1147 



Loosanoff, Victor L., Harry C. Davis, and Paul E. Chanley. 1966. 



Dimensions and shapes of larvae of some marine bivalve mollusks. Malacologia 

 4 (2) : 351-435. 



Among other species, Mercenaria mercenaria and M. campechiensis were reared 

 and grown past metamorphosis from eggs or recently released larvae of known 

 parents. Photomicrographs and length-width measurements of larvae are given. 

 In laboratory cultures only a few straight-hinge larvae of M. mercenaria were 

 less than 100 p long, and most fully formed straight-hinge veligers were 

 approximately 105x80 "p. An umbo is visible at a length of about 125-130 p. 

 The umbo becomes better defined as larvae grow, but never as prominent as in 

 Anomia, Crassostrea or Teredo. Some larvae begin to metamorphose at only 

 170 p long, but most at 200-215 p. Larvae longer than 230 p are uncommon. 

 At metamorphosis length is only 5-15 p greater than width. Larvae of 

 M. mercenaria from widely separated areas did not differ in size at 

 metamorphosis, nor did larvae reared at 5 different temperatures. Larvae of 

 M. campechiensis were hatched from parents taken at Apalachicola, Fla. All 

 stages were identical to similar stages of M. mercenaria. Early straight- 

 hinge veligers were 100-110 p. Metamorphosis occurred most commonly at 

 175-215 p. Spawning behavior of the two species was also virtually the same. 

 When grown under identical conditions, including temperature, larvae grew at 

 the same rate and began to metamorphose at the same time. Reciprocal crosses 

 of the 2 species produced viable larvae which grew to metamorphosis and then 

 to adult stage. These hybrids were fertile, and their larvae also were reared 

 to adult stage. - J.L.M. 



1148 



Loosanoff, V. L. , J. E. Hanks, and A. E. Ganaros. 1957. 



Control of certain forms of zooplankton in mass algal cultures. Science 

 125 (3257) : 1092-1093. 



In one experiment, adult and juvenile bivalves of several species including 

 Venus mercenaria, were kept for one month in running water to which a 

 Dipterex-treated culture of Chlorella was added continuously. All mollusks 

 behaved normally, fed well, grew, and showed no unusual mortality. - J.L.M. 



1149 



Loosanoff, V. L. , C. L. MacKenzie, Jr., and H. C. Davis. 1960. 



Progress report on chemical methods of control of molluscan enemies. U.S. 

 Fish Wildl. Serv., Biol. Lab., Milford, Conn., Bull. 24(8): 3-20. 



This is a progress report on studies underway. It deals principally with 

 boring snails and sea stars. Experiments were done first in the laboratory, 

 then evaluated by field tests. In the laboratory, a barrier made of sand 

 8 inches wide mixed with orthodichlorobenzene stopped all oyster drills which 

 came in contact with it for approximately 14 months. Polydora larvae 

 apparently were not affected, nor were Crepidula, oysters, tunicates, Teredo 

 and other invertebrates. After 14 months the chemical began to lose its 

 strength. Barriers also were effective against sea stars, but a heavy coat 

 of silt destroyed their effectiveness. Effectiveness of other chemicals and 

 mixtures of chemicals also was tested. On a 12-inch wide barrier, Urosalpinx 

 and Thais were stopped at the edge of the barrier, Nassa penetrated 4 inches, 

 and Polinices 8 to 10 in. A small experimental barrier was established on 

 tidal flats outside the Milford laboratory. Sea stars that traversed it 

 usually were carried across by wave action. Oysters and Venus mercenaria 

 were placed directly on the barrier. Adult clams survived, but none was able 

 to dig into the substrate through the barrier. Small clams were placed 

 inside and outside the barrier. All dug in. Deaths were insignificant, and 

 clams inside the barrier did not grow more slowly than those outside. The 

 chemical was still active after 14 months. Clams survived for 10 days after 

 being kept in the laboratory in mixtures of orthodichlorobenzene and 

 tetrachloroethylene, and a mixture of orthodichlorobenzene and 

 monochlorobenzene in seawater at a rate of 10 ppm. This was much higher 



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