scholarly journals Ice-algal carbon supports harp and ringed seal diets in the European Arctic: evidence from fatty acid and stable isotope markers

2021 ◽  
Vol 675 ◽  
pp. 181-197
Author(s):  
EH Kunisch ◽  
M Graeve ◽  
R Gradinger ◽  
T Haug ◽  
KM Kovacs ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Stable Isotope ◽  
Sea Ice ◽  
Carbon Sources ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
Carbon Supports ◽  
Ringed Seals ◽  
European Arctic

Sea-ice declines in the European Arctic have led to substantial changes in marine food webs. To better understand the biological implications of these changes, we quantified the contributions of ice-associated and pelagic carbon sources to the diets of Arctic harp and ringed seals using compound-specific stable isotope ratios of fatty acids in specific primary producer biomarkers derived from sea-ice algae and phytoplankton. Comparison of fatty acid patterns between these 2 seal species indicated clear dietary separation, while the compound-specific stable isotope ratios of the same fatty acids showed partial overlap. These findings suggest that harp and ringed seals target different prey sources, yet their prey rely on ice and pelagic primary production in similar ways. From Bayesian stable isotope mixing models, we estimated that relative contributions of sympagic and pelagic carbon in seal blubber was an average of 69% and 31% for harp seals, and 72% and 28% for ringed seals, respectively. The similarity in the Bayesian estimations also indicates overlapping carbon sourcing by these 2 species. Our findings demonstrate that the seasonal ice-associated carbon pathway contributes substantially to the diets of both harp and ringed seals.

Effects of oyster age on selective suspension-feeding and the chemical composition of biodeposits: insights from fatty acid analysis

2020 ◽  
Vol 644 ◽  
pp. 75-89
Author(s):  
T Sakamaki ◽  
K Hayashi ◽  
Y Zheng ◽  
M Fujibayashi ◽  
O Nishimura
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Stable Isotope ◽  
Organic Carbon ◽  
Isotope Ratios ◽  
The Body ◽  
Stable Isotope Ratios ◽  
Suspension Feeding ◽  
Carbon And Nitrogen ◽  
Body Tissues

The study objective was to clarify how the growth stages of the Pacific oyster Crassostrea gigas affect selective suspension-feeding of particulate organic matter (POM) and the composition of biodeposits. A day-long (22 h), continuous-flow mesocosm experiment was conducted with 3, 15, and 27 mo old oysters. The suspended particulate matter (PM), settled PM (mostly biodeposits in the oyster mesocosms), and oyster soft tissues were analysed to determine the content of fatty acids, organic carbon, and nitrogen, as well as the carbon and nitrogen stable isotope ratios to trace compositional changes in POM through oyster biodeposition. Regardless of oyster age, the stable isotope ratios of biodeposits were similar to those of the body tissues but not to those of the suspended PM, indicating that oysters selectively fed on assimilable fractions of POM. Compared with the suspended PM, a higher concentration of long-chain polyunsaturated fatty acids was found in the body tissues and, consequently, in the biodeposits; in contrast, the concentrations of shorter-chain fatty acids were generally lower in the biodeposits. Furthermore, the biodeposits produced by the older oysters had higher carbon, nitrogen, and fatty acid contents compared with the biodeposits produced by the 3 mo old oysters. The oxygen consumption rate of biodeposits was positively related to organic carbon content, but less so to fatty acid composition. Our findings demonstrate that older oysters not only produce larger amounts of biodeposits, but that these biodeposits have higher organic and fatty acid contents, potentially exhibiting greater effects on biogeochemical and ecological processes in nearby benthic habitats.

Comparisons of fatty acid and stable isotope ratios in symbiotic and non-symbiotic brittlestars from Oban Bay, Scotland

2000 ◽  
Vol 80 (2) ◽  
pp. 311-320 ◽  
Author(s):  
J. Douglas McKenzie ◽  
Kenneth D. Black ◽  
Maeve S. Kelly ◽  
Lyn C. Newton ◽  
Linda L. Handley ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Isotope Ratios ◽  
Symbiotic Bacteria ◽  
Stable Isotope Ratios ◽  
Fatty Acid Profiles ◽  
Carbon And Nitrogen ◽  
Order Of Magnitude ◽  
One Year ◽  
To Receive

The bed-forming brittlestars Ophiothrix fragilis, Ophiocomina nigra and Amphiura chiajei from Oban Bay, Scotland were studied using methods previously employed to study chemoautotrophic symbioses. Ophiothrix fragilis and A. chiajei both contain symbiotic bacteria (SCB) while Ophiocomina nigra is non-symbiotic. Samples were taken of Ophiothrix fragilis at approximately two-week intervals for one year. Symbiotic bacteria numbers were determined by direct counting of homogenates of the arms of 50 individual brittlestars. Water samples were analysed for chlorophyll content. Stable isotope ratios for carbon and nitrogen were determined for each homogenate sample. Regular SCB counts were made on the infaunal brittlestar A. chiajei. Homogenate samples of Ophiothrix fragilis, A. chiajei and the non-symbiotic Ophiocomina nigra were analysed to produce fatty acid profiles for each species. Symbiotic bacteria count varied by up to one order of magnitude in both Ophiothrix fragilis and A. chiajei with no evidence of seasonality in this variation. Symbiotic bacteria number was inversely correlated with δ15N but no relationship was established with δ13C. 16:1ω7 and 18:1.ω7 fatty acids were used as putative bacterial markers. Both symbiotic species had higher percentages of 16:1ω7 than the non-symbiotic Ophiocomina nigra. However, only Ophiothrix fragilis appeared to receive appreciable quantities of 18:1ω7 from its SCB. The SCB are heterotrophic and may contribute to the nitrogen budget of the host. The two symbiotic species studied here derive the bulk of their nutrition from conventional feeding but SCB make significant, additional contributions.

Exploring yellow perch diets in Lake Michigan through stomach content, fatty acids, and stable isotope ratios

2015 ◽  
Vol 41 ◽  
pp. 172-178 ◽  
Author(s):  
Austin Happel ◽  
Sara Creque ◽  
Jacques Rinchard ◽  
Tomas Höök ◽  
Harvey Bootsma ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stable Isotope ◽  
Stomach Content ◽  
Yellow Perch ◽  
Lake Michigan ◽  
Isotope Ratios ◽  
Stable Isotope Ratios

scholarly journals Fatty Acids and Stable Isotope Ratios in Shiitake Mushrooms (Lentinula edodes) Indicate the Origin of the Cultivation Substrate Used: A Preliminary Case Study in Korea

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1210
Author(s):  
Ill-Min Chung ◽  
So-Yeon Kim ◽  
Jae-Gu Han ◽  
Won-Sik Kong ◽  
Mun Yhung Jung ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stable Isotope ◽  
Lentinula Edodes ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
Shiitake Mushroom ◽  
Shiitake Mushrooms ◽  
Potential Applications ◽  
Cultivation Substrate

Shiitake mushroom (Lentinula edodes) is commonly consumed worldwide and is cultivated in many farms in Korea using Chinese substrates owing to a lack of knowledge on how to prepare sawdust-based substrate blocks (bag cultivation). Consequently, issues related to the origin of the Korean or Chinese substrate used in shiitake mushrooms produced using bag cultivation have been reported. Here, we investigated differences in fatty acids (FAs) and stable isotope ratios (SIRs) in shiitake mushrooms cultivated using Korean and Chinese substrates under similar conditions (strain, temperature, humidity, etc.) and depending on the harvesting cycle. The total FA level decreased significantly by 5.49 mg∙g−1 as the harvesting cycle increased (p < 0.0001); however, no differences were found in FAs between shiitake mushrooms cultivated using Korean and Chinese substrates. Linoleic acid was the most abundant FA, accounting for 77–81% of the total FAs during four harvesting cycles. Moreover, the SIRs differed significantly between the Korean and Chinese substrates, and the harvesting cycles resulted in smaller maximum differences in SIR values compared to those of the cultivation substrate origins. Our findings contribute to the identification of the geographical origin of shiitake mushrooms and may have potential applications in international shiitake-mushroom markets.

scholarly journals Spatial and Temporal Variability of Ice Algal Trophic Markers—With Recommendations about Their Application

2020 ◽  
Vol 8 (9) ◽  
pp. 676
Author(s):  
Eva Leu ◽  
Thomas A. Brown ◽  
Martin Graeve ◽  
Jozef Wiktor ◽  
Clara J. M. Hoppe ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Sea Ice ◽  
Temporal Variability ◽  
Climate Change Impacts ◽  
Isotope Ratios ◽  
Arctic Sea Ice ◽  
Stable Isotope Ratios ◽  
Spatial And Temporal Variability ◽  
Web Studies ◽  
The Impact

Assessing the relative importance of sea ice algal-based production is often vital for studies about climate change impacts on Arctic marine ecosystems. Several types of lipid biomarkers and stable isotope ratios are widely used for tracing sea ic-associated (sympagic) vs. pelagic particulate organic matter (POM) in marine food webs. However, there has been limited understanding about the plasticity of these compounds in space and time, which constrains the robustness of some of those approaches. Furthermore, some of the markers are compromised by not being unambiguously specific for sea ice algae, whereas others might only be produced by a small sub-group of species. We analyzed fatty acids, highly branched isoprenoids (HBIs), stable isotope ratios of particulate organic carbon (POC) (δ13C), as well as δ13C of selected fatty acid markers during an Arctic sea ice algal bloom, focusing on spatial and temporal variability. We found remarkable differences between these approaches and show that inferences about bloom characteristics might even be contradictory between markers. The impact of environmental factors as causes of this considerable variability is highlighted and explained. We emphasize that awareness and, in some cases, caution is required when using lipid and stable isotope markers as tracers in food web studies and offer recommendations for the proper application of these valuable approaches.

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