Studies on the strength of adhesion of some common marine fouling diatoms

The Radial Flow Chamber was used to determine the attachment strengths of four marine diatoms, Amphora coffeaeformis var. perpusilla, Navicula corymbosa (procumbent species), Achnanthes brevipes var. intermedia and Licmophora gracilis var. anglica (stalk producing species), common on the hulls of in‐service shipping. The influence of incubation times (1 to 96 h) and surface roughness (smooth and two grades of surface roughness) on the attachment strength of the diatoms was investigated.

The diatoms showed marked variation in their relative strength of adhesion, with the Amphora and Licmophora spp. being the strongest and weakest attached, respectively. For all diatoms there was an increase in attachment strength with incubation time, although marked differences were observed in the rate of increase. By providing protection from fluid flow, the two roughened surfaces increased the attachment strength of all diatoms throughout the incubation period. However, under these conditions the strongest adhesion was recorded by the small procumbent Amphora, and to a lesser extent, Navicula spp. There • appeared, therefore, to be a direct relationship between the morphology and adhesive strength of the diatoms. These results appeared to correlate well with the abundance and observed distribution pattern recorded for these genera on in‐service shipping.

Key words:

• ship‐fouling diatoms
• strength of adhesion
• surface roughness

Notes

Present Address: Keith Borer Consultants, Mountjoy Research Centre, Durham DH1 3UR, UK.