eLearning

David W. Schindler

ABSTRACT
The results of bottle and mesocosm experiments
were compared with those obtained in whole-
ecosystem experiments at the Experimental Lakes
Area. Unless they can be cleverly designed to mimic
major ecosystem processes and community compo-
sitions, smaller-scale experiments often give highly
replicable, but spurious, answers. Problems with
appropriate scaling are difficult to deduce without
direct comparisons with whole-ecosystem experi-
ments. Reasons aremany, but include inappropriate
spatial scales to include whole communities, in
particular predators and nocturnally active animals;
temporal scales that are too short to assess accu-
rately the response of slow-responding organisms
and biogeochemical processes; and elimination of
key littoral–pelagic and catchment–lake interac-
tions. Identical studies of limnological processes in
lakes of a large range of sizes reveals that scaling
correction is also necessary when extrapolating
from small lakes to large ones. Accurate manage-
ment decisions cannot be made with confidence
unless ecosystem scales are studied.
Key words: mesocosms; ecosystem experiments;
Experimental Lakes Area; spatial and temporal
scales.