Aspects of feeding and lipid deposition and utilization in the lampreys, Lampetra fluviatilis L and Lampetra planeri Bloch
Moore, JW.; Potter, IC.
Journal Anim Ecol 453: 699-712
All species of non-filamentous algae found in the water and on the sediment of Highland Water (New Forest, England) contributed to the diet of larval lampreys (Lampetra planeri). The algae formed only 0.01 and 0.3% of the total volume of the gut contents in the winter and summer, respectively, although in a more productive stream their contribution was greater (1.5%). Between the onset of metamorphosis in August and the period just before spawning in April, the amount of lipid in L. planeri fell from 14.6 to 8.9% of the wet weight. During metamorphosis in L. fluviatilis the lipid content decreased from 14.1% in September to 7.9% in the following March. The progressive decrease in percentage of lipid in metamorphosing L. planeri and L. fluviatilis was accompanied by an increase in percentage of water. In L. fluviatilis the absolute lipid content declined throughout metamorphosis whereas the absolute water content rose initially and then fell during November. The combined loss of lipid and water at this time resulted in a decline in the animal's wet weight. Lipids in adult L. fluviatilis fell from about 18% in migrants caught in the estuary during October to 3% in spent animals taken from tributary rivers in late March. In the migratory period the amount of neutral lipid in the lipid fraction decreased from about 80 to 14-22%. The migrating males contained more lipid in the liver than females but less in the gonads.