management Programme (GloBallast). For this programme, six countries were identified for its initial phase (China, India, Iran, South Africa and Ukraine). Mumbai port was chosen as the demonstration site for this activity in India.
CSIR-National Institute of Oceanography, Goa has been identified by the Ministry of Shipping, Govt, of India as a lead R & D agency for helping the ministry in addressing ballast water management issues in India and preparing comprehensive port specific management plans for the country.
Facts & Figures
- Bioinvasion through shipping has been recognized as a growing environmental threat.
- Over 90% of the world's cargo is mobilized trans-oceanically through shipping.
- Black-stripped mussel, Mytilopsis sallei, has been reported to have invaded the Indian waters sometime during 1960s.
- India being one of the major maritime countries is susceptible to bioinvasion from the rest of the world’s oceans, and hence warrants a close monitoring of its port environment.
- Measures such as Open Ocean exchange of Ballast water, treatment of ballast water onboard before releasing and treatment facilities at the ports are some of the important precautions, which needs to be taken.
References: (1) Anil A.C, Venkat K., Sawant S.S., Dileepkumar M., Dhargalkar V.K., Ramaiah N., Harkantra S.N., Ansari Z.A. 2002. Marine bioinvasion: concern for ecology and shipping. Current Science 83 (3): 214-218 Anil A.C. (2012). A perspective of marine bioinvasion. Eds: S. Sonak. TERI Press:203-213. (3) Ahlstedt S.A. (1994). Invasion and impacts of the zebra mussel in the United States. Journal of Shellfish Research 13:330-333.(4) Globallast. 2001. Stopping the ballast water stowaways London: International Maritime Organization. 8 pp. [Global Ballast Water Management Programme, March 2001, International Maritime Organization] (5) Karande AA, Menon KB (1975). Mytilopsis sallei, a fresh immigrant in Indian harbours (vol. 7, pp. 455-466), Bulletin Department of Marine Science, University of Cochin. (6) Pearce F. 1995 How the Soviet seas were lost New Science 2003:38-42 (7) Pearce F. (1995). How the Soviet seas were lost New Science 2003:38-42 (Note: Reference numbering in the above section will change since the 3rd reference is newly added)