New ¹H NMR-Based Technique To Determine Epoxide Concentrations in Oxidized Oil

A new method to determine epoxide concentrations in oxidized oils was developed and validated using ¹H NMR. Epoxides derived from lipid oxidation gave signals between 2.90 and 3.24 ppm, well separated from the signals of other lipid oxidation products. To calibrate, soybean oils with a range of epoxide concentrations were synthesized and analyzed using ¹H NMR by taking the <i>sn</i>-1,3 glycerol protons (4.18, 4.33 ppm) as internal references. The ¹H NMR signals were compared to the epoxide content determined by titration with hydrogen bromide (HBr)–acetic acid solution. As expected, the signal response increased with concentration linearly (<i>R</i>² = 99.96%), and validation of the method gave results comparable to those of the HBr method. A study of the oxidative stability of soybean oil was performed by applying this method to monitor epoxides during thermal lipid oxidation. The epoxide content increased over time and showed a different trend compared to peroxide value (PV). A phenomenological model was suggested to model epoxides derived from lipid oxidation

Stable carbon and nitrogen isotope values for <i>C. centralis</i> (circles) and ice algae (triangles).

<p>Stable carbon and nitrogen isotope values for <i>C. centralis</i> (circles) and ice algae (triangles).</p

Large, Omega-3 Rich, Pelagic Diatoms under Arctic Sea Ice: Sources and Implications for Food Webs

<div><p>Pelagic primary production in Arctic seas has traditionally been viewed as biologically insignificant until after the ice breakup. There is growing evidence however, that under-ice blooms of pelagic phytoplankton may be a recurrent occurrence. During the springs of 2011 and 2012, we found substantial numbers (201–5713 cells m⁻³) of the large centric diatom (diameter >250 µm) <i>Coscinodiscus centralis</i> under the sea ice in the Canadian Arctic Archipelago near Resolute Bay, Nunavut. The highest numbers of these pelagic diatoms were observed in Barrow Strait. Spatial patterns of fatty acid profiles and stable isotopes indicated two source populations for <i>C. centralis</i>: a western origin with low light conditions and high nutrients, and a northern origin with lower nutrient levels and higher irradiances. Fatty acid analysis revealed that pelagic diatoms had significantly higher levels of polyunsaturated fatty acids (mean ± SD: 50.3±8.9%) compared to ice-associated producers (30.6±10.3%) in our study area. In particular, <i>C. centralis</i> had significantly greater proportions of the long chain omega-3 fatty acid, eicosapentaenoic acid (EPA), than ice algae (24.4±5.1% <i>versus</i> 13.7±5.1%, respectively). Thus, <i>C. centralis</i> represented a significantly higher quality food source for local herbivores than ice algae, although feeding experiments did not show clear evidence of copepod grazing on <i>C. centralis</i>. Our results suggest that <i>C. centralis</i> are able to initiate growth under pack ice in this area and provide further evidence that biological productivity in ice-covered seas may be substantially higher than previously recognized.</p></div

Hierarchical clusters of ice algae (triangles) and <i>C. centralis</i> (circles) fatty acid profiles overlaid on the first two principal component axes.

<p>Hierarchical clusters of ice algae (triangles) and <i>C. centralis</i> (circles) fatty acid profiles overlaid on the first two principal component axes.</p

Mean abundance (±SD) of selected fatty acids (expressed as mass % of total fatty acids) in ice algae and pelagic diatom <i>Coscinodiscus centralis</i> collected in spring 2012.

<p><i>*Thirteen fatty acids used for MANOVA, cluster and principal component analyses</i></p><p><i>EPA eicosapentaenoic acid, SFA saturated fatty acids, MUFA monounsaturated fatty acids, PUFA polyunsaturated fatty acids</i>.</p><p>Mean abundance (±SD) of selected fatty acids (expressed as mass % of total fatty acids) in ice algae and pelagic diatom <i>Coscinodiscus centralis</i> collected in spring 2012.</p

Distribution of <i>C. centralis</i> near Cornwallis Island, Nunavut, Canada.

<p><b>A</b>) Qualitative estimates of <i>C. centralis</i> abundances in spring, 2011. <b>B</b>) Densities (cells m⁻³) of <i>C. centralis</i> in the water column in spring 2012. Interpolation of cell densities was plotted using Ocean Data View v 4.6.1 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114070#pone.0114070-Schlitzer1" target="_blank">[23]</a>. Station colours correspond to the clusters identified in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114070#pone-0114070-g004" target="_blank">Fig. 4</a>; black indicates cluster 1, red is cluster 2 and green is cluster 3.</p

Relationship between δ¹⁵N and A) concentrations (mg m⁻³) of <i>C. centralis</i> fatty acids in the water column and B) PUFA (%) of <i>C. centralis.</i>

<p>Colours correspond to the clusters identified in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114070#pone-0114070-g004" target="_blank">Fig. 4</a>; black indicates cluster 1, red is cluster 2 and green is cluster 3.</p

