Marine sponges are one of the most abundant benthic animals in the world, taking on a kaleidoscope of different colours and an array of forms. Sponges play an integral role in marine ecosystems as they can alter water quality through water filtration, collect bacteria, and process carbon, nitrogen and phosphorus.

Even more fascinating, marine sponges are able to influence primary production in nutrient-depleted environments, fuelling productivity throughout ecosystems by making carbon biologically available to other organisms.

Sponge samples in the SIMS research aquarium.
Penny conducting sampling in the SIMS research aquarium.

These ancient and enigmatic creatures contain diverse communities of microorganisms that are involved in different types of biogeochemical cycles. Due to the variability of oxygen levels in sponges from water flow and the thickness of sponge tissue, sponges can perform anaerobic ammonium oxidation, anaerobic denitrification and aerobic nitrification to simultaneously.

Previous research has shown that denitrification in sponges is often incomplete resulting in the release of nitrous oxide (N2O), a powerful greenhouse gas with a lifetime of ~120 years. However, the amount of nitrous oxide released has not yet been quantified.⁠

PhD candidate Penny Chiou from UNSW aims to quantify the nitrous oxide emission in marine sponges using Gas-Chromatography Mass Spectrometry (GC-MS) in the SIMS aquarium, in order to understand their role in influencing atmospheric nitrous oxide concentrations. She will also look into the microbial composition and nitrogen metabolic pathways within these sponges by analysing Metagenomic Assembly Genomes (MAGs) and will later incorporate stable isotopic analysis and in situ measurements. ⁠

Her research will help inform us on how sponge ecology impacts nitrogen cycling and allow us to better understand the molecular interactions between sponge hosts and their associated microbes. ⁠

Wild sponge populations in Sydney Harbour.
Penny Chiou