nudibranch, bryozoan, Zoobotryon verticillatum, Okenia zoobotryon, predator-prey, chemistry, larvae
In the Indian River Lagoon, the nudibranch Okenia zoobotryon and its egg masses are found attached to the bryozoan Zoobotryon verticillatum throughout the year. Okenia zoobotryon is thought to live, feed, and reproduce exclusively on Z. verticillatum, which would make this a very specialized predator-prey interaction. The primary goal of my study was to document certain aspects of the ecological and chemical relationships between Z. verticillatum and O. zoobotryon. Specifically, I wanted to understand the cues used by the nudibranch to locate and remain on Z. verticillatum. Population surveys on Z. verticillatum, as well as other potential hosts, were performed. From these surveys, I found a small number of O. zoobotryon adults and egg masses on the red macroalga S. filamentosa mixed with Z. verticillatum (0.01 and 0.05 g/wet-weight, respectively), none on the bryozoan Amathia distans, and none on the red macroalga Gracilaria tikvahiae. To determine if prey identification was associated with an adult cue, I ran paired-choice trials. In these, the adults did not significantly prefer Z. verticillatum. Next, laboratory culture of larvae of O. zoobotryon was performed. During larval culture some aspects of this previously undocumented life-history were recorded; adults of this species developed from planktotrophic veliger larvae that hatched out of egg masses between 4 and 6 days, the time post-hatching to settlement was 7-8 days, and metamorphosis occurred approximately 24 hours after settlement. The final question addressed in this study was; "Does O. zoobotryon feed on and take up chemicals from Z. verticillatum?" To address this question, high-performance liquid chromatography was performed on extracts of Z. verticillatum and O. zoobotryon. Both organisms were compared and found to contain similar compounds, which suggest that the nudibranch is feeding on Z. verticillatum and taking up chemicals. Concentrations of compounds in Z. verticillatum varied between populations in the northern and southern regions of the Indian River Lagoon. There are, also, differences between the chemical composition of Z. verticillatum in the IRL (northern and southern) and the California species identified by Sato and Fenical (1983).
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Master of Science (M.S.)
College of Arts and Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Robinson, Nicole, "Interactions Between The Nudibranch Okenia Zoobotryon And Its Bryozoan" (2004). Electronic Theses and Dissertations. 230.