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theses

Molluscan bivalve shellfish are well-known for the suite of ecosystem services they provide within the nation’s estuaries, with one of the most highlighted being their ability to filter the water column. Based on previous research, increasing bivalve species biodiversity should augment the provision of ecosystem services and theoretically, stabilize estuaries. A direct examination of potential interspecific population interactions amongst species within this functional group, however, has not yet been explored. This study examines that gap and forges a better link between theory and potential real-world limitations. This research used two common species within Delaware Bay, USA – Crassostrea virginica (Gmelin) and Geukensia demissa (Dillwyn) – to explore potential particle removal relationships when placed in monoculture and cohabitation. The objective was to answer the question of whether these two species exhibit interspecific competition for food resources. Using the highly controlled Clearance Method as well as a more variable flow through system, interspecific competition did not result between these two bivalve filter-feeding species. Particle removal amounts under the static and variable conditions were similar among single and mixed species populations. In the flow through systems, where filtration of a native particle community was examined, C. virginica exhibited particle preferences based on size and possibly quality (the methods did not allow for examination of plankton speciation). Overall, the results provide evidence of complementary resource use and link previously modeled results of ecosystems with experimental data on coexisting bivalve species. The second component of this research was an exploration of the management of bivalve shellfish, specifically focusing on the regulation of aquaculture within the United States. This section of the research analyzed the diverse policy systems implemented within four states to develop the thesis that U.S. shellfish aquaculture production is dependent upon industry supportive state-level regulations. Several key factors to successful industry development arose out of the four state analysis. The first factor in successful state industry growth is a single contact point between grower and the state permitting authorities (point-of-contact). Connected to the point-of-contact is the premise that vertical integration of permitting from federal permits through to local boards or review councils (vertical integration) occurs via that singular regulatory liaison. Furthermore, states with older regulatory structure (age) continually work to improve permitting efficiencies but do not have recent changes in regulation that cause short-term industry instability. Changes to regulation can cause uncertainty within the industry, limiting short-term growth while growers wait for regulatory measures to finalize. This is especially evident in states with numerous, recent changes. Finally, the primary factor to successful state shellfish aquaculture is political will or capital within the Executive Branch (political will). It is through cohesive agreement among all agencies within the Executive Branch, including the Governor’s Office, that progress within states can be achieved with greatest efficiency.

ETD_8786

Ph.D.

Includes bibliographical references

by Amanda Ann Wenczel

doi:10.7282/T3GH9ND8

ETD doctoral

The author owns the copyright to this work.