Abstract
There is an urgency for the management of microplastic pollution in the global oceans with a potential solution being bioplastic created from biopolymers. While there is evidence that petroleum-derived polymers can impact marine organisms, little is understood about whether these products affect behaviour and physiology of marine teleost fish. This thesis examines the potential effects of petroleum-derived microplastics and biopolymer microplastics on the escape performance and aerobic metabolism of a rocky reef fish, Forsterygion capito. Specifically, I looked at whether exposure to polyethylene (PE) polymer microplastic (MPs) or a newly designed edible food coating (EFC) polymer microplastic would affect six escape performance variables (distance travelled, speed, max speed, latency, responsiveness, and directionality), two routine swimming variables (distance travelled and mean speed), and five metabolic variables (standard metabolic rate, maximum metabolic rate, aerobic scope, excess post-exercise oxygen consumption (EPOC), and post-exercise metabolic recovery time). 134 F. capito were exposed to either control (no plastic polymer), PE or EFC treatments over a 5-week period in a laboratory setting. F. capito were video recorded for two minutes prior to the assessment of escape performance to observe routine swimming. For escape performance, F. capito were individually placed in a behavioural experiment arena and exposed to a stimulus to initiate an escape response which was video recorded. Intermittent respirometry was carried out to measure the aerobic metabolism of F. capito. Fish were chased for 5 minutes then individually placed in a respirometry chamber where their oxygen consumption was measured for 16 hours. I found an effect of PE MPs on latency, max speed and responsiveness and an effect of EFC MPs on max speed only in escape performance (Chapter 2). Both routine swimming variables, mean speed and distance travelled, were significantly reduced by PE MPs while EFC MPs caused little effect (Chapter 2). Interestingly, I found only PE MPs had an effect on the aerobic metabolism influencing standard metabolic rate, EPOC and trends showing a longer recovery time while EFC MPs had little effect (Chapter 3). Overall, PE MPs had a greater effect on the escape performance, routine swimming, and aerobic metabolism of F. capito compared to EFC MPs. However, there was still an effect of EFC MPs on the escape performance of F. capito thus the EFC polymer is not a suitable alternative to petroleum-derived polymers in plastic production. This thesis demonstrates the effects of petroleum-derived MPs and biopolymer MPs on the anti-predator behaviour and physiology of marine teleost fish. These effects may lead to a decline in prey populations leading to altered predator-prey dynamics and shifts in the ecosystem. The ever-increasing number of MPs in the ocean calls for concern over plastic pollution management with policies needing to be developed globally.