Data pre‐treatment and choice of resemblance metric affect how fatty acid profiles depict known dietary origins

Happel, Austin; Czesny, Sergiusz J.; Rinchard, Jacques; Hanson, S. Dale

doi:10.1007/s11284-017-1485-9

Cited by 25 publications

(15 citation statements)

References 62 publications

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“…To detect differences in FA and AA composition between taxa, lakes and trophic states, we used permutational multivariate ANOVA (PERMANOVA) with permutation of residuals under restricted model and Type III sums of squares. We operated the multivariate statistical methods on Euclidean distances without transforming the data (Happel et al 2017). We conducted PERMANOVA with lake and taxon as fixed factors.…”

Section: Statistical Analysesmentioning

confidence: 99%

Nutritional quality of littoral macroinvertebrates and pelagic zooplankton in subarctic lakes

Vesterinen

Keva

Kahilainen

et al. 2020

Limnology & Oceanography

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Littoral benthic primary production is considered the most important energy source of consumers in subarctic lakes. We analyzed essential fatty acid (EFA) and amino acid (EAA) content of 23 littoral benthic macroinvertebrate taxa as well as cladocerans and copepods from pelagic and littoral habitats of 8–9 subarctic lakes to compare their nutritional quality. Pelagic crustacean zooplankton had significantly higher EFA and total FA content (on average 2.6‐fold and 1.6‐fold, respectively) than littoral macroinvertebrates in all our study lakes. Specifically, docosahexaenoic acid (DHA), one of the most important EFA for juvenile fish, was almost exclusively found in pelagic copepods. In littoral macroinvertebrates, only Lymnaea (Gastropoda), Eurycercus (Cladocera), and Gammarus (Amphipoda) contained a low amount of DHA, whereas most littoral invertebrate taxa contained moderate amounts of eicosapentaenoic acid (EPA). The difference in DHA content may explain why so many generalist fish shift their diet to pelagic zooplankton at their peak abundance in mid/late‐summer. Meanwhile, the differences in EAA content between pelagic zooplankton and littoral invertebrates were much lower than for EFA suggesting a wider availability of EAA in subarctic lakes, except for methionine. In the studied subarctic lakes, EFA and EAA variation in consumers was more related to taxon‐specific than lake‐specific characteristics. This indicates that climate‐induced changes in the abundance and community structure of zooplankton vs. littoral macroinvertebrates will be important parameters in determining the availability of EFA and EAA to juvenile fish, and potentially fish production.

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Section: Statistical Analysesmentioning

confidence: 99%

Nutritional quality of littoral macroinvertebrates and pelagic zooplankton in subarctic lakes

Vesterinen

Keva

Kahilainen

et al. 2020

Limnology & Oceanography

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“…Using calibration curves of standard solutions of known lipid mixtures (Nu-Chek Prep, Inc.), we calculated fatty acid content, and data were expressed as percentages relative to total fatty acid (fatty acid %) and as content related to insect DW (mg g/DW). Happel, Czesny, Rinchard, and Hanson (2017) compared several methods of data transformations for proportional data of fatty acids. They found no clear advantage of any transformation compared to no transformation.…”

Section: Fatty Acid Analysismentioning

confidence: 99%

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

et al. 2019

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1. Aquatic and terrestrial ecosystems differ fundamentally in the abundance of longchained polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA; 20:5n-3), which are produced by aquatic algae, but only in low quantities by terrestrial plants. Aquatic insects, such as Chironomidae (non-biting midges) feed on algae during their larval stage, making them rich in EPA and therefore high-quality prey for insectivores after emergence. However, the magnitude of EPA subsidies from aquatic insects may be different among water bodies in response to abiotic (e.g. nutrient load) as well as biotic factors (e.g. food web structure).2. To test the predation effects of crucian carp (Carassius carassius), nutrient concentrations, and Chironomidae community composition on the fatty acid export from aquatic ecosystems, we conducted a 25-day experiment across 20 1,500-L mesocosms covering a total phosphorus (TP) gradient of 20-1,000 µg/L.3. Twice a week, we collected adult emerging Chironomidae and found differences in fatty acid composition in the two most abundant chironomid species emerging from the mesocosms. Two PUFAs, α-linolenic acid and EPA, contributed to most of the variation in Chironomidae fatty acid content across the nutrient gradient.Whereas the proportions of α-linolenic acid were positively correlated to the mesocosm TP concentration, we found a negative correlation for the proportions of Chironomidae EPA and mesocosm TP concentration. However, despite lower biomass-specific EPA content at higher TP, higher biomass of emerging Chironomidae at intermediate TP concentrations resulted in higher total export of PUFAs from water to land. 4. Predation pressure from carp decreased the biomass of emerging Chironomidae on average 8-fold. Chironomidae biomass showed a hump-shaped relationship along the TP-gradient and was strongly influenced by periphyton biomass. 5. Export rates of EPA and fatty acids in general responded in a quadratic manner along the nutrient gradient, reaching a maximum value at a TP of 400 µg/L and decreasing thereafter.

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“…The literature includes studies that report fatty acids as either percent composition or as absolute concentrations. Rarely are both reporting systems used within the same paper, but for those few instances where both have been included, the results have highlighted the fact that these two reporting systems do not necessarily convey the same information or support the same conclusions (Happel, Czesny, Rinchard, & Hanson, ; Henriques, Dick, Tocher, & Bell, ; Sprague, Dick, & Tocher, ). Therefore, we believed it was important to consider and compare the resulting variance structures between these two reporting systems.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variance in fatty acid and stable isotope signatures across trophic levels in large river systems

Fritts

Knights

Lafrancois

et al. 2018

River Research & Apps

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Fatty acid and stable isotope signatures allow researchers, managers, and policy makers to better understand food webs, food sources, and trophic relationships.Research in marine and lentic systems has indicated that the variance of these biomarkers can exhibit substantial differences across spatial and temporal scales, but this type of analysis has not been completed for large river systems. Our objectives were (a) to evaluate variance structures for fatty acids and stable isotopes (i.e., δ 13 C and δ 15 N) of seston, threeridge mussels, hydropsychid caddisflies, gizzard shad, and bluegills across spatial scales (10s-100s of km) in large rivers of the Upper Mississippi River Basin, USA, that were sampled annually for 2 years and (b) to evaluate the implications of this variance on the design and interpretation of trophic studies. The greatest variance for both stable isotopes was present at the largest spatial scale for all taxa (except seston δ 15 N), indicating that these isotopic signatures are responding to factors at a larger geographic level rather than being influenced by local-scale alterations. Conversely, the greatest variance for fatty acids was present at the smallest spatial scale (i.e., among individuals) for all taxa except caddisflies, indicating that the physiological and metabolic processes that influence fatty acid profiles can differ substantially between individuals at a given site. Our results highlight the need to consider the spatial partitioning of variance during sample design and analysis, as some taxa may not be suitable for use in assessing ecological questions at larger spatial scales. KEYWORDS carbon stable isotope, fatty acid, food webs, lotic, multivariate variance, nitrogen stable isotope

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Data pre‐treatment and choice of resemblance metric affect how fatty acid profiles depict known dietary origins

Cited by 25 publications

References 62 publications

Nutritional quality of littoral macroinvertebrates and pelagic zooplankton in subarctic lakes

Nutritional quality of littoral macroinvertebrates and pelagic zooplankton in subarctic lakes

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

Spatial and temporal variance in fatty acid and stable isotope signatures across trophic levels in large river systems

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