Accumulation of metals by marine picoplankton

Pumping rates in undisturbed suspension-feeding bivalves were measured with a thermistor microflowmeter. Pumping rates are related to the dry weight of Clinocardium nuttallii, Macoma nasuta, Mytilus californianus and Chlamys hastata as the following equations: P=0.85 W^0.84, P=0.23 W^0.855, P=2.216 W^0.715, and P=2.419 W^0.943 respectively. Pumping rate and gill area increase at the same rate in C. nuttallii, M. californianus and C. hastata. The pumping rate per unit gill area is highest for C. nuttallii (approximately 0.14 cm³/s/cm²), with intermediate values for M. californianus (0.08 cm³/s/cm²) and C. hastata (0.11 cm³/s/cm²); the lowest rate was found in the deposit-feeder M. nasuta (0.0057 to 0.0089 cm³/s/cm²), which also has the smallest gill to body weight. C. nuttallii has the relatively smallest gill of the suspension feeders and the highest pumping rate per unit gill area. The absolute pumping rates, however, were highest for the filibranchs M. californianus and C. hastata. Indications are given that these differences are the results of different fluid-mechanical/ecological strategies to minimize the cost-benefit ratio.Contribution No. 132 of the Marine Science and Maritime Studies Center, Northeastern University