species like narrow dnckweed (Lemna valdivi- 

 ana), an Asiatic sniailweed {Polyyoninn cespito- 

 sum) , water-meal ( Wolffia papidifera) , and heart- 

 leaf pondweed {Potamogeton puleher) for shaded 

 areas. Special consideration is jriven to the dis- 

 covery of new food plants, and to outstanding 

 strains of well-known species for use on low-grade 

 habitat. These studies are coiTelated with the 

 management of water levels and chemical analj'ses 

 of soil and water at regular intervals. 



Fertilization and hnliitat iin prorenient. — At the 

 Patusent Center it lias been found tlnit, in lime- 

 deficient soils in wliich iron oxides are plentiful, 

 iron unites with soluble pliosphates to form insolu- 

 ble compounds, thereby depriving many plants of 

 the phosphorus essential for successful growth. 

 This information promises to modify' costly fer- 

 tilization practices on such sites. 



Waterfo-icI-I-ead shot research underway. — A 

 icmiprehensive study of the effects of lead shot and 

 proposed substitutes for lead shot on waterfowl 

 was initiated at Patuxent late in 1964, where the 

 talents of waterfowl biologists, a pathologist, a 

 chemist, and a physiologist are available. The 

 purpose is to determine relative toxicities of lead 

 and substitute shot, improved methods for diag- 

 nosing and assessing the extent of lead poisoning, 

 the importance of lead as a cause of impaction, and 

 the possibility of additive effects of lead and pesti- 



Appret-iable waterfowl mortalit.v results from ingestion of 

 lead shot; and for surviving birds the ph.vsiological 

 effects of lead poisoning have not been fully determined. 

 Here, a Patuxent Center biologist is administering shot 

 of a new alloy, part of a comprehensive investigation 

 in search of a nontoxic, ballistically suitable substitute 

 for lead. The physiological effects on experimental 

 birds of alloys used in the research will be measured. 

 (Photo by Frederick C. Schmid) 



cidal poisoning. By tlie end of the yeai (19G4), 

 pen facilities and specialized equipment had been 

 acquired. 



A marsh plant circular series. — Illustrations of 

 approximately 1,000 species of mai-sh and water 

 plants of eastern United States and Canada are 

 being made at Patuxent. A series of circulars 

 depicting natural groups of plants is in prepara- 

 tion, such as Circular 187, "Pondweeds and Pond- 

 weedlike Plants of Eastern North America" 

 (Hotchkiss, 1964.) Drawings have been com- 

 pleted for bulrushes and submerged aquatic plants, 

 other tlian pondweeds, and will be used in the next 

 two publications in the series. 



An Alaska tiiil research assistant che<'king a butilehead 

 ne.st as a pjirt of a waterfowl growth study on Tetlin 

 Lakes. ( Photo by Uavid R. Klein ) 



23 



