Using stable isotope analysis to study skin mucus exudation and renewal in fish

Abstract

Fish skin mucus is proposed as a novel target for the study of physiological condition and to conduct minimally invasive monitoring of fish. Whereas mucus composition has been a major interest of recent studies, no practical techniques have been proposed to gain understanding of the capacity and rhythm of production and exudation. Here, we use stable isotope analysis (SIA) with a labelled meal, packaged in gelatin capsules, to evaluate mucus production and renewal in a fish model, the gilthead sea bream (Sparus aurata). Mucus 13C- and 15N-enrichment reached the higher levels at 12h post-ingesta without significant differences at 24h When the formation of new mucus was induced, 13C-enrichment in the new mucus doubled whereas the 15N-enrichment only increased by 10%. All these results indicated the feasibility of adopting SIA in mucus studies and allow us to propose this methodology to improve knowledge of mucus turnover in fish and other animals.