Presenter: Olivia R. Davis

Faculty Sponsor: Thea Popolizio

School: Salem State University

Research Area: Biology

Session: Poster Session 3, 1:15 PM - 2:00 PM, Concourse, B9

ABSTRACT

Macroalgal diversity was assessed between September and November of 2024 and 2025 at 22 intertidal sites across Massachusetts, New Hampshire, and Maine. Specimens were identified using morphological characteristics alongside DNA barcoding, which enabled the detection of cryptic species that may be overlooked by morphology alone. Species occurrence was analyzed using presence/absence data, and community composition was quantified with non-metric multidimensional scaling (NMDS) based on Jaccard distance to reveal spatial patterns across the northern New England coastline.

Introduced species were widespread, co-occurring with native taxa. Over 50% of non-native taxa were cryptic, highlighting the limitations of morphology-based surveys and the value of molecular tools for accurate biodiversity assessment. Although these cryptic introductions did not dominate overall community structure, they represent a substantial component of intertidal assemblages and may influence long-term ecological monitoring.

This study establishes a quantitative baseline of macroalgal communities in northern New England and underscores the widespread presence of cryptic introduced species. Integrating morphological identification, DNA barcoding, and multivariate analyses revealed hidden diversity missed by traditional surveys. These methods provide a foundation for standardized, long-term monitoring, while expanded future sampling could clarify ecological impacts and guide conservation strategies.