182
J. E . a. RAYMONT
culture of zooplankton with fertilization experiments (e.g. Raymont and
Miller, 1962) has also not yielded precise data on the rate of zooplankton
production in relation to phytoplankton crop. Investigations by Reeve
(1963) have made an important contribution in dealing with the efficiency of utilization of phytoplankton, even though the species studied
(Artemia) is not a marine plankton animal. Our knowledge of the
metabolism of zooplankton animals is excessively limited, though
Conover (1 962) has maintained Calunus hyperboreus for considerable
periods of time and has been able to relate feeding to activity, and to
respiration, and to make some estimates of efficiency and growth. A
survey of our knowledge of aspects of metabolism, including utilization
of food, excretion, and respiration (Raymont, 1963) reveals that data on
maintenance and growth requirements and even of the metabolic food
reserves of zooplankton are very 1imit)ed (cf. Raymont et al., 1964).
Investigations of the metabolism of plankton have been handicapped
because of the difficulties of culturing zooplankton species in the
laboratory. Although it is possible to obtain egg production from
Calanus Jinmarchicus and C. hyperboreus, and to rear various stages, so
far the culture of successive generations has eluded us. Jacobs (1961)
made an important contribution in growing Pseudodiaptmus coronutwr
in the laboratory through several generations, using phytoplankton aa
food, but this copepod is not a truly planktonic species. The most important recent advance is that of Zillioux and Wilson* (unpublished)
who bred Acartia tonsa through five successive generations using phytoplankton cultures as food. Continuation of such experiments should
allow the medium and the food requirements of planktonic animals to be
accurately defined, as with the work of Provasoli and his colleagues (e.g.
Shiraishi and Provasoli, 1959) on the nonplanktonic copepod Tigriopw.
Only then can we study adequately the factors affecting the metabolism
and growth of plankton animals. Meanwhile mathematical models help
us to appreciate the problems and point the way to future research.
D. THE FEEDING OF ZOOPLANKTON
The trophic relationships of animal plankton species is a complex
problem. Perhaps the copepods are best known for their food requirements and of these Calanus has been particularly studied. An excellent
summary is included in the work of Marshall and Om (1955): a wide
variety of diatoms is utilized as food, from the large Coscinodiscus and
Ditylum to the smaller species such as Skebtonema and Nitzmhia
closterium. Dinoflagellates such as Peridinium, Gymnodinium, md
Prorocentrum are also widely eaten, but there is some selection; for
I a m greatly indebted to the authors for permission to use the unpublished data
J. E . a. RAYMONT
culture of zooplankton with fertilization experiments (e.g. Raymont and
Miller, 1962) has also not yielded precise data on the rate of zooplankton
production in relation to phytoplankton crop. Investigations by Reeve
(1963) have made an important contribution in dealing with the efficiency of utilization of phytoplankton, even though the species studied
(Artemia) is not a marine plankton animal. Our knowledge of the
metabolism of zooplankton animals is excessively limited, though
Conover (1 962) has maintained Calunus hyperboreus for considerable
periods of time and has been able to relate feeding to activity, and to
respiration, and to make some estimates of efficiency and growth. A
survey of our knowledge of aspects of metabolism, including utilization
of food, excretion, and respiration (Raymont, 1963) reveals that data on
maintenance and growth requirements and even of the metabolic food
reserves of zooplankton are very 1imit)ed (cf. Raymont et al., 1964).
Investigations of the metabolism of plankton have been handicapped
because of the difficulties of culturing zooplankton species in the
laboratory. Although it is possible to obtain egg production from
Calanus Jinmarchicus and C. hyperboreus, and to rear various stages, so
far the culture of successive generations has eluded us. Jacobs (1961)
made an important contribution in growing Pseudodiaptmus coronutwr
in the laboratory through several generations, using phytoplankton aa
food, but this copepod is not a truly planktonic species. The most important recent advance is that of Zillioux and Wilson* (unpublished)
who bred Acartia tonsa through five successive generations using phytoplankton cultures as food. Continuation of such experiments should
allow the medium and the food requirements of planktonic animals to be
accurately defined, as with the work of Provasoli and his colleagues (e.g.
Shiraishi and Provasoli, 1959) on the nonplanktonic copepod Tigriopw.
Only then can we study adequately the factors affecting the metabolism
and growth of plankton animals. Meanwhile mathematical models help
us to appreciate the problems and point the way to future research.
D. THE FEEDING OF ZOOPLANKTON
The trophic relationships of animal plankton species is a complex
problem. Perhaps the copepods are best known for their food requirements and of these Calanus has been particularly studied. An excellent
summary is included in the work of Marshall and Om (1955): a wide
variety of diatoms is utilized as food, from the large Coscinodiscus and
Ditylum to the smaller species such as Skebtonema and Nitzmhia
closterium. Dinoflagellates such as Peridinium, Gymnodinium, md
Prorocentrum are also widely eaten, but there is some selection; for
I a m greatly indebted to the authors for permission to use the unpublished data