UNIVERSITY OF KWAZULU–NATAL MICROPLASTIC CONCENTRATIONS ON THE URBAN COASTLINE OF KWAZULU–NATAL, SOUTH AFRICA, AND ITS IMPACT ON JUVENILE FISH TRISHAN NAIDOO JUNE 2018 Microplastic concentrations on the urban coastline of KwaZulu– Natal, South Africa, and its impact on juvenile fish TRISHAN NAIDOO Submitted in fulfilment of the academic requirements for the degree of Philosophical Doctorate in the School of Life Sciences, University of KwaZulu–Natal, Durban June 2018 As the candidate‘s supervisor I have/have not approved this thesis/dissertation for submission. Signed: _____________ Name: _____________D Glassom Date: _____________22 June 2018 ABSTRACT The global production of plastics per annum has increased from 1.5 million tonnes in the 1950‘s to 300 million tonnes today. Following this increasing production trend, plastic concentrations have increased over time in marine environments. Improper sewage treatment, industrial spillages, garbage and fishing activities among many others, have made the marine environment a sink for plastic debris. The main aims of this study were to determine (1) microplastic levels within five estuaries along the Durban coastline and on intervening beaches, (2) the incidence of plastic ingestion by estuarine mullet, (3) the effects of plastic ingestion on long–term fish health and (4) the plastic concentrations along the KwaZulu–Natal coastal shelf. To achieve these aims (1) plastic was isolated from estuarine sediment, beach sediment and the surface water of each estuary, (2) fish from the most polluted estuary were dissected to investigate the incidence of plastic ingestion, (3) small juvenile fish were kept in tanks and fed plastics for three months to monitor their growth and survival and (4) coastal water samples were collected using a manta trawl net to quantify floating debris in the ocean. Overall, an attenuating plastic concentration trend away from the city centre was found, with the Durban Harbour, Isipingo and uMgeni Estuaries having the highest contamination levels. The highest recorded plastic levels were found in the Bayhead area of the harbour, with 745.4 ± 129.7 particles per 500 mL, which mostly consisted of plastic fragments. Fibres dominated other estuaries with proportions ranging from 38% of total plastics in the uMgeni Estuary to 66% in the Mdloti. Plastic particle concentration in estuarine sediment generally increased from larger to smaller size classes. High plastic concentrations were also found on the coastal shelf of KwaZulu–Natal, with sites south of the harbour having the highest plastic concentrations, however no seasonal differences were found. There is also evidence pointing toward long range movement of particles and thus pollution at the source must be dealt with before it reaches the open ocean. Seventy three percent of the mullet sampled at the harbour ingested plastic particles with an average of 3.751 ± 4.667 (S.D.) particles per fish. Particles that were ingested were mainly fibres that are thought to come from sewage inputs to the harbour. Juvenile fish in microplastic feeding experiments had lower growth and survival than control fish. This has possible economic and ecological consequences for future fish stocks that use urban estuaries as nursing areas. ii PREFACE The work described in this dissertation was carried out at the School of Life Science, University of KwaZulu–Natal, Durban, under the supervision of Dr. David Glassom and Prof. Albertus J. Smit. Research findings within this dissertation represent the original work by the author, and have not been submitted in part or in whole for any other degree or diploma to any other tertiary institution. Where use has been made of the work of others it is duly acknowledged in the text. I certify the above statement is correct: Trishan Naidoo, June 2018 ________ Dr. David Glassom, June 2018 iii DECLARATION 1 – PLAGIARISM I, Trishan Naidoo, declare that 1. The research reported in this thesis, except where otherwise indicated, is my original research. 2. This thesis has not been submitted for any degree or examination at any other university. 3. This thesis does not contain other persons‘ data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons. 4. This thesis does not contain other persons' writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: a. Their words have been re–written but the general information attributed to them has been referenced b. Where their exact words have been used, then their writing has been placed in italics and inside quotation marks, and referenced. 