Threats of microplastics pollution to the marine ecosystem of Tanzanian coastal waters

World Ocean’s day is fast approaching! This week we will share some short articles from current grantees under WIOMSA’s MASMA and MARG programmes. 

Threats of microplastics pollution to the marine ecosystem of Tanzanian coastal waters

Bahati Sosthenes Mayoma (1)*, Farhan R. Khan (2), Salum Hemed (1), Moses Joel Shimba (1) 

Plastic pollution is one of the emerging global environmental challenges which pose ecological and economic threats to aquatic ecosystems. Globally, it is estimated that about 311 million tons of plastics are produced yearly. The significant amount of plastics ends up in the aquatic environment of which about 4.8–12.7 million metric tons enter the oceans. It is estimated that out of the top leading countries in plastic waste generation ten are located along the Indian Ocean ream, the waste produced is directly affecting the ecosystems in the Western Indian Ocean (WIO) region.  Once plastic debris is released in the water, the debris undergoes fragmentation into minute pieces called microplastics (defined as small particles with less than 5mm). These particles may be eaten or taken in any other form by marine and coastal species while in the body the particles affect physiological functions.

There are more than 663 marine species including endangered species that have been affected by microplastic debris these include marine birds, turtles, dolphins, fish, seagrass, coral reef, and polychaetes. Species like bivalve (cockles and blue mussels) can accumulate and translocate nano plastic particles in their cells and tissues. Microplastics interfere with physiological body process and sometimes physical impairments which in most cases increase vulnerability to predators. The effect does not only end to marine organism but also potential risk to human health and food safety. 

Marine microplastics does not only affect marine species but also have negative impacts on the economy of the countries surrounding the ocean and adjacent areas. In the WIO region, small islands of Comoro, Madagascar, Mauritius, Seychelles, Reunion and Zanzibar that rely heavily on the tourism industry are likely to be impacted by ongoing plastics and microplastic damping. The current management practice for plastics waste in the WIO region is primarily focusing on physical removal of large plastics (macroplastics) through annual beach cleaning combined with public awareness. Despite the potential risks from macro and microplastics waste in marine biodiversity, human health and economic welfare, little effort is been directed to combat microplastics including understanding their physical properties and distribution patterns in the coastal sediments and indicator species.

The University of Dodoma with support from WIOMSA through it is Marine Research Grant (MARG) is working to unveil the physical properties and distribution patterns of microplastics in Tanzania coastal waters. The results will also assist other WIO region countries to align policy and management measures related to microplastics. Initial findings indicate significant accumulation of microplastics in the sediments with the highest level observed in Dar es Salaam (2960 particles/500g) and the lowest in Pemba (7 particles/500g) along the coast. Finding also suggests the level of microplastics in the tissue of marine species (cockles) are high in Dar es Salaam (4 particles per individual animal) compared to other coastal waters (1 particle per individual).  The prevalence of microplastics pollutants in sediments and cockles’ tissues corresponds with socio-economic activities around the coastal area which signify potential health risks from seafood and general human health. 

Authors Institution and address:

1. Department of Biotechnology and Bioinformatics, School of Biological Sciences, The University of Dodoma, P.O. Box 338, Dodoma, Tanzania 

2. Department of Science and Environment, Roskilde University, Universitetsvej1, P.O Box260, DK-4000 Roskilde, Denmark. 

*Corresponding author: bsosthenes@yahoo.com 

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