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.