Biomarker-based H-Print quantifies the composition of mixed sympagic and pelagic algae consumed by Artemia sp.

• Published in: Journal of Experimental Marine Biology and Ecology
• Main Authors: Brown, Thomas A., Belt, Simon T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Highly branched isoprenoid (HBI); H-Print; Sea ice algae; Sympagic carbon; Foodweb; Arctic; ice algae; Sea ice
• Online Access: https://pure.uhi.ac.uk/en/publications/377979cd-b5b4-4187-9abf-5362f09351e1; https://doi.org/10.1016/j.jembe.2016.12.007; https://pureadmin.uhi.ac.uk/ws/files/2045441/Brown_and_Belt_2017_PURE.pdf; http://linkinghub.elsevier.com/retrieve/pii/S0022098116303392

Quantifying the importance of sea ice microalgae as a food source in Arctic ecosystems is becoming an increasingly important research objective as sea ice extent and thickness continue to reduce. Recently, the analysis of certain diatom-derived highly branched isoprenoid (HBI) lipid biomarkers has provided a means of qualitatively distinguishing between sympagic (sea ice) and pelagic algae in Arctic animals. By combining the abundances of these lipids into an HBI-fingerprint, or “H-