Ms Yufei Zhou1, Dr. Alejandro Trujillo-González1, Dr. Simon Nicol2, Marion Boutigny, Dr. Roger Huerlimann3, Prof. Stephen Sarre1, Prof. Dianne Gleeson1
1University Of Canberra, Canberra, Australia, 2Pacific Community, New Caledonia, 3Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
Biography:
Yufei Zhou is doing her Ph.D. research on tuna and marine ecology at the University of Canberra. Initially, her dream was to embark on a scientific cruise and conduct marine biology research on the open ocean. However, she reconsidered after discovering she suffers from seasickness. Despite this, Yufei remains passionate about marine biology and is now focused on exploring innovative ways to apply new technology in the field without needing to be on a boat.
Abstract:
Gut samples are commonly used in diet and gut microbiome analyses of wild animals, especially marine fish. However, without consistent and tested sampling protocols, the utility of fish gut samples may be limited. Fish caught by commercial fisheries are often sampled hours, days, or even weeks after capture, usually when the catch is unloaded at port. This delay in sampling provides time for DNA degradation and decomposition in the gut microbiome community, potentially leading to unreliable and inaccurate conclusions.
In this study, we investigated the changes in the gut samples of skipjack tuna (Katsuwonus pelamis) which were transferred and preserved in RNAlater® at five different time points (immediately, 2 hours, 24 hours, 12 days, and 24 days after fish capture). We assessed the DNA quality change and the community degradation of the gut microbiome over time.
Our findings revealed a decrease in DNA quality and an increase in PCR difficulty as the sampling period extended, with significant changes occurring after 24 hours. Similarly, the gut microbiome community showed significant decomposition within the first 24 hours. Over time, the relative abundance of two bacterial families, Vibrionaceae and Bradyrhizobiaceae, changed significantly, indicating their potential to serve as gut microbiome degradation indicators. Therefore, we recommend that gut samples from marine fish should be appropriately preserved in DNA/RNA preservatives within two hours to achieve the highest reliability. Conversely, samples preserved after 24 hours may not achieve reliable results.