Table1.docx

<p>Mortality from incidental bycatch in longline fishery operations is a global threat to seabird populations, and especially so for the albatross family (Diomedeidae) in which 15 out of 22 species are threatened with extinction. Despite the risks, fisheries remain attractive to many species of seabird by providing access to high-energy foods in the form of discarded fish and offal, target fish, and baited hooks. Current policy regarding fisheries management is increasingly aimed at discard reform, exemplified by a discard ban initiated in the European Union Common Fisheries Policy in 2014. While there is global agreement on the importance of minimizing the waste inherent in bycatch and discards, there is also growing concern that there is a need to understand the extent to which marine animals rely on fisheries-associated resources, especially at the colony and individual levels. We used a novel adaptation of quantitative fatty acid signature analysis (QFASA) to quantify fisheries-associated prey in the diet of two threatened North Pacific albatross species. Diet was estimated with QFASA using multiple lipid classes from stomach oil collected from incubating and chick-brooding Laysan and black-footed albatrosses across three breeding seasons. Prey-specific error was estimated by comparing QFASA estimated diets from known “simulated” diets, which informed the level of precaution appropriate when interpreting model results. Fisheries-associated diet occurred in both albatross species across both the incubation and chick-brood stages; however, neither species relied on fisheries food as the dominant food source (consisting of <10% of the total pooled proportional diet in each species). While total diet proportion was low, the incidence of fisheries-associated resources in albatross diets was highest in the 2009–2010 breeding season when there was a strong central Pacific El Niño. Additionally, the diets of a few individuals consisted almost entirely of fisheries-associated food, indicating that some birds might specialize on this foraging tactic. QFASA proved a tractable method for estimating the importance of fisheries-associated resources in albatross diet, and, as a tool, has the potential to enable long-term monitoring of diet and fisheries reliance of breeding colonies in the northwestern Hawaiian Islands.</p

Table2.XLSX

<p>Mortality from incidental bycatch in longline fishery operations is a global threat to seabird populations, and especially so for the albatross family (Diomedeidae) in which 15 out of 22 species are threatened with extinction. Despite the risks, fisheries remain attractive to many species of seabird by providing access to high-energy foods in the form of discarded fish and offal, target fish, and baited hooks. Current policy regarding fisheries management is increasingly aimed at discard reform, exemplified by a discard ban initiated in the European Union Common Fisheries Policy in 2014. While there is global agreement on the importance of minimizing the waste inherent in bycatch and discards, there is also growing concern that there is a need to understand the extent to which marine animals rely on fisheries-associated resources, especially at the colony and individual levels. We used a novel adaptation of quantitative fatty acid signature analysis (QFASA) to quantify fisheries-associated prey in the diet of two threatened North Pacific albatross species. Diet was estimated with QFASA using multiple lipid classes from stomach oil collected from incubating and chick-brooding Laysan and black-footed albatrosses across three breeding seasons. Prey-specific error was estimated by comparing QFASA estimated diets from known “simulated” diets, which informed the level of precaution appropriate when interpreting model results. Fisheries-associated diet occurred in both albatross species across both the incubation and chick-brood stages; however, neither species relied on fisheries food as the dominant food source (consisting of <10% of the total pooled proportional diet in each species). While total diet proportion was low, the incidence of fisheries-associated resources in albatross diets was highest in the 2009–2010 breeding season when there was a strong central Pacific El Niño. Additionally, the diets of a few individuals consisted almost entirely of fisheries-associated food, indicating that some birds might specialize on this foraging tactic. QFASA proved a tractable method for estimating the importance of fisheries-associated resources in albatross diet, and, as a tool, has the potential to enable long-term monitoring of diet and fisheries reliance of breeding colonies in the northwestern Hawaiian Islands.</p

Image1.pdf

<p>Mortality from incidental bycatch in longline fishery operations is a global threat to seabird populations, and especially so for the albatross family (Diomedeidae) in which 15 out of 22 species are threatened with extinction. Despite the risks, fisheries remain attractive to many species of seabird by providing access to high-energy foods in the form of discarded fish and offal, target fish, and baited hooks. Current policy regarding fisheries management is increasingly aimed at discard reform, exemplified by a discard ban initiated in the European Union Common Fisheries Policy in 2014. While there is global agreement on the importance of minimizing the waste inherent in bycatch and discards, there is also growing concern that there is a need to understand the extent to which marine animals rely on fisheries-associated resources, especially at the colony and individual levels. We used a novel adaptation of quantitative fatty acid signature analysis (QFASA) to quantify fisheries-associated prey in the diet of two threatened North Pacific albatross species. Diet was estimated with QFASA using multiple lipid classes from stomach oil collected from incubating and chick-brooding Laysan and black-footed albatrosses across three breeding seasons. Prey-specific error was estimated by comparing QFASA estimated diets from known “simulated” diets, which informed the level of precaution appropriate when interpreting model results. Fisheries-associated diet occurred in both albatross species across both the incubation and chick-brood stages; however, neither species relied on fisheries food as the dominant food source (consisting of <10% of the total pooled proportional diet in each species). While total diet proportion was low, the incidence of fisheries-associated resources in albatross diets was highest in the 2009–2010 breeding season when there was a strong central Pacific El Niño. Additionally, the diets of a few individuals consisted almost entirely of fisheries-associated food, indicating that some birds might specialize on this foraging tactic. QFASA proved a tractable method for estimating the importance of fisheries-associated resources in albatross diet, and, as a tool, has the potential to enable long-term monitoring of diet and fisheries reliance of breeding colonies in the northwestern Hawaiian Islands.</p