Understanding the abundance and nitrous oxide production potential of two common ascidians

Synopsis

Ascidians (often also called sea squirts) are commonly found in coastal waters of Australia, where they create expansive animal ‘forests’. Our recent work has discovered that the ascidian Herdmania grandis produces significant amounts of nitrous oxide, a potent greenhouse gas. H. grandis has also become more abundant in temperate reefs impacted by ocean warming, indicating that its overall nitrous oxide production might increase in the future as temperature rise. It is however unknown if these abundance trends seen for H. grandis also apply to other ascidian species and if other species also produce large amounts of nitrous oxide. This information is important to understand how much ascidians contribute to global nitrous oxide emissions.

Aims

This project will focus on two common but morphologically distinct ascidians which occupy different rocky reef environments: the intertidal/ subtidal Pyura praeputialis (also called Cunjevoi) and the subtidal Pyura spinifera (also called Sea tulip).

Specifically, we will ask:

a) What are the abundances of P. spinifera and P. praeputialis and how have they changed over time or with ocean warming?

b) Do P. spinifera and P. praeputialis produce nitrous oxide, and if yes, in which quantities?

c) What is the potential overall nitrous oxide production of P. spinifera and P. praeputialis when scaled to surveyed reef habitats and coastal zones?

This project will involve a combination of field surveys, analytical experiments in state-of-the-art facilities and spatial modelling.

Student benefits

This project would benefit students with an interest in marine ecology, climate change, and an eagerness to understand the ecological roles of understudied invertebrates. Ideally the candidate will be an enthusiastic SCUBA diver, and comfortable developing general laboratory, coding and mapping skills. This student will work closely with PhD candidates and PostDocs investigating nitrous oxide production by marine invertebrates.

Supervisors

Professor Adriana Vergés and Professor Torsten Thomas