Rheological properties of exopolymeric secretions in HABs may be functions of length scale

9 pages, 4 figures.-- The 12th International Conference on Harmful Algae (12th ICHA) took place at DGI-Byen in central, Copenhagen on 4-8 September 2006Measurements were made of the rheology of seawater, algal cultures and HABs by two methods. The first used concentric cylinders separated by a gap of 500 μm, while the second used fish-gills of pore size ~25-35 μm. More recently the yield stress of lumpy, organic floc suspension has been shown to depend strongly on the length scale of the measurements. Measuring the rheology of HABs and natural waters at different length scales now has the potential to elucidate the scales of polymer structures associated with bioengineering by plankton, particularly in HABsN