Particle removal by Northern bay scallops Argopecten irradians irradians in a semi-natural setting: Application of a flow-cytometric technique

Abstract

The feeding activities of bivalve mollusks have direct impacts on suspended particles in nature. Feeding is also related to the carrying capacity of a particular system for maximal aquaculture production. Particle removal is known to be dependent upon particle characteristics, including size and type, because particle retention efficiency is size dependent, and bivalves are able to select particles actively to improve the quality of food ingested. Our goal was to quantify particle clearance by northern bay scallops of natural seston under semi-natural conditions, i.e., in raceway tanks receiving a constant flow of untreated, estuarine water. Particle clearance rate (CR) was determined based upon particle counts in tank inflow and outflow streams. A flow-cytometric technique was developed allowing rapid quantification of particles with different sizes and characterization by presence or absence of chlorophyll fluorescence simultaneously. CR varied greatly (ranging from 0.06 to 3.02 L h − 1 gDW − 1 ) among sizes and types of particles. CR of large particles was generally higher than that of the smaller particles. Under the specific conditions of this experiment, particle selectivity appeared to be ineffective because scallops did not show a higher CR on phytoplankton than on detritus. This study demonstrated the feasibility of this flow-cytometric approach to measure differential clearance of different particles in natural seston by suspension-feeding organisms.