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Ocean blooms: the rise in jellyfish numbers, a concern for marine ecosystem

  • Posted By
    10Pointer
  • Categories
    Environment
  • Published
    8th Feb, 2021

Context

A substantial increase has taken place in the population of jellyfish due to increasing sea temperature in the Arabian Sea.

What are the causes of the increase in the number?

  • Increasing global warming
  • Rise in sea temperature
  • Increase of extreme climatic events or disaster weather events 

The increase occurred at Gulf of Mannar and Andaman and Nicobar Islands which are mostly coinciding with El Nino events indicative of an increase in sea surface temperature.

El Niño and the Southern Oscillation (ENSO)

  • El Niño and the Southern Oscillation (ENSO) is a periodic fluctuation in sea surface temperature and the air pressure of the overlying atmosphere across the equatorial Pacific Ocean.
  • ENSO has a major influence on weather and climate patterns such as heavy rains, floods and drought.
  • El Niño has a warming influence on global temperatures, while La Niña has the opposite effect.

Impacts of the rise in Jellyfish numbers

  • Reduction in sardine fishery: The proliferation of jellyfish has also resulted in the overfeeding of sardine larvae, leading to a considerable reduction in sardine fishery.
  • Frequent coral bleaching: It has increased the frequent bleaching at the coastline.
  • Economic impacts: Jellyfish swarms and beach strandings have increased which has led to adverse impacts on aquatic ecology and human enterprises like clogging of fishing nets and disruption of tourism.

Important facts on Jellyfish

  • Jellyfish (Cnidaria) belongs to the phylum Cnidaria.
  • They are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles.
  • The tentacles are armed with stinging cells and may be used to capture prey and defend against predators.
  • Life cycle: the medusa is normally the sexual phase, which produces planula larva that disperses widely and enters a sedentary polyp phase before reaching sexual maturity.