Widgeongrass Uudy in Mame.—Y.ar\y results 

 from a study by the Maine Unit to measure re- 

 sponse of waterfowl foods in experimentally 

 plu<rged saltmarsh ditches suggest direct applica- 

 tions to saltmarsh management. 



Practices designed to widen the ditclies, com- 

 bined with plugging to hold shallow "potholes" of 

 water on tlie ebb tide, offer much promise as a 

 means of encouraging growth of widgeongrass, an 

 important waterfowl food plant. To date, hold- 

 ing water m the ditches has not increased mosquito 

 production. The impoundments were quickly in- 

 vaded by mummicliogs (FiinduJus heteroclitii^), 

 which effectively controlled mosquito larvae. 



Factors infxiencing estahlishment of Widgeon- 

 grass. — This research was conducted by the 

 Louisiana Unit on Rockefeller Wildlife Refuge. 



Physical factors of the aquatic environment, 

 sucli as turbidity, fluctuating water levels, and 

 water depth, were found to be controlling influ- 

 ences in the establishment of new as well as growth 



of mature stands of widgeongrass. Correlations 

 existed between vegetative production and water 

 depth and turhidit\-. The greatest production was 

 obtained in water depths of about 2-1: inches. 



Increase in percentage of soluble salts inhibited 

 seed genni nation by increasing osmotic pressure of 

 tlie soil solution so that the seed had difficulty in 

 absorbing water. Soluble soil salts greater than 

 1.12 percent were extremely hannful to gennina- 

 tion of widgeongrass seed. The plant was ob- 

 served growing in salinity ranges of 2,075 ppm to 

 18,500 ppm in ponds under study, and 1,160 ppm 

 to 19,000 ppm in experimental tanks. There was 

 no correlation between chlorides and widgeongrass 

 growth. 



The most important biotic factor affecting plant 

 growth was algal cover, wliich decreased widgeon- 

 grass density by reducing liglit. The species was 

 found to have two growing seasons, and these 

 were controlled by a temperature range of 18.5° C. 

 to 30° C. Temperatures above 30° C. and below 

 18.5° C. inhibited growth. 



Typical wftod duck habitat in a tupelo giim swamp along the Ocmulgee River in Georgia. The typo also support.>i 

 excellent populations of minks and raccoons. (Photo by Brooke Meanley) 



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