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Di Filippo, Carla

The outbreak of sea star wasting disease along the Pacific Northwest in 2013 is associated with a shift in sea star community structure, with the normally abundant Pisaster ochraceus decreasing in abundance relative to Evasterias troschelii in and around Vancouver, BC. This change in relative abundance could directly affect the abundance and distribution of important prey species such as Mytilus trossulus (mussels) and Balanus glandula (barnacles), with Mytilus observed to exclude and decrease species richness of additional prey species in the intertidal. Previous research indicates that Pisaster prefers mussels over barnacles, however with Evasterias being understudied, these preferences are unknown. The goal of this research project was to improve our understanding of Evasterias prey preferences, feeding rates, and whether diet affects sea star growth. We conducted a lab experiment using organisms collected from Burrard Inlet, BC, and provided Evasterias with a diet of mussels, barnacles, or both, and recorded prey consumption and predator growth rate. Additionally, we conducted a feeding rate experiment between Evasterias and Pisaster. Results show the growth rate of Evasterias was higher when mussels were available. However, the proportion of mussels or barnacles consumed did not differ when sea stars were presented with only one or both prey species, suggesting that they did not have a strong prey preference. The number of mussels consumed overall was lower than that of barnacles, but tissue mass consumed was higher in mussels than that of barnacles. The feeding rates between Pisaster and Evasterias showed similarity. Although the strength of dietary preferences of Evasterias and Pisaster may differ, our results suggest that Evasterias may nevertheless play a similar ecological role when it becomes abundant on rocky shores.

Text

University of British Columbia. APBI 499

Vancouver : University of British Columbia Library

10.14288/1.0376076

Land and Food Systems, Faculty of

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/