LAUSR

Abstract Carbon and nitrogen stable isotope ratios of sub-fossil invertebrate remains are potentially powerful indicators of nutrient flux, habitat-specific resource utilization, and trophic interactions in lentic food webs, but are rarely estimated for multiple species within lakes. Here we examined historical time series of δ13C and δ15N in remains of individual invertebrate taxa representing pelagic, littoral and benthic habitats during the 20th century in five boreal lakes of central Canada. We applied a novel statistical approach based on Generalized Additive Models (GAMs) to quantify the differences in centennial means and trends (i) between invertebrate remains and sedimentary organic matter (SOM), and (ii) among different taxa within each lake to evaluate the coherence of isotope signals during the 20th century. Differences in mean δ13C and δ15N were usually significant (p