HOW TO KNOW THE SEAWEEDS 



may profit much from examining the beach drift which often accumu- 

 lates in quantity in coves or along sand beaches adjoining rocky areas. 

 It is among these cast specimens that many of the species of the 

 deeper, infratidal waters may be found and selected with much greater 

 ease than through the use of a boat and dredge. If driftweed is ex- 

 amined after a storm while the material is still fresh and has not been 

 exposed long to the bleaching and drying action of the sun and air, 

 many specimens in good condition may be selected. 



Apart from rocky shore habitats the algologist finds many other 

 situations in which seaweeds may be found. Many areas in which 

 surf is light or absent, such as the sandy or muddy shores of bays, 

 lagoons and estuaries, will yield specimens. Such quiet habitats are 

 especially well populated in tropical regions, and within the range 

 of the mangrove the algal flora of its roots is an interesting one which 

 should not be overlooked. The piling of wharves and the rock or 

 concrete of artificial breakwaters will yield many species. Indeed, 

 along the vast sandy stretches of the Gulf of Mexico, these will be 

 the principal algal habitats. Even mobile objects may have their 

 seaweed floras. Thus, boat hulls will yield several species as may 

 also the backs of sea turtles and several kinds of crabs. Particular 

 species have even been found attached to the intersegmental grooves 

 of isopods parasitic on certain fishes. 



Beyond the level of low tide, and apart from those cast ashore in 

 drift, the algae of infratidal waters must be obtained by means of 

 diving or by some manner of dredging. In very quiet, surfless waters 

 a collector may wade about observing the bottom by means of a glass- 

 bottom bucket and reaching specimens with ease. In depths of more 

 than three feet, observation is best afforded by a face plate and col- 

 lections made by placing specimens in a skiff as they are obtained 

 by the diver. In depths of more than ten feet the diver must be pro- 

 vided with breathing apparatus in order to spend the time below the 

 surface necessary for the selection of specimens. The "aqua-lung" has 

 recently become popular with skin-divers and its use may readily 

 be learned in most any area of warm, quiet water where these sports- 

 men thrive. In colder waters the diver must be provided with the 

 standard heavy diving suit and helmet. It is this heavy suit which is 

 normally used by the commercial seaweed collectors who harvest 

 Gelidium and other agar-yielding seaweeds from the infratidal beds 

 along the Pacific Coast. 



Apart from those areas where skin-diving may be done comfort- 

 ably, the collecting of infratidal algae is best accomplished by the 

 use of a dredge handled by a powered winch on shipboard. The use 

 of various devices of this sort is described by Sverdrup, Johnson & 



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