270
D. H. CUSHINO
be very exact t o be used in a description of oceanic circulation as Reid
(1962b) did. The distribution of P04.P at the surface has quite a
different character, which cannot be interpreted so easily, presumably
because surface phosphorus is less conservative than that at 100 m.
Yet that at 100 m cannot be conservative in the sense that salinity is so
described. Hence there must be a very profound connection between
phosphorus and zooplankton to generate such a correlation in spatial
detail. If phosphorus is converted to algae, in its turn converted to
animal flesh, one might expect an inverse correlation during a period of
time. Then if distance from the coast indicated time from the point of
upwelling, the inverse correlation should be obvious in the horizontal
distributions of phosphorus and zooplankton-but there is a positive
correlation in detail. When phosphorus is used in the production cycle,
it is converted to animal flesh, organic residue (dissolved and particulate) and a stock of algae, so the algal population may constitute
only a transient component in the system (Harvey et al., 1935). The
phosphorus in the water at any point, P,, may be considered as a
residue of productive processes, P, < P,, the initial quantity available
for production, i.e. the quantity available at 200 m in an upwelling
area. Then P, - P, = P,, the minimum quantity used in production.
Strictly, we would expect P, to be directly correlated with 8, the
quantity of zooplankton ; also, since P, = P, - P,, we might expect
an inverse correlation between P, and 8 (provided that enough production had occurred), which is not observed. Let us define P, in more
detail, distinguishing that part of production which is locked in the
stock of algae, P,, that absorbed into animal flesh, .Pu, and that which
is regenerated by animal grazing, BPu. This quantity may consist of
two parts : (a) the loss of material into the water a~ the animal eats the
algal cells, and (b) excretion by the animals. Then, P, = PT - P, -
.PU + BP,. If we then suppose that BPu > .P, because ,Pu includes
the nutrient locked in the zooplankton and note that P, < PR, the
correlation between P, and 8 is explained. The quantity of phosphorus excreted must be less than the quantity in animal flesh, but the
quantity lost from the daily production in the act of grazing may be
high and could itself be greater than the daily increment to animal
flesh. Then the observed phosphorus at the surface in the upwelling
area would be mainly regenerated phosphorus. If the production cycle
in an upwelling area is really a temperate one, then perhaps the observations of nutrients may comprise mainly regenerated material. It
should not be surprising because the turnover rate of phosphorus in
lakes was shown to be rapid (Hayes and Coffin, 1951) ; the same processes probably occur in the sea and Cushing and Nicholson (1963)
D. H. CUSHINO
be very exact t o be used in a description of oceanic circulation as Reid
(1962b) did. The distribution of P04.P at the surface has quite a
different character, which cannot be interpreted so easily, presumably
because surface phosphorus is less conservative than that at 100 m.
Yet that at 100 m cannot be conservative in the sense that salinity is so
described. Hence there must be a very profound connection between
phosphorus and zooplankton to generate such a correlation in spatial
detail. If phosphorus is converted to algae, in its turn converted to
animal flesh, one might expect an inverse correlation during a period of
time. Then if distance from the coast indicated time from the point of
upwelling, the inverse correlation should be obvious in the horizontal
distributions of phosphorus and zooplankton-but there is a positive
correlation in detail. When phosphorus is used in the production cycle,
it is converted to animal flesh, organic residue (dissolved and particulate) and a stock of algae, so the algal population may constitute
only a transient component in the system (Harvey et al., 1935). The
phosphorus in the water at any point, P,, may be considered as a
residue of productive processes, P, < P,, the initial quantity available
for production, i.e. the quantity available at 200 m in an upwelling
area. Then P, - P, = P,, the minimum quantity used in production.
Strictly, we would expect P, to be directly correlated with 8, the
quantity of zooplankton ; also, since P, = P, - P,, we might expect
an inverse correlation between P, and 8 (provided that enough production had occurred), which is not observed. Let us define P, in more
detail, distinguishing that part of production which is locked in the
stock of algae, P,, that absorbed into animal flesh, .Pu, and that which
is regenerated by animal grazing, BPu. This quantity may consist of
two parts : (a) the loss of material into the water a~ the animal eats the
algal cells, and (b) excretion by the animals. Then, P, = PT - P, -
.PU + BP,. If we then suppose that BPu > .P, because ,Pu includes
the nutrient locked in the zooplankton and note that P, < PR, the
correlation between P, and 8 is explained. The quantity of phosphorus excreted must be less than the quantity in animal flesh, but the
quantity lost from the daily production in the act of grazing may be
high and could itself be greater than the daily increment to animal
flesh. Then the observed phosphorus at the surface in the upwelling
area would be mainly regenerated phosphorus. If the production cycle
in an upwelling area is really a temperate one, then perhaps the observations of nutrients may comprise mainly regenerated material. It
should not be surprising because the turnover rate of phosphorus in
lakes was shown to be rapid (Hayes and Coffin, 1951) ; the same processes probably occur in the sea and Cushing and Nicholson (1963)