Abstract
Microplastics are ‘emerging’ contaminants that threatens freshwaters and may have negative impact on the aquatic organisms. However, Botswana has no information on the status of microplastics, including freshwater like the Okavango Delta- the largest, inland wetland hosting wildlife, tourism, and supporting the socio-economic lifestyle of inhabitants. This study assessed the spatial distribution and characterization of microplastics in surface water and in the digestive organs of fish (Tilapia sparrmanii) from the Okavango delta. Surface water samples (156) and whole intact fish (15) were collected and analysed for microplastic contents by wet peroxide oxidation, potassium hydroxide (fish only), density separation, extraction, and stereomicroscope identification. The weight of microplastics for surface water samples varied from 138.18 to 381.67 µg m−3 and abundance ranged from 10.18 to 22.67 items L−1 with significant difference observed between sites in both variables. In tilapia, the highest microplastic abundance were found in the intestines then the stomach and the gills from the fish samples. Most prevailing size ranges of microplastics in fish and water samples were 1–2 mm and 2–3 mm while the most abundant shapes were fragments and fibres, respectively. Translucent microplastics were dominant in all samples. The results indicate the presence of microplastics in the Okavango delta even though they are very low (µg m−3). This baseline information will provide insights on the loads of microplastics in surface water and the quantities ingested by fish in the Okavango delta hence the need for monitoring. It would also guide on the need for effective policies addressing plastic and microplastic pollution.
Similar content being viewed by others
Data availability
This manuscript has no additional associated data.
References
Abbasi, S., Soltani, N., Keshavarzi, B., Moore, F., Turner, A., & Hassanaghaei, M. (2018). Microplastics in different tissues of fish and prawn from the Musa Estuary, Persian Gulf. Chemosphere, 205, 80–87. https://doi.org/10.1016/j.chemosphere.2018.04.076
Alomar, C., & Deudero, S. (2017). Evidence of microplastic ingestion in the shark Galeus melastomus Rafinesque, 1810 in the continental shelf off the western Mediterranean Sea. Environmental Pollution (barking, Essex : 1987), 223, 223–229. https://doi.org/10.1016/j.envpol.2017.01.015
AVMA. (2020). Guidelines for the Euthanasia of Animals. Available at: https://www.avma.org/sites/default/files/2020-02/Guidelines-on-Euthanasia-2020. Accessed 17 May 2022.
Bahri, A. R. S., Ikhtiar, M., Baharuddin, A., & Abbas, H. H. (2020). Identification of Microplastic in Tilapia Fish (Oreochromis mossambicus) at Tallo River in Macassart. International Journal of Science and Healthcare Research, 5(3), 406–411. www.ijshr.com. Accessed 17 May 2022.
Bartsch, P., Edwards, T. M., & Brock, J. W. (2019). Prevalence of eight phthalate monoesters in water from the Okavango Delta, Northern Botswana. Bulletin of Environmental Contamination and Toxicology, 103, 274–279. https://doi.org/10.1007/s00128-019-02630-0
Batel, A., Linti, F., Scherer, M., Erdinger, L., & Braunbeck, T. (2016). Transfer of benzo[a]pyrene from microplastics to Artemia nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants. Environmental Toxicology and Chemistry, 35(7), 1656–1666. https://doi.org/10.1002/etc.3361
Bolaane, B. (2011). Solid waste management practices in the Okavango Delta Ramsar Site. Environmental Science Research, 215–230.
