Barnacles antifouling compounds

Tomono, Y Hirota, H and Fusetani, N. (1998) Antifouling compounds against barnacle (Balanus amphitrite) larvae from the marine sponge Acanthella cavernosa, in Sponge Sciences Multidisciplinary Perspectives (eds Y. Watanabe and N. Fusetani), Springer-Verlag, Berlin, Heidelberg, pp. 413-424. 

ANTIFOULING AGENTS. Various chemical substances added to paints and coatings to combat mildew and crustaceous formations, such as barnacles on the hull of a ship. In the past, large quantities of mercury compounds have been used in this manner. With growing environmental concern over possible mercury pollution, manufacturers have been turning to other, sometimes less efficacious compounds, Research continues to find compounds of a less toxic, but equally effective power of the mercury compounds. Bis(tributyltin) fluoride has been used on ship bottoms. See also Mercury. 

Tin is a soft, pliable metal, but it is not used as such, because below 13°C, it slowly changes to a different allotype and forms a powder. Steel is plated with tin to make cans for food, and tin is also used in solders. Some tin compounds have been employed as antifouling agents in paint for ships and boats to prevent barnacles. However, even at low concentrations, these compounds are deadly to marine life, especially to oysters. Tin is thought to be an essential element for some living things, and this may also be true for humans. 

When the surface roughness increases by 30 i, the fuel consumption necessary for maintaining the same speed increases by I %. Hence, when the surface roughness increases by 1 mm, the fuel consumption increases by 30%. Marine animals and plants such as barnacles and algae adhere to the ships hull and it can be a serious problem. On account of these reasons, a large amount of organotin compounds have been used in antifouling paint. But environmental problems occurred as described above, and this book will not describe them in further detail [93-97]. 

For the primary antifouling screening, a barnacle assay is used in most cases. For this test, mass reared cyprid larvae of barnacle species like for example Balanus amphitrite are injected in dishes containing solutions of test compounds in seawater. After one hour, the settlement inhibition in regard to biodde-free controls is determined. 

The extracts of the brown alga Bifurcaria bifurcata that had shown seasonal variation were examined as settlement inhibitors of two marine bacteria and the barnacle Balanus amphitrite [131]. The increased activity during April-June corresponded to the seasonal maximum concentration of the major diterpene ele-ganediol 43 found in the crude extracts [132], but isolated compounds were not individually tested for their antifouling activity [131]. 

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