MEPS 252:159-172 (2003)  -  doi:10.3354/meps252159

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

Robert A. Stead1,2,*, Raymond J. Thompson1, J. Roberto Jaramillo1,3

1Ocean Sciences Centre, Memorial University of Newfoundland, St. John¹s, Newfoundland A1C 5S7, Canada
2I-MAR & Departamento de Recursos Naturales y Medio Ambiente, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
3Instituto de Embriología, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

ABSTRACT: 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 68Ge/14C 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 (<0.01 to 5.77 µgPM h-1) when compared with deposit feeding (2067.4 to 6872.3 µgPM h-1), although in one case suspension-feeding individuals ingested 93.7 µgPM h-1. Scope for growth was always positive in deposit feeders (113.8 to 372.4 J d-1), whereas under suspension-feeding conditions it was mostly negative and could not meet metabolic requirements. In addition, mortality of Y. hyperborea increased at suspended particle concentrations above 0.085 mg ml-1. Although deposit feeding is the principal feeding strategy followed by Yoldia hyperborea, suspension feeding is invoked at low suspended particle loads and may serve as a strategy for capturing highly nutritional particles suspended at the sediment-water interface.

KEY WORDS: Yoldia · Protobranchia · Deposit-feeding · Suspension-feeding · Absorption efficiency · Ingestion rate · Gut passage time · Scope for growth

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