The effect of diets of phytoplankton and suspended bottom material on feeding and absorption of raft mussels (Mytilus galloprovincialis Lmk)

Abstract

Measurements of feeding rate and absorption efficiency were performed to assess the nutritional value of sedimentary organics combined with phytoplankton for raft mussels (Mytilus galloprovincialis Lmk) in Ria de Arosa (Galicia, N.W. Spain). Both clearance rate and absorption efficiency reached a maximum on mixed diets in which the proportions of phytoplankton and sediment particles were similar. Consequently, maximum absorption rates were reached on laboratory suspensions that closely resembled features of natural seston from the Ria. Values of absorption efficiency recorded with suspended sediments (around 13%) do not apply to the detrital component of ingestion in mixed diets, leading to the conclusion that a positive effect of phytoplankton on absorption efficiency of sedimentary organics is taking place. On the other hand, comparison of results for mixed and monoalgal diets also suggests that the occurrence of silt in the ingesta enhances absorption of microalgae, possibly through improving mechanical treatment within the stomach. It was concluded that mixing of bottom material with phytoplankton in the water filtered by raft mussels greatly increases growth potential, provided that no reduction of phytoplankton concentration below 40% of particulate volume takes place. Mussels with different locations in the Ria exhibit variable degrees of infection by the parasitic protozoa Marteilia refringens. Concomitant differences in physiological behaviour could be attributed to digestive impairment caused by parasitization.

Seasonal changes in C, N and P budgets of green-lipped mussels Perna viridis and removal of nutrients from fish farming in Hong Kong

“…Owing to the down-regulation of AE with increasing TPM, absorption rate was not related to either TPM or ƒ, showing that in response to the fluctuation in food conditions, mussels might keep absorption relatively constant. Generally, absorption increases with increasing POM and achieves a maximum value at an intermediate value of POM, above which the absorption rate can be kept stable (Navarro et al 1996, Wong & Cheung 1999.…”

Open water integrated multi-trophic aquaculture: constraints on the effectiveness of mussels as an organic extractive component

“…(5) was derived to estimate average mussel AE values at different dietary OCs based on relationships reported by Bayne et al (1987), Navarro et al (1991Navarro et al ( , 1996, Figueiras et al (2002), and Reid et al (2010). This equation was also used to examine effects on BI 1 and BI 2 resulting from the presence of a wide range of seston OCs.…”

Feeding adaptations of the pearl oysters Pinctada margaritifera and P. maxima to variations in natural particulates

“…RiisgArd (1991) suggested that the comparatively low growth rates of Mytilus edulis in laboratory studies using pure algal diets may be due to the use of unnaturally high algal concentrations that lead to suboptimal conditions (valve closure, reduced metabolism and reduced growth). Navarro et al (1996) found that the occurrence of inorganic particles in the ingesta of mussels M. galloprovincialis enhanced absorption of microalgae in the field.…”