WELCH, J.M.* *; WALTERS, L.J.; YOUNG, C.M.: Effects of flow on larval release behavior of the bryozoan Bugula neritina

The ubiquitous arborescent bryozoan Bugula neritina lives attached to substrata and is subjected to tidal currents in estuarine areas. Itslarvae have a very short planktonic period (minutes to hours), so the timing of release relative to the state of the tide is critical in determining how far the larvae will be transported during their planktonic existence. Prior work has found that B. neritina release larvae upon exposure to bright lights after a period of darkness, akin to sunrise in the field. However, no prior research has considered whether B. neritina alters its behavior in flow to release larvae during a particular state of the tide. We compared the larval release behavior of B. neritina in still water and in 1 and 5 cm s^-1 flows in a flow tank. There was no difference between release in 1 cm s^-1 flow and still water. However, in 5 cm ^-1 flow, B. neritina released fewer larvae than in still water. This indicates that B. neritina preferentially releases larvae in still water or very slow flow, suggesting a selective pressure to retain larvae close to their parent population, presumably to remain in a favorable habitat.