Invasive tunicate (Ascidiacea) metabolic and filtration rates in comparison to native tunicate and bivalve species

摘要

Several invasive species of tunicates (Ascidiacea) have become cosmopolitan andwidely distributed in coastal areas worldwide over the past few decades. These nonindigenoustunicates have consequently caused fouling problems in aquaculture andmarine harbors. The goal of our project was to enrich the understanding of howinvasive tunicates interact with other organisms in the ecosystem. Two species ofinvasive tunicates (Didemnum vexillum and Botrylloides violaceus) and one speciesof native tunicate (Aplidium glabrum) were evaluated for their metabolic rates. Thefiltration rates for native blue mussels (Mytilus edulis) and invasive tunicates(Diplosoma listerianum) were determined. D. vexillum regenerated NH4+ at a fasterrate than A. glabrum and B. violaceus. Both tunicates and blue mussels were feedingon phytoplankton as their major food source, although the size of particles utilizedby different organisms was not examined in this study. Invasive tunicates werestrongly competing with mussels to filter feed, but were not inhibiting mussel’sfiltration rate.