Browne, M. A., Galloway, T. S., & Thompson, R. C. (2010). Spatial patterns of plastic debris along estuarine shorelines. Environmental Science & Technology, 44(9), 3404–3409. https://doi.org/10.1021/es903784e
Campanale, C., Massarelli, C., Savino, I., Locaputo, V., & Uricchio, V. F. (2020). A detailed review study on potential effects of microplastics and additives of concern on human health. International Journal of Environmental Research and Public Health. https://doi.org/10.3390/ijerph17041212
Cedervall, T., Hansson, L. A., Lard, M., Frohm, B., & Linse, S. (2012). Food chain transport of nanoparticles affects behaviour and fat metabolism in fish. PLoS ONE, 7(2), 1–6. https://doi.org/10.1371/journal.pone.0032254
Cole, M., Lindeque, P., Halsband, C., & Galloway, T. S. (2011). Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin, 62(12), 2588–2597. https://doi.org/10.1016/j.marpolbul.2011.09.025
Dahms, H. T. J., van Rensburg, G. J., & Greenfield, R. (2020). The microplastic profile of an urban African stream. Science of the Total Environment, 731, 138893. https://doi.org/10.1016/j.scitotenv.2020.138893
Dalu, T., Banda, T., Mutshekwa, T., Munyai, L. F., & Cuthbert, R. N. (2021). Effects of urbanisation and a wastewater treatment plant on microplastic densities along a subtropical river system. Environmental Science and Pollution Research, 28(27), 36102–36111. https://doi.org/10.1007/s11356-021-13185-1
Dalu, T., Malesa, B., & Cuthbert, R. N. (2019). Assessing factors driving the distribution and characteristics of shoreline macroplastics in a subtropical reservoir. Science of the Total Environment, 696, 133992. https://doi.org/10.1016/j.scitotenv.2019.133992
Di, M., & Wang, J. (2018). Microplastics in surface waters and sediments of the Three Gorges Reservoir, China. Science of the Total Environment, 616–617, 1620–1627. https://doi.org/10.1016/j.scitotenv.2017.10.150
Ding, L., fan Mao, R., Guo, X., Yang, X., Zhang, Q., & Yang, C. (2019). Microplastics in surface waters and sediments of the Wei River, in the northwest of China. Science of the Total Environment, 667, 427–434. https://doi.org/10.1016/j.scitotenv.2019.02.332
Ding, L., Zhang, S., Wang, X., Yang, X., Zhang, C., Qi, Y., & Guo, X. (2020). The occurrence and distribution characteristics of microplastics in the agricultural soils of Shaanxi Province, in north-western China. Science of the Total Environment, 720, 137525. https://doi.org/10.1016/j.scitotenv.2020.137525
Dris, R., Gasperi, J., & Tassin, B. (2018). Sources and fate of microplastics in urban areas: A focus on Paris megacity. In In: Wagner, M., Lambert, S. (Eds) Freshwater Microplastics (The Handbo, pp. 69–83). Springer, Cham. https://doi.org/10.1007/978-3-319-61615-5_4
Garstang, M., Ellery, W. N., McCarthy, T. S., Scholes, M. C., Scholes, R. J., Swap, R. J., & Tyson, P. D. (1998). The contribution of aerosol- and water-borne nutrients to the functioning of the Okavango Delta ecosystem, Botswana. South African Journal of Science, 94(5), 223–229.
Greven, A. C., Merk, T., Karagöz, F., Mohr, K., Klapper, M., Jovanović, B., & Palić, D. (2016). Polycarbonate and polystyrene nanoplastic particles act as stressors to the innate immune system of fathead minnow (Pimephales promelas). Environmental Toxicology and Chemistry, 35(12), 3093–3100. https://doi.org/10.1002/etc.3501
Hidalgo-Ruz, V., Gutow, L., Thompson, R. C., & Thiel, M. (2012). Microplastics in the marine environment: A review of the methods used for identification and quantification. Environmental Science and Technology, 46(6), 3060–3075. https://doi.org/10.1021/es2031505
Hoellein, T. J., Shogren, A. J., Tank, J. L., et al. (2019). Microplastic deposition velocity in streams follows patterns for naturally occurring allochthonous particles. Scientific Reports. https://doi.org/10.1038/s41598-019-40126-3
Huang, Y., Liu, Q., Jia, W., Yan, C., & Wang, J. (2020). Agricultural plastic mulching as a source of microplastics in the terrestrial environment. Environmental Pollution, 260, 114096. https://doi.org/10.1016/j.envpol.2020.114096
Hurley, R., Woodward, J., & Rothwell, J. J. (2018). Microplastic contamination of river beds significantly reduced by catchment-wide flooding. Nature Geoscience, 11, 251–257. https://doi.org/10.1038/s41561-018-0080-1
Junk, W. J., Brown, M., Campbell, I. C., Finlayson, M., Gopal, B., Ramberg, L., & Warner, B. G. (2006). The comparative biodiversity of seven globally important wetlands: A synthesis. Aquatic Sciences, 68(3), 400–414. https://doi.org/10.1007/s00027-006-0856-z
Kärrman, A., Schönlau, C., & Engwall, M. (2016). Exposure and effects of microplastics on wildlife. A review of existing data. 39. https://www.diva-portal.org/smash/get/diva2:921211/FULLTEXT01. Accessed 20 May 2020.
