Date of Award

Fall 2022

Document Type


Degree Name

Master of Science (MS)



Committee Chairperson

S. Anne Boettger, Ph.D.

Committee Member

Michael Rosario, Ph.D.

Committee Member

Sharon Began, Ph.D.


Hemic neoplasia (HN) is a bivalve disease characterized by uncontrolled proliferation of abnormal hemocytes that invade solid tissue, similar to vertebrate leukemia, ultimately leading to death. High disease prevalence has been reported in many bivalve populations, yet disease etiology and development remain minimally understood. In this study, nine East Coast populations of soft-shell clams (Mya arenaria) were evaluated between 2011-2012 to identify environmental and health factors associated with HN. PCA analysis and statistical testing were used to compare data at and between each population based on HN status. The percentage of organisms with terminal stage 4 HN (76-100% neoplastic cells) was used to group sites into those of high and low disease incidence; with average terminal HN of 6.46% and 28.15% and organismal survival of 60.8% and 20.2% detected for low and high HN sites, respectively. Analysis revealed pollutants including PCBs (Aroclor 1221), PAHs (pyrene and fluoranthene), organochlorinated pesticides (methoxychlor, toxaphene, endrin, BHCs, aldrin, Endosulfan, and heptachlor) and heavy metals (iron, aluminum, chromium, copper, nickel, and zinc); as well as sediment organic content were strongly associated with HN prevalence and survival. On average, high HN sites displayed 1422 mg/kg total pollutants and 49.2% organic content, while low HN sites displayed 388 mg/kg and 36.5%, respectively. Water temperature was also associated with HN and mortality, emphasizing concerns about rising ocean temperatures associated with climate change. Overall, higher pollutant levels or elevated water temperatures increased HN incidence indicating disease transmission through viral infection is likely due to reduced immunity in M. arenaria.

Included in

Biology Commons