Petersen, J. E. University of Maryland, Horn Point Lab, petersen@hpl.umces.edu
Kemp, M. University of Maryland, Horn Point Lab, kemp@hpl.umces.edu

 
EFFECTS OF PHYSICAL SCALE ON MEAN PROPERTIES AND ON VARIANCE IN EXPERIMENTAL PLANKTONIC ECOSYSTEMS
 
Distortions in the temporal and spatial scales of enclosed experimental ecosystems (mesocosms) are often cited as potential sources of unrealistic behavior. As part of University of Maryland's Multiscale Experimental Ecosystem Research Center, we investigated effects of variations in the depth, radius, and water residence time in planktonic-benthic mesocosms ranging in volume from 0.1 to 10 m3. We found that these scaling attributes affected both the mean and variance of ecological properties. For instance, mean primary productivity expressed per unit area was independent of depth under light-limited conditions, but was directly proportional to depth under nutrient-limited conditions. Although the relative contribution of wall periphyton to total volumetric productivity decreased with increasing radius, productivity per unit wall area actually increased with increasing radius. Variance in ecological properties among replicates tended to decrease with increasing mesocosm size, but was maximal at intermediate water residence times. We conclude that multi-scale experiments (i.e. those that explicitly examine effects of scale) can serve two complementary purposes. First, they increase our understanding of scale effects in nature. Second, they allow design of scale-sensitive experiments, the results of which can be systematically compared among experiments and extrapolated to nature.
 
Day: Thursday, Feb. 4
Time: 02:45 - 03:00pm
Location: Hilton of Santa Fe
 
Code: SS51TH0245E