Klein, S., Dimzon, I. K., Eubeler, J., & Knepper, T. P. (2018). Analysis, occurrence, and degradation of microplastics in the aqueous environment. In Handbook of Environmental Chemistry (Vol. 58). https://doi.org/10.1007/978-3-319-61615-5_3
Kooi, M., Besseling, E., Kroeze, C., van Wezel, A. P., & Koelmans, A. (2018). Modeling the fate and transport of plastic debris in freshwaters: Review and guidance. In M. Wagner, & S. Lambert (Eds.), Freshwater Microplastics (pp. 125–152). Springer, Cham. https://doi.org/10.1007/978-3-319-61615-5_7
Kurugundla, C. N., Parida, B. P., Buru, J. C., & Paya, B. (2018). Revisiting hydrology of Lake Ngami in Botswana. Hydrology: Current Research. https://doi.org/10.4172/2157-7587.1000301
Lambert, S., & Wagner, M. (2018). Microplastics are contaminants of emerging concern in freshwater environments: an overview. In S. Wagner, & M. Lambert (Eds.), Freshwater Microplastics (pp. 1–23). Springer, Cham. https://doi.org/10.1007/978-3-319-61615-5_1
Lenz, R., Enders, K., Fischer, F., Brandt, J., Fischer, D., & Labrenz, M. (2021). Measuring impacts of microplastic treatments via image recognition on immobilised particles below 100μm. Microplastics and Nanoplastics, 1(12).
Li, C., Busquets, R., & Campos, L. C. (2020). Assessment of microplastics in freshwater systems: A review. Science of the Total Environment, 707, 135578. https://doi.org/10.1016/j.scitotenv.2019.135578
Li, J., Ouyang, Z., Liu, P., Zhao, X., Wu, R., Zhang, C., Lin, C., Li, Y., & Guo, X. (2021). Distribution and characteristics of microplastics in the basin of Chishui River in Renhuai, China. Science of the Total Environment, 773, 145591. https://doi.org/10.1016/j.scitotenv.2021.145591
Lu, K., Qiao, R., An, H., & Zhang, Y. (2018). Influence of microplastics on the accumulation and chronic toxic effects of cadmium in zebrafish (Danio rerio). Chemosphere, 202, 514–520. https://doi.org/10.1016/j.chemosphere.2018.03.145
Lusher, A. L., Welden, N. A., Sobral, P., & Cole, M. (2017). Sampling, isolating and identifying microplastics ingested by fish and invertebrates. Analytical Methods, 9(9), 1346–1360. https://doi.org/10.1039/C6AY02415G
Masura, J. et al. (2015). Laboratory methods for the analysis of microplastics in the marine environment: recommendations for quantifying synthetic particles in waters and sediments. NOAA Technical Memorandum NOS-OR&R-48. https://marinedebris.noaa.gov/sites/default/files/publications-files/noaa_microplastics_methods_manual. Accessed 20 May 2020.
