Date of Award
Spring 5-3-2024
Level of Access Assigned by Author
Open-Access Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Ecology and Environmental Sciences
Advisor
Amanda Klemmer
Second Committee Member
Brian Olsen
Third Committee Member
Jessica Muhlin
Additional Committee Members
Bob Steneck
Catherine Matassa
Abstract
The structure of a biological community is the result of many interacting factors—abiotic, biotic, disturbances and chance events, both in the present and in the past. In many ecosystems the presence of a foundation species shapes the outcomes of these interacting factors. Foundation species are abundant species having a large influence on community structure. I explored the role of a foundation species, Ascophyllum nodosum (rockweed), on influencing the physical conditions and community of its ecosystem, and any cascading effects of disturbance to that foundation species to the community. Chapter 1 is an investigation of the relationship between habitat complexity and invertebrate community. I compared complexity and community composition across a chronosequence of sites with different times since human disturbance. Complexity increased across the chronosequence with temporal distance from disturbance. Invertebrate abundance and richness were influenced by multiple measures of complexity, community composition by a single measure. In Chapter 2 I looked at the community-shaping role rockweed plays under physically harsh and benign conditions; and whether human disturbance affects the role. I found that rockweed maintains community diversity but not abundance when shifting from physically benign to physically harsh environments. The effects of disturbance, rockweed harvesting, affects the community in harsh and benign conditions to the same extent. Chapter 3 was an examination of how human disturbance affects the role of a foundation species to ameliorate physical conditions of the environment. I measured light, temperature, and desiccation rate before and after rockweed harvest. Modelling suggests that the removal of biomass and canopy height after rockweed harvest influences temperature and light, but not desiccation. Whether those effects of changed light and temperature conditions affected the benthic community was the focus of Chapter 4. I studied the benthic community before and after harvest and found no change to the community. These four investigations demonstrate community composition and variation in a foundation-species dominated system can be resilient to disturbance.
Recommended Citation
Webber, Hannah, "The Foundation Roles of Rockweed, Ascophyllum nodosum (Linneaus) Le Jolis, in Maine's Rocky Intertidal zone" (2024). Electronic Theses and Dissertations. 3954.
https://digitalcommons.library.umaine.edu/etd/3954