NATURAL PHENOMENA 



waters; and causes other unpleasant conditions at resort areas. 



Research on this problem has added to knowledge of substances 

 which attack the nervous system. New weapons against human 

 disease may well be developed by medical science as a result of 

 research in this phenomenon. 



THE SARGASSO SEA 



The central part of the Atlantic Ocean has remained the subject 

 of myth and legend for a longer period than any other part of the 

 ocean. The term "Sargasso Sea" is derived from the name given by 

 the early Portuguese navigators. "Sargacao" so-called from the fact 

 that the berries found on the weed resemble grapes (sarga). It was 

 traversed by Columbus as he sailed westward and the masses of 

 weed, supposedly hampering the progress of the ships, nearly caused 

 a mutiny among his crew. 



Whether the Sargasso Sea was known prior to the discovery of 

 America is still open to question. There are grounds for believing 

 that the Phoenicians were acquainted with its presence. Before the 

 beginning of the Christian era there are references to the sea west 

 of the Pillars of Hercules (Gibraltar), and certain parts of the sea 

 are represented as being unnavigable because of the seaweed. Also, 

 there is a record of this fact that a Portuguese sailor told Columbus 

 that one of the obstacles to be overcome in the westward voyage 

 to India was weeds. To Columbus, however, must be credited its 

 discovery and the first authentic record of the occurrence of gulf- 

 weed in this area. On his first voyage westward he encountered 

 Sargasso Weed for a number of days; and likewise on his return 

 voyage. In his log, it is noted that Columbus carefully recorded the 

 occurrence of this brown, floating weed. 



Gulf Weed 



Viewed from a small vessel, such as that used by Columbus and 

 other mariners of his time, the patches of Sargassum undoubtedly 

 looked vastly more formidable than they really were. This region 

 is one of light winds; hence the sailing vessel made slow progress. 

 It is therefore little wonder that stories developed of widespread 

 distribution of the thickly-matted weed impeded the progress of the 

 vessels. These stories, it is interesting to note, originated not with 

 Columbus, but with his followers. Columbus himself records the 

 occurrence in an accurate manner. 



The increased knowledge of the ocean banished many of these 

 myths concerning ships enmeshed in seaweed, being forced into the 

 center of the mass, and gradually disappearing. With this increase 

 in knowledge, many theories have been advanced to account for the 

 existence of the Sargasso Sea. A Major Rennel observed "that the 

 waters of the Atlantic have a greater tendency toward the middle of 

 the ocean than otherwise and this seems to indicate a reduced level 

 forming a kind of hollow space or depressed surface". Another 

 theory, according to Findlay, was that it "Is the vortex of an im- 

 mense eddy and which is caused by the influence of the trade winds 

 and the Gulf Stream", while others maintain that it is a raised sur- 

 face kept in position by the currents surrounding it. 



A considerable portion of knowledge concerning the Sargasso 

 Sea is to be found in the records of the Challenger Expedition of 1873. 

 Many studies have been made since that date of the physical, 

 chemical, and biological nature of this oceanic area. But that ex- 

 pedition undoubtedly gave the first systematic study of the region. 



Following the work of the expedition, 0. Krummel (1891), 

 O. Wings (1923), and A. E. Parr (1939) wrote interesting and 

 informative papers concerning the Sargasso Sea. The basis for 



Krummel's investigations was provided by the records of floating 

 weeds observed from German ships crossing the North Atlantic and 

 entered in their log books as required by "Deutsche Seewarte" over 

 a period of many years. From these data regarding floating weeds, 

 he plotted the frequency of observations and the boundaries of the 

 Sargasso Sea and subdivided it into more or less concentric regions 

 showing various degrees of frequency of the floating weed. Wing's 

 material, on the other hand, consisted of actual samples collected by 

 various Danish research and merchant ships. Parr also collected 

 samples during hydrographic cruises to Central American waters. 

 His very extensive work covering his observations of the Sargasso 

 Weed is contained in the Bulletin of the Bingham Oceanographic 

 Collection, Volume 6, Article 7, issued December 1939, in New Haven, 

 Conn. 



The Sargasso Sea is oval in shape and extends from about lat. 

 25°N. to 30°N., between long. 40°W. to 73°W. Isolated patches and 

 streamers of weed are frequently encountered outside these limits, 

 and the entire area shifts a few degrees to the north and south 

 during yearly cycles. As can be seen from the charts, the Sargasso 

 Sea is the center of the oceanic circulation and is an area of weak 

 and variable currents. It is bounded on the south by the North 

 Equatorial Current, flowing westward; on the west and north by the 

 Florida Current and the Gulf Stream, flowing northward and east- 

 ward; and on the east by the North African Current. 



The temperature of the sea water is high while the decrease in 

 temperature is small compared with other parts of the ocean. Its 

 position in the lower latitudes, coupled with the freedom from 

 strong currents, permits the radiation from the sun to maintain a 

 relatively high water temperature in the surface layers. 



The waters of the Sargasso Sea are characterized by relatively 

 high salinity, 36-37 parts per thousand, as compared to 35 parts per 

 thousand in the South Atlantic. The area is situated at a con- 

 siderable distance from any coast, thus there is no dilution by the 

 less saline discharge from continental rivers. As this is a region of 

 high temperature, conditions are favorable for evaporation and in- 

 creased salinity. This latter factor is further augmented by the 

 relatively high percentage of sunny days. 



The waters of the Sargasso Sea are very transparent. Again 

 this is a combination of factors such as lack of continental sediments 

 reaching the region, and the relatively small quantity of plankton, 

 the microscopic organisms, plants and animals, which abound in 

 other parts of the sea. The color is a very deep blue contrasted to 

 the green or greenish blue, characteristic of the open ocean. 



Sargassum Weed, or "Gulf Weed" as it is commonly known to 

 seamen, is not native to the Sargasso Sea, although for many years 

 it was thought to be so; it being assumed that it grew on the bottom 

 and then, becoming detached, floated to the surface. It is now well 

 established, however, that Sargassum, a brown algae, grows along the 

 coast and is loose, reaching the Sargasso Sea by way of the Florida 

 Current and the Gulf Stream. These plants are kept afloat by air 

 bladders and grow vegetatively, propagating by fragmentation, but 

 apparently do not form fruiting bodies. These floating masses 

 form a characteristic environment with numerous associations in- 

 cluding other plants (algae) and animal forms. 



The weed is generally found floating in little islands or bunches, 

 not matted but with branches loosely intertwined, varying in size 

 from 1 and 2 feet to 2 and 3 yards in diameter. When a wind of low 

 force is blowing, the weed patches are usually formed into long 

 lanes or streamers. The spacing of the lanes of wind-driven 

 Sargassum is an indication of the depth of the mixed layer and 

 isothermal water. The general color of the weed is olive, the younger 

 branches being more golden olive with decaying parts dark brown. 

 One estimate of the quantity of Sargassum has been made. 

 Nets were towed for a known length of time and distance and the 

 resultant catch weighed. On the basis of these observations the 

 aggregate amount of this weed in the Sargasso Sea is estimated to 

 be about 20,000,000 tons. 



Sargassum affords protection to swarms of minute crabs, fish, 

 and other animals, not usually found in the open sea. These animals 

 are an excellent example of "protective coloration". Their color 

 allows them to blend in with the gulfweed in such a manner that 

 only the closest scrutiny reveals their presence. The animals are 

 very abundant, and represent a large number of species. 



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