Dr Jin Yan Lim1,2,3, Dr Marko Terzin1,4, Dr Juliano Morais1, Dr Renee Gruber1, Dr Mike Emslie1, Dr Neal Cantin1, Dr Patrick Laffy1,2,3, Dr Yun Kit Yeoh1,2,3
1Australian Institute of Marine Science, Townsville, Australia, 2James Cook University, Townsville, Australia, 3AIMS@JCU, Townsville, Australia, 4University of Melbourne, Parkville, Australia
Biography:
Dr Jin Yan Lim is an academic, microbiologist, and marine researcher specialising in aquaculture health and microbial ecology.
She earned her Doctor of Philosophy (PhD) from The University of Queensland, where her early research focused on molecular biology and bacterial dynamics. She later served as a Postdoctoral Research Fellow at James Cook University (JCU), investigating the early life microbiome of marine species like the giant grouper to improve sustainable hatchery production.
Building on her expertise in tropical marine systems, she now works with the Australian Institute of Marine Science (AIMS). Her current research focuses on how environmental microorganisms and complex microbial systems can be used to monitor and protect fragile marine ecosystems.
Abstract:
As marine heatwaves increase in frequency and severity, transitioning environmental DNA (eDNA) into scalable biomonitoring applications is critical for reef management. While visual surveys remain the gold standard for tracking coral reef community composition, here we evaluated seawater eDNA as a complementary tool to quantify these ecological shifts. During the 2023–2024 summer marine heatwave, we collected 2 L seawater samples from 16 reefs across three Great Barrier Reef (GBR) sectors. Sampling occurred across three distinct intervals: pre-heatwave, during peak heat stress, and eight months post-peak. Extracted DNA was amplified via metabarcoding using CoralITS2 and CoralITS2_acro primers. Both primer sets revealed distinct responses. In two sectors, community composition shifted significantly between pre- and peak heat stress. This shift was associated with changes in several putative sponge taxa. Furthermore, composition at eight months post-peak did not deviate from peak, indicating a lack of community recovery within this timeframe. In the third sector, compositional differences between the pre and peak phases were markedly smaller than the changes observed in the eight-month follow-up samples. This divergence in community response was likely driven by varying thermal trajectories. The first two sectors experienced a larger increase in Degree Heating Weeks (DHW) between the pre-heatwave and peak sampling points (delta DHW = 3.1 °C-weeks) compared to the third sector (delta DHW = 1.50 °C-weeks), corroborating the immediate compositional shifts observed in the two former sectors. These results demonstrate that seawater eDNA is a sensitive approach to quantify the impacts of thermal stress on coral reef ecosystems.