822 



NATURE 



[August 26, 1920 



much controversy, and have been useful in stimu- 

 lating further research, but I believe it is now ad- 

 mitted that Putter's samples of water from the Bay 

 of Naples and at Kiel were probably polluted, that 

 his figures were erroneous, and that his conclusions 

 must be rejected, or at least greatly modified. His 

 estimates of the -plankton were minimum ones, wbjle 

 it seems probable that his figures for the organic 

 carbon present represent a variable amount of organic 

 matter arising from one of the reagents used in the 

 analyses." The later experimental work of Henze, 

 of Raben, and of Moore shows that the organic carbon 

 dissolved in sea-water is an exceedingly minute 

 quantity, well within the limits of experimental error. 

 Moore puts it at the most at one-millionth part, or 

 I mgm. in a litre At the Dundee meeting of the 

 Association in igi2 a discussion on this subject took 

 place, at which Putter still adhered to a modified 

 form of his hypothesis of the inadequacy of the 

 plankton and the nutrition of lower marine animals 

 by the direct absorption of dissolved organic matter. 

 Further work at Port Erin since has shown that, 

 while the plankton supply as found generally dis- 

 tributed would prove sufficient for the nutrition of 

 such sedentary animals as Sponges and Ascidians, 

 which require to filter only about fifteen times their 

 own volume of water per hour, it is quite inadequate 

 for active animals such as crustaceans and fishes. 

 These latter are, however, able to seek out and cap- 

 ture their food, and are not dependent on what they 

 may filter or absorb from the sea-water. This result 

 accords well with recorded observations on the ir- 

 regularity in the distribution of the plankton and 

 with the variations in the occurrence of the migra- 

 tory fishes which may be regarded as following and 

 feeding upon the swarms of planktonic organisms. 



This, then, like most of the subjects I am dealing 

 with, is still a matter of controversy, still not com- 

 pletely understood. Our need, then, is research, more 

 research, and still more research. 



Our knowledge of the relations between plankton 

 productivity and variation and the physico-chemical 

 environment is still in its infancy, but gives promise 

 of great results in the hands of the biochemist and 

 the physical chemist. 



Recent papers by S0rensen, Palitzsch, Witting, 

 Moore, and others have made clear that the amount 

 of hydrogen-ion concentration as indicated by the 

 relative degree of alkalinity and acidity in the sea- 

 water may undergo local and periodic variations, and 

 that these have an effect upon the living organisms in 

 the water and can be correlated with their presence 

 and abundance. To take an example from our own 

 seas, Prof. Benjamin Moore and his assistants in their 

 work at the Port Erin Biological Station in succes- 

 sive years from iqi2 onwards have shown '* that the 

 sea around the Isle of Man is a good deal more alka- 

 line in spring (sav April) than it is in summer (say 

 July). The alkalinitv, which gets low in summer, 

 increases somewhat in autumn, and then decreases 

 rapidly, to disappear during the winter; and then 

 once more, after several months of a minimum, 

 begins to come into evidence again in March, and 

 rapidlv rises to its maximum in April or May. This 

 periodic change in alkalinity will be seen to correspond 

 roughly with the changes in the living microscopic 

 contents of the sea represented by the phyto-plankton 

 annual curve, and the connection between the two will 

 be seen when we realise that the alkalinity of the 

 sea is due to the relative absence of carbon dioxide. 

 In early spring, then, the developing myriads of 



•3 See Moore, etc., Bie-Chetn. Jottrn., vol. vi., p. 266, igi2. 

 2* " Photosynthetic Phenomena in Sea-water," Trans. Liverpool Biol. 

 Soc, vol. xxix., p. 233, 1915. 



NO. 2652, VOL. TO5] 



Diatoms in their metabolic processes gradually use 

 up the store of carbon dioxide accumulated during 

 the winter or derived from the bicarbonates of calcium 

 and magnesium, and so increase the alkalinity of the 

 water until the maximum of alkalinity, due to the 

 fixation of the carbon and the reduction in amount 

 of carbon dioxide, corresponds with the crest of the 

 phyto-plankton curve in, say, April. Moore has cal- 

 culated that the annual turnover in the form of 

 carbon which is used up or converted from the in- 

 organic into an organic form probably amounts to 

 something of the order of 20,000-30,000 tons of 

 carbon per cubic mile of sea-water, or, say, over an 

 area of the Irish Sea measuring 16 square miles and 

 a depth of 50 fathoms ; and this probably means a 

 production each season of about two tons of dry 

 organic matter, corresponding to at least ten tons of 

 moist vegetation, per acre — which suggests that we 

 may still be very far from getting from our seas any- 

 thing like the amount of possible food-matters that 

 are produced annually. 



Testing the alkalinity of the sea-water may there- 

 fore be said merely to be ascertaining and measuring 

 the results of the photosynthetic activity of the great 

 phyto-plankton rise' in spring due to the daily increase 

 of sunlight. 



The marine biologists of the Cafnegie Institution, 

 Washington, have made a recent contribution to the 

 subject in certain observations on the alkalinity of the 

 sea (as determined by hydrogen-ion concentration), 

 during which they found in tropical mid-Pacific a 

 sudden change to acidity in a current running east- 

 wards. Now in the Atlantic the Gulf Stream and 

 tropical Atlantic waters generally are much more 

 alkaline than the colder coastal water running south 

 from the Gulf of St. Lawrence — that is, the colder 

 Arctic water has more carbon dioxide. This suggests 

 that the Pacific easterly set may be due to deeper 

 water, containing more carbon dioxide ( = acidity), 

 coming to the surface at that point. The alkalinity 

 of the sea-water can be determined rapidly by mixing 

 the sample with a few drops of an indicator and 

 observing the change in colour; and this method of 

 detecting ocean currents by observing the hydrogen- 

 ion concentration of the water might be useful to 

 navigators as showing the time of entrance to a 

 known current. 



Oceanography has many practical applications, 

 chiefly, but by no means wholly, on the biological 

 side. The great fishing industries of the world deal 

 with living organisms, of which all the vital activities 

 and the inter-relations with the environment are 

 matters of scientific investigation. Aquiculture is as 

 susceptible of scientific treatment as agriculture can 

 be ; and the fisherman, who has been in the past too 

 much the nomad and the hunter — if not, indeed, the 

 devastating raider — must become in the future the 

 settled farmer of the sea if his harvest is to be less 

 precarious. Perhaps the nearest approach to cultiva- 

 tion of a marine product, and of the fisherman reap- 

 ing what he has actually sown, is seen in the case 

 of the oyster and mussel' industries on the west coast 

 of France, in Holland, America, and, to a less extent, 

 on our own coast. Much has been done by scientific 

 men for these and other similar coastal fisheries since 

 the days,- when Prof. Coste in France in 1859 intro- 

 duced oysters from the Scottish oyster-beds to start 

 the great industrv at Arcachon and elsewhere. Now 

 we buy back the descendants of our own oysters from 

 the French ostreiculturists to replenish our depleted 

 beds. 



It is no small matter to have introduced a new and 

 important food-fish to the markets of the world. The 

 remarkable deep-water "tile-fish," new to science and 



