Department or Program

Environmental Studies


Average seawater temperatures have been steadily increasing for the past four decades, creating drastic ecosystem shifts for many aquatic species. Commercial landings of softshell clams across the state have decreased by almost 75%, as a result high rates of predation due to warming temperatures (Beal et al., 2018). The mortality rate of soft-shell clams is known to correlate with higher densities of milky ribbon worms (Cerebratulus lacteus) (MRW). Past studies have found that 100% of soft-shell clams died with MRW present and 0% died in the absence of MRW. While the milky ribbon worm is known to significantly impact ecosystems, the reason of the species’ recent increase is unknown. The main goal of this study is to test whether sediment variation across various sites can shed light on the occurrence of milky ribbon worms. To test the impact of sediment variation on the increase in milky ribbon worms, three plots were placed along each tidal zone at all six sites along the Casco Bay. Samples were collected once in July and once in August. One of the sites, Cousin’s Cove had the highest abundance of softshell clams out of all the sites and no MRW presence in July; while in August, Cousin’s Cove had MRW presence at all tidal zones and no softshell presence. The presence of MRW at Cousin’s cove seems to have wiped out the softshell clam population at the site within a month’s time. This study determined that MRW occurs at sites with the highest concentrations of "clayey silts". The softening of mudflats in coastal Maine may be attributed to historic human activity and/or low wave energy. Both of which promote the deposition of fine sediments, which support the tunneling of microorganisms like MRW. Further research over a longer time period as well as assessing LOI, nitrate and conductivity of all samples is necessary to provide a more detailed insight on how sediment variation impacts the occurrence of the milky ribbon worm.

Level of Access

Restricted: Campus/Bates Community Only Access

First Advisor

Carissa Aoki

Date of Graduation


Degree Name

Bachelor of Arts

Number of Pages


Components of Thesis

1 pdf file


Available to Bates community via local IP address or Bates login.