FLOC POPULATION CHARACTERISTICS MEASURED WITH INSSEV DURING THE ELBE ESTUARY INTERCALIBRATION EXPERIMENT

Individual flee data obtained with the in situ video camera settling v elocity instrument (INSSEV) during the Elbe estuary Intercalibration E xercise, June 1993, are presented in a variety of scattergraph formats and processed to determine individual flee dry mass. The dry mass dat a are displayed in spectral formats with respect to size, and settling velocity. Similar flee population characteristics to those found in U K estuaries are shown; in particular there is a wide range of effectiv e densities in the smaller flee sizes whereas all the largest flocs ha ve a low effective density. The data are specifically assembled for co mparison with results from a settling tube, deployed at similar time a nd depth. The data indicate that the INSSEV system is able to measure a higher proportion of larger flocs than the settling tube, supporting claims that bottom withdrawal settling tube systems are destructive o f the larger, lower density flocs.