Quantifying Coralline Algae Diversity and Assessing its Role in Community Structure in the Northwest Atlantic

Curtis Morris¹, Jarrett Byrnes¹

¹University of Massachusetts, USA

Facilitation cascades, where a basal habitat-forming taxon, such as coralline algae, facilitates a secondary habitat-forming taxon which in-turn supports a larger community, are increasingly recognized as ubiquitous and important in the function of critical ecosystems. Coralline algae facilitate the recruitment of foundation species across latitudes and ecosystem types, including kelp forests. Despite the known importance of kelp forests as a foundational ecosystem and the ongoing threat of climate driven range contractions and shifts to alternative stable states, we still do not know to what extent coralline algae play a role in the recruitment of kelp or the stabilization of alternate states in the Northwest Atlantic. The cryptic morphology of coralline algae makes assigning species-level identification difficult, much less the assessment of ecosystem services provided by those species. While coralline algae do contribute to kelp recruitment, that facilitation role may vary among different coralline species. Furthermore, alternative ecosystem states contain different assemblages of coralline algae, suggesting that these algae may play a role in the ecology of differing ecosystem states. Therefore, it is essential to identify the role of coralline algae in the facilitation cascade of kelp species in Northwest Atlantic kelp forests and their role in the stabilization of alternative stable states. Our study objectives are to: (1) Overcome cryptic morphology and identify the species assemblage of coralline algae using DNA sequencing; (2) Identify the role of coralline algae in a kelp recruitment facilitation cascade; (3) Identify the role of coralline algae in stabilizing alternate stable states. We will discuss current study design and present preliminary sequencing results for coralline samples collected in the Gulf of Maine. This study will advance our understanding of the role of coralline algae in temperate reef ecology across systems.