Studying invasive marine species at Southern Cross University

Marine ecologist and Southern Cross University PhD candidate Ricardo Miranda explains his research into kelp, invasive species and ocean warming.

I'm a marine ecologist and PhD student and I work on two of the main threats to marine ecosystem - climate change and invasive species.

Oceans are predicted to warm in the future and this can alter the health and abundance of marine species and how they interact with each other.

I'm developing a staged test on how warming oceans and species invasion can change seaweed herbivory in marine ecosystems.

To test this we collected herbivores or marine snails, native algae and invasive algae to develop an experiment at National Marine Science Centre.

We placed these marine creatures in 20 large musicals or tanks that simulate both present and future ocean conditions.

We conducted three experiments to evaluate how temperature and the presence of invasive seaweed can change how much snails consumed seaweed.

Our results clearly showed that warming oceans increased consumption of two common native algal species because snails were hungry and increased their aggression rate.

Importantly however for the common kelp, invasion actually reduces this increased consumption in warmer temperature and we think that was because the chemicals that leach from the invasive seaweed inhibit grazing by snails under warmer conditions.

Ocean warming and invasion together had a positive feedback for kelp by reducing kelp loss through snail grazing.

This suggests that invasion may sometimes be positive in future oceans in this case enhancing the persistence of kelp in warming oceans where they might otherwise be over grazed.