ZoBell — 194 — Marine Microbiology 



light-reflecting surfaces are fouled less readily than dark or discolored 

 ones. (3) By serving as a source of food. Barnacles, mussels, tunicates, 

 and other fouling organisms are nourished by bacteria (see page 173). 

 (4) By promoting the deposition of the calcareous cements of sessile organ- 

 isms. (5) By increasing the concentration of plant nutrients, including 

 CO2 and ammonia, which result from the bacterial decomposition of 

 organic matter. 



Table XLI. — Numbers of different types of fouling organisms found per square inch of 

 glass slide after dijfferent periods of submergence in the sea at La Jolla, California (from ZoBell, 

 1939b).— 



Under certain conditions the primary film formers may form a pro- 

 tective layer over antifouling paints designed to discourage barnacles, or 

 they may otherwise effectively reduce the toxicity of antifouling paints. 

 Bacteria attack and slowly decompose certain protective surface ma- 

 terials. On the other hand, under certain conditions bacterial films may 

 help to keep surfaces free from larger fouling organisms by the production 

 of antibiotic substances. The interrelationships among the organisms in 

 fouling cumulations are very complex and not well understood. The 

 available information stresses the desirability of taking microorganisms 

 into account in the scientific approach to the preparation of antifouling 

 surfaces (ZoBell, 19386). 



Algae, particularly species of Ectocarpus and Herposiphonia, diatoms, 

 hydroids, barnacles, oysters, bryozoans, and serpulids were the most 

 abundant sedentary organisms observed on submerged surfaces by Coe 

 and Allen (1937) during their nine years' study at La Jolla, California. 

 Sixty species of diatoms, 15 species of algae, and 8 species of foraminifera 

 were commonly recognized on submerged plates, along with a diversity of 

 sponges, hydroids, nemerteans, annelids, bryozoans, mollusks, crusta- 

 ceans, and ascidians. No record was kept of the presence of bacteria and 

 allied microorganisms. 



Bacteria associated with wood-borers : — Wooden structures exposed 

 in the sea are subject to the depredations of several kinds of destructive 

 animals of which the drilhng mollusk or " ship-worm," Teredo navalis, and 

 the boring gribble, Limnoria lignorum, are the commonest. Details re- 

 garding these and other boring animals and the extent to which they dam- 

 age pihngs, wooden boats, timbers, etc., are given in the literature sum- 

 marized by Crosthwaite and Redgrave (1920). Additional informa- 

 tion is given by Kofoid (1923) who believes that Limnoria digests the 

 wood which it swallows. DoulDt is expressed that Teredo utilizes wood as 

 food. 



It is an inadequately explored possibility that these and other wood- 

 boring animals depend partly or largely upon bacteria for their nutrition. 

 Plankton organisms have been regarded as the principal food of Teredo 

 navalis, although Dore and Miller (1923) found that wood loses about 

 80 per cent of its cellulose and 15 to 56 per cent of its hemicelluloses during 



