found that time of death was generally related to 

 the size of the dose. Four teaspoonfuls of an un- 

 concentrated suspension of Anabaena lemmer- 

 manni killed a great blue heron in 14 minutes. 

 Olson further states "Extensive algae blooms are 

 potentially dangerous to waterfowl, especially 

 where the principal component is Anabaena flos- 

 aquae or Anabaena lemmermanni, . . . To fore- 

 stall wildfowl losses, it would be desirable to keep 

 surface waters free of heavy algae growths". 



Lead poisoning 



The most demonstrative cause of waterfowl 

 mortality from pollution is lead poisoning. Twelve 

 million pounds of lead shot are expended annually 

 over the Nation's best waterfowl habitats. The 

 shot remains there relatively unchanged. Water- 

 fowl frequently ingest these shot and die. Annual 

 mortality is estimated at roughly 1 million birds. 



The major ammunition companies and several 

 conservation organizations currently are conduct- 

 ing research to develop a relatively nontoxic shot; 

 this endeavor should be continued until a satis- 

 factory solution is discovered and this annual 

 source of pollution is stopped. A change in shot- 

 type and adjustment of industry to its production 

 and use would seem possible in 4 years. 



Disease 



An understanding of the ecological relationships 

 of wildlife disease, water pollution, and water 

 quality characteristics is yet to be obtained. 

 Botulism, fowl cholera, and aspergillosis all can 

 affect birds in aquatic habitats. Although certain 

 conditions of temperature, alkalinity, organic mat- 

 ter, and other factors in the environment are 

 suspect as contributing to disease outbreaks no 

 exact parameters can be defined. Offal from poul- 

 try houses, dumped directly into estuaries in 

 Maine, was suspected of causing recent wildlife 

 losses from fowl cholera. 



no species become extinct because of water pollu- 

 tion. 



The bald eagle, the symbol of the United States, 

 has declined drastically in parts of the United 

 States. Studies are underway to determine the 

 cause. Although pesticides are largely suspect, it 

 has been suggested that lead poisoning, due to 

 eating ducks that died from crippling or lead 

 poisoning, might be involved. 



Water quality requirements for endangered 

 species of fish and wildlife should receive State and 

 Federal review on all applicable interstate waters 

 and be of the highest quality obtainable. 



Recommendation: To preserve suitable waterfowl 

 food plants, salinity fluctuations in a 24-hour period 

 should not exceed \%r in fresh to slightly brackish water 

 (0 to "i.S'/cc); I'U in moderately brackish water (3.5 to 

 13. 5%^); and A7cc in strongly brackish to marine waters 

 (13.5 to 35^^.). 



For optimum growth of aquatic food plants, at least 

 10 percent of incident light at the water surface should 

 reach a depth of 6 feet. Light penetration to this depth 

 must not be less than 5 percent of the incident light. 



To prevent the destruction of food plants, reductions 

 in light below the 5-percent levels should not prevail 

 for more than 7 days. This is especially important dur- 

 ing the local growing season. 



The submerged aquatic plants of greatest value as 

 wildfowl foods thrive best in waters with a summer pH 

 range of 7.0 to 9.2. 



For the protection of water birds, the habitat 

 should be free of oil. No pesticides should occur in the 

 water at concentrations which adversely affect the 

 health and use of wildlife either directly or through 

 accumulation of these materials which render them 

 unfit for food of other wildlife or for man. Levels satis- 

 factory for aquatic organisms should also be safe for 

 wildlife, but biological magnification must be con- 

 sidered. 



Fertilization by the addition of organic wastes, fer- 

 tilizers, or other materials should be so limite'd that 

 nuisance growths are not induced. 



Rare and endangered species of wildlife 



Finally, it is believed that the preservation of 

 individual wildlife species presents a challenge 

 and obligation to this generation and to those that 

 follow. To meet this challenge environmental re- 

 quirements for wildlife must be maintained so that 



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