Blue mussel ( Mytilus edulis) quality of preferred prey improves digestion in a molluscivore bird (Common Eider, Somateria mollissima)

• Published in: Canadian Journal of Zoology
• Main Authors: Varennes, Elisabeth, Hanssen, Sveinn A., Bonardelli, John C., Guillemette, Magella
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2015
• Subjects: Common Eider; Somateria mollissima
• Online Access: http://dx.doi.org/10.1139/cjz-2015-0066; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjz-2015-0066; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjz-2015-0066

Benthivorous predators like sea ducks rely on abundant but low-quality food. Because they ingest whole blue mussels (Mytilus edulis L., 1758), including shells, they have to consume large quantities of food to maintain energy balance. Digestive processes may therefore limit energy assimilation in these predators, although selecting mussel types that minimize shell ingestion may improve foraging profitability. To test this prediction, we first quantified mussel quality from different sizes and habitats by measuring energy content and various features of mussel morphology. Then, we conducted digestive experiments on captive Common Eiders (Somateria mollissima (L., 1758)) fed with various mussel types to determine their impact on Eiders’ digestion. Aquacultured and small mussels were of better quality, because of higher energy content and less resistant shells. These mussel characteristics allowed faster digestive processes for an equal digestibility compared with large intertidal mussels. Previous studies showed that aquacultured and small mussels were generally preferred by sea ducks. Hence, prey-selection behaviours and digestive processes seem closely connected in these highly digestive-constrained predators.