1143 



Loosanoff, V. L. , H. C. Davis, and P. E. Chanley. 1953. 



Lack of relation between age of oysters or clams and quality of their 

 spawn. Oyster Inst. N. Am., Trade Rept. 133: 1-2. 



This paper also was issued as Bull. 4 (Vol. 17) of the Fishery Biological 

 Laboratory, U.S. Fish and Wildlife Service, Milford, Conn, on 21 July 1953, 

 as a 2-page, duplicated issue. The abstract appears above. - J.L.M. 



1144 



Loosanoff, Victor L. , Harry C. Davis, and Paul E. Chanley. 1953. 



Behavior of clam larvae in different concentrations of food organisms. Anat. 

 Rec. 117(3): 586-587 (abstract). 



Larvae of Venus mercenaria were fed concentrations of food organisms ranging 

 from 6,500 to 1x10^ cells/cc of water. Foods were a pure culture of Chlorella 

 sp. averaging 8 \i in diam, and a mixed culture, largely small Chlorella 

 averaging about 3 u. With large cells optimum concentrations were about 

 50,000 cells/cc; when small cells were fed, 400 to 500 thousand were needed. 

 Heavy concentrations of food killed larvae. This again depended on cell size. 

 Larvae died within a few days in 350,000 cells/cc of large Chlorella and 

 sometimes within 24 hrs in 750,000 cells/cc. When small cells were fed, larvae 

 grew well in 750,000 cells/cc. In large concentrations the filtrate, the cells, 

 or a combination of the two, may be lethal. Larvae do not feed merely 

 mechanically, but appear to have a mechanism for controlling food intake. 

 When cell concentration was heavier than optimum, many larvae had fewer 

 organisms in their stomachs than in lower concentrations. In a heavy con- 

 centration for a long time, the regulating mechanism was lost and larvae 

 became choked with food cells. If not too seriously injured, larvae removed 

 to seawater containing optimum concentrations of food expelled excess food 

 and developed normally. Qualitative selectivity of food also was observed. 

 In a mixture of Porphyridium (3 u) and Chlamydomonas (10 u) , larvae neglected 

 the smaller cell in favor of the larger. - J.L.M. 



1145 



Loosanoff, Victor L. , Harry C. Davis, and Paul E. Chanley. 1953. 



Effect of overcrowding on rate of growth of clam larvae. Anat. Rec. 117(3): 

 645-646. 



Rates of growth and survival were determined in cultures maintained at 

 different densities but receiving the same concentration of food, and 

 cultures in which an increase in larval population was accompanied by a 

 proportional increase in food. Food was a unialgal culture of Chlorella sp. 

 Larvae in all cultures grew to metamorphosis but their rate of growth was 

 inversely related to population density. In the first set of experiments 

 (4 levels of larval density) larval populations varied from 6.5 to 50 

 larvae/cc, and rate of growth was inversely related to population density. 

 In the second series (also 4 levels) larvae in the least crowded culture 

 grew faster than those in the next higher density. The next group died 

 within 4 days, and the densest culture within 48 hrs. - J.L.M. 



1146 



Loosanoff, V. E. , H. C. Davis, and P. E. Chanley. 1955. 



Food requirements of some bivalve larvae. Proc. Natl. Shellf. Assn. 45: 66-83. 



Bivalve larvae fall into 2 groups, those like American oyster, which can 

 utilize only a few of many food forms, and those like Venus mercenaria, which 

 can thrive on most food organisms of the right size. When oyster and hard 

 clam were held under identical conditions and fed mixed nannoplankton in which 

 cells of small green algae predominated, larvae of hard clam grew rapidly and 

 metamorphosed in about 13 days, while those of Crassostrea virginica stopped 

 growing on reaching straight-hinge stage and eventually died. (Abstracter's 

 note: This is a review paper.) - J.L.M. 



321 



