Researchers at William & Mary’s Virginia Institute of Marine Science (VIMS) have discovered a new species of Antarctic dragonfish, Akarotaxis gouldae or Banded Dragonfish, which has been discovered in waters off the western Antarctic Peninsula. Named in honor of the retired Antarctic research and supply vessel (ARSV) Laurence M. Gould and its crew, this species sheds light on the uncharted biodiversity and delicate nature of the Antarctic ecosystem.
Published in the journal Zootaxa, the discovery of Akarotaxis gouldae began with genetic analysis. While trawling for zooplankton off the coast of Antarctica, researchers initially believed the larval specimens they found were Akarotaxis nudiceps, a closely related dragonfish.
However, comparison of their DNA to Akarotaxis nudiceps specimens housed in collections at VIMS, Yale University, and the Muséum national d’Histoire naturelle in Paris, France revealed significant variations in mitochondrial gene regions, indicating that the larval samples belonged to a distinct species.
Lead author Andrew Corso conducted groundbreaking research for his Ph.D. at W&M’s Batten School of Coastal & Marine Sciences at VIMS under the mentorship of esteemed faculty advisors Eric Hilton and Deborah Steinberg.
Using DNA evidence as their guiding light, Corso and his colleagues embarked on a global quest, meticulously extracting and analyzing adult Akarotaxis gouldae samples from top ichthyology collections. The results were nothing short of astounding – revealing striking morphological differences that have the potential to reshape our understanding of these species.
“There are two distinct bands on the sides of adult Akarotaxis gouldae that are not present on Akarotaxis nudiceps, so we were surprised that the species already existed in collections but had been previously overlooked,” said Corso. “In the world of fish taxonomy, it’s becoming common to distinguish species with genetics alone. Genetic testing is an extremely valuable tool, but our discovery highlights the importance of early life stage morphology and natural history collections like those at VIMS and other institutions.”
Genetic testing has unearthed fascinating evolutionary insights. By employing a cutting-edge technique known as time-calibrated phylogeny, Corso and his collaborator, Thomas Desvignes, have determined that Akarotaxis gouldae evolved into a distinct species around 780,000 years ago. This incredible revelation emerged from an era when the Southern Ocean lay blanketed under vast sheets of ice.
“This process essentially looks at the rate of genetic mutations as a guide for a species’ evolutionary history,” said Corso. “We hypothesize that a population of dragonfishes may have become isolated within deep trenches under glaciers, surviving on food pushed in by the moving ice. Once the glaciers retreated, this subpopulation had become distinct enough to be reproductively incompatible with Akarotaxis nudiceps.”
Antarctic dragonfishes are shrouded in mystery, residing in the remote Southern Ocean and spending the majority of their adult lives in the depths of the sea. While existing research hints at their nesting behavior in shallower coastal waters and the surface-dwelling nature of their offspring during the larval stage, the reproductive capabilities of female dragonfishes appear to be limited.
Furthermore, the distribution of Akarotaxis gouldae seems to be confined to the waters around the western Antarctic Peninsula, as opposed to Akarotaxis nudiceps, which is found in the waters surrounding the southern continent.
These enigmatic dragonfishes play a critical role in the Antarctic ecosystem, serving as prey for a variety of species, including the iconic penguins of Antarctica. Notably, a 2022 study by Corso has drawn a concerning link between diminishing Antarctic silverfish populations and the warming waters and reduced ice in the Southern Ocean. This raises crucial questions about the impact of environmental changes on the delicate balance of the Antarctic marine life.
“Akarotaxis gouldae appear to have one of the smallest ranges of any fish endemic to the Southern Ocean,” said Corso. “This limited range combined with their low reproductive capacity and the presence of early life stages in shallower waters suggest that this is a vulnerable species that could be impacted by the krill fishery.”
The waters around the western Antarctic Peninsula are a crucial habitat for diverse marine life, yet they are heavily targeted by the international Antarctic krill fishery. Managed by the Conservation of Antarctic Marine Living Resources (CCAMLR), commercial fishing vessels trawl for krill in these waters, reaching depths of up to 250 meters. However, CCAMLR has highlighted the challenges of accurately identifying and managing the potential bycatch of larval and juvenile finfish during these operations.
“Since we know so little about the biodiversity of this area, we feel caution should be taken in extracting resources until we have a better understanding of the impact on the greater ecosystem,” said Corso.
The ARSV Laurence M. Gould was named after Laurence McKinnley Gould, the chief scientist on the first expedition to Antarctica. Surprisingly, the organism Akarotaxis gouldae was not named after the famous geologist but in honor of the vessel and its remarkable scientific contributions.
For over two decades, the ARSV Laurence M. Gould played a vital role in supporting the U.S. National Science Foundation’s Antarctic Program, focusing on the study of the Southern Ocean. However, despite its invaluable service, the charter for the Gould was not renewed this year, citing economic reasons and evolving research priorities.
It’s crucial to recognize the immense impact of the Gould and advocate for continued support of such important scientific endeavors in Antarctica.
The ARSV Laurence M. Gould and its dedicated crew played a crucial role in advancing Antarctic research conducted by VIMS and other esteemed institutions. Dr. Corso’s mentor, Professor Steinberg, oversees extensive, groundbreaking studies focusing on the profound impacts of climate change on zooplankton communities in the western Antarctic Peninsula and their cascading effects on the marine food web. This vital research hinges on consistent and meticulously timed sampling, which is heavily reliant on the presence of support vessels such as the Gould.
“To me, the loss of the ARSV Laurence M. Gould marks a setback in the scientific study of the Antarctic region,” said Corso. “Antarctica is warming faster than anywhere in the Southern Hemisphere, and there is untold biodiversity in the region that we’re only beginning to understand. By naming this fish after the ship, we hope to honor its scientific contributions while also bringing attention to the need for additional resources to study this unique ecosystem.”
Journal reference:
- Andrew D. Corso, Thomas Desvignes, Jan R. Mcdowell, Chi-Hing Christina Cheng, Ellen E. Biesack, Deborah K. Steinberg, Eric J. Hilton. Akarotaxis gouldae, a new species of Antarctic dragonfish (Notothenioidei: Bathydraconidae) from the western Antarctic Peninsula. Zootaxa, 2024; DOI: 10.11646/zootaxa.5501.2.3