Methods for assessing biodiversity, abundance and distribution of Antarctic sea anemones

Our current knowledge on Antarctic sea anemone biodiversity is poor, with less than 50% of species identified. Most species descriptions date back to early last century and recent work has suggested that taxonomic uncertainty is high. One of the challenges in identification of sea anemones biodiversity is the paucity of rigid taxonomic features. A modern approach using genetic techniques could help resolve some of these problems. We used DNA sequencing of the mitochondrial CO1 and 16S gene regions, and nuclear ITS sequence combined with genotyping using Single Nucleotide Polymorphisms (SNPs) on 387 individual sea anemones from the Southern Ocean and Macquarie Island to identify and resolve taxonomic discrepancies. We found that all three genetic markers were able to distinguish between species, although hypervariable markers such as SNPs are needed to distinguish between some closely related species. Understanding sea anemone biodiversity is, however, just one part of understanding their role in the ecology of the Southern Ocean. Many Antarctic sea anemones have distributions that extend beyond depths that are accessible by SCUBA diving, hence to study the ecology of key sea anemone species requires alternate approaches. We used ROVs and photoquadrat surveys to understand sea anemone distribution and relationships with their environment. These studies found that sea anemone distribution was correlated to ecological engineer and habitats that comprised of hard substrates. This combination of phylogenetic studies with distribution studies has given us an insight into the complex relationships of the Antarctic benthic ecosystem and the role sea anemones play.