MEPS 141:37-45 (1996)  -  doi:10.3354/meps141037

Growth, filtration and respiration in the mussel Mytilus edulis: no evidence for physiological regulation of the filter-pump to nutritional needs

Clausen I, Riisgård HU

The specific growth rate of blue mussels Mytilus edulis fed Rhodomonas sp. algal cells in laboratory experiments increased with increasing food concentration to obtain a maximum value of about 9.5% d-1, irrespective of a relatively high concentration of silt (5 mg l-1) added to the water. Likewise, the net growth efficiency increased with the specific growth rate to a maximum value of about 75%. Measurements of the relationship between respiration and growth showed that the energy cost of growth constituted 12% of the growth. The filtration rate of a 100 mg dry wt 'standard' mussel was high and constant (about 30 ml min-1) at algal concentrations below about 6000 cells ml-1 when measured in both short-time (5 h) and long-time (9 to 14 d) experiments. High algal concentrations of 1.3 to 2.4 x 104 cells ml-1 reduced the filtration rate by about 40%. The estimated growth, presuming maximum filtration rate, satisfactorily described the actual growth at algal concentrations <5000 cells ml-1, and the concentration necessary for maximum growth was estimated at 4500 cells ml-1 (corresponding to 5.6 µg chlorophyll a l-1). The mean specific growth rate in M. edulis transferred in net bags to a fjord system (Kertinge Nor/Kerteminde Fjord, Denmark) was about 6% d-1. The results show that there is no physiological regulation of the filtration rate to nutritional needs, and that food uptake in nature (median concentration in Danish waters = 5.1 µg chlorophyll a l-1) is characterized by the full exploitation of the capacity of the bivalve filter-pump.

Actual and estimated growth · Feeding and effects of silt · Costs of growth · Net growth efficiency · Regulation of filtration rate

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