Filtration of king scallops (Pecten maximus)

Filtration rates of hatchery-reared king scallop (Pecten maximus L.) juveniles, fed a single species alga diet (Pavlova lutheri (Droop) Green), were measured at a range of temperatures (6-21 degreesC). Weight specific filtration rate (ml min(-1) g(-1) (live weight)) of juveniles of a selected size range of 17-19 mm shell height (0.26-0.36 g live weight) increased with temperature above 16 degreesC and decreased below 11 degreesC, but was not significantly different between these two temperatures. Measurements at 16 degreesC using juveniles with a wider size range of 10-25 mm shell height (0.05-0.8 g live weight) gave the allometric equation: filtration rate (ml min(-1)) = 12.19 x weight (g)(0.887). Filtration rate decreased significantly when the cell concentration was greater than 200 cells mul(-1) (4.25 mg (organic weight) l(-1)). With six other algae food species, filtration rates similar to those with P lutheri were only achieved with Chaetoceros calcitrans (Paulsen) Takano. All other algae species tested were cleared from suspension at significantly lower rates. Experiments with diet mixtures of P lutheri and these other algae suggested that this was usually a reflection of lowered filtration activity, rather than pre-ingestive rejection of cells. In experimental outdoor nursery rearing systems, the filtration rate was inversely proportional to the concentration of cells in the inflow, in the range 5-210 cells mul(-1). It was not affected by flow rate (2-130 l h(-1) equivalent to 0.12-28.38 l h(-1) g(-1) (live weight)) with scallop juveniles stocked from 2 to 62 g l(-1) The results are discussed in relation to on-growing scallops at field sites. (C) 2004 Elsevier B.V. All rights reserved.