Abstract
The increased use and rapid disposal of plastic products is leading to the widespread accumulation of plastic debris in marine ecosystems. As plastics breakdown, they are often mistaken as a food source leading to mechanically derived internal damage through abrasion, ulcers and digestive congestion resulting in a loss in body condition. In addition to direct ingestion of plastics is the potential threat of exposure to highly toxic chemicals that are used during the manufacturing of plastics. Exposure to these chemicals can induce adverse effects and maladaptive behavioural changes in organisms. However, little is known about the sub-lethal effects of microplastic exposure on the behaviour, olfactory ability and health of coral reef fishes. To investigate this, we exposed Spiny chromis damselfish (Acanthochromis polyacanthus) and Ambon damselfish (Pseudochromis amboinensis) recruits to a range of different plastic particles to quantify changes in behaviours important for successful recruitment. Using a standardised test to quantify escape and swimming performance, we found that when A. polyacanthus were exposed to plastic particles, the kinematic behaviours that underpin successful predator evasion were altered indicating that microplastic exposure could lead to higher predation rates. These changes were largely driven by an inability to recognise chemical alarm cues as an indication of risk. In addition to microplastic induced changes in anti-predator behaviour, biomarkers associated with oxidative damage, oxidative stress and antioxidant metabolism also indicated that microplastic exposure has a negative effect on the health of the fish. Additionally, A. polyacanthus and P. amboinensis exposed to DEHP microplastics, showed the greatest levels of oxidative stress and damage. Interestingly, predation rate of P. amboinensis individuals did not differ between microplastic treatments during mesocosm survival trials when exposed to predator fish P. fuscus. Overall, these changes suggest that microplastic pollution on coral reefs could have potential ecological ramifications in coral reef ecosystems.