Lipid classes of mussel seeds Mytilus galloprovincialis of subtidal and rocky shore origin

The lipid class composition in juveniles of the mussel Mytilus galloprovincialis of rocky shore and subtidal origin were compared after transfer to a subtidal environment in the Ria de Arousa (northwest Spain). The experiment was conducted between November 27, 1995 and July 3, 1996. In addition to mussel origin, the influence of the different environmental parameters on the changes in lipid classes was studied. At the start of the experimental period, only the relative percentage of the triacylglycerols (energetic function) was significantly higher in the subtidal specimens. However, when the initial absolute contents were examined, the phospholipids and sterols were also significantly higher in this mussel group. Differences in the relative percentages of phospholipids and sterols were maintained until day 22 of the experiment. Our results show that during the first 36 days of the experimental period the mussel origin participated significantly in the model explaining the variance of triacylglycerols, phospholipids and sterols. These results suggest the initial differences in content and relative percentages of the lipid classes studied are possibly linked to the contrasting environmental conditions in which the two mussel groups had previously developed (subtidal and rocky shore habitats). In contrast, 50 days into the experiment the origin term did not participate in the model of variance of these lipid classes. These results in turn suggest that during the course of the investigation the mussel seeds of rocky shore origin were able to exploit the available food resources in the subtidal habitat. Based on these results, the influence of mussel origin and environmental parameters on the changes in lipid classes of both mussel groups is discussed.