seawater instead of unicellular algal culture and storing in gently aerated 

 tanks in a solarium - after 24 to 72 hrs the bloom can be used to feed lar- 

 vae. This is best until major and less costly advances are made in highly 

 technical systems. - J.L.M. 



297 



Castagna, Michael, and Paul Chanley. 1966. 



Salinity tolerance limits of some species of pelecypods from Virginia. 

 Proc. Natl. Shellf. Assn. 56: 1 (abstract). 



Species are not named. Most pelecypods studied were more euryhaline than 

 their natural distribution would indicate. - J.L.M. 



298 



Castagna, M., and P. Chanley. 1973. 



Salinity tolerance of some marine bivalves from inshore and estuarine 

 environments in Virginia waters on the western mid-Atlantic coast. 

 Malacologia 12(1): 47-96. 



Although temp usually is considered the most important ecological factor 

 influencing distribution of animals, salinity is usually the more obvious 

 factor in estuaries. Hard clam is abundant at moderately high salinities 

 from the Gulf of St. Lawrence to Fla. In Va. it is found in a variety of 

 substrata intertidally and subtidally at salinities above 10°/°o. Other 

 authors have reported that the salinity range is 12.5 to 46°/oo. Growth 

 of adults is slow or zero below 17.5°/°° to 19°/°°. Larvae appear to 

 require slightly higher salinity than juveniles or adults. Metamorphosis 

 did not occur below 17.5°/°° to 20°/°°. Larval growth improved with 

 increasing salinity from 15°/°° to 27.5°/°°. Eggs developed normally from 

 20°/°o to 35°/°° and the optimum was about 27.5°/oo. It was concluded that 

 the approximate minimum salinity at which adult Mercenaria mercenaria 

 survive is 12.5°/°°, and larvae 15°/°°. - J.L.M. 



299 



Castagna, Michael, and John N. Kraeuter. 1976. 



A mariculture system for growing the hard clam, Mercenaria mercenaria. 

 Proc. Natl. Shellf. Assn. 66: 100 (abstract). 



The Glancy-Wells (centrif uged, incubated seawater) solarium method is used 

 for growing algal food. Clams are spawned with temperature stimulation and 

 stripped sperm. Larvae are grown in clarified incubated seawater until set. 

 Juveniles are immediately transferred to flowing seawater tables and held 

 until 2 mm hinge to lip. Then they are planted in a nursery area on an 

 intertidal flat at 30 0/ft^, protected from predators by a crushed stone 

 aggregate cover, and prevented from washing away by 2 ft high plastic screen 

 baffles. Where rays are a problem, a plastic screen fence is built. Cost 

 of growing clams is about 1.5C each. Survival over winter was about 88%. 

 The system is simple, uses little energy, and is relatively inexpensive. 



- J.L.M. 



300 



Castagna, M., and J. N. Kraeuter. 1976. 



The aggregate protection method of culturing the hard clam, Mercenaria 

 mercenaria. 10th European Symposium on Marine Biology, Ostend, Belgium. 

 Vol. I: 33 (abstract). 



A low technology method utilizing hatchery-raised seed clams and field grow- 

 out techniques is presented. This technique is economically feasible and 

 can be taught to most individuals within a week. The Wells-Glancy method 

 (centrifuged, incubated seawater) of raising food is used. Larvae set in 

 8-10 days and are supplied with natural seawater until they reach 2 mm. 

 They are then placed in nursery plots, protected from predation by a layer 

 of gravel or aggregate. Movement is prevented by a system of baffles. Field 

 survival of a test group of 600,000 clams approached 80%. Costs of raising 

 the clams for the first year are included, but not stated in the abstract. - 



- J.L.M. 



82 



