Os ácidos gordos usados como bio marcadores para desvendar os segredos da fase oceânica da lampreia-marinha (Petromyzon marinus, L.): uma espécie ancestral adaptada aos nossos dias

Abstract

The agnathans probably arose as the first vertebrates about 530 million years ago, in Cambrian period and after the evolutionary “boom” of multicellular organisms. The genus Petromyzon comprises only one anadromous and parasitic species, Petromyzon marinus L., known as sea lamprey which is widely distributed on both sides of the North Atlantic. Sea lamprey migrates twice during its life cycle between freshwater and seawater. Although the freshwater phase of the life cycle of this species is well studied, the oceanic trophic phase is still poorly understood because few specimens have been captured in this environment. To overcome this lack of knowledge, various studies using fatty acids as biomarkers have been developed by our research group in the last ten years. Recently, we studied the population structure of sea lamprey sampled in the main Portuguese river basins using both morphological characters and heart tissue fatty acid signature. Our results suggest the existence of three sea lamprey stocks entering Portuguese river basins. Due to the paucity of information regarding the feeding ecology of sea lampreys in the marine environment, we used the fatty acids as biomarkers to the extent that fatty acids can be used as general diet indicators and bio markers for identification of food web relationships. With our data we manage to distinguish two feeding strategies in sea lampreys from the west coast of Portugal, one typical of a top predator of a marine food web with a planktonic base, and the other much more diverse. The gathered information has implications in terms of management and conservation of sea lamprey in the Iberia Peninsula. These studies demonstrate the potential for fatty acid profile as a biomarker to discriminate stocks and to distinguish feeding strategies.