5. This thesis does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the thesis and in the References sections. Signed: Trishan Naidoo, June 2018 iv DECLARATION 2 – PUBLICATIONS Details of contributions to publications that form part of and/or include research presented in this thesis: Publication 1 Naidoo, T., Glassom, D., Smit, A.J. 2015. Plastic pollution in five urban estuaries of KwaZulu–Natal, South Africa. Marine Pollution Bulletin. 101: 473-480. Publication 2 Naidoo, T., Smit, A.J., Glassom, D. 2016. Plastic ingestion by estuarine mullet Mugil cephalus (Mugilidae) in an urban harbour, KwaZulu–Natal, South Africa. African Journal of Marine Science. 38: (1) 145-149. Publication 3 Naidoo, T., Goordiyal, K., Glassom, D. 2017. Are nitric acid (HNO3) digestions efficient in isolating microplastics from juvenile fish? Water, Air and Soil Pollution. 228: (12) 1-11. Author’s contributions: Trishan Naidoo – Undertook sampling activities and write–up of draft manuscripts. David Glassom – Had original idea of the research and had a major impact on study design and editing the manuscript. Albertus. J. Smit – Developed both ideas in study design and sampling techniques and was involved in editing the manuscript. Kimerra Goordiyal – Examined the four species of juvenile fish for microplastics and added this field data to publication 3 for verification of the method (Chapter 6). She was also involved in the write–up of these results. Signed: Trishan Naidoo, June 2018 v TABLE OF CONTENTS ABSTRACT _________________________________________________________ ii PREFACE __________________________________________________________ iii DECLARATION 1 – PLAGIARISM ____________________________________ iv DECLARATION 2 – PUBLICATIONS __________________________________ v LIST OF FIGURES ___________________________________________________ x LIST OF TABLES __________________________________________________ xiii ACKNOWLEDGMENTS ____________________________________________ xiv CHAPTER 1 _________________________________________________________ 1 Introduction ____________________________________________________________ 1 1.1 History of plastic production ______________________________________________ 1 1.2 Characteristics and uses _________________________________________________ 1 1.3 General constituents, structure and characteristics ___________________________ 2 1.4 Plastic types and sources _________________________________________________ 3 1.5 Plastic sizes ____________________________________________________________ 5 1.6 Fragmentation, buoyancy and biofouling ___________________________________ 6 1.7 The effects of high plastic concentrations on biota and the environment __________ 7 1.8 Plastic pollution along the South African coastline ____________________________ 9 1.9 Local distribution around Durban ________________________________________ 10 1.10 Thesis composition and main aims ________________________________________ 11 CHAPTER 2 ________________________________________________________ 13 Pilot Study _____________________________________________________________ 13 2.1 Determining the quantity of sediment to collect _____________________________ 13 2.2 Sediment collection, processing and analysis ________________________________ 13 2.3 Results of the pilot study ________________________________________________ 14 2.3.1 Estuarine sediment _________________________________________________ 14 2.3.2 Beach sediment ____________________________________________________ 17 2.4 Discussion and conclusion of pilot study ___________________________________ 17 vi CHAPTER 3 ________________________________________________________ 18 Plastic pollution in five urban estuaries of KwaZulu–Natal, South Africa _________ 18 3.1 Abstract ______________________________________________________________ 18 3.2 Introduction __________________________________________________________ 18 3.3 Material and methods __________________________________________________ 20 3.3.1 Site ______________________________________________________________ 20 3.3.2 Field collection ____________________________________________________ 21 3.3.3 Laboratory processing _______________________________________________ 22 3.3.4 Statistical anaylsis __________________________________________________ 22 3.3.5 Multivariate analyses ________________________________________________ 23 3.4 Results _______________________________________________________________ 23 3.4.1 Total number of plastic particles _______________________________________ 23 3.4.2 Estuarine sediment _________________________________________________ 23 3.4.3 Beach sediment ____________________________________________________ 24 3.4.4 Surface water ______________________________________________________ 27