Bioassay of the morphogenetic activity with doubly sterile-filtered water from tidal pools and a main channel of the lagoon.
(A): Dilution series of the seawater samples with UCM were tested to estimate the potential morphogenetic activity on axenic Ulva gametes. Controls show the morphogenetic activity on gametes without bacteria, with the bacterial strain MS2, with the bacterial strain MS6 and the completely resembled morphology with both strains (MS2 and MS6). To estimate the MS2-like activity, the cell numbers of the germlings were counted 14 days after inoculation. (B) To estimate the MS6-like activity, the percentage of algae with a normal cell wall was evaluated 7 days after the first cell wall deformation was observed in axenic control cultures. Error bars represent (A) confidential intervals (P = 0.95; n = 60 individual algae) or (B) standard deviations (n = 60 individual algae). The dotted line indicates the maximum growth and development under axenic conditions.