Temporal Variation in Abundance of Microplastics in Prawns (f. Indicus) Caught in Sabaki River Estuary, Kenya

Abstract

Plastic pollution constitutes planetary crisis which impacts negatively on ecosystems, biodiversity, climate and human health. Although presence of microplastics in prawns is well acknowledged, little has been reported on temporal variability of these contaminants, particularly in prawns caught in tropical estuaries. This study examined seasonal variations of microplastics (MPs) in prawns (F. Indicus) caught in Sabaki estuary in Kenya, during Jan-Mar-dry, Apr-June-wet, July-Oct-dry and Nov-Dec-wet seasons. Microplastics were extracted by digesting prawns’ gut using 10% KOH. Extracted MPs were manually identified and counted using a stereo microscope and, FTIR used to confirm their polymers. The results revealed prawns were contaminated at 47.5 %, 53%, 39%, and 46%, during Jan-Mar-dry, Apr-June-wet, July-Oct-dry and Nov-Dec-wet seasons, respectively. Seasons significantly (P≤0.05) influenced levels of MPs contamination in prawns with the highest level of contamination occurring during the Apr-Jun-wet season. Female prawns were more contaminated than males at 50.3% and 42.5%, respectively. White, blue, transparent and others colored MPs were observed at 68%, 19%, 11% and 2%, respectively, and two types of MPs polymers namely PE and ABS were observed at 27% and 63%. Unearthing of variations of MPs contamination in prawns from Sabaki estuary supports strategies aimed at conservation of prawns, while protecting seafood consumers.