HANSON and BELL: SUBTIDAL AND INTERTIDAL MARINE FOULING 



SURFACE FLOAT 



SUFIFACE PANEIS 



consisted of soft silt and sediment with a few rock 

 outcroppings. Acorn barnacles, BaZanas crenatus, 

 densely covered the few rock outcroppings, but 

 were otherwise not present. At a depth of 18 m, 

 light penetration was low and bottom currents 

 appeared to be generally slow. In contrast, the 

 bottom at Skagit Island was virtually free of silt 

 and was predominantly covered with cobble and 

 rock outcroppings. The cobble and rock were 

 densely covered with B. crenatus. At 18 m, 

 light penetration was moderate and the bottom 

 currents were consistently more rapid than those 

 at the Kiket Island site. 



Fouling Colonization of 

 the Construction Materials 



The fouling resistances of the different test 

 materials were compared using the dry weights of 

 organisms collected during periodic sampling. The 

 dry weight data for the 1-m level are shown in 

 Table 1. Weight data of the removable material 

 from the 15.3-m and 6. 1-m levels were negligible 

 except for the plates of wood and concrete col- 

 onized by Balanus crenatus (Table 2). 



,', BOTTOM PANELS 

 I 



COPPER-NICKEL ALLOY.— There was no 

 removable material through the first 58 days. The 



Figure 2. — A schematic of the array of subtidal test panels used 

 to measure biofouling with inset showing details of test plate 

 attachment. 



1973). Weekly minimum, mean, and maximum 

 temperature and salinity readings are presented 

 in Figure 3. Average weekly temperatures ranged 

 from 6.2°C to 11.8°C. Average weekly salinities 

 ranged from 17.5 to 29.7 g/liter; pH ranged from 

 7.1 to 8.2; and dissolved oxygen concentrations 

 ranged from 10.5 to 13.3 mg/liter. Lincoln et al. 

 ( 1970) and Bendiner et al. ( 1972) have detailed the 

 physical oceanography and vertical stratification 

 of the Kiket Island area. The physicochemical 

 characteristics of North Skagit Bay led Stober et 

 al. (1973) to classify the study area as a well mixed 

 estuary. 



Qualitative observations of the study area were 

 made periodically while scuba diving. The bottom 

 in the vicinity of the fouling plates at Kiket Island 



32 p 



30 

 _ 28 

 °! 26 

 >. 24 

 1 22 

 o 20 

 '^ 18 



16 



14 



12 



' '"'■i'i'iilil'|i'l"l|| 4" •'■ 



■■'''' 



DEC. 

 1971 



JAN FEB MAR, APR 



MAY JUNE 

 1972 



JULY AUG, SEPT. 



20 

 19 

 18 

 17 

 16 

 15 

 14 

 13 

 12 

 II 

 10 

 9 

 8 

 7 

 6 

 5 

 4 

 3 

 2 



E'ffifiijjjipitfo''" 



II I I I 1 I I I r [ . 



I I I I I I I I ■' I I I I I  I 



DEC. 

 1971 



FEB. MAR. APR. 



MAY JUNE 

 1972 



JULY AUG. SEPT. 



32 



30 

 28 

 26 

 24 

 22 

 20 

 IB 

 16 

 14 

 12 



68 

 66 

 64 

 62 



60 

 58 

 56 — 



54 t 



52 a. 



50 ^ 



48 ^ 



46 



44 



42 



40 



38 



36 



34 



32 



Figure 3. — Weekly mean, minimum, and maximum salinity 

 measurements (a) and water temperature (b) recorded in the 

 Kiket Island area (data from Stober et al. 1973). 



379 



