Plastic pollution in an estuary: A preliminary study on the Rupsha river in southwestern Bangladesh

Plastic pollution is one of the major threats to the biodiversity of coastal mangrove forest Sundarbans. The current research focused on the preliminary assessment of plastics load to benthic biodiversity in a major estuary, the Rupsha in southwestern Bangladesh. Visual studies were conducted at five different sampling sites based on human activities, viz Kalibari ghat (S1), Rupsha ferry ghat (S2), Lobonchora ghat (S3), Rupsha bridge ghat (S4) and Putimari ghat (S5 as reference site).  Thirteen (13) different plastic types under three categories were identified from the five-study sites. These categories belong to (i) fishing related debris: net, line, buoy, other fishing materials (ii) domestic useable plastics: bottle, bucket, bag/film, foamed polystyrene and polythene, and (iii) category of other types including packet, rope, pipe and shoes. Among all types, packet and polythene were the most abundant in number and both of them were the highest in number in Rupsha ferry ghat (8.67±3.79 for polythene and 9.33±5.86 for packet) whereas lowest in S5 (0.67±0.58 for polythene). Overall, the highest number of plastics (individual items) was identified in S2 station (36±12.5) following to S4 station (24.33±1.53) and lowest at S5 (3.33±0.58). Biodiversity index were also calculated where higher species richness (D) and Shannon index (H) were observed to be higher in S5 compared to other sampling sites.