The Indian Ocean 'garbage patch': Empirical evidence from floating macro-litter.

Area of Science:

• Marine Science
• Environmental Science
• Oceanography

Background:

• Marine litter is a pervasive global issue, with documented accumulation zones in major ocean gyres.
• While the Pacific and Atlantic garbage patches are well-studied, empirical data on marine litter in the Indian Ocean remain scarce.

Purpose of the Study:

• To investigate the distribution and characteristics of macro-litter in the under-researched south-west Indian Ocean during the austral summer 2019-2020.
• To identify potential accumulation zones and assess the prevalence of plastic debris in this oceanic region.

Main Methods:

• Conducted an at-sea survey over 24 days, involving 216 hours of observation and covering 5464 km.
• Systematically recorded and quantified man-made items, focusing on macro-litter, including plastic fragments, packaging, and fishing gear.

Main Results:

• Observed 1623 man-made items, with over 99% being plastics, and nearly 60% of these items were white.
• Floating litter exhibited patchy distribution, with a notable accumulation southeast of Madagascar (30°S; 59-67°E), registering 75.2 items/km².
• Minimal litter (0.1 items/km²) was found south of 40°S, indicating limited distribution in colder, southern waters.

Conclusions:

• The study detected a significant accumulation of marine litter in the southern Indian Ocean, specifically southeast of Madagascar.
• The findings underscore the necessity for continued research and monitoring of marine litter in the south-west Indian Ocean to understand its dynamics and impacts.