ENERGY I N ANIMAL ECOLOGY
87
60:
5040 -
30 -
20 -
tiAdult removal
'\
1 0
[ , , , , , , , 'a----L , \ '
0
1 0 20 30 40 50 60 70 80 90
L
100
F
FIG. 4. The relation between P , and P when adult Dapknia are preferentially removed.
The numerals 1, 3 and 5 refer to food levels. There is deviation from Eq. (11) which is
more marked at high food levels and high values of F.
free g). Ketchum and Redfield (1949) analysed six species of Chloraphycae and found a total calorific range of 5.1-5.5 kcal/g (5.9-6.4
kcal/ash-free g), indicating that neither the Chlamydomonas nor the
Daphnia are unusual in this respect.
Richman then demonstrated that filtering rate in Daphnia is independent of algal concentration over a fourfold concentration range
and evaluated the filtration rate of different size Daphnia. The filtration
rate per animal increases with age but algae acquired per mg of tissue
falls off. A young animal is in this sense better nourished than an old
one, which may explain to some degree the higher growth rate in small
animals. From the above data, Richman could compute the growth
curve and energy consumption of Daphnia.
He then determined oxygen consumption (6.5 + 0.7 pl/mg/h dryweight) for various sizes and conditions of Daphnia. These values agreed
in general with other values in the literature for planktonic Crustacea
(7.2 + 4.3 pl/mg dry-weight/li 0, for seventeen species of planktonic
Crustacea). R.Q. for Daphnia was also measured and found to vary from
c. 0.75 for starved animals to c. 1.00 for fed animals. Energy expenditure
could be computed by taking the consumption of 1 ml oxygen as
equivalent to 0.005 cal heat produced (the calorific equivalent of oxygen
consumption varies only 5% over the R.Q. range 0.71-1.00).
Richman defined the energy of growth as the calorific equivalent
of the protoplasm added t o the animal and defined the energy of reproduction as the calorific value of the young animals produced. These
plus the energy equivalent of respiration were assumed equal t o the
total assimilated energy during the time interval of measurement. The
87
60:
5040 -
30 -
20 -
tiAdult removal
'\
1 0
[ , , , , , , , 'a----L , \ '
0
1 0 20 30 40 50 60 70 80 90
L
100
F
FIG. 4. The relation between P , and P when adult Dapknia are preferentially removed.
The numerals 1, 3 and 5 refer to food levels. There is deviation from Eq. (11) which is
more marked at high food levels and high values of F.
free g). Ketchum and Redfield (1949) analysed six species of Chloraphycae and found a total calorific range of 5.1-5.5 kcal/g (5.9-6.4
kcal/ash-free g), indicating that neither the Chlamydomonas nor the
Daphnia are unusual in this respect.
Richman then demonstrated that filtering rate in Daphnia is independent of algal concentration over a fourfold concentration range
and evaluated the filtration rate of different size Daphnia. The filtration
rate per animal increases with age but algae acquired per mg of tissue
falls off. A young animal is in this sense better nourished than an old
one, which may explain to some degree the higher growth rate in small
animals. From the above data, Richman could compute the growth
curve and energy consumption of Daphnia.
He then determined oxygen consumption (6.5 + 0.7 pl/mg/h dryweight) for various sizes and conditions of Daphnia. These values agreed
in general with other values in the literature for planktonic Crustacea
(7.2 + 4.3 pl/mg dry-weight/li 0, for seventeen species of planktonic
Crustacea). R.Q. for Daphnia was also measured and found to vary from
c. 0.75 for starved animals to c. 1.00 for fed animals. Energy expenditure
could be computed by taking the consumption of 1 ml oxygen as
equivalent to 0.005 cal heat produced (the calorific equivalent of oxygen
consumption varies only 5% over the R.Q. range 0.71-1.00).
Richman defined the energy of growth as the calorific equivalent
of the protoplasm added t o the animal and defined the energy of reproduction as the calorific value of the young animals produced. These
plus the energy equivalent of respiration were assumed equal t o the
total assimilated energy during the time interval of measurement. The