Mattsson, K., Ekvall, M. T., Hansson, L. A., Linse, S., Malmendal, A., & Cedervall, T. (2015). Altered behavior, physiology, and metabolism in fish exposed to polystyrene nanoparticles. Environmental Science and Technology, 49(1), 553–561. https://doi.org/10.1021/es5053655
Milzow, C., Kgotlhang, L., Bauer-Gottwein, P., Meier, P., & Kinzelbach, W. (2009). Regional review: The hydrology of the Okavango Delta, Botswana - Processes, data and modelling. Hydrogeology Journal. https://doi.org/10.1007/s10040-009-0436-0
Mmopelwa, G., Mosepele, K., Mosepele, B., Moleele, N., & Ngwenya, B. (2009). Environmental variability and the fishery dynamics of the Okavango delta, Botswana: The case of subsistence fishing. African Journal of Ecology, 49, 119–127. https://doi.org/10.1111/j.1365-2028.2008.01058.x
Mogobe, O., Masamba, W., & Mosepele, K. (2019). Trace metal concentrations in a pristine Ramsar site: the Okavango Delta. Applied Sciences. https://doi.org/10.1007/s42452-019-1602-1
Murray-Hudson, M., Wolski, P., & Ringrose, S. (2006). Scenarios of the impact of local and upstream changes in climate and water use on hydro-ecology in the Okavango Delta, Botswana. Journal of Hydrology, 331(1–2), 73–84. https://doi.org/10.1016/j.jhydrol.2006.04.041
Nash, D. J., Meadows, M. E., & Gulliver, V. L. (2006). Holocene environmental change in the Okavango Panhandle, northwest Botswana. Quaternary Science Reviews, 25(11–12), 1302–1322. https://doi.org/10.1016/j.quascirev.2005.11.004
Nel, H. A., Dalu, T., & Wasserman, R. J. (2018). Sinks and sources: Assessing microplastic abundance in river sediment and deposit feeders in an Austral temperate urban river system. Science of the Total Environment, 612, 950–956. https://doi.org/10.1016/j.scitotenv.2017.08.298
Ockelford, A., Cundy, A., & Ebdon, J. E. (2020). Storm response of fluvial sedimentary microplastics. Scientific Reports, 10(1), 1–10. https://doi.org/10.1038/s41598-020-58765-2
Omer, N. H. (2019). Water quality parameters- science, assessments and policy (K. Summers (Ed.)). https://doi.org/10.5772/intechopen.89657
Pedà, C., Caccamo, L., Fossi, M. C., Gai, F., Andaloro, F., Genovese, L., Perdichizzi, A., Romeo, T., & Maricchiolo, G. (2016). Intestinal alterations in European sea bass Dicentrarchus labrax (Linnaeus, 1758) exposed to microplastics: Preliminary results. Environmental Pollution, 212, 251–256. https://doi.org/10.1016/j.envpol.2016.01.083
Peng, J., Wang, J., & Cai, L. (2017). Current understanding of microplastics in the environment: Occurrence, fate, risks, and what we should do. Integrated Environmental Assessment and Management, 13(3), 476–482. https://doi.org/10.1002/ieam.1912
Prata, J. C., da Costa, J. P., Lopes, I., Duarte, A. C., & Rocha-Santos, T. (2019). Effects of microplastics on microalgae populations: A critical review. Science of the Total Environment, 665, 400–405. https://doi.org/10.1016/j.scitotenv.2019.02.132
Ramberg, L., Hancock, P., Lindholm, M., Meyer, T., Ringrose, S., Sliva, J., Van As, J., & VanderPost, C. (2006). Species diversity of the Okavango Delta, Botswana. Aquatic Sciences, 68(3), 310–337. https://doi.org/10.1007/s00027-006-0857-y
Rochman, C. M., Hoh, E., Kurobe, T., & Teh, S. J. (2013). Ingested plastic transfers’ hazardous chemicals to fish and induces hepatic stress. Scientific Reports, 3, 1–7. https://doi.org/10.1038/srep03263
Rodrigues, M. O., Abrantes, N., Gonçalves, F. J. M., Nogueira, H., Marques, J. C., & Gonçalves, A. M. M. (2018). Spatial and temporal distribution of microplastics in water and sediments of a freshwater system (Antuã River, Portugal). Science of the Total Environment, 633, 1549–1559. https://doi.org/10.1016/j.scitotenv.2018.03.233
Romeo, T., Pietro, B., Pedà, C., Consoli, P., Andaloro, F., & Fossi, M. C. (2015). First evidence of presence of plastic debris in stomach of large pelagic fish in the Mediterranean Sea. Marine Pollution Bulletin, 95(1), 358–361. https://doi.org/10.1016/j.marpolbul.2015.04.048
Shanmugam, V., Das, O., Neisiany, R. E., Babu, K., Singh, S., Hedenqvist, M. S., Berto, F., & Ramakrishna, S. (2020). Polymer recycling in additive manufacturing: An opportunity for the circular economy. Material Circular Economy. https://doi.org/10.1007/s42824-020-00012-0
Solomon, B. (2021). Plastic waste materials management and reuse in the construction industry: The case of selected first grade contractors in Addis Ababa. (Doctoral dissertation, St. Mary’s University). http://197.156.93.91/bitstream/123456789/6684/1/Btie.pdf. Accessed 18 Sept 2021.
Stolte, A., Forster, S., Gerdts, G., & Schubert, H. (2015). Microplastic concentrations in beach sediments along the German Baltic coast. Marine Pollution Bulletin, 99(1–2), 216–229. https://doi.org/10.1016/j.marpolbul.2015.07.022
Su, L., Deng, H., Li, B., Chen, Q., Pettigrove, V., Wu, C., & Shi, H. (2019). The occurrence of microplastic in specific organs in commercially caught fishes from coast and estuary area of east China. Journal of Hazardous Materials, 365, 716–724. https://doi.org/10.1016/j.jhazmat.2018.11.024
Szaky, T. (2015). The many challenges of plastic recycling. Waste Not: Sustainable Brands Issue in Focus. http://www.sustainablebrands.com/news_and_views/waste_not/tom_szaky/many_challenges_plastic_recycling
Thompson, R. C., Moore, C. J., vom Saal, F. S., & Swan, S. H. (2009). Plastics, the environment and human health: current consensus and future trends. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 364(1526), 2153–2166. https://doi.org/10.1098/rstb.2009.0053
Thompson, R., Moore, C., Andrady, A., Gregory, M., Takada, H., & Weisberg, S. (2005). New directions in plastic debris. Science. https://doi.org/10.1126/science.310.5751.1117b
Todd, M. C., Andersson, L., Ambrosino, C., Hughes, D., Kniveton, D. R., Mileham, L., ... & Wolski, P. (2011). Climate change impacts on hydrology in Africa: Case studies of River Basin water resources. In African Climate and Climate Change (pp.123-153). Springer, Dordrecht. https://doi.org/10.1007/978-90-481-3842-5_6
Turner, A. (2018). Black plastics: Linear and circular economies, hazardous additives and marine pollution. Environment International, 117(February), 308–318. https://doi.org/10.1016/j.envint.2018.04.036
Van Cauwenberghe, L., & Janssen, C. R. (2014). Microplastics in bivalves cultured for human consumption. Environmental Pollution, 193, 65–70. https://doi.org/10.1016/j.envpol.2014.06.010
Wagner, M., & Lambert, S. (2017). Freshwater microplastics: Emerging environmental contaminants? https://doi.org/10.1007/978-3-319-61615-5
Waldschläger, K., & Schüttrumpf, H. (2019). Effects of particle properties on the settling and rise velocities of microplastics in freshwater under laboratory conditions. Environmental Science and Technology, 53(4), 1958–1966. https://doi.org/10.1021/acs.est.8b06794
Waldschläger, K., Lechthaler, S., Stauch, G., & Schüttrumpf, H. (2020). The way of microplastic through the environment – Application of the source-pathway-receptor model (review). Science of the Total Environment, 713, 136584. https://doi.org/10.1016/j.scitotenv.2020.136584
Wang, M. H., He, Y., & Sen, B. (2019). Research and management of plastic pollution in coastal environments of China. Environmental Pollution, 248, 898–905. https://doi.org/10.1016/j.envpol.2019.02.098
Wang, W., Ndungu, A. W., Li, Z., & Wang, J. (2017). Microplastics pollution in inland freshwaters of China: A case study in urban surface waters of Wuhan, China. Science of the Total Environment, 575, 1369–1374. https://doi.org/10.1016/j.scitotenv.2016.09.213
Wang, W., Yuan, W., Chen, Y., & Wang, J. (2018). Microplastics in surface waters of Dongting Lake and Hong Lake, China. Science of the Total Environment, 633, 539–545. https://doi.org/10.1016/j.scitotenv.2018.03.211
WHO. (2019). Microplastics in Drinking-Water; Licence: CC BY-NC-SA 3.0 IGO: World Health Organization: Geneva.
