16 GROWTH OF PLANTS 



ducks, geese, and swan. In 1918, almost simultaneously \vith the opening 

 and enlargement of the Albemarle and Chesapeake Canal, however, these 

 plants began to die out, and by the end of 1926 vast areas were practically 

 denuded of their aquatic seed plants. This destruction of the plant life 

 produced an enormous economic loss affecting thousands of the residents, 

 who derived their living from gunning and fishing. Shooting clubs and 

 sportsmen practically abandoned their large investments in the region be- 

 cause wild ducks and geese in any appreciable numbers were no longer at- 

 tracted there. At the request of Mr. William E. Corey, a prominent sports- 

 man of New York, who had been interested in the region for many years, 

 the Boyce Thompson Institute for Plant Research, Inc., in 1925 undertook 

 a study of the causes for the disappearance of the duck food plants, and of 

 methods of re-seeding depleted areas. Early the fol o^\^Lng year Dr. Bourn 

 was assigned to the investigation. 



Studies were made continuously from 1926 to 1930, inclusive, o the phys- 

 ical, chemical, and biological conditions of the water. During this time eco- 

 logical experiments were carried on for the purpose of determining varieties 

 of plants resistant to existing conditions and to determine the best methods 

 of re-seeding the barren areas. The ecological investigations led naturally 

 to physiological experiments in the laboratory to determine the factors 

 limiting the growth of submerged angiosperms. These experiments were 

 continued for six years. 



Fig. 6 shows the location of North Bay and Back Bay, Virginia, and 

 Currituck Sound, North Carolina, as well as land and other bodies of water 

 in the general region. The three bodies of water involved in this study are 

 protected from the salty waters of the Atlantic Ocean by a continuous sand 

 bar that partially encloses Albemarle Sound to the south as well. On rare 

 occasions very heavy storms drive some ocean water over the lower, nar- 

 rower places in the sand bar. Currituck Sound is connected mth the waters 

 about Norfolk and Portsmouth, Virginia, including the estuary of the James 

 River and Hampton Roads by the North Landing River and Chesapeake 

 and Albemarle Canal. During the first World War this canal was ^videned, 

 the sea-level locks were abandoned and not replaced after mdening. This 

 gives a free water connection between Currituck Sound and the salty waters 

 about Norfolk. Before the locks -were restored, as a result of this study, 

 there was considerable movement of water from the Norfolk region toward 

 Currituck Sound when the wdnd blew from the north and from Currituck 

 Sound toward the Norfolk region when the wind blew from the south. 



Early in these studies we began determinations of the salt content of 

 the water of the various regions involved by a titration method developed 

 by Dr. F. E. Denny.^ Titrations were made monthly for four years at 26 

 stations shoAvn on the map in Fig. 7. Fig. 8 shows the average of the 48 deter- 

 minations for each station. By examination of this curve it will be seen that 

 the average salt concentration at the stations gradually increased from 

 Station Number 1, Corey's boathouse, to Station Number 26, Pungo Ferry, 



