B. Weight 



The weight of the fouling complex on each panel was determined 

 in an effort to make a quantitative estimate of the rates of setting 

 and growth of organisms. Panels exposed for 1-month periods can be 

 considered to represent primarily the setting rate of organisms, although 

 some growth also occurs during the month. Panels exposed for longer 

 periods (2 months, 3 months, etc.) are considered to represent the 

 accumulation resulting from both setting and growth. Figure 7 shows 

 the wet weight (in air) in ounces of the fouling on 1-month, 2-month, 

 and 3-month panels. The weight of the fouling on 1-month panels indicates 

 that little or no biological attachment occurred from October through 

 April. Organisms began to set in May and reached peak setting in 

 August. The weight of fouling on 2- and 3-month panels indicates 

 that setting and subsequent growth of organisms were most rapid 

 during the period August to October. Surface water temperatures 

 near the fouling rack increased in May to 67°F. and decreased in 

 October to 65°F. (Fig. 5). Attachment in this area appeared to be 

 limited generally to the period when temperatures were above 65°F. 

 The curves showing the weight of fouling on panels exposed for 2 

 and 3 months indicate that growth proceeded at a rapid rate after 

 attachment had reached its peak. The sharp drop of the curves after 

 October is significant because it indicates lack of subsequent growth 

 following cessation of attachment in September and October. 



Figure 8 is a plot of accumulated wet weight (in air) of fouling on 

 panels exposed for increasing lengths of time and the cumulative weight 

 of fouling on panels exposed for 1-month periods. The accumulated 

 weight curve exhibits a typical sigmoid shape resulting from both 

 attachment and growth. New attachment began in May. Both attachment 

 and growth went on at an accelerated rate from July to September. 

 New attachment decreased sharply in September, whereas growth 

 continued at a relatively rapid rate for the remainder of the test 

 year. New attachment declined to practically nil from October through 

 April. 



C. Organisms 



1. Barnacles 



Barnacles were the first macroscopic organisms to appear on 

 the panels after the start of the test in April. Figure 9A is a plot of 

 the number of individuals, their average diameter, and average height 

 on the monthly panels from April 1956 through March 1957. Barnacle 



