Date of Award

Fall 2013

Project Type


Program or Major


Degree Name

Master of Science

First Advisor

Larry G Harris


Competition for space can influence community dynamics in the sessile biofouling community. Within recent decades, community dynamics have shifted towards a community dominated by tunicates. This research proposed predation as a mechanism driving this shift.

In the Gulf of Maine, the non-native species Botrylloides violaceous became abundant when predators (i.e. the benthic fish Tautogolabrus adspersus and the sea star Asterias rubens) removed the cryptogenic (i.e. native) tunicate Molgula citrina. Moreover, B. violaceus was present in higher amounts in habitats with low abundances of M. citrina than it was in areas in which the two tunicate species were both abundant. Furthermore, laboratory feeding trials showed that abundant local predators T. adspersus and A. rubens readily consumed large amounts of M. citrina..