Name: Madeline McKenzie
Degree: PhD
Topic: Upside-down jellyfish (Cassiopea) as a model organism for biomonitoring environmental variability
Institution: James Cook University
Supervisors: Distinguished Professor Michael Kingsford and Dr. Shelley Templeman
Expected completion: April 2025
Email: madeline.mckenzie@my.jcu.edu.au
About you: Originally from the United States, I earned a Bachelor of Science degree from the University of Nebraska-Lincoln in 2015. Shortly thereafter, I moved to Townsville, Queensland, to pursue a Master of Science in Marine Biology and Ecology at James Cook University. My master's research introduced me to the captivating world of gelatinous organisms, focusing on the upside-down jellyfish Cassiopea. During this project, I investigated the effects of the herbicide hexazinone on Cassiopea and its endosymbiotic zooxanthellae. This experience sparked my passion for research, setting me on the path to my PhD.
Following my master's degree, I worked at TropWATER, which is James Cook University's Centre for Tropical Water and Aquatic Ecosystem Research. In this role I contributed to a National Environmental Science Program (NESP) project investigating the impacts of priority pesticides on non-target tropical aquatic species. The outcomes of this three-year project (NESP Project 3.1.5) have informed national water quality guidelines and risk assessments to better protect aquatic ecosystems. This work deepened my interest in ecotoxicology and inspired my current doctoral research.
As a PhD candidate, my research focuses on assessing the potential of Cassiopea as a biomonitor for contaminants of emerging concern (CECs), including organic ultraviolet filters, petroleum hydrocarbons, and microplastics. These jellyfish have already proved to be useful biomonitors to other contaminants, and I wanted to further explore this.
Now nearing the completion of my PhD, with an anticipated completion in early 2025, I have been fortunate to secure a position with the Tropical Ecotoxicology and Risk Assessment (TERA) team at the Australian Institute of Marine Science (AIMS). I am excited to continue advancing our understanding of how pollution affects Australia’s tropical marine ecosystems, contributing to their protection and sustainable management.
Research summary: The worlds’ oceans are increasingly exposed to a diversity of contaminants stemmed from anthropogenic activities, many considered to be ‘contaminants of emerging concern’ (CECs). For several CECs, their influence on marine ecosystems is unknown. Historically, biomonitors have been used as an effective time-integrated tool to monitor contaminant loads in ecosystems. The upside-down jellyfish (Cassiopea) has shown promise as a biomonitor to a range of marine contaminants, such as herbicides and trace elements. Changes in size, photosynthetic efficiency, and zooxanthellae density can be measured as sub-lethal responses to contaminant exposure. My PhD research focuses on the utility of Cassiopea as a biomonitor to a range of CECs, including organic ultraviolet filters, petroleum hydrocarbons, and microplastics in both single exposure and mixture experiments. The findings from this research will aid in developing early detection and quantification tools to help assess risks associated with these contaminants, thereby supporting the maintenance of healthy coastal marine systems.