Fatty acids differentiate consumers despite variation within prey fatty acid profiles

Abstract

Techniques that biochemically trace foraging habits of predators rely on the assumption that intra‐specific variation in prey species is smaller than variation among them. At the same time, these techniques often show that diets can induce drastic changes in the biochemical profiles of prey species, especially across different ecosystems. We tested if intra‐specific variation in fatty acid profiles of prey species added enough noise to confound quantitative fatty acid signature analysis (QFASA) using a controlled feeding experiment. Steelhead trout (Oncorhynchus mykiss) were fed either alewife (Alosa pseudoharengus) or round goby (Neogobius melanostomus) from either Lake Ontario or Cayuga Lake for a period of 8 weeks. Fatty acid profiles were significantly different between prey species and between lake of origin within each species. Differences in fatty acid profiles of steelhead trout strongly reflected prey species differences, whereas differences related to prey origin (lakes) were noted at a much lesser extent. QFASA performed remarkably well given the differences observed between the lakes prey originated from. Our results indicate that QFASA models for steelhead trout are probably not specific to one lake, and could provide estimates for other freshwater systems where alewife and round goby serve as the primary forage.

Model for estimating thiamine deficiency-related mortality of Atlantic salmon (Salmo salar) offspring and variation in the Baltic salmon M74 syndrome

“…In addition, one fatty acid change in the north-south direction of the Baltic Sea prevails, regardless of species (Keinänen et al 2017;Lind et al 2018). These enabled the estimation of feeding history regarding dietary species, and the feeding area of feeding and spawning salmon using fatty acid signature analysis (Keinänen et al 2018) similarly to other salmonines (Happel et al 2017(Happel et al , 2019.…”

Comparison of Bayesian and numerical optimization-based diet estimation on herbivorous zooplankton

“…Creating a well-working resource library is difficult, since large variance and multimodality can interfere with adequate differentiation between different resources. Large variance generally makes the estimates less accurate, but this should not be a problem for modern FA diet estimation methods [42]. While multimodality itself is not a problem, all current diet estimation methods assume unimodality, hence the removal of multimodality from our FA library.…”

Review of Estimating Trophic Relationships by Quantitative Fatty Acid Signature Analysis

“…It is obviously shown that the predator taxa of QFASA are dominated by marine species, mainly including marine mammals, seabirds, and fishes. In addition, as shown in Figure 3, there have been several studies focused on the diet of freshwater fishes in recent years [22,23,25,26], such as Salvelinus namaycush by Happel et al [22].…”

“…QFASA has become a promising approach in dietary estimation since it was proposed and its applications are shown in Table 2. In recent years, Wang et al [11] estimated the diets of threatened S. fischeri, and concluded that infertile eggs yolks can be used to evaluate the diet of breeding female S. fischeri for better understanding the source and timing of nutrients during reproduction; Magnone et al [15] estimated the diet of P. orbignyanus by QFASA, determined CC and validated the model with a controlled experiment, which quantified the diet of lower vertebrates (P. orbignyanus) for the first time; Magnone et al [14] used QFASA to generate a food web model in the aquatic environment to find out the trophic relationships among the species; Conners et al [20] estimated two albatross species by QFASA, and adapted the QFASA model, which introduced a combination of FAs and fatty alcohols; Goetsch et al [19] estimated the diet composition of M. angustirostris, and suggested that the seals mainly fed on mesopelagic fishes; Knox et al [24] estimated the diet of A. pusillus doriferus, finding that elasmobranchs accounted for more in the diet of males than previous reports, and showed that prey composition varied among males; Happel et al [25] used a controlled trial to test the influence of intraspecific difference in FA signatures of prey on the QFASA model, indicating that QFASA used for steelhead trout may not only be used for a specific lake, but also for other freshwater systems with alewife and round goby as the main food; Tao [26] estimated the diet composition of Channa. argus using the QFASA model, and then calculated the biomagnifcation factors (BMFs) of the alternative halogenated flame retardants (AHFRs) based upon the results.…”