Why is it in the News?
- A recent study by CSIR-National Institute of Oceanography (Goa) and Academy of Scientific and Innovative Research (Ghaziabad) revealed significant microplastic contamination in commercially important fish along the Goan coast, highlighting risks to fish health, human consumers, and coastal livelihoods.
- Published in Environmental Research (August 2025), the study provides first-of-its-kind detailed analysis for the Mandovi estuarine system, which contributes 97% of Goa’s fish output.
Relevance:
- GS 3 – Environment & Ecology
- Pollution of aquatic ecosystems, plastic pollution, marine biodiversity loss.
- Bioaccumulation and trophic transfer of pollutants.
- GS 2 – Governance
- Policy implications: Waste management, regulation of fishing gear, biodegradable alternatives.
- Coastal livelihood protection and public health measures.
Basic Concepts
1. Microplastics
- Tiny plastic particles (<5 mm) from degraded fishing gear, wastewater, packaging, textiles, and tire residue.
- Persist in marine environments due to non-biodegradability.
2. Bioaccumulation & Trophic Transfer
- Bioaccumulation: Microplastics ingested by small organisms accumulate in larger predators.
- Trophic transfer: Microplastics move up the food chain, eventually reaching apex predators and humans.
3. Estuarine Ecosystems
- Ecologically critical zones supporting juvenile fish, filter feeders, and commercial species like anchovy, sardine, and mackerel.
- Highly vulnerable to pollution due to shallow waters and sediment accumulation.
Key Findings of the Study
| Aspect | Observation |
| Sample Studied | 251 fish across 9 species (finfish and shellfish) from various depths in Mandovi estuary |
| Microplastic Particles Found | 4,871 total; 3,369 plastic polymers (19 types) |
| Source of Pollution | Fishing material, wastewater, e-waste, textiles, tire residue, packaging |
| Distribution in Water Column | Benthic (sea floor/sediments) > Pelagic (open water) |
| Species-wise Concentration | Anchovy: 8.8 MP/ind (pelagic), Catfish: >10 MP/ind (benthic), Bamboo shark: 3.5 MP/ind (apex predator) |
| Accumulation Patterns | Longer-bodied fish accumulate fewer particles; more in digestive tract than gills |
| Shapes of Microplastics | Fibres (53%), Fragments (29.9%), Films (13.1%), Beads (4%) |
| Colours | Blue (37.6%), Black (24.3%), Red (12%), Others (discoloured, transparent, green, pink/purple, yellow, orange) |
| Health Effects on Fish | Oxidative stress, gene disruption, reproductive impairment, lower growth |
| Health Risks for Humans | Immune dysfunction, neurotoxicity, higher cancer risk |
| Economic & Livelihood Risks | Declining fish quality may reduce market demand, affecting coastal fishing communities |
Why It Matters
Public Health
- Fish are protein-rich staples; consumption of contaminated fish poses serious health risks.
Environmental Concerns
- Demonstrates the pervasive nature of plastic pollution, especially in benthic habitats.
Policy Implications
- Urgent need for better waste management, fishing gear regulation, and research into biodegradable alternatives.
Socioeconomic Impact
- Coastal communities dependent on fisheries face livelihood threats if fish quality declines.
Quick Revision
- Mandovi-Zuari Estuary: 97% of Goa’s fish output.
- Bioaccumulation & Trophic Transfer: Microplastics move from plankton → small fish → large predators → humans.
- Microplastic Types: Fibres > Fragments > Films > Beads.
- Key Risk Group: Benthic fish (close to sediments) > Pelagic fish.
- Human Health Concerns: Immunotoxicity, neurotoxicity, cancer risk.
- Source Identification: Microplastic shape and colour help trace origin.
