THE PRODUCTION O F MARINE PLANKTON
191
the blooms of phytoplankton and the growth of zooplankton being
somewhat out of phase. Provided the blooming of the phytoplankton is
not too accelerated, however, the “wastefulness” is not excessive and in
any event the partly used phytoplankton crop serves as food for deeper
living zooplankton and for the benthos.
Oceanic depths have a much reduced zooplankton population. The
main limitation would appear to be the amount of particulate orgahic
matter available as food. While the vertical migrations of the zooplankton to different levels in the oceans carries organic particles such as
faecal pellets to greater depths where they can be used by the deeper
filter-feeding zooplankton, the nutritive vitlue of such particles is
probably not very high. Protozoa, especial1.y ciliates, feeding on the
relatively much greater quantities of dissolved organic matter in the
deep oceans, either directly or via bacteria, Sorm a second food source
for filter-feeders. Some bathypelagic planktonic species may feed
directly on bacteria but the density of micro-organisms in the open
oceans is probably never high. Organic aggregates can be formed from
dissolved organic matter in the oceans and this material may serve as
another source of food for the zooplankton. At moderate depths in
certain warmer seas the deeper-living phytoplankton may also form a
subsidiary food supply.
Carnivorous species are always prominent in deep-sea zooplankton
populations; they appear to be capable of feeding on a wide variety of
planktonic animals.
The precise nutritive requirements are known only for very few
species of zooplankton, mainly Culanus. In inshore waters phytoplankton production is more than sufficient for zooplankton growth and
reproduction over the spring and summer; during winter the total
quantity of particulate organic matter is probably also sufficient for
maintenance requirements, if it is assumed th,at all such organic matter
can be assimilated by the animals. The requirements of oceanic and
especially of deep-sea zooplankton species art? virtually unknown, and
the amount of particulate matter in the open oceans, especially at great
depths, appears to be very limited. Any clear ,assessment of the production of oceanic zooplankton must await metabolic studies on oceanic
species.
REFERENCES
Abbott, B. C. and Ballantine, D. (1957). J . Mar. 13iol. Ass. U . K . 36, 169-189.
Toxin from Gymrwdinium venqficum Ballantine
Allen, E. J. andNelson, E. W. (1910). J . Mar. Biol. .tiss. U.K. 8,421474. On the
artificial culture of marine plankton organism.
Anderson, G. C. (1964). fimnol. & Oceumgr. 9,284-302. The seasonal and geographic distribution of primary productivity 08 the Washington and Oregon
coasts.
191
the blooms of phytoplankton and the growth of zooplankton being
somewhat out of phase. Provided the blooming of the phytoplankton is
not too accelerated, however, the “wastefulness” is not excessive and in
any event the partly used phytoplankton crop serves as food for deeper
living zooplankton and for the benthos.
Oceanic depths have a much reduced zooplankton population. The
main limitation would appear to be the amount of particulate orgahic
matter available as food. While the vertical migrations of the zooplankton to different levels in the oceans carries organic particles such as
faecal pellets to greater depths where they can be used by the deeper
filter-feeding zooplankton, the nutritive vitlue of such particles is
probably not very high. Protozoa, especial1.y ciliates, feeding on the
relatively much greater quantities of dissolved organic matter in the
deep oceans, either directly or via bacteria, Sorm a second food source
for filter-feeders. Some bathypelagic planktonic species may feed
directly on bacteria but the density of micro-organisms in the open
oceans is probably never high. Organic aggregates can be formed from
dissolved organic matter in the oceans and this material may serve as
another source of food for the zooplankton. At moderate depths in
certain warmer seas the deeper-living phytoplankton may also form a
subsidiary food supply.
Carnivorous species are always prominent in deep-sea zooplankton
populations; they appear to be capable of feeding on a wide variety of
planktonic animals.
The precise nutritive requirements are known only for very few
species of zooplankton, mainly Culanus. In inshore waters phytoplankton production is more than sufficient for zooplankton growth and
reproduction over the spring and summer; during winter the total
quantity of particulate organic matter is probably also sufficient for
maintenance requirements, if it is assumed th,at all such organic matter
can be assimilated by the animals. The requirements of oceanic and
especially of deep-sea zooplankton species art? virtually unknown, and
the amount of particulate matter in the open oceans, especially at great
depths, appears to be very limited. Any clear ,assessment of the production of oceanic zooplankton must await metabolic studies on oceanic
species.
REFERENCES
Abbott, B. C. and Ballantine, D. (1957). J . Mar. 13iol. Ass. U . K . 36, 169-189.
Toxin from Gymrwdinium venqficum Ballantine
Allen, E. J. andNelson, E. W. (1910). J . Mar. Biol. .tiss. U.K. 8,421474. On the
artificial culture of marine plankton organism.
Anderson, G. C. (1964). fimnol. & Oceumgr. 9,284-302. The seasonal and geographic distribution of primary productivity 08 the Washington and Oregon
coasts.