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PRODUCTION OF LIFE IN THE SEA
Author(s) -
HARVEY H. W.
Publication year - 1942
Publication title -
biological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.993
H-Index - 165
eISSN - 1469-185X
pISSN - 1464-7931
DOI - 10.1111/j.1469-185x.1942.tb00438.x
Subject(s) - nutrient , photosynthesis , phytoplankton , turbidity , seawater , environmental chemistry , algae , botany , biology , ecology , environmental science , chemistry
Summary .This review deals with the production of plants in the sea, which is controlled by a mosaic of factors, many of which are interrelated. Observations are collected and discussed, which relate to (i) the compounds of nitrogen and phosphorus directly utilized by the phytoplankton, and their rate of supply to the photosynthetic zone; (ii) the depth of this zone, which is determined by the quantity of light energy entering the water daily and the transparency of the water; (iii) the influence of temperature, of light, and of the concentration of nutrient salts, upon the growth rate of some diatoms; (iv) the dual effect of turbulence which, on the one hand, carries nutrient salts from below into the photosynthetic zone and, on the other hand, carries plant organisms to depths below the zone and, in some areas, increases the turbidity of the water thereby reducing the depth of the photosynthetic zone; (v) grazing by herbivores which deplete the breeding stock of plants but also excrete nutrient salts directly into the photosynthetic zone; (vi) the regeneration of nutrient salts by bacteria and enzymes; (vii) the supply of iron and other trace elements, of which manganese and divalent sulphur compounds are needed by some species of diatoms, The supply of such minor constituents is thought to play a considerable role in the distribution of plant life in the southern South Atlantic, where there is a high concentration of nutrient salts in the waters throughout the year and great differences in the density of the flora between different areas. Estimates of the magnitude of the annual production of plants below a square metre, arrived at by various indirect methods, are compared. Fluctuations in the annual plant production from year to year in the English Channel, assessed from the quantities of phosphate present in the water during the winter, show a marked correlation with the density of the fauna. Recent attempts to estimate the standing crop of phytoplankton in terms of food for animals are described, and tentative estimates of the carbon and phosphorus content of the standing crop below a square metre, when at its maximum in several seas, are compared.