Ceraesignum maximum larvae were obtained from field- collected adults, in Moorea. Individual adult C. maximum were chiseled from the coral matrix intact in their tubes, transported to the laboratory in coolers of seawater, and their brooding status ascertained by gently poking each snail until it retracted deep into its shell. If late-stage capsules were observed attached to the inside of the shell, a mesh-sided cage (mesh = 150 µm) was secured around the tube with cable-ties, and the adult (with mesh enclosing the openings to their tubes) was then placed in a large tank with flowing seawater. Swimming larvae were released by females after 1–3 days.
Fragments (approximately 2x3 cm) of live coral were collected from the lagoon on the morning of each experiment and left for 2 h in flowing ambient seawater to recover. Fragments were examined under a microscope prior to each experiment to ensure that polyps were extended.
For this experiment:
Treatments were established in 1 Liter plastic tubs filled with filtered seawater (FSW; mesh size = 0.5 µm). Each tub contained one of five treatments: fragments of live Porites lobata, Pocillopora sp., or Porites rus, coral rubble (fragments had been scrubbed and dried in full sun for 2–3 days prior), or a control of FSW only (n = 4 replicate tubs per treatment). Twenty 2-d posthatch D. maximum larvae from a single female were gently pipetted into each tub, released a few cm above the substrate. In all cases, the velum (the ciliated larval swimming structure) was extended. Tubs were maintained in a flowthrough seawater table and examined after 24 h under a dissecting microscope. The tub and each fragment were thoroughly searched for any settlers, and all larvae scored as either live or dead. If larvae were dead, it was noted whether the larval shells were empty of tissue (i.e., presumably consumed by the coral). This experiment was repeated 3 days later with 1 days posthatch larvae from a different female, and with the addition of a treatment of live Millepora sp. (referred to as run 2).