144
E. D. 9. CORNER AND ANTHONY Q. DAVIES
TABLE VII. SEASONAL CHANQES IN NITROQEN CONTENT OF c. jinmarchicus
FROM THE CLYDE SEA-AREA. (Calculated from the data of om, 1934.)
N BS yo body \vt 5.91 6.40 6.95 7.11 7.41 9.80 9.80 8.00 8.00 7.65 6.95 6.80
Month
Nov. Dec. Jan. Feb. Afar. Apr. May June July Aug. Sept. Oct.
Orr (1934), who also determined protein as body N x 6-25, found
a reciprocal relationship between the levels of protein and lipid in
Calanusfinmurchicus. The level of protein was maximal, 55%, in May
when lipid was minimal, 22% : the protein level was minimal, 35%, in
March when lipid was maximal, 45%. This inverse relationship has
also beeen observed by Raymont et al. (1969) for Illeganyctiphanas
norvegica; and for many other species by Nakai (1955), whose data
show that although the levels of lipid and protein in the animals can
vary greatly, the sum of both fractions remains markedly constant
(82.0-89.5% dry body weight).
Included in Table VI are various values for the ratio by weight of
nitrogen to phosphorus. The ratio varies widely with different groups.
For example, Beers (1966) found values of 6.23-6-74 for euphausiidsmysids; 12.2-12.4 for copepods and chaetognaths; and 21.2 for siphonophores. Thus, the N : P ratio increases with the " wateriness '' of
the animal.
Redfield et al. (1963) proposed that the average ratio by atoms of
N : P in zooplankton is 16.0 :1, fairly close to the value of 15.5 :1 for
phytoplankton (see Section 111). However, Beers's data, when similarly
expressed, show large departures from this value. Thus, his ratio for
mixed copepods was 27.7:1, similar to an earlier high value of 24:l
found by Harris and Riley (1956) but higher than that of 21.2:l
calculated from the data of Butler et al. (1969). Beers also obtained a
high value, 27.1 :1, for cliaetognaths: in fact, only his values for
euphausiids-mysids and '' other crustacea " are near to that of 16.5 :1
proposed by Redfield et al. (1963).
Recently, Beers and Herman (1969) have determined the nitrogen
and phosphorus contents of total, mixed zooplankton collccted from
two hydrographic stations near Bermuda. Considerable variation was
found during the two-year period of the survey. Thus, at one station,
nitrogen varied from 0.77 to 14.5% dry weight (average 6.7%) ; and
phosphorus from 0.06-1-1 % (average 0.74%). At the other station,
the range for nitrogen was 2.4-11% dry weight (average 7.5%); and
the phosphorus range 0.25-1-2% (average 0434%). It is interesting to
note that the average ratio of nitrogen to phosphorus by atoms waa
E. D. 9. CORNER AND ANTHONY Q. DAVIES
TABLE VII. SEASONAL CHANQES IN NITROQEN CONTENT OF c. jinmarchicus
FROM THE CLYDE SEA-AREA. (Calculated from the data of om, 1934.)
N BS yo body \vt 5.91 6.40 6.95 7.11 7.41 9.80 9.80 8.00 8.00 7.65 6.95 6.80
Month
Nov. Dec. Jan. Feb. Afar. Apr. May June July Aug. Sept. Oct.
Orr (1934), who also determined protein as body N x 6-25, found
a reciprocal relationship between the levels of protein and lipid in
Calanusfinmurchicus. The level of protein was maximal, 55%, in May
when lipid was minimal, 22% : the protein level was minimal, 35%, in
March when lipid was maximal, 45%. This inverse relationship has
also beeen observed by Raymont et al. (1969) for Illeganyctiphanas
norvegica; and for many other species by Nakai (1955), whose data
show that although the levels of lipid and protein in the animals can
vary greatly, the sum of both fractions remains markedly constant
(82.0-89.5% dry body weight).
Included in Table VI are various values for the ratio by weight of
nitrogen to phosphorus. The ratio varies widely with different groups.
For example, Beers (1966) found values of 6.23-6-74 for euphausiidsmysids; 12.2-12.4 for copepods and chaetognaths; and 21.2 for siphonophores. Thus, the N : P ratio increases with the " wateriness '' of
the animal.
Redfield et al. (1963) proposed that the average ratio by atoms of
N : P in zooplankton is 16.0 :1, fairly close to the value of 15.5 :1 for
phytoplankton (see Section 111). However, Beers's data, when similarly
expressed, show large departures from this value. Thus, his ratio for
mixed copepods was 27.7:1, similar to an earlier high value of 24:l
found by Harris and Riley (1956) but higher than that of 21.2:l
calculated from the data of Butler et al. (1969). Beers also obtained a
high value, 27.1 :1, for cliaetognaths: in fact, only his values for
euphausiids-mysids and '' other crustacea " are near to that of 16.5 :1
proposed by Redfield et al. (1963).
Recently, Beers and Herman (1969) have determined the nitrogen
and phosphorus contents of total, mixed zooplankton collccted from
two hydrographic stations near Bermuda. Considerable variation was
found during the two-year period of the survey. Thus, at one station,
nitrogen varied from 0.77 to 14.5% dry weight (average 6.7%) ; and
phosphorus from 0.06-1-1 % (average 0.74%). At the other station,
the range for nitrogen was 2.4-11% dry weight (average 7.5%); and
the phosphorus range 0.25-1-2% (average 0434%). It is interesting to
note that the average ratio of nitrogen to phosphorus by atoms waa