Free Amino Acid Pools of Five Species of Freshwater Oligochaetes

Abstract

The concentrations of free amino acids (FAA) were measured in five species of freshwater Oligochaeta (Limnodrilus hoffmeisteri, Tubifex tubifex, Potamothrix moldaviensis, Potamothrix vejdovskyi, and Stylodrilus heringianus) collected from southeastern Lake Michigan. Alanine represented between 23.1 and 41.8% of the total FAA pool and was the most abundant amino acid in all species. Leucine, valine, and glutamic acid were, respectively, the next most abundant and had similar relative concentrations in all species except T. tubifex. In T. tubifex, glutamic acid, asparagine, and aspartate were the second, third, and fourth most abundant FAA, respectively. Relative to other freshwater invertebrates, the total FAA pool of Lake Michigan oligochaetes was small. Differences in innate physiological and/or biochemical processes, dietary intake, and reproductive status may have contributed to the quantitative and qualitative differences observed among species. Identification of individual oligochaetes to species was accomplished by multivariate statistical analysis of the FAA profiles. A potential exists for the application of this technique for identifying immature oligochaetes.