II 



ENVIRONMENT OF THE OYSTER 



IT is understood that for eggs to be produced and developed through 

 the spawning, swarming, and spatting periods there must exist 

 certain pre-requisites in the biological and physical conditions of the 

 environment. 



The Biological Conditions for the oyster are not markedly different 

 from those of any other highly organized living marine animal, and con- 

 sequently do not afford any special clue of a practical value to man. Oyster 

 eggs must originate in oysters that have themselves found suitable or at 

 least tolerable conditions. The food stored in the eggs is a hereditary gift 

 from the parents. The external conditions that are not immediately de- 

 structive to oyster eggs are to some extent favourable to the production 

 of minute organisms that may serve as food for the larva, spat, and adult 

 oyster, thus supplying a most important biological necessity. Compe- 

 tition for food and place, defence against enemies, and other physiological 

 or bionomic activities on the part of the oyster are so nearly identical with 

 those of other animals that it would not help in our present purpose to 

 consider them in detail. The functions of cells, tissues, organs, individuals, 

 or whole collections of oysters on an oyster bed or in an oyster bay, when 

 analyzed, bear a relation to the physical environment with which we can 

 deal to greater advantage. 



The Physical Conditions of natural oyster-producing, as compared 

 with non-oyster-producing, areas will determine the prime essentials, not 

 only for the life of the oyster, but for the successful production of eggs, 

 larvee, and spat. Along our coast the oyster lives and breeds in compara- 

 tively shallow bays, coves, and estuaries of rivers that are sheltered from 

 the deep, cold, often stormy waters of the gulf and ocean by islands or 

 projecting long sand-bars; that have areas of less than three fathoms depth, 

 a tidal fluctuation of only 3 to 5 feet, and some admixture of river water; 

 with rather hard bottom of rock, stones, gravel, clay or sand, often over-laid 

 with a dark-coloured, light, loose, fluffy ooze of organic origin, but no deep, 

 heavy, sticky mud or shifting sand. The salinity generally lies between 

 1-012 and 1-020 (distilled water being 1-000) but varies a few degrees with 

 the ebb and flow of the tide and with the amount of river water. In the 

 early part of July the temperature of the water approximates to 20° C. 

 (= 68° F.) and, owing to the small exchange of tidal water and the great 

 amount of heated sand, there is no great and sudden variation. Such 



