diameter of 6 nm on the control panels and 11 mm on a test panel after 

 k months' submergence. At Pier No. 91 they appeared on 12 of the 35 con- 

 trol panels and on 23 of the l|-2 test panels, attaining a maximum diameter 

 of 6 mm on the control panels and 12 mm on a test panel after k months' 

 submergence. At Pier Wo. 90, 19 of the test panels were from. 2Cf^ to 

 100^ covered, vhile at Pier No. 91, 6 of the control panels were fl-om 

 25^ to 70^ covered and 17 of the test panels were from 20^ to 100^ covered. 



e. Mpllusca (nonborin^ mollu8.ks ). A trace of t^llus 

 (iDUSsels) occurred on a single" test panel at each location. A length of 

 32 mm after h months' suhmergence was recorded for a single specimen at 

 Pier No. 90. 



f. Chordata (tuQicates ) . Two colonies of tunicates occurred 

 on a single control panel at Pier No. 91. 



A36.05 Summary and Conclusions 



1, Installation . Two test boards of the panel type installed 

 Jtme 15, 19hk, at different locations at the U. S. Naval Station at 

 Seattle, Washington, are still heing operated. The results of these 

 tests have "been summarized to the e^d of 19^7. 



• 2. Test BesiatB . 



a. Borers . Teredinidae were very active at "both locations ," 

 the "breeding season extending from the middle of March to the middle of 

 January at Pier No. 90 and from the middle of January to the middle of 

 December at Pier No. 91. The attack at "both locations rated very heavy 

 each year, with panels "becoming riddled in as short a period as 5 months 

 at each location. Limnoria also were active, the attack rating slight 

 at "both locations in 19Jt-5 and only a trace in 19h6 and 191^7. 



"b. Fouling Organisms . Silt, algae, and lnverte"brate 

 animals "belonging to 6 phyla contri"buted to fouling of the panels. The 

 latter comprised hydroids, encrusting and filamentous Bryozoa, marine 

 worms, "barnacles, mussels, and tunicates. Of these organisms, hydroids 

 occurred with the greatest frequency; "barnacles and encrusting Bryozoa 

 occurred with less frequency-, while the occurrence of the others, as 

 well as the algae, was merely sporadic or occasional. 



3. Eecent Addenda . The Teredinidae attack was very heavy at 

 Pier No. 90 during ISkQ and 19l»-9, and in "both years the Limnoria attack 

 rated as slight. The same situation o"btained at Pier No. 91 during 

 "both years. 



161 



