THE PRODUCTION O F MARINE PLANKTON
175
obtain approximate plankton volumes, the plankton during the summer
in the Bering Sea and Sea of Okhotsk exceeds 1.0 cc/mJ (Table V).
Similar values are found in summer in the sou:h-western Barents Sea.
By contrast the biomass in the Laptev and eastern Siberian Sea is low
(0.07 cc/m3) and is even more reduced in the central Arctic basin
(Table V).
Regional comparisons of biomass arc usual1.r. expressed in terms of
unit volume, and the density of zooplankton is of the utmost significance
for the nutrition of higher trophic levels. But with the great difference
in depth between coastal and oceanic regions, the biomass beneath a
unit area of sea surface is sometimes considered. Riley et al. (1949)
compared the production beneath a square metre of sea surface for
coastal areas south of New York, for the semitrcpical Sargasso Sea area,
and for the mixed continental slope water between. Riley found that the
inshore water showed its typical greater richness; the mean ratios for
the volumes of zooplankton of the three areas: coastal, “slope”, and
tropical waters, were approximately 10: 4: 1. Oceanic plankton also
appears to have a generally lower organic content. Despite the greater
depth of oceanic areas and the much greater crop fluctuations near
shore, especially in coastal boreal waters, Riley’s investigations generally
confirm the original view that tropical waters are usually poorer in
zooplankton biomass than temperate waters, especially inshore areas.
Grice and Hart (1962) provide a more recent comparison for approximately the same region. They investigated the zooplankton of the
upper two hundred metres of water between New York and Bermuda
and confirmed the richness of the coastal areas. In numerical abundance,
the ratio between coastal, “slope” and Sargasso Sea waters averaged
some 22 : 4: 1. By volume, the same comparison yielded ratios of approximately 50:3:1. Their results confirmed the very much greater seasonal fluctuations in neritic waters (approximately x 30) as compared
with the subtropical Sargasso waters (approximately x 4). Although
in coastal regions virtually the whole column of water from surface to
bottom was sampled, but only the upper 200 meixes in oceanic stations,
the greater richness of coastal waters is still evident. The volume in the
coastal area exceeds that of most boreal northern Atlantic regions. The
very low quantity found for the Sargasso Sea is similar to the values
suggested for subtropical Pacific and Australian oceanic regions
(Table V).
Despite the low biomass of zooplanktoil in trol ical waters, apart from
areas of upwelling or divergence, it has been suggested, notably by
Cushing (1959a and b), that in tropical oceans in view af the more rapid
utilization and regeneration of nutrients the system of plankton production may be more efficient even though gross production is much lower
175
obtain approximate plankton volumes, the plankton during the summer
in the Bering Sea and Sea of Okhotsk exceeds 1.0 cc/mJ (Table V).
Similar values are found in summer in the sou:h-western Barents Sea.
By contrast the biomass in the Laptev and eastern Siberian Sea is low
(0.07 cc/m3) and is even more reduced in the central Arctic basin
(Table V).
Regional comparisons of biomass arc usual1.r. expressed in terms of
unit volume, and the density of zooplankton is of the utmost significance
for the nutrition of higher trophic levels. But with the great difference
in depth between coastal and oceanic regions, the biomass beneath a
unit area of sea surface is sometimes considered. Riley et al. (1949)
compared the production beneath a square metre of sea surface for
coastal areas south of New York, for the semitrcpical Sargasso Sea area,
and for the mixed continental slope water between. Riley found that the
inshore water showed its typical greater richness; the mean ratios for
the volumes of zooplankton of the three areas: coastal, “slope”, and
tropical waters, were approximately 10: 4: 1. Oceanic plankton also
appears to have a generally lower organic content. Despite the greater
depth of oceanic areas and the much greater crop fluctuations near
shore, especially in coastal boreal waters, Riley’s investigations generally
confirm the original view that tropical waters are usually poorer in
zooplankton biomass than temperate waters, especially inshore areas.
Grice and Hart (1962) provide a more recent comparison for approximately the same region. They investigated the zooplankton of the
upper two hundred metres of water between New York and Bermuda
and confirmed the richness of the coastal areas. In numerical abundance,
the ratio between coastal, “slope” and Sargasso Sea waters averaged
some 22 : 4: 1. By volume, the same comparison yielded ratios of approximately 50:3:1. Their results confirmed the very much greater seasonal fluctuations in neritic waters (approximately x 30) as compared
with the subtropical Sargasso waters (approximately x 4). Although
in coastal regions virtually the whole column of water from surface to
bottom was sampled, but only the upper 200 meixes in oceanic stations,
the greater richness of coastal waters is still evident. The volume in the
coastal area exceeds that of most boreal northern Atlantic regions. The
very low quantity found for the Sargasso Sea is similar to the values
suggested for subtropical Pacific and Australian oceanic regions
(Table V).
Despite the low biomass of zooplanktoil in trol ical waters, apart from
areas of upwelling or divergence, it has been suggested, notably by
Cushing (1959a and b), that in tropical oceans in view af the more rapid
utilization and regeneration of nutrients the system of plankton production may be more efficient even though gross production is much lower