of secondary production (in columns M , and M,) to primary production
(in column D ) . Taking those in column N,, which are the simplest
ratios, they range from 34-23.9%, with a mean of 12.4%. Slobodkin
(1959) has presented evidence that the average figure should be about
lo%, whereas Steele (1965) thinks that ecological efficiency should be
higher, so long as the greater proportion of transfer occurs amongst
young and very efficiently growing animals. The sources of data are
very varied, in quality and in numbers of observations, and the correspondence of the transfer coefficients to expected values is a measure
of the reliability of the radiocarbon measurements and the estimates of
secondary production. It should be recalled that some estimates are
based on Hentschel's counts from water samples, on the " Meteor "
expedition (1933), and that nets of many different designs have been
used. Perhaps they all catch zooplankton well enough for our present
purposes and perhaps the present doubts on the efficiency of zooplankton sampling, is, in a simple-minded way, misleading. Further, the
assumptions that the loss of nauplii is balanced by gain of algae and
that the proportions escaping are small are roughly justified.
C. The production at the third trophic level
The composition of the third trophic level in the sea is not completely known. There are predatory copepods and a large number of
other planktonic predators and there are also plankton-eating fish,
mainly clupeids. So, the secondary production as estimated in Table IV
includes carnivorous copepods, arrow worms, jelly-fish, ctenophores,
etc., which are really in the third trophic level. Excluded are the
plankton-eating fish and molluscs. Very little is known about the
abundance of squids and, since they are in economic and fishery terms
comparable t o fish, they will be treated as such.
The simplest way of estimating the tertiary production is to take
1% of the primary production and 10% of Dhe secondary production,
both in carbon. Column 0 in Table IV gives the first, and columns P,
and P, give the two estimates (for continuous and intermittent upwelling) from the second. If columns D and M , are compared, it will
be seen that they are correlated (Fig. 15A) (r = 0.77, P < 0-01) ; the
regression of the radiocarbon on the secondary production estimates the
average transfer coefficient. The two estimates proceed from independent ones of primary and secondary production and it is assumed in
both that there is a 10% efficiency between secondary and tertiary
produetion. They are therefore not entirely independent, but the
degree of correlation between them suggests that the basic methods are
sufficient for our present purposes.
(in column D ) . Taking those in column N,, which are the simplest
ratios, they range from 34-23.9%, with a mean of 12.4%. Slobodkin
(1959) has presented evidence that the average figure should be about
lo%, whereas Steele (1965) thinks that ecological efficiency should be
higher, so long as the greater proportion of transfer occurs amongst
young and very efficiently growing animals. The sources of data are
very varied, in quality and in numbers of observations, and the correspondence of the transfer coefficients to expected values is a measure
of the reliability of the radiocarbon measurements and the estimates of
secondary production. It should be recalled that some estimates are
based on Hentschel's counts from water samples, on the " Meteor "
expedition (1933), and that nets of many different designs have been
used. Perhaps they all catch zooplankton well enough for our present
purposes and perhaps the present doubts on the efficiency of zooplankton sampling, is, in a simple-minded way, misleading. Further, the
assumptions that the loss of nauplii is balanced by gain of algae and
that the proportions escaping are small are roughly justified.
C. The production at the third trophic level
The composition of the third trophic level in the sea is not completely known. There are predatory copepods and a large number of
other planktonic predators and there are also plankton-eating fish,
mainly clupeids. So, the secondary production as estimated in Table IV
includes carnivorous copepods, arrow worms, jelly-fish, ctenophores,
etc., which are really in the third trophic level. Excluded are the
plankton-eating fish and molluscs. Very little is known about the
abundance of squids and, since they are in economic and fishery terms
comparable t o fish, they will be treated as such.
The simplest way of estimating the tertiary production is to take
1% of the primary production and 10% of Dhe secondary production,
both in carbon. Column 0 in Table IV gives the first, and columns P,
and P, give the two estimates (for continuous and intermittent upwelling) from the second. If columns D and M , are compared, it will
be seen that they are correlated (Fig. 15A) (r = 0.77, P < 0-01) ; the
regression of the radiocarbon on the secondary production estimates the
average transfer coefficient. The two estimates proceed from independent ones of primary and secondary production and it is assumed in
both that there is a 10% efficiency between secondary and tertiary
produetion. They are therefore not entirely independent, but the
degree of correlation between them suggests that the basic methods are
sufficient for our present purposes.