Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Big fish, small fish, no fish; when size (and quality) matters for genetic species identifications of fishes? (#117)

Sharon A Appleyard 1
  1. CSIRO National Research Collections Australia, Hobart, TAS, Australia

Natural history collections are repositories of biodiversity. In the 'omics' era, collections provide critical access to a wealth of molecular information inherent in collection specimens. In this presentation, we outline several published studies (Appleyard et al. 2021,; Appleyard et al. 2022, and highlight an ongoing research collaboration, that are all built on the CSIRO Australian National Fish Collection. In Appleyard et al. (2021), we compared DNA barcoding and identification success for frozen and formalin-fixed tissues obtained from adult specimens. Using 230 samples from adult fishes (consisting of >160 fish species), in good quality DNA (without exposure to formalin), up to 88% of the specimens were correctly matched at the species level, whereas up to 58% of the specimens exposed to formalin for less than 8 weeks were also correctly identified to species. In Appleyard et al. (2022), whole larval specimens (and single eyeballs <1mm in diameter) from controlled and in-field 5% formalin exposure experiments were analysed. DNA barcoding and genetic species identification was 100% successful in cultured yellowtail kingfish fixed in formalin for up to 6 months, while barcoding of wild caught fish larvae enabled species identification of 93% of up to 8-weeks formalin fixed specimens. Additionally, with collaborators from SARDI, the ANFC is using tagged molecular assays in a current study evaluating the potential of DNA meta-barcoding to harvest ecological data from broad scale ichthyoplankton surveys. 

Collectively these studies highlight, that within parameter constraints, single sourced and bulked DNA samples of fishes (irrespective of size), combined with a variety of extraction methodologies and sequencing approaches results in accurate genetic identifications. Success however relies on reference sequences from vouchered adult specimens deposited in publicly available databases such as those in our extensive sequence library from Classes Actinopterygii and Elasmobranchii in the Barcode of Life Datasystem, BOLD.