Date of Award

5-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Paul Bologna

Committee Member

Matthew Aardema

Committee Member

Meiyin Wu

Abstract

Many tunicate species have invaded the Western North Atlantic coast in the last century. These tunicates can have negative impacts on important industries like shellfish aquaculture, but they also foul natural and anthropogenic surfaces leading to displacement of native communities. During the summer of 2017 and 2018, the spatial distribution and recruitment of tunicate species in Zostera marina (Eelgrass) beds in Barnegat Bay, New Jersey were assessed. Samples were collected during the summer by excavating all eelgrass from a 0.125m2 area. Samples were then assessed for tunicate presence, as well as percent coverage of tunicates. In 2017, Botrylloides violaceus was the most commonly identified species and was found at Barnegat Inlet and Ham Island. Botryllus schlosseri, Didemnum vexillum, and Ascidiella aspersa were also identified, but were less abundant. Tunicate coverage increased substantially at Barnegat Inlet from June to August, but decreased at Ham Island during this period. Didemnum vexillum was only found at Ham Island, while Ascidiella aspersa was only found at Barnegat Inlet. In 2018, a broader survey of Barnegat Bay was done, which included numerous sample sites throughout the bay. Botryllus schlosseri was the most commonly identified species during this larger survey. A regression analysis demonstrated that there was a significant positive relationship between Z. marina biomass and tunicate biomass. This suggests that when there is more seagrass biomass there is more spatial area for colonization and growth of ascidians. However, there was one outlier that showed the potential negative effects of tunicate growth on seagrass. This outlier is evidence of the fact that tunicates can overgrow and kill seagrass. These results suggest that fouling invasive tunicates could have a negative impact on eelgrass communities by smothering blades and reducing plant viability. This research is the first evaluation of invasive tunicates living among the seagrass beds in New Jersey and indicates both spatial and temporal variability in presence and prevalence.

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