Full-text - Norsk entomologisk forening

Contribution from the No, rnczian IBP~PT- UM sections
Oxygen consumption, caloric values, water and ash content of
some dominant terrestrial arthropods from alpine
habitats at Finse, south Norway
SIGMUND HAGVAR & EIVIND OSTBYE
Higvar, S. & Ostbye, E. 1974. Oxygen consumption, caloric values, water and ash
content of some dominant terrestrial arthropods from alpine habitats at Finse,
south Norway. Norsk ent. Tidsskr. 21, 117-126.
Caloric values, water and ash content, and oxygen consumption are given for
some dominant invertebrate species (mostly Coleoptera) from alpine habitats at
Finse, south Norway, about 1200-1400 m a.s.1. Mean caloric values ranged from
5228 to 6365 callg dry weight, and the ash content varied from 2.9 to 6.3 Olo of the
dry weight. In severa1 Coleoptera species, the water percentage decreased markedly
with increasing dry weight. The water weight in mg per animal first increased,
then decreased, with increasing dry weight. It is anticipated that these changes are
caused by a higher percentage of fat being accumulated with increase in dry weight.
Oxygen consumption was measured at 5O, lo0, 15O, and 20' C. Active specimens
in some cases showed an oxygen consumption severa1 times higher than resting
specimens. Different stages in the development (eggs - larval stages - pupae -
imagines) can show very different levels of oxygen consumption. Therefore, temperature
variations in the natural habitat, the length of each developmental stage,
and the activity pattern must be taken into consideration when calculating the
respiration of a specimen of a given species under natural conditions.
S. HSgvur & E. Dstbye, Zoological Institute, University of Oslo, Blindern, Oslo 3,
Norwuy.
To get a picture of the energy flow through
alpine communities, the main factors in the
energy budget of the dominant species must
be studied. This work presents data on oxygen
consumption, caloric values, and water and
ash content of some dominant alpine invertebrate
species in south Norway. The animals
were collected in different alpine habitats
between 1200 and 1400 m a.s.1. at Finse,
situated in the north-western part of the
Hardangervidda mountain plateau (60°36'N
- 7'3O'E).
This paper is part of an analysis of a high
mountain ecosystem. The authors shared the
planning of this study and the sampling of
the material. The treatment of the data and
the main task of writing was the responsibility
of the first author.
MATERIAL AND METHODS
Animals used for measuring oxygen consumption
were either collected immediately before
the experiment or stored at outdoor tempera-
tures for one or a few days. Measurements
were made at 5O, 10°, 15' and 20°C, the
temperature being kept within + O.l°C by
submerging the respirometers into a 50 1
waterlglycerol bath containing a cooler and
a thermomixer. In most of the experiments,
a modified type of volumetric respirometers
was used (Scholander & Iversen 1958). A
constant pressure respirometer (Engelmann
1963) was used for some measurements of
respiration at different developmental stages
of Zygaena exulans Hochw. at 20°C. When
using this type, a control respirometer without
animals was run at the same time to
record effects due to changes in the atmospheric
pressure during the experimental
time.
During the experiments, the activity of the
animals was noted. The data presented in
the following figures and tables refer to animals
which showed very little or no movement
at al1 during the experiments. Animals
which were clearly active often showed a
much higher respiration, and these are treated
separately in this presentation.
8 - hórsk eni. Tidsskr.