Date of Award

Summer 8-18-2023

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth Sciences

Advisor

Sean M.C. Smith

Second Committee Member

Kate Beard

Third Committee Member

Andrew Reeve

Additional Committee Members

Lauren Ross

Matthew Baker

Abstract

Bacteria pollution closures of Maine’s coastal shellfish harvest areas have substantial negative consequences for coastal businesses and communities. Sustainability solutions for Maine’s shellfish harvesting areas and businesses require new types of knowledge and information to protect water quality and public health while avoiding unnecessary fishery closures. Coastal management agencies have interests in tools to support science-based management decision-making related to pollution and sustainability solutions for businesses and communities.

Prior research into land-sea connections has demonstrated uses of geographic information and statistical methods to facilitate management and science communication. Research in Maine has focused on identification and comparison of attributes influencing coastal conditions. Examinations of coastal settings based on proxy spatial data metrics for pollution sources, delivery, and residence time (SDR) attributes have demonstrated capacity to identify locations with varied pollution vulnerability when paired with water quality sampling data.

This research starts from the proof of concept from previous work and cogeneration of knowledge with stakeholders in Maine. Advancements include the strategic process for selecting and assembling proxy spatial data metrics, procedures to identify coastal pollution response units (CPRUs), and approaches used to document associations of CPRU settings with pollution problems. Outcomes include delineations of land-sea connection domains and identification of seven CPRU setting types. Results indicate similarity among locations derived from proxy metrics and bacteria sampling data based on selected pollution attributes and equal weighting of SDR attribute categories. Lands adjacent to tidal boundaries, “margin watershed areas” (MWAs), comprise 9.8% of the CPRU land area. However, MWAs were not found to increase the predictability of vulnerability to bacteria pollution.

Multiple information gaps are assumed to influence results and limit direct applications from the analyses, including: 1) Biases in bacteria sampling from management activities, 2) Static nature of proxy metrics describing land-sea connection processes, 3) Domain outlet specifications, 4) Influence of large river flows and ocean input, 5) Stochastic events, 6) Equal weighting of SDR pollution culprit categories. However, research outcomes provide a defensible framework for coastal pollution vulnerability evaluations, guidance for targeting pollution problems, and new information to support research and management decisions related to coastal planning and monitoring activities.

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