of 12 replicate panels exposed for six months at two sites (Fox Island 

 and Giants Neck) . The shorter exposure period effectively sampled the 

 fouling and wood-boring species over the year and allowed the communities 

 to be compared on a seasonal basis. 



We adopted the six replicate and six month exposure period sampling 

 method in November 1978, collecting the first samples in May 1979. Four 

 overlapping six month exposure periods (February, May, August, and 

 November) were collected each year from 1979-1981. To further improve 

 Hata collection, four changes were made in processing exposure panels. 

 First biota on asbestos and wood panels were considered different assemb- 

 ages and were processed separately. Second, the additional parameters 

 of canopy cover (panel surface covered by an organism beyond its direct 

 attachment, primary cover, on the panel), f reespace (panel surface not 

 covered by the direct attachment of live or dead organisms) , and dead 

 Balanus (panel surface covered by empty tests and basal plates of barnacles) 

 were added in February 1980 to the data collected. Third, to avoid any 

 bias caused by the vertical displacement of panels which were collected 

 from overlapping exposure periods, the placement of three replicate 

 panels on the top and three replicate panels on the bottom level of a 

 rack was begun in May 1980 (Fig. 1). Prior to this time, panels from 

 overlapping collection periods were placed on different levels. Fourth, 

 the use of radiographs for counting shipworms and estimating percent 

 destruction was also initiated in May 1980. This latter method consider- 

 ably reduced the amount of time needed for processing wood panels and 

 provided a permanent record of the infestations (Table 2) . 



