Recent Research AccomplisliDicnts 



9 



THE CHEMISTRY OF OCEAN WATERS 



AND SEDIMENTS 



Chemical stiulics in occanograpliy have 

 been devoted largeK' to those components 

 of sea water which are used by organisms 

 in their hfe cycle: oxygen, carbon dioxide, 

 nitrogen compounds, phosphate, siHcates, 

 etc. Although mixing of the oceans through 

 the ages has brought the principal inorganic 

 constituents to a monotonous uniformity, 

 \aried only by the addition or loss of small 

 quantities of water, this is not true of those 

 which enter substantially into the struc- 

 ture of living organisms. Phosphate and 

 nitrate, on which fertility depends, are in 

 general about fifty percent more abundant 

 in the Pacific and Indian Oceans than in 

 the Atlantic. In the Mediterranean, the 

 quantities are much smaller. On a local 

 scale the difference between each bank or 

 embavment is even more marked. Although 

 the causes of these differences are not well 

 understood, they reflect the basic produc- 

 tivity just as surely as the fertility of the 

 land is fixed by its climate, its geology, and 

 the availability of crops suitable for each 

 region. 



Ninety percent of the nutrients in the 

 sea are trapped in the greater depths where 

 for the want of light they cannot be used 

 bv living plants. Only as vertical exchanges 

 of water take place by turbulent processes 

 and by upwelling are those substances 

 brought near enough to the surface to per- 

 mit their use. In exceptional places these 

 processes are of such violence that great 

 fertility results, but over most of the ocean 

 the exchange is slow, so slow in fact that 

 much of the available energy of the sun 

 is wasted for lack of material to work 

 upon in producing living matter. The high 

 fertility of certain tropical waters can be 

 traced to elements set free by the decom- 

 position of organisms as far away as the 

 Antarctic. 



Since 1930 laboratory studies and surveys 

 at sea of the distribution of oxygen and 

 phosphate in the western Atlantic, the Car- 

 ribbean, and the eastern north Pacific have 

 substantiated the older concepts of the nu- 

 trient cycle. As a result, a theoretical ap- 



proach toward understanding the water 

 movements and biological processes which 

 combine to produce or limit the produc- 

 tivity of given areas and the rate of cir- 

 culation of nutrient materials between the 

 surface and deep layers has already been 

 made. 



Recently it was demonstrated that several 

 other elements often present in the soil in 

 minute cjuantities may profoundly influence 

 its fertility and the nutritive value of the 

 plants produced. Likewise it has been 

 shown that among the minor constituents 

 of sea water, iron and manganese may be 

 present in such small (quantities as to limit 

 the growth of plants. 



Organic chemistry has scarcely been ap- 

 plied to sea water itself and only in a lim- 

 ited degree to marine sediments, although 

 it is obviously of interest in connection with 

 the formation of petroleum. It is known 

 that sea water contains small residues of 

 highly stable organic matter, that larger 

 (quantities are found wherever living or- 

 ganisms are undergoing decay, and that 

 significant (quantities occur in marine sedi- 

 ments. 



THE BIOLOGY OF THE OCEANS 



About the beginning of this century the 

 scope of marine biology began to expand 

 in many directions as attention shifted 

 froin description and phylogeny of organ- 

 isms to the mechanisms of their life pro- 

 cesses. Thus the many elements involved 

 in the production and growth of organisms 

 and in controlling their abundance, mi- 

 grations, swarming, etc., became the domi- 

 nant subjects of research. 



The need for understanding fish fluctu- 

 ations and allied problems has occasioned 

 many studies on plankton, which directly 

 or indirectly provides food for fish. Plank- 

 ton fluctuates normally in abundance from 

 season to season and also from year to 

 year. The kinds of organisms present de- 

 pend to some extent on the season, but one 

 which is abundant one year may be scarce 

 or absent the next or even for a series of 

 years. In some areas, notably off Plymouth, 

 England, the annual variations have been 



