Fig. 2

Clearance rate on nanophytoplankton cells, measured for three consecutive seasons for mussels varying in mean size from 1.5 to 25 mm. The clearance rate is expressed as the litres of water cleared of cells per hour per individual mussel. There were no significant differences in either the slope or the intercept between the 3 years (models 1–3). The data from the 3 years were combined, and it was further tested whether the regression coefficient different significantly from the expected value of 2 (model 4). The regression coefficient did not differ significantly from the expected value, and one regression line was fitted using a slope of two (black line) (log R _C  = log (−3.41 ± 0.04) + 2 log Length). The small insert at the left shows the clearance rates of the smallest mussels only (<10 mm). Both axes are on log scale