eDNA reveals distribution of critically endangered estuarine pipefish (Syngnathus watermeyeri) in South Africa

Miss Georgia Nester^1,2, Mr Matthew Heydenrych³, Dr Tina Berry^1,4, Dr Zoe Richards^2,5, Mr Johan Wasserman⁶, Dr Nicole White¹, Dr Maarten De Brauwer⁷, Professor Mike Bunce⁸, Ms Miwa Takahashi¹, Dr Louw Claassens^9,10

¹Curtin University, Perth, Australia, ²Coral Conservation and Research Group (Curtin University), Perth, Australia, ³School of Biological Sciences (University of Western Australia), Perth, Australia, ⁴eDNA Frontiers (Curtin University), Perth, Australia, ⁵Collections and Research (Western Australian Museum), Perth, Australia, ⁶Department of Botany and DSI/NRF Research Chair in Shallow Water Ecosystems (Nelson Mandela University), , South Africa, ⁷CSIRO Coasts and Ocean Research Program, Hobart, Australia, ⁸Curtin University, Perth, Australia, ⁹Palau International Coral Reef Center, , Palau, ¹⁰Department of Zoology and Entomology (Rhodes University), South Africa

Abstract:

South Africa’s estuarine pipefish (Syngnathus watermeyeri) is a species on the brink. It is the only ‘Critically Endangered’ member of the Syngnathidae family in the world and was classified as Extinct in 1994, before being rediscovered in 2007. The effective management of rare and threatened species relies on knowledge of their distribution and habitat preferences. In this study, eDNA sampling and traditional seine netting were undertaken across the historical range of the estuarine pipefish in the Eastern Cape of South Africa. At 39 sites across the five estuaries, five surface water samples were collected for eDNA analysis (n=195) and three seine netting hauls (n=117) were conducted. Habitat and environmental data were also collected at each location to explore potential correlations with pipefish presence/absence. We successfully detected S. watermeyeri in two estuaries (Kariega and Bushmans) using both survey methods. In contrast, null detections in the Kasouga, East Kleinemonde and West Kleinemonde estuaries, adds to the growing body of evidence that the estuarine pipefish has been extirpated from these locations and is now only found in two estuarine systems. Importantly, the rate of positive detections using eDNA was more than four times that of traditional seine netting. Results confirm that the occurrence of S. watermeyeri is highly dependent on the presence of dense beds of submerged macrophytes like Zostera capensis (eelgrass). This work further validates the use of species-specific qPCR assays and provides the foundation for developing a long-term eDNA-based monitoring program for this Critically Endangered species.

Biography:

Georgia is undertaking her PhD within the TrEnD laboratory at Curtin University in Western Australia. Her PhD project, ‘Monitoring blue biodiversity: examining diversity patterns in oceanic environments using environmental DNA’, involves collaborations between Curtin University, the Knysna Basin Project, the Western Australian Museum and the Australian Antarctic Division. The project aims to use environmental DNA to determine patterns in marine biodiversity in areas that are severely underrepresented in the literature and provide innovative methods of monitoring threatened species. Georgia is experienced in using metabarcoding techniques as demonstrated through her PhD and through a scholarship she was awarded in 2018 in partnership with Chevron and Curtin University. She is also proficient with bioinformatic workflows having completed an internship at the Pawsey Supercomputing Centre in 2019. She is passionate about improving how we apply eDNA technologies to our marine environment and how they can be beneficial for conservation and hopes to continue research in this realm.