KERUBO, JOYCE OMBONGI

Photo
KERUBO, JOYCE
Project Title
MICROPLASTIC POLLUTION ALONG THE KENYA COAST IN THE WESTERN INDIAN OCEAN (WIO), REGION
Degree Name
DOCTOR OF PHILOSOPHY DEGREE IN MARINE BIOLOGY
Project Summary

Plastics enter the ocean inform of either large debris or microplastics that are a product of breakdown from the large debris or are primarily microplastics suchs as beads used in beauty products. Plastic pollution impacts in oceans are considerable world over. Microplastics (MPs) are tiny plastic particles measuring between 0.1μm and 5000 μm, make an important part of plastic pollution and form a pathway to the aquatic food web including humans. And although this is a global problem, there are limited studies along the Kenyan Coast in the Western Indian Ocean (WIO). This study looked at MPs in the surface waters, sediments and fish within three sites (Tudor, Port Reitz and Mida Creek) that were sampled in January/February and September 2018. Water samples were collected by towing neuston nets of 500 μm (large) and 250 μm (medium) mesh sizes and sieving 50 litres of seawater through a 20 μm net (small) size. Sediment samples were collected from the intertidal zone using a 3.6 cm diameter corer up to 10 cm deep. Fish were obtained from fishermen on site and local landing beaches. Samples were digested in 10 % Potassium Hydroxide and, microplastics extracted by Thompson’s improved density separation protocol using super saturated (0.8 μm) Sodium Chloride (NaCl) solution (1.2g cm-3). Total concentrations of MPs in both water and sediments, was highest in Tudor Creek followed by Port-Reitz and finally Mida. In the water column smallest MPs (20-250μm) recorded the highest concentration while in the sediments, MPs of the large size (500-4999 μm) were the most abundant. In fish, MPs concentration was highest in demersal fish followed by pelagic fish and in both types, omnivores recorded highest MPs concentrations followed by carnivores and finally grazers. Polyethylene (PE) polymers were the most abundant (63.9 %), followed by polypropylene (PP) (27%), while 9.1 % were unknown. Based on the results, the marine ecosystems along the Kenya coast are polluted with MPs.