In the photic zone, the first "fouler" can be either bacteria and/or 

 diatoms (depending on geographical location). ' The normal temporal 

 sequence is: (1) bacteria, bacteria and diatoms, or diatoms and protozoa; 

 (2) sessile microorganisms (bacteria and/or diatoms) ; (3) colonial micro- 

 organisms; and (4) macroorganisms . °° The initial step varies from location 

 to location, even if only a few miles apart. There have also been some 

 cases where the barnacles have been the "pioneer" species. The organisms 

 will begin to attach readily only after the concentration of organisms on 

 a surface is much greater than that of the surrounding water. °^''^ 



Within the photic zone, a stratification is set up, especially in calm 

 waters. In the Central Pacific, about 4 to 5 miles offshore, in the top 

 300 ft it is something like this:^l 



1. Calcareous Zone with barnacles, anemones, etc 



2. Algae Zone with ulva, other green algae, and red algae 



3. Free Zone, just below the Algae Zone 



4. Lower Zone with tubeworms, hydroids, bryozoa, etc. 



Although the bacterial population on a surface decreases with depth, bac- 

 teria are found to the bottom, no matter what the depth. "°'^'^' This 

 microbial growth is reponsible for the establishment of the fouling commun- 

 ity under relatively adverse conditions because it: (1) attracts the larvae 

 of foulers, (2) serves as a food source, and (3) passivates inhospitable 

 surfaces. 



The decrease of fouling with depth and distance from shore does not 

 appear to be influenced by any single environmental factor. "3,66 Probable 

 factors include: (1) decreased water temperature, (2) lack of organic 

 matter (food), (3) currents, and (4) available attachment surfaces. Any 

 of the above can become limiting; i.e., there may be enough organic matter 

 in the water for sustenance, but there may be few solid surfaces available 

 for attachment. Thus, the presence of fouling organisms (especially of 

 larvae) in that region would be limited. With decreasing fouling as a 

 function of depth and as distance from shore increases, there is a concur- 

 rent decrease in the speciation;^-^'' ' i.e., as bryozoans increase in 

 numbers, the barnacle population decreases. Since the bryozoans and/or 

 hydroids are usually smaller than barnacles and/or mussels, the total 

 biomass attached will decrease. ^^ Predominant open ocean fouling organisms 



27 



