Clearance rates of the great scallop (Pecten maximus) and blue mussel (Mytilus edulis) at low natural seston concentrations

Abstract

my supervisors; Øivind Stand, Peter Cranford and Svein Rune Erga that have spent much time in directing and improving the thesis. Øivind led the project and his advices, clear mind, overview and always positive attitude made the fulfillment of this PhD not only possible but to an enjoyable task. Peter has guided me through the bivalve eco-physiology and the experimental methodology, providing vital advices and comments. Svein Rune has supported me from day one in this task. Thanks! I would like to thank my co-authors for their contribution in the papers; Øivind Strand, Jan Aure, Peter Cranford, Arne Duinker, Tonje Castberg, Asbjørn Svardal and Cathinka Krogness. The extent of the eco-physiological measurements would not have been possible without the commitment of Cathinka Krogness. This thesis was improved as a result of suggestions, comments and discussion with Jan Aure, Jon Grant, Aad Smaal, Cedric Bacher, Marianne Alunno-Bruscia, Stein Mortensen, Raymond Bannister and Rune Rosland. The CANO project in general and specifically the CANO bivalve team provided a dynamic environment in which small and larger challenges have been addressed. Thanks to all the 5

Potential methodological influences on the determination of particle retention efficiency by suspension feeders: Mytilus edulis and Ciona intestinalis

“…The feeding chambers employed were the same as described by Strohmeier et al (2009Strohmeier et al ( , 2012. In brief, the internal dimensions of the chambers were 3.8 cm wide, 19.5 cm long and 8.1 cm high, with an internal design that constrains recirculation of water past the suspension feeders when an acceptable flow speed is provided.…”

“…CRs were calculated as the product of the flow rate to the chamber and the RE of particles averaged over the 3.75 to 7.75 μm size range. Suitable flow rates for the chambers were previously identified by Strohmeier et al (2009;1114 l h −1 for mussels of similar size as used in the present study) to ensure that measured CRs are flow independent. However, additional tests were conducted to further investigate the possibility of flow effects on RE.…”

Clearance rate of the mussel Mytilus galloprovincialis. II. Response to uncorrelated seston variables (quantity, quality, and chlorophyll content)

“…Hawkins et al (1999) and James et al (2001), using Perna canaliculus, and Hawkins et al (2001), using Chlamys farreri, observed a reduction in filtration activity, although without total cessation. Pascoe et al (2009) observed a reduction in both CR and the number of feeding animals for M. edulis, a reduction that was also observed recently by Strohmeier et al (2009) for M. edulis and Pecten maximus. Filgueira et al (2009) performed a 9-h experiment and observed a constant and high CR in M. galloprovincialis during the first 3 h. These results differ from the present study in which mussels that were fed diets containing high organic content responded with a significant reduction in CR (eq.…”

“…Hawkins et al (1999) y James et al (2001, trabajando con Perna canaliculus, y Hawkins et al (2001), con Chlamys farreri, observaron una reducción en la actividad de filtración, pero sin cesarla. Pascoe et al (2009) observaron en M. edulis una reducción tanto en TA como en el número de animales alimentándose, reducción que también fue observada recientemente por Strohmeier et al (2009) en M. edulis y Pecten maximus. Filgueira et al (2009), en un experimento de 9 h, observaron una TA constante y alta en M. galloprovincialis durante las primeras 3 h. Estos resultados difieren del presente trabajo en que aquí los mejillones que fueron alimentados con dietas con alto contenido orgánico presentaron una reducción significativa de TA (ec.…”

Field clearance of an intertidal bivalve bed: relative significance of the co-occurring blue mussel Mytilus edulis and Pacific oyster Crassostrea gigas

“…To what degree the boundary layer develops depends on current speed and turbulent mixing of the water column , van Duren et al 2006. When the boundary layer is established, bivalve clearance decreases the phytoplankton concentration in the boundary layer, and when phytoplankton is depleted, the bivalves will close the valves and stop clearing the water (Dolmer 2000b, Newell et al 2001, Strohmeier et al 2009). At Agger Tange, both very low water depth and very low velocities prevail, and near-bed algal depletion is expected to be a common phenomenon and very likely to contribute to the observed low clearance activity of the bivalve bed.…”