True sea snakes (Family Elapidae: Subfamily Hydrophiinae) are predatory, live bearing, fully marine reptiles that form the most biodiverse group of marine reptiles on earth.
Western Australia (WA) hosts 22 species, including five which are endemic to WA, making it a global hotspot of sea snake endemism.
Two small range WA endemics, A. foliosquama, the leaf-scaled sea snake and A. apraefrontalis, the short-nosed sea snake, were thought to be restricted to two reefs in the Timor Sea, to the West of WA: Ashmore and neighbouring Hibernia Reef (Lukoschek et al., 2013).
Ashmore Reef has been historically referred to as the Sea Snake Capital of the World, by Mick Guinea, as it once contained ~17 species, making it the most biodiverse sea snake assemblage ever recorded. However, over the last 30 years, sea snakes virtually disappeared from Ashmore Reef and declined significantly at adjacent reefs.
|Leaf scaled sea snake Shark Bay full size|
Leaf-scaled and short-nosed sea snakes have not been recorded in the Timor Sea since 1998. Consequently, they were presumed extinct and listed as Critically Endangered under the Australia’s federal environmental protection legislation, the Environmental Protection and Biodiversity Conservation (EPBC) Act (1999), in 2011.
However, subsequent examination of museum records showed that there had been a very small number of sightings in coastal WA (Sanders et al, 2015, D’Anastasi et al., 2016). This provided a window of hope that undiscovered populations may occur elsewhere.
In 2013, Blanche D’Anastasi from James Cook University set out to address major knowledge gaps for true sea snakes in WA because sea snakes are so chronically understudied. She also wanted to see if she could find the missing sea snakes.
To document the distribution and connectivity of true sea snakes in WA, Blanche collaborated with scientists from the WA Department of Parks and Wildlife (Parks and Wildlife), WA Department of Fisheries (DoF), Miami University, Stanford University/NASA, Florida International University and the Australian Institute of Marine Science, to undertake sea snake surveys (non-lethal tissue collection, counts and habitat use assessments) while SCUBA diving, snorkelling, using manta-tows, and at low tide walks. She also established the Australian Sea Snakes national sighting program, to gather additional data from public sightings.
|Short nosed sea snake Ningaloo courting pair (Image: Grant Griffin WA Parks and Wildlife)|
Whilst out on a WA DoF vessel in Shark Bay in 2013, Blanche captured two interesting little sea snakes. An assessment of the scale shapes and DNA showed that they were leaf-scaled sea snakes – one of the two species thought extinct. An ongoing collaboration with WA DoF led to the discovery of total of 15 leaf-scaled sea snakes, indicating that a breeding population was present in Shark Bay.
The discovery was profound, because it provides a second chance to protect a species thought extinct. The story becomes even more interesting, as the sea snakes were discovered in the lush seagrass beds of subtropical Shark Bay, some 1400 kilometres south of the snake’s only known habitat in the Ashmore Reef complex.
“We had thought that this species was only found on tropical coral reefs,” Ms D’Anastasi said. “Finding them in seagrass beds in Shark Bay was a genuine surprise and informs future research. In the future, surveys for A. foliosquama need to include seagrass and perhaps other habitats, to get a more realistic idea of the habitat that they require. Then we can focus our efforts on protecting the right places and the right habitats from human impacts.”
A second extraordinary discovery occurred when Parks and Wildlife officer Grant Griffin sent a photo of a pair of snakes taken on Ningaloo Reef to Ms D’Anastasi for identification in April 2013.
“We were blown away, these potentially extinct snakes were there in plain sight, living on one of Australia’s natural icons, Ningaloo Reef,” Ms D’Anastasi said. “What is even more exciting is that they were courting, suggesting that they are members of a breeding population and hopefully producing the next generation of short nosed sea snakes.”
Where to from here for the newly discovered populations of leaf-scaled and short nosed sea snakes?
Whilst the findings provide incredible incentive to protect these two small range endemic species, reducing the effects of threatening processes and preventing future declines of sea snakes will be a serious and ongoing challenge.
The unexplained disappearance of sea snakes from Ashmore reef highlights this challenge and demonstrates that marine reserves alone cannot prevent sea snake extinctions. Further research is required to understand what the key threatening processes are to sea snakes and how they cause populations to decline.
“Undertaking the research required to find out what is making sea snakes decline will take time, but there are things that can be done in the meantime to better protect sea snakes,” Ms D’Anastasi said. “For example, examining the cumulative effects of existing human impacts, such as coastal and marine developments, will help determine how threatened particular populations or species might be. It is also crucial to have a look at what developments and activities are proposed in areas where the critically endangered leaf scaled and short-nosed sea snakes may occur.”
In the longer term, Blanche aims to work collaboratively with state and federal government agencies to prepare a sea snake research and conservation strategy.
|PhD student Blanche D’Anastasi releasing an olive sea snake (Image: Graeme Petrie)|
In the meantime, Blanche is undertaking the first major study of Aipysurus pooleorum, the Shark Bay sea snake, examining its genomic connectivity and habitat requirements. The data will help determine how far these species move to breed, its capacity for recovery following declines and its habitat requirements.
Note: The Global Finprint Team recently discovered sea snakes in very low abundances at Ashmore reef in the Timor Sea, providing a glimmer of hope that remnant populations might remain at the former sea snake capital of the world. You can watch the video footage here.
The paper: New range and habitat records for threatened Australian sea snakes raise challenges for conservation by Blanche Renee D’Anastasi, Jean-Paul Hobbs, Colin A Simpfendorfer, Lynne Van Herwerden, Vimoksalehi Lukoschek is published in the journal, Biological Conservation
Blanche is a passionate conservation geneticist and ecologist. She applies her research on threatened marine vertebrates to management and conservation. Blanche most recently received an award in memory of Dr Glen Almany, in recognition of her passionate pursuit of positive change by breaking down traditional barriers between science and community, industry and resource managers.
Blanche is currently undertaking a PhD project at the ARC Centre of Excellence for Coral Reef Studies, James Cook Univeristy, on threatened Western Australian true sea snakes. She is using ecology and conservation genomics to find out how to best conserve sea snakes, which are mysteriously declining in marine reserves. Blanche is supervised by Dr. Vimoksalehi Lukoschek, Dr. Lynne van Herwerden, Prof. Colin Simpfendorfer, James Cook University and Dr. Jean-Paul Hobbs, Curtin University. Previously Blanche studied the genetic connectivity of the endangered narrow sawfish, during her Honours research project.
Blanche has a background in conservation advocacy, law and policy, having worked primarily on coastal dolphin conservation, fisheries and marine reserve campaigns. She is a member of the IUCN Sea Snake Specialist Group and a contributor to the IUCN’s Global Status Review of Sawfish. She is also a proud recipient of the prestigious Vodafone World of Difference Scholarship, which allowed her to undertake important conservation work. In the future Blanche plans to continue to work at the science-policy interface.
Facebook group: Australian sea snakes https://www.facebook.com/Australian-Sea-Snakes-107828136222392/