Department or Program

Environmental Studies

Abstract

Rocky intertidal ecosystems are structured by environmental conditions and are particularly sensitive to climate change driven stressors such as ocean warming and acidification (Fernandez et al., 2020; Kleisner et al., 2017). This study examined algal and invertebrate community composition across eight rocky intertidal sites spanning northern and southern regions along the Gulf of Maine to assess how tidal height, site, and region shape species distributions and interactions. Surveys quantified percent cover and total count across low, mid, and high tidal zones, and patterns were analyzed using two-way ANOVA and Tukey HSD post hoc tests. Algal community composition varied significantly with tidal height and site (p < 0.05), with a significant interaction (p = 0.0013), indicating spatial variability in vertical zonation. Green, brown, and red algae each exhibited distinct regional and tidal patterns, with red and green algae dominating lower zones, while brown algae was constrained to the mid by exposure and competition. Sessile organisms, including Semibalanus balanoides and Mytilus edulis, were strongly influenced by tidal height and site/region (p < 0.05), reflecting limits imposed by desiccation stress and space availability. Mobile organisms also showed significant tidal and site/regional effects (p < 0.05), consistent with grazer and producer interactions influencing algal distributions. Species-specific analyses revealed significant interactions between canopy-forming algae and sessile invertebrates, supporting the role of interspecific competition in shaping community structure. Overall, the results align with classical intertidal zonation theory while revealing region-specific variability likely driven by temperature regimes, wave exposure, and interspecific competition. These findings underscore the importance of integrating applicable conservation efforts by understanding latitudinal gradients and biological interactions within the intertidal ecosystem along the Gulf of Maine.

Level of Access

Open Access

First Advisor

Justin Baumann

Date of Graduation

5-2026

Degree Name

Bachelor of Arts

Number of Pages

52

Components of Thesis

1. pdf

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