94
CORDON A. RILEY
They concluded that the algae were lacking in active transport systems
and were dependent upon simple diffusion for heterotrophic growth.
However, Hellebust (1968) reported that some species are capable of
heterotrophic uptake a t substrate concentrations comparable to the
minimum levels required by bacteria, and there now seems to be little
doubt that some algae at least have effective transport systems.
Relative biomasses of the different kinds of cells, as reported by
Hamilton et al. (1968), might even suggest that deep sea algae are more
effective than bacteria in their competition for available substrates,
although admittedly there is still considerable question as to what
proportion of the small coloured cells reported by these authors are
actually living algae.
(b) Variations in production and consumption with depth. Returning
to the problem of allocating the available production in the marine
environment to the various kinds of consumers, the situation in the
Sargasso Sea will be examined once more, for this area provides more
complete data than any other place in the open ocean. This is largely
a matter of reworking and amplifying the analyses described in items
(1) to (4) of the introductory section. Unfortunately, however, the
problem seems more difficult now than it did when Riley et al. ( I 965)
published the original a,nalyses, and the results will be less clear cut.
Item (1) was an estimate of net phytoplankton production obtained
by Menzel and Ryther (1960). Their average was 200 mg Cam- 2.day-1
on a mean annual basis. In recent years the C14 method has been criticized because of the difficulty of proper correction for self absorption
on filters, and the International C14 Laboratory at Charlottenlund Slot
has recommended that all of the older values should be increased 45%
to bring them more nearly in line with modern information, Whether
this correction is really adequate remains to be seen. Goldman (1968)
has recommended burning the material and determining absolute
activity by gas counting methods. He compared the two methods,
using cultures of various algae. Results varied considerably, but in
general the values obtained by absolute counts were about three times
as high as those analyzed by the traditional method. The fact that
there were systematic differences among different species of algae
raised some doubts as to whether the results obtained with natural
populations might also vary in a rather unpredictable way depending
upon the species composition of the population.
This is where the situation stands at the moment. It remains to
be seen whether the accumulated C14 data can be salvaged by application of an arbitrary correction factor or will have to be discarded. In
CORDON A. RILEY
They concluded that the algae were lacking in active transport systems
and were dependent upon simple diffusion for heterotrophic growth.
However, Hellebust (1968) reported that some species are capable of
heterotrophic uptake a t substrate concentrations comparable to the
minimum levels required by bacteria, and there now seems to be little
doubt that some algae at least have effective transport systems.
Relative biomasses of the different kinds of cells, as reported by
Hamilton et al. (1968), might even suggest that deep sea algae are more
effective than bacteria in their competition for available substrates,
although admittedly there is still considerable question as to what
proportion of the small coloured cells reported by these authors are
actually living algae.
(b) Variations in production and consumption with depth. Returning
to the problem of allocating the available production in the marine
environment to the various kinds of consumers, the situation in the
Sargasso Sea will be examined once more, for this area provides more
complete data than any other place in the open ocean. This is largely
a matter of reworking and amplifying the analyses described in items
(1) to (4) of the introductory section. Unfortunately, however, the
problem seems more difficult now than it did when Riley et al. ( I 965)
published the original a,nalyses, and the results will be less clear cut.
Item (1) was an estimate of net phytoplankton production obtained
by Menzel and Ryther (1960). Their average was 200 mg Cam- 2.day-1
on a mean annual basis. In recent years the C14 method has been criticized because of the difficulty of proper correction for self absorption
on filters, and the International C14 Laboratory at Charlottenlund Slot
has recommended that all of the older values should be increased 45%
to bring them more nearly in line with modern information, Whether
this correction is really adequate remains to be seen. Goldman (1968)
has recommended burning the material and determining absolute
activity by gas counting methods. He compared the two methods,
using cultures of various algae. Results varied considerably, but in
general the values obtained by absolute counts were about three times
as high as those analyzed by the traditional method. The fact that
there were systematic differences among different species of algae
raised some doubts as to whether the results obtained with natural
populations might also vary in a rather unpredictable way depending
upon the species composition of the population.
This is where the situation stands at the moment. It remains to
be seen whether the accumulated C14 data can be salvaged by application of an arbitrary correction factor or will have to be discarded. In