94 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



shell is used solely as a protection and a place of abode and without 

 design upon the fleshy parts of the oyster, the food of the Martesia 

 being found in the incurrent streams of water passing through the 

 external orifice of the chambers. 



Algce. — Two species of algae, which have not been identified, are 

 found upon the oyster-beds of Louisiana. One of these is a species of 

 Ulva, a green form with expansive fronds, its appearance well meriting 

 its popular names of " sea lettuce" and "sea cabbage." This is quite 

 abundant in some places during the summer, but seems to die down 

 in winter. It appears to cause no serious annoyance to the oystermen 

 as it is readily removed from the shells. The second is a species of 

 Floridece, which maintains a luxuriant growth throughout the winter. 

 It consists of purplish-brown, slender-branching filaments, growing in 

 dense tufts upon the shells. While it in no manner injures the oysters, 

 except so far as it serves as a basis for the collection of mud and silt, 

 it is a source of great annoyance to oystermen on account of the diffi- 

 culty of its removal, and it not infrequently happens that fishing on a 

 bed is temporarily abandoned because of its abundance. If oysters 

 are sent to the markets or canneries with this seaweed attached the 

 filaments almost certainly become mixed with the meats and fluids and 

 render the opened product almost worthless. 



Crevasses. — Practically the entire oyster region of Louisiana is so 

 situated with respect to the Mississippi Eiver as to be subject to the 

 influence of crevasses occurring at almost any part of its course south 

 of the mouth of the Eed Eiver. In 1890 great damage was caused by 

 the Nita crevasse, which discharged through Blind Eiver into Lake 

 Maurepas, and thence via Lake Pontchartrain and Lake Borgne into 

 Mississippi Sound. This affected the oysters in St. Bernard Parish 

 and Mississippi Sound as far as Biloxi. 



In the spring of 1897 the river broke through the levee at Bohemia, 

 and, in a minor degree, at other places on the east bank of the river, 

 and killed all the oysters in the vicinity of Quarantine and California 

 bays; and several years ago the Pass a Loutre crevasse, which has not 

 yet been closed, produced a similarly disastrous effect in Garden Island 

 Bay. Instances might be multiplied, but those noted are probably the 

 most striking ones occurring within the last few years. 



The effects of a crevasse are twofold; it deposits mud and freshens 

 the water, both of which are more or less disastrous to the oysters. 

 Crevasses occur during periods of high water, when the river is carry- 

 ing large quantities of materials scoured from its watershed, and when 

 this sediment-laden stream strikes the salt water, either at its mouth or 

 through a temporary discharge resulting from a crevasse, its velocity 

 is checked and the mud in suspension is deposited, while at the same 

 time the salt water precipitates certain materials which have entered 

 into actual solution. When these materials are thrown down upon the 

 oyster-beds the oysters are smothered and the shells buried. 