Windsor, F. M., Tilley, R. M., Tyler, C. R., & Ormerod, S. J. (2019). Microplastic ingestion by riverine macroinvertebrates. Science of the Total Environment, 646, 68–74. https://doi.org/10.1016/j.scitotenv.2018.07.271
Wright, S. L., & Kelly, F. J. (2017). Plastic and human health: A micro issue? Environmental Science & Technology, 51(12), 6634–6647. https://doi.org/10.1021/acs.est.7b00423
Xiong, X., Zhang, K., Chen, X., Shi, H., Luo, Z., & Wu, C. (2018). Sources and distribution of microplastics in China’s largest inland lake – Qinghai Lake. Environmental Pollution, 235, 899–906. https://doi.org/10.1016/j.envpol.2017.12.081
Yakushev, E., Gebruk, A., Osadchiev, A., et al. (2021). Microplastics distribution in the Eurasian Arctic is affected by Atlantic waters and Siberian rivers. Communication Earth & Environment. https://doi.org/10.1038/s43247-021-00091-0
Yang, Y., Liu, W., Zhang, Z., et al. (2020). Microplastics provide new microbial niches in aquatic environments. Applied Microbiology and Biotechnotechnology, 104, 6501–6511. https://doi.org/10.1007/s00253-020-10704-x
Zhao, S., Zhu, L., Wang, T., & Li, D. (2014). Suspended microplastics in the surface water of the Yangtze Estuary System, China: First observations on occurrence. Marine Pollution Bulletin, 86(1–2), 562–568. https://doi.org/10.1016/j.marpolbul.2014.06.032
Zubris, K. A., & Richards, B. K. (2005). Synthetic fibers as an indicator of land application of sludge. Environmental Pollution (barking, Essex: 1987), 138(2), 201–211. https://doi.org/10.1016/j.envpol.2005.04.013
Acknowledgements
Gratitude is accorded to the Department of Earth and Environmental Sciences, BIUST for the support during sample collection.
Funding
This work was funded by the Office of Deputy Vice Chancellor- Research, Development and Innovation, Botswana International University of Science and Technology as a graduate initiation grant number S00352 to BCD.
Author information
Authors and Affiliations
Contributions
All the authors have contributed in the conceptualization, sampling, analysis, and writing and editing the manuscript.
Corresponding author
Ethics declarations
Ethics approval
This study did not utilize human subjects or experimental animals.
Competing interests
The authors declare no competing interests.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Ditlhakanyane, B.C., Ultra, V.U. & Mokgosi, M.S. Microplastic load in the surface water and Tilapia sparrmanii (Smith, 1840) of the river systems of Okavango Delta, Botswana. Environ Monit Assess 194, 572 (2022). https://doi.org/10.1007/s10661-022-10263-w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10661-022-10263-w