Date of Award

Fall 12-16-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Amanda Klemmer

Second Committee Member

Hamish Grieg

Third Committee Member

Brian Olsen

Additional Committee Members

Kathryn Miller

Abstract

The rocky intertidal ecosystem is an important ecological and cultural aspect of the picturesque Maine coast, playing a vital role in not only Maine’s coastal ecosystem, but also to Maine’s economy. It’s distinct community structure along the sharp elevational gradient and the presence of daily stressors (wave action, heat, and desiccation), make the rocky intertidal ecosystem an important model ecosystem to monitor for effects from anthropogenic impacts. In this thesis, I describe attempts to monitor and understand the impacts of two of these anthropogenic impacts on this system: climate change and industrial harvesting of Ascophyllum nodosum along Maine’s coast. For my second chapter, I worked with the National Park Service to develop a rocky intertidal rapid assessment protocol to monitor the intertidal community and species ranges within the rocky intertidal ecosystem. This protocol consisted of point-intersect transect surveys and was developed and tested at Acadia National Park (ANP) in Maine. I found that, in the intertidal ecosystem at ANP, environmental conditions such as aspect and slope do not directly structure the intertidal community, but they are important in dictating species’ elevational ranges. Compared to the current long-term monitoring efforts at ANP, this rapid assessment protocol, through this pilot study, provides park managers with both comparable and novel data while using 20% of the time and labor compared with the current long-term monitoring protocol. This can therefore be used to better assess the status of the ecosystem over time, giving park managers an invaluable tool in understanding the rocky intertidal ecosystem.

In my third chapter, I worked to understand the impact of Maine’s harvesting of Ascophyllum nodosum on the invertebrate communities which are associated with the macroalgal canopies. This was done by performing a Before-After Control-Impact (BACI) experiment and looking at invertebrate communities in harvested and unharvested sites before harvesting occurred, a month after harvesting occurred, and one year after harvesting occurred. I found that despite being similar in the pre-harvest surveys, the invertebrate communities in the harvested sites were significantly different from the invertebrate abundances in the unharvested sites one month after harvest. Both abundances, however, returned to pre-harvest levels in the one-year post-harvest surveys, showing a full recovery in the invertebrate abundances in the harvested sites. As macroalgal harvesting is increasing on a worldwide scale, and with the potential destabilization of the rocky intertidal ecosystem due to climate change, these results help inform fisheries management priorities when considering the management and conservation of the rocky intertidal ecosystem.

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