**3. Discussion**

This study reports our growing understanding of the microbiome composition of PalA-containing *S. adareanum*. To enhance our understanding of the ecology of the PalA-containing ascidian, *S. adareanum*, we investigated the ascidian colony microbiome and PalA chemistry levels at an individual lobe level, and compared the ascidian microbiome to the plankton. This comparison allowed us to address questions regarding variability in PalA content and whether a conserved core microbiome occurs across these PalA-containing Antarctic ascidians, thereby supporting the logic that if a microbial producer synthesizes PalA, the producing organism should be present in all PalA-containing *S. adareanum*

samples. Before this study, however, we did not have quantitative data at the level of the individual ascidian lobe that forms the pedunculated *S. adareanum* colonies (Figure 1). This discussion focuses on the core microbiome, then takes a broader look at secondary metabolite distributions about the microbiome and in other marine invertebrates as well as the biosynthetic potential of core membership, and concludes with information gained from our initial cultivation e ffort.
