Abundance and distribution of subsurface microfibres and seabed macrolitter in Thoothukudi, Gulf of Mannar, South-east coast of India

Aim: Considering the potential harm caused by plastic pollution to the marine ecosystem, the present study was conducted to elucidate the status of microfiber and macrolitter in the selected areas of Thoothukudi on the South-east coast of India. Methodology: The abundance and distribution of subsurface microfibers in four locations of Tuticorin inshore waters were estimated by filtering subsurface waters using a 250µm mesh epineuston net. The non-biodegradable macrolitter on the seabed at three locations of Thoothukudi was estimated by swept area method. Results: Among the four selected stations, a higher quantity of microfibres was observed in the subsurface waters at 5m depth close to nearshore areas, with the highest mean numerical abundance of 3.13±0.3 nos.m l-1. The annual difference in the subsurface microfibre abundance varied significantly between stations (p<0.05). Plastics were the most dominant litter constituents on the sea beds among three stations. A significant seasonal variation (p<0.05) with maximum mean total macrolitter abundance was noticed on the seabed at Kayalpattinam (45.81± 9.3 kg km-2). The estimated mean macrolitter abundance at all the stations was higher than the reported national average of 10.95±3.05 kg km-2. Interpretation: This study revealed variations in the abundance and distribution of microfibers and macrolitters in the selected areas of Tuticorin. The study emphasises the role of land and marine-based anthropogenic activities in the plastic pollution of this region. Key words: Abundance, Gulf of mannar, Microfibres, Macrolitter, Subsurface waters, Seabed