Factors Controlling Attachment of Bryozoan Larvae: A Comparison of Bacterial Films and Unfilmed Surfaces

Abstract

The effects of individual species of marine bacteria on the attachment of larvae of the bryozoan Bugula neritina were examined in the laboratory. Bacteria, grown to mid-exponential phase and allowed to adsorb to polystyrene petri dishes, attached at densities of 106-107 cells cm–2. Bryozoan attachment assays (30 min) were used to compare the effects of adsorbed cells of three species of bacteria with unfilmed surfaces. Larvae permanently attached, at high percentages (65-94%), to unfilmed polystyrene, hydrophobic (i.e., low wettability, low surface energy) control surfaces. This activity agrees with reports in the literature. Films of individual species of bacteria can influence bryozoan attachment. Three separate strains of the bacterial species Deleya marina inhibited attachment, but two other species of marine bacteria did not. Measurements indicated that all five bacteria tested differed in their cell-surface hydrophobicity, but that their films were similar in that they were all highly wettable (i.e., high surface free energy). Our data indicate that factors in addition to substratum surface energy determine attachment of bryozoan larvae especially when bacterial films are present. Bacterial extracellular materials may be involved.