The experiments described in the present paper were undertaken so that an assessment
could be made of the importance of these larvae in the oxygen balance of
polluted streams (Phelps, 1944), where under certain conditions they are very
abundant (Edwards, 1957). The effect of the oxygen concentration of the water
upon the oxygen consumption of fully grown Chironomus larvae has been studied
by Ewer (1942) and Walshe-Maetz (1953). The influence of two other factors of
primary importance in determining the rate of oxygen consumption, namely, body
size and environmental temperature, have been investigated in the present study;
work has been confined to 3rd- and 4th-instar larvae and to only two environmental
temperatures.
The investigation may be of interest, however, from a more general viewpoint for
it is possible with this species, as it is to some extent with the majority of the aquatic
arthropods, to distinguish experimentally between an increase in size, indicated by
total weight, volume and surface area measurements, and growth expressed in terms
of the weight of body constituents other than water (dry weight). The former
expression of growth is generally discontinuous whilst the latter is continuous
(Teissier, 1931). In consequence of this type of growth pattern, the relationship of
oxygen consumption to surface area can be separated from the relationship of
oxygen consumption to an exponential function of dry weight. Generally such
a separation may be made, by a statistical treatment of the data, only when the
exponential function relating oxygen consumption to weight is sufficiently different
from that relating surface area to weight. The variability of biological material and
the limited size range of most experimental animals are such that a satisfactorily
conclusive separation is rarely possible (see Kleiber, 1947).
The experiments described in the present paper were undertaken so that an assessment
could be made of the importance of these larvae in the oxygen balance of
polluted streams (Phelps, 1944), where under certain conditions they are very
abundant (Edwards, 1957). The effect of the oxygen concentration of the water
upon the oxygen consumption of fully grown Chironomus larvae has been studied
by Ewer (1942) and Walshe-Maetz (1953). The influence of two other factors of
primary importance in determining the rate of oxygen consumption, namely, body
size and environmental temperature, have been investigated in the present study;
work has been confined to 3rd- and 4th-instar larvae and to only two environmental
temperatures.
The investigation may be of interest, however, from a more general viewpoint for
it is possible with this species, as it is to some extent with the majority of the aquatic
arthropods, to distinguish experimentally between an increase in size, indicated by
total weight, volume and surface area measurements, and growth expressed in terms
of the weight of body constituents other than water (dry weight). The former
expression of growth is generally discontinuous whilst the latter is continuous
(Teissier, 1931). In consequence of this type of growth pattern, the relationship of
oxygen consumption to surface area can be separated from the relationship of
oxygen consumption to an exponential function of dry weight. Generally such
a separation may be made, by a statistical treatment of the data, only when the
exponential function relating oxygen consumption to weight is sufficiently different
from that relating surface area to weight. The variability of biological material and
the limited size range of most experimental animals are such that a satisfactorily
conclusive separation is rarely possible (see Kleiber, 1947).
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