SECT. 4] GEOGRAPHIC VARIATIONS IN PRODUCTIVITY 377 



huge production rates of the benthic flora. How can they be maintained even 

 in impoverished tropical seas? The answer lies in the great advantage which 

 benthic plants have in the problems of obtaining nutrients. Unlike the phyto- 

 plankton, they are not confined to a given parcel of water which they can leave 

 only through the force of gravity or feeble swimming. Low though the con- 

 centrations of nutrients may be in the water which bathes them, its continual 

 renewal by tides and currents provides the sessile plants with an inexhaustable 

 supply of these essential materials. 



During the summer of 1957, a brief and rather preliminary study was made 

 of the relative importance of benthic and planktonic algae in the primary 

 production of a small estuarine pond near Woods Hole (Robert Barth, un- 

 published manuscript). At the time of the study, the pond contained a dense 

 bloom of dinoflagellates and a rather inconspicuous quantity of green algae 

 (Ulva and Enteromorpha) around its edges. Yet productivity measurements 

 indicated that the phytoplankton contributed no more than about 1% of the 

 daily organic production of the pond. 



Vinogradov (1953) has estimated that the benthic algae cover a minimum 

 area of 10 11 m 2 , about 0.1% of the ocean's surface, and that their mean standing 

 crop is some 10 15 g. If we may assume, conservatively, that these plants are 

 annuals, in other words that their standing crop is roughly equivalent to their 

 annual production, the latter would amount to at least one-tenth of the most 

 recent estimates of the ocean's phytoplankton production (Steemann Nielsen 

 and Jensen, 1957 ; Ryther, 1960). More extensive and precise quantitative 

 studies of the benthic algae may well reveal that they play a considerably 

 greater role in the relative productivity of the sea, perhaps equally as important 

 as the phytoplankton. This interesting, if tenuous, idea must remain a subject 

 for present speculation, a challenge for future investigators. It is obvious, 

 however, that estimates of primary production of coastal and inshore regions 

 which fail to take the benthic flora into account must be quite unrealistic. 



References 



Apollonio, S., 1957. Plankton productivity studies in Allen Bay, Cornwallis Island, 



N.W.T., 1956. (Unpublished manuscript.) 

 Apollonio, S., 1959. Hydrobiological measurements on IGY drifting station Bravo. 



Nat. Acad. Sci., I.G.Y. Bull., 27, 16-19. 

 Austin, T. S., 1957. Summary, oceanographic and fisheries data, Marquesas Islands Area, 



August-September, 1956 (Equipac). Spec. Sci. Rep., U.S. Fish. Wild. Serv., Fish., 



217, 1-186. 

 Banse, K., 1959. On upwelling and bottom-trawling off the southwest coast of India. 



J. Mar. Biol. Assoc. India, 1, 33-49. 

 Berge, G., 1958. The primary production in the Norwegian Sea in June 1954, measured 



by an adapted 14 C technique. Rapp. Cons. Explor. Mer, 144, 85-91. 

 Blinks, L. R., 1955. Photosynthesis and productivity of littoral marine algae. J. Mar. 



Res., 14, 363-373. 

 Brouardel, J. and E. Rink, 1956. Determination de la production de matiere organique 



en Mediterranee a l'aide du ^C. C. R. Acad. Sci. Paris, 243, 1797 1799. 



