periods. Observations of water temperature, salinity, currents, trans- 

 parency, and underwater visibility were made at the rack location 

 during each monthly visit. 



Test panels were identified by a number engraved on a plastic tag 

 attached to each panel. Before immersion each test panel was weighed 

 in sea water and in air. At the termination of its exposure period, 

 each panel was again weighed in sea water and in air. Immediately 

 after removal, each test panel was examined and an estimate made 

 of the percent of surface of both concave and convex sides covered 

 by various fouling organisms. The panels were photographed, packed 

 in preservative, and returned to the Hydrographic Office for careful 

 examination to determine the type and number of fouler s. 



The various large forms, such as tunicates, bryozoans, and colonial 

 hydroids on each panel were counted and the maximum and average 

 height and diameter were determined. Smaller forms were counted 

 by means of a random strip sampling technique. A template designed 

 to expose a unit of surface area of the panel was laid across portions 

 of the panel showing representative fouling types; numbers and sizes 

 of the various organisms within the unit area were then determined. 

 By this method, the total number of organisms on the panel was 

 computed along with the maximum and average sizes of each form. 

 The examination was performed on both the concave and the convex 

 sides. Following this identification and counting procedure, the panels 

 were allowed to dry thoroughly over a period of days and were again 

 photographed. Specific identification of most organisms has not yet 

 been made. 



III. RESULTS 



In April 1957, one complete year of fouling data, indicating the 

 seasonal progression and degree of fouling, was accumulated. 



A. Environment 



The fouling rack is situated in a typical estuarine location. 

 Currents are tidal, the flood setting westward and the ebb eastward. 

 The surface current is strong, averaging 1.5 knots at maximum flood 

 and ebb. The current near the bottom at the fouling rack is somewhat 

 weaker, averaging 0.5 knot but at times attaining 1.0 knot at maximum 

 flood or ebb. During all seasons a positive salinity gradient exists 

 between the surface and the bottom. The strength of this gradient depends 



