What are the consequences of spreading of “Dead Zones” on marine ecosystem? (Answer in 150 words)

Marine dead zones are areas of severe hypoxia, usually created when excess nitrogen and phosphorus stimulate algal blooms whose decomposition consumes dissolved oxygen.

Ecological consequences

• Fish, shellfish and benthic organisms suffocate or migrate, causing mortality and biodiversity loss.
• Food webs are disrupted; habitat compression reduces nursery grounds and alters predator–prey relations.
• Some blooms release toxins, threatening marine animals, coastal communities and food safety.
• Hypoxia changes nutrient cycling and can release phosphorus, reinforcing eutrophication; certain microbes generate nitrous oxide.

Socio-economic effects

• Declining fish stocks damage fisheries, aquaculture, tourism and coastal livelihoods.
• Species displacement can create transboundary conflicts over shared waters and resources.

Keywords: UPSC GS1; inclusive development; constitutional values.

Controlling fertiliser runoff, sewage and industrial discharge through watershed management, wastewater treatment and ecosystem monitoring is essential to restore oxygen balance.