Absorption efficiency, ingestion rate, gut passage time and scope for growth in suspension- and deposit-feeding Yoldia hyperborea

Laboratory feeding experiments were conducted to study the importance of suspension-­feeding in the protobranch bivalve Yoldia hyperborea at different suspended particle concentrations in order to evaluate the importance of this feeding strategy when compared with its known strategy of deposit feeding. Standard feeding variables (absorption efficiency, AE; gut passage time, GPT; ingestion rate, IR) were estimated by quantifying super(68)Ge/ super(14)C in dual-labelled Thalassiosira nordenskioldii fed to Y. hyperborea. For the first time, results were also used to estimate scope for growth (SFG) in a protobranch bivalve. Absorption efficiency was higher when Y. hyperborea was deposit feeding (87.7 to 94.8%) than it was during suspension feeding (50.1 to 71.7%), whereas GPT was similar in most cases and ranged between 8.15 and 20.11 h. However, IRs for suspended particulate matter (SPM, dry weight) were mostly negligible (