Jellyfish Blooms in Kerala

GS3 – Environment

Context

Sudden jellyfish blooms have been observed in Kerala’s Cochin backwaters, raising ecological and economic concerns.

What is a Jellyfish Bloom?
  • A dense aggregation of jellyfish triggered by environmental changes, typically during April–May and October–December across Indian coasts.
Species Reported:
  • Acromitus flagellatus, Blackfordia virginica, Pleurobrachia sp., Pelagia noctiluca.
Causes:
  1. Nutrient Overload: Eutrophication from agricultural runoff increases phytoplankton, jellyfish prey.
  2. Environmental Degradation: Warming waters and pollution deplete oxygen, favouring jellyfish over fish.
  3. Coastal Dynamics: Tides, winds, and currents push jellyfish toward shores, increasing bloom density.
Kerala’s Unique Bloom Pattern:
  • Extended Bloom Periods compared to other coasts.
  • Persistent Salinity: Backwaters remain saline during dry months, supporting jellyfish survival.
  • Low River Discharge: Delays flushing of jellyfish out to sea.
  • Tidal Mixing: Maintains warm conditions suitable for bloom persistence.
Impacts:
  • Fisheries Affected: Jellyfish block fishing nets, damage gear, and reduce fish catch.
  • Tourism Losses: Jellyfish stings deter beach tourism, affecting local economies.
  • Ecosystem Imbalance: Jellyfish dominate degraded environments, lowering biodiversity.
  • Biogeochemical Shifts: Blooms speed up organic matter decomposition and disrupt nutrient cycles.
About Jellyfish:
  • Belong to phylum Cnidaria, soft-bodied, gelatinous, and unable to resist strong ocean currents.
  • Found in marine and brackish ecosystems across climate zones.
  • Highly responsive to variations in temperature, salinity, and nutrient concentration.
Positive Ecological Roles:
  • Zooplankton Regulation: Feed on small organisms, maintaining ecological balance.
  • Nutrient Cycling: Decaying jellyfish contribute to coastal nutrient flows.
  • Biochemical Applications: Being researched for use in nutraceuticals and pharmaceuticals.

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