ABGRALL, M-J.*; WALTERS, L.J.: Settlement preferences and recruitment of the bryozoan Bugula neritina on drift macroalgae in Mosquito Lagoon, Florida

In Mosquito Lagoon (the northernmost region of the Indian River Lagoon, Florida), significant differences in the abundance and diversity of drift macroalgae were found when sampled on a monthly basis from January 1998 – March 2000. In the winter months, the arborescent bryozoan Bugula neritina was commonly found attached to available drift species in the order Gigartinales, Rhodophycea. However, it was rarely found on these same algal species when they were attached. In replicated single and multiple-choice trials in the laboratory that included the seagrass Halodule wrightii and the macroalgae Hypnea cervicornis, Gracilaria armata, Gracilaria tikvahiae, Enteromorpha compressa, Agardhiella subulata and Dasya rigidula, the two species of red algae Gracilaria were significantly preferred in both types of trials. Despite having a similar morphology to G. armata, Dasya rigidula was avoided by settling larvae of B. neritina and greater than 60% larval mortality occurred in the bioassays. To determine if the preferred settlement choice of B. neritina is due to the morphology of Gracilaria or secondary chemicals, field trials were run comparing recruitment on attached versus drift G. armata and attached versus drift mimics. Bugula neritina never recruited on attached G. armata and rarely on mimics (drift or attached); however, large numbers of larvae recruited on drift G. armata.