tridium botulinum, has killed millions of water 

 birds. Jensen and Williams (1964) state "When 

 conditions are favorable — suitable temperature, 

 an organic medium to satisfy food requirements, 

 and an absence of atmospheric oxygen (the orga- 

 nism is a strict anaerobe) — the spores germinate 

 and multiply." Although the exact qualities of the 

 water favoring its production cannot always be 

 categorized, anaerobic conditions in shallow, fringe 

 areas of ponds or reservoirs often are indicted as 

 contributory to botulism outbreaks. Maintenance 

 of adequate water circulation in all parts of these 

 shallow reservoirs might deter production of the 

 toxic bacteria. Also, accumulation of organic 

 wastes from mills and other sources should be 

 prevented in aquatic habitats, particularly where 

 botulism has been a problem. 



PH 



The chapter in Waterfowl Tomorrow, by Mc- 

 Callum (1964), entitled "Clean Water, and 

 Enough of It," summarizes many of the water pol- 

 ludon problems of aquatic habitats. McCallum 

 states "Acid mine water has destroyed or seriously 

 damaged the waterfowl value of more than 4,000 

 miles of streams in the United States. Working as 

 well as abandoned coal mines discharge an esti- 

 mated 3.5 million tons or more of acid each year 

 into streams, most of them east of the Mississippi 

 River." Mardn and Uhler (1939) point to the fact 

 that "acidity may affect the growth of plants by 

 checking the work of nitrifying bacteria and 

 thereby preventing the normal decay of humus, or 

 by increasing the accumulation of carbon dioxide 

 and accompanying toxic organic substances." 



In bioassays with aquatic plants, Sincock 

 (1966) found that when the pH of the water in 

 some test vessels dropped to 4.5, readhead-grass 

 (Potamogeton perjoUatus), a valuable waterfowl 

 food plant, died within a few days. Similarly, in 

 Back Bay, Va., between August and November, 

 1963, the aquatic plant production in pounds per 

 acre declined from 1 64 to 1 3 ; this atypical decline 

 was immediately preceded by an atypical decline 

 in pH to 6 5 compared to previous midsummer 

 readings of 7.7 to 8.5. 



Generally, the submerged aquatic plants of 

 greatest value as waterfowl foods thrive best in 

 waters with a summer pH range of 7.0 to 9.2. 



Alkalinity 



bicarbonate alkalinity. Few waters with less than 

 25 mg/1 bicarbonate alkalinity can be classed 

 among the better waterfowl habitats. Many water- 

 fowl habitats productive of valuable waterfowl 

 foods, such as sago pondweed {Potamogeton 

 pectinatus) , widgeongrass (Riippia maritima and 

 R. occidentalis) , banana waterlily (Castalia 

 flava), wild celery {Vallisneria americana) and 

 others, have a bicarbonate alkalinity range of 35 

 to 200 mg/1. 



Definitive, submerged aquatic plant communi- 

 ties develop in waters with different concentrations 

 of bicarbonate alkalinity. It is logical to presume 

 that excessive and prolonged fluctuation in alkalin- 

 ity would not be conducive to stabilization of any 

 one plant community type. There is not sufficient 

 experimental evidence available to define the ef- 

 fects of various degrees and rates of change in 

 alkalinity on aquatic plant communities. Fluctua- 

 tions of 50 mg/1 probably would contribute to 

 unstable plant communities. Fluctuations of this 

 magnitude are quite possible due to canals con- 

 necting watersheds, diversion of irrigation water, 

 flood diversion canals, etc. 



Salinity 



Generally, waters with reasonably high bicar- 

 bonate alkalinity are more productive of valuable 

 waterfowl food plants than are waters with low 



Salinity may have a twofold effect on wildlife: a 

 direct one affecting the body processes of the spe- 

 cies involved and an indirect one altering the en- 

 vironment, making living and species perpetuation 

 difficult or impossible. 



Direct Effect of Salinity 



A review of the available literature produced 

 very little information on possible effects of salinity 

 upon game mammals. There was a single reference 

 made in which a 0.9-percent solution of sodium 

 chloride was listed as innocuous to mammals 

 (Selye, 1943). 



As evidenced by the literature, salinity has a 

 very detrimental effect on all of the domestic 

 species of the order Galliformes (chickens and 

 turkeys). A solution of 0.9-percent sodium chlo- 

 ride used by Barred Rock chickens for drinking 

 purposes was extremely toxic, causing numerous 

 deaths (Krista, et al., 1961). The birds exhibited 

 water retention in the body and marked renal 

 changes. While working with turkey poults, it was 

 found that a 0.5-percent sodium chloride solution 

 was fatal to 50 percent of the individuals tested 

 and in addition that various sodium compounds 

 (sodium citrate, sodium carbonate) in 0.75- per- 

 cent solutions also were very toxic (Scrivner, 



94 



