SEA-WATER SYSTEM AT POINT WHITNEY SHELLFISH LABORATORY 



151 



a concrete cover, the floor was properly 

 sloped for adequate drainage and flushing, 

 and a direct fresh-water connection was 

 installed. Since no substance which we 

 were sure was not toxic to invertebrate 

 larvae appeared to be practical for sealing 

 green concrete, we allowed the tank to 

 leach out naturally in sea water. It is 

 particularly important to note that 

 "green" concrete had significant toxicity to 

 Pacific oyster larvae for more than 9 

 months after the tank was completed. 



In the course of conducting a 3-year 

 bioassay on adult Olympia and Pacific 

 oysters, additional sea-water storage 

 capacity was needed. To provide this at 

 a reasonable cost, we erected nine 5,000- 

 gallon unpainted Douglas-fir storage 

 tanks, which were lined with 4-mil poly- 

 ethylene sheet. This made a generally 

 satisfactoiy liner which prevented attacks 

 by marine borers and provided proven 

 nontoxic water contact surfaces. We 

 found that the 4-mil sheet, unless very 

 carefully handled, was subject to abrasion 

 or cutting. After 2 years, replacement 

 was made with shaped 8-mil polyvinyl- 

 chloride liners. These liners were found 

 to be toxic. At writing, we are still 

 trying to determine what component of 

 the liners was the source of the toxicity. 

 In previous tests, solid polyvinyl-chloricle 

 fittings were nontoxic. We have to 

 assume that some type of plasticizer used 

 in the bonding of the seams or manu- 

 facture of the film may be the toxic agent. 



Overhead feed lines have always been 

 difficult to maintain in trouble-free opera- 

 tion. In order to solve this problem at 

 Point Whitney, and provide easy clean- 

 ing, the aquarium distribution lines were 

 2-inch liard rubber with T or cross fittings 

 in place of elbows at each turn. Instead 

 of placing potentially troublesome valves 

 on the ends of the distribution lines, a 

 2-inch neoprene radiator hose was 

 clamped to the end of a hard-rubber pipe 



nipple, and the flow was adjusted by 

 means of a wooden pinch clamp. Water 

 flowed into 8-inch-deep open wooden 

 header troughs running the length of each 

 room. The header trough has an advan- 

 tage in that holes may be bored any place 

 along the trough to provide flow through 

 glass tubes of constant orifice for individ- 

 ual or groups of aquariums or trays, the 

 only limitation in capacity being the size 

 of the distribution line itself. Even 

 though marine plywood was used, teredos 

 {Bankia) riddled the header trough and 

 lower aquarium trays. The trough was 

 coated with hot roofing tar, and the trays 

 were rebuilt with polyester resin coating. 

 This has been satisfactory. 



Clearing sea-water lines of marine foul- 

 ing organisms is a potential problem in 

 any area where surface waters are used. 

 At Point Whitney, common fouling or- 

 ganisms are mussels, barnacles, oysters, 

 tunicates, serpulid worms, and sea 

 anemone. In addition to reducing the rate 

 of water flow, they also compete with ex- 

 perimental animals for food, and contrib- 

 ute metabolites to the water. At Point 

 Whitney, provision was originally made 

 both for cleaning by hot water and for 

 mechanical removal. Several sources of 

 hot water were tried, including domestic 

 furnace, domestic hot water, recirculation 

 of specially heated water, and a portable 

 steam cleaner unit of the type used in 

 automotive repair shops. None of these 

 supplied enough heat to kill all fouling 

 organisms throughout the lines. We fi- 

 nally obtained a 400-gallon heavy steel 

 tank, mounted this over a firebox, and used 

 it to provide a charge of boiling water of 

 sufficient volume to completely fill each 

 separable unit of sea-water intake and 

 discharge lines. It has been satisfactory 

 and economical to use, since thorough 

 cleaning about twice a year is adequate. 

 However, owing to the difficulty of remov- 

 ing salt water from the lower end of the 



