Diatom community structure on commercially available ship hull coatings

Diatoms are primary colonizers of both antifouling and fouling-release ship hull coatings. There are few published studies which report on diatom community development on modern ship hull coatings. This study reports diatom communities on eight commercial marine ship hull coatings exposed at three static immersion sites along the east coast of Florida, viz. Daytona, Sebastian, and Miami. The coatings tested were three ablative copper systems (Ameron ABC-3, International BRA-640, and Hempel Olympic 76600), two copper-free biocidal systems (E-Paint SN-1, Sherwin Williams HMF), and three fouling-release (FR) systems (International Intersleek 700, International Intersleek 900, and Hempel Hempasil). One hundred and twenty-seven species comprising 44 genera were identified, including some of the more commonly known foulers, viz. Achnanthes, Amphora, Cocconeis, Entomoneis, Licmophora, Melosira, Navicula, Nitzschia, Synedra, and Toxarium. A significant difference was seen among sites, with the more estuarine site, Sebastian, having lower overall diatom abundance and higher diversity than Daytona and Miami. Copper coatings were primarily fouled by Amphora delicatissima and Entomoneis pseudoduplex. Copper-free coatings were fouled by Cyclophora tenuis, A. delicatissima, Achnanthes manifera, and Amphora bigibba. FR surfaces were typified by C. tenuis, and several species of Amphora. The presence of C. tenuis is new to the biofouling literature, but as new coatings are developed, this diatom may be one of many that prove to be problematic for static immersion. Results show coatings can be significantly influenced by geographical area, highlighting the need to test ship hull coatings in locations similar to where they will be utilized.