THE OYSTER-INDUSTRY. 237 



62. FATALITIES TO WHICH OYSTEES ARE SUBJECT. 



Sediment. — In addition to tlie active, animate enemies of the oyster, the beds suffer seriously, at certain times, 

 from the elements, as has beeu pointed out frequently in the preceding pages. Great storms will sweep the oysters 

 all off the beds, bury them under shifting sand or mud, or heap upon them the drifting wrack torn from tlie shores. 

 Beds which lie at the mouths of rivers are liable to be injured by floods also, which keep the water wholly fresh, or 

 bringdown enormous quantities of silt and floating matter, which settles on the beds and smothers the oysters. 



A few years ago a large tract of peat was drained at Grangemouth, Scotland. The loose mud and moss was 

 carried down the drains upon an oyster-bed in the estuary ; the consequence was that the oysters were covered over 

 with mud. and entirely destroyed. Nothing is so fatal to oysters as a mud storm, except it be a sand storm. The 

 mud and the sand accumulate in the oyster's delicate breathing organs, and suffocate him. 



Mr. John A. Eyder, already quoted in the previous paragraphs, writes as follows about mud, as injurious to 

 oysters : 



"The origin of the black ooze at the bottom can be traced directly to the sediment held in suspension in the 

 water, which slowly ebbs and flows in and out of the iuclosure, carrying with it in its going and comiug a great 

 deal of light organic and inorganic debris, the former part of which is maiuly derived from the comminuted 

 ft-agments of plants growing iu the creek. This seemed to be the true history indicated by what was noticed in 

 studying the box-collector. The same opinion is held as to the origin of this mud by both Coste and Fraiche in 

 their works on oyster-culture. 



"There is probably no worse enemy of the oyster-culturist than this very mud or sediment. It accumulates oa 

 the bottom of the oyster-grounds, where, in course of time, it may become deep enough to cause serious trouble. 

 Especially is this true of ponds from which the sea ebbs, and to which it flows through a narrow channel. The 

 falling leaves from neighboring trees in autumn also contribute to this pollution, as well as heavy rains which 

 wash deleterious materials into it. 



"Adult oysters which are immersed in part in this mud struggle hard to shut it out from their shells. If one 

 will notice the inside of the shells of oysters which have grown in a muddy bottom, it will often be seen that there 

 are blister-like cavities around the edges of the valves filled with mud, or a black material of a similar character. 

 There is not the slightest doubt in my mind, that in these cases the animal, in order to keep out the intruding mud 

 has had recourse to the only available means at its command. A great many of the oysters in the pond are 

 affected in this manner, but it is extremely uncommon to find shells of this kind in opening oysters coming from a 

 hard bottom. It is easy to understand that such efibrts at keeping out the mud from the shell will not only waste 

 the life-forces of the animal, but also tend to greatly Interfere with its growth. The importance, therefore, of 

 artificial preparation is apparent, where it is desirable to establish ponds for the successful culture of this mollusk. 



"Only in one case have I observed that the mud tended to impair the flavor and color of the oyster. In this 

 instance the animal was thoroughly saturated with the black ooze, the very tissues seeming to be impregnated 

 with the color, the stomach and intestine loaded to engorgement with the mud, the animal manifesting every sign 

 of being in a decidedly sickened condition. The cause of this was probably that the shell, with its tenant, had 

 sunken too deeply into the mud when the ingestion of the black ooze commenced, giving rise to the remarkable 

 changes which I have recorded. No doubt had this condition of things for any length of time, the animal would 

 have been smothered by the mud." * 



Mm AND THE YOTTNG FRY. — "The accumulation of the slightest quantity of sediment around a young oyster 

 would tend to impede its respiration, and in that way destroy it, yet in the natural beds there are so few naturally clean 

 places which remain so, that it is really surprising that so many young oysters pass safely through the critical periods 

 of their lives without succumbing to the smothering effects of mud and sediment. When it is borne in mind, that at 

 the time the iufant oy.ster settles down and fixes itself once and for all time to one place, from which it has no jjower 

 to move itself, it measures at the utmost one-eightieth of an inch, it will not be hard to understand how easily the 

 little creature can be smothered, even by a very small pinch of dirt. The animal, small as it is, must already begin 

 to breathe just in the same way as its parents did before it. Like them its gills soon grow as little filaments covered 

 with cilia, which cau.se a tiny current of water to pass in and out of the shell. The reader's imagination may be here 

 allowed to estimate the feeble strength of that little current, which is of such vital importance to the tiny oyster, 

 and the ease with which it may be stopped by a very slight accumulation of dirt. Mobius estimates that each oyster 

 which is born has rrjixrooTJ ^^ '^ chance to survive and reach adult age. So numerous aud eftective are the adverse 

 conditions which surround the millions of eggs matured by a single female, that only the most trifling fraction ever 

 develop, as illustrated by the above circulation. The egg of the oyster being exceedingly small aud heavier thau 

 water, immediately falls to the bottom upon being set free by the parent. Should the bottom be oozy or composed 

 of sediment, its chances of development are meager indeed. Irrecoverably buried, the eggs do not, in all probability, 

 have the chance to begin to develop at all. The chances of impregnation are also reduced, because the male aud 



* Johu A. Eyder in report of T. B. Ferguson, a fisb commissioner of Maryland, for Idril, pp. 48, 49. 



