Attachment studies in marine fungi

Abstract

The strength of attachment of ascospores of six marine Ascomycotina (Amylocarpus encephaloides, Ceriosporopsis circumvestita, Eiona lunicata, Groenhiella biveslia, Halosphaeria appendiculata. Unidentified Ascomycete “A") was investigated in a Fowler Radial Flow Chamber at various times after settlement. Strength of adhesion varied from 1.06–5.57 Nm⁻² at one h settlement for the different species tested, with E. tunicata withstanding the higher shear stresses (4.45–5.57 Nm⁻²). The forces required to dislodge spores increased with settlement time, with the exception of Unidentified Ascomycete “A”; and C. circumvestita. The mean number of spores attached to the surface per unit area, after initial settlement also increased with time, with the exception of Eiona tunicata. This greater attachment can be attributed to (a) initial attachment by means of the “sticky”; appendages, and (b) secondary mucilage production by the spores once contact was made with the surface. These studies complement earlier investigations which indicated that spore appendages aid attachment. On contact with the substratum spores release mucilage, as has been demonstrated for H. appendiculata. This mucilage forms a strong attachment point for the spores prior to germination and germ‐tube production. The latter also produces mucilage which aids attachment, as demonstrated for G. bivestia. Spore attachment occurs in various ways and differs from species to species. Those with a number of strategies for securing spore attachment must have a competitive advantage, over those which lack these, in the colonisation of substrata.