1946) . There was a significant drop in egg produc- 

 tion by wliite leghorn chickens that drank a 1.0- 

 percent salt solution and a 0.7-percent salt solution 

 used for drinking water caused a significant mor- 

 tality in day-old chicks. It is reported that a 0-52- 

 percent salt solution used for drinking water 

 retarded growth in domestic chickens (Rosenberg 

 and Sess, 1954). Using a 0.35-percent salt solu- 

 tion for drinking water increased mortality of baby 

 chicks, however, water containing 0.30, 0.26, and 

 0.25 percent salt was nontoxic (Doll, et al., 1946). 



Correlation of this toxicity to avian game was 

 indicated when a group of ornamental pheasants 

 (order Galliformes) and chickens were salt poi- 

 soned; all the pheasants succumbed, but only a 

 few of the chickens (Field and Evans, 1946). 

 Young ducklings were killed or retarded in growth 

 as a result of salt poisoning by solutions equal to 

 those found on the Suisun Marsh, Calif., during 

 the summer months (Suisun Marsh is formed by 

 the combined deltas of several rivers; i.e., Sacra- 

 mento, San Joaquin, and the Middle River. Grif- 

 fith, 1963). Salinity maxima during July (1956 to 

 1960) varied from 0.55 to 1.74 percent; the 

 means varied from 0.07 to 1.26 percent. During 

 3 of these years the mean salinity level exceeded 

 levels reported as causing mortality in domestic 

 chickens. Adult quail preferred dehydration to 

 drinking water having a salt concentration that 

 would be fatal to juvenile chickens and detrimental 

 to egg production (Bartholemew and MacMillan, 

 1961). 



These conditions must be kept in mind because 

 there is a potential hazard of a sodium compound 

 buildup in the Lower Colorado River area to levels 

 that would be toxic to avian game. 



Indirect Effects of Salinity 



Indirect effects of salinity on wildlife would gen- 

 erally be restricted to that action imposed upon the 

 vegetative growth along the river. Modification of 

 a segment of the associated vegetation can result 

 in a complete change in the environment. The 

 game animals affected by a modification of sub- 

 mergent and emergent vegetation would be mainly 

 the various species of waterfowl. 



Different habitats, of use to a great variety of 

 wildlife, develop under different concentrations of 

 salinity. In coastal areas, where the salinity gen- 

 erally represents various dilutions of sea water, the 

 habitats can be categorized as fresh to slightly 

 brackish (0 to 3.5%o), moderately brackish (3.5 

 to 13.5%c), and strongly brackish to marine 

 (13.5 to 35.0%o). Valuable submerged aquatic 

 plants occurring in the first category are bushy 



pondweed, Najas quadalupensis, northern naiad, 

 Najas flexilis, several pondweeds, Potamogeton 

 spp., wild celery, Vallisneria americana, and 

 watershield, Brasenia schreber. 



In moderately brackish waters, some of the 

 better waterfowl foods are sago pondweed, Pota- 

 mogeton pectinatus, muskgrasses, Chara spp, 

 homed pondweed, ZanichelUa pahistris, and a few 

 pondweeds, Potamogeton spp-, that thrive in both 

 fresh waters and moderately brackish waters. 



Important food plants for waterfowl in the most 

 saline waters are widgeongrass, Ruppia maritima, 

 shoalgrass, Diplanthera wrighti, spiny naiad, Najas 

 marina, and eelgrass, Zostera marina. 



Probably the most important consideration, in 

 regard solely to salinity and the plant communities 

 which develop, is the degree of fluctuation. Ob- 

 servations and bioassays by Bourn (1932), Martin 

 and Uhler (1939), Sincock (unpublished data), 

 and others have demonstrated the destructive ef- 

 fects of rapid fluctuations in salinity on aquatic 

 plants. Plasmolysis of the tender leaves and stems, 

 induced by changes in osmotic presure of the 

 varied water salinities, results in death of the 

 plants. 



Based on empirical knowledge, it is believed 

 that salinity fluctuations in a 24-hour period could 

 be 1, 2, and A^cc in each of the three respective 

 salinity classes without causing harm to most of 

 the aquatic plants. 



Emergent marsh plants also have varying toler- 

 ances to water salinity; generally, they are not as 

 sensitive to minor changes as are the submerged 

 aquatic plants. Fresh water marshes are normally 

 much more productive of wildlife food plants than 

 strongly saline marshes. 



The reaction of vegetation associated with 

 waterfowl marshes to salinity has become an im- 

 portant consideration in the management of those 

 marshes. Salinity of 6%c and above is detrimental 

 to many prime, submergent waterfowl food plants 

 (Tester, 1963). Controlled salinity levels, how- 

 ever, have become a valuable tool in marsh man- 

 agement. Undesirable marsh plants can be con- 

 trolled or eliminated and desirable plants encour- 

 aged by manipulation of salinity levels (California 

 Department of Fish and Game, 1963). For ex- 

 ample, the seeds of cattail (an undesirable plant) 

 will not germinate in a solution having 7 mmhos 

 conductivity while alkali bulrush (desirable plant) 

 will germinate in solutions of up to 9 mmhos con- 

 ductivity (Kauship, 1963). Therefore, raising 

 salinity levels to 8 mmhos conductivity would 

 eliminate cattail, but allow alkali bulrush to 

 flourish. 



The germination of seeds and the growth of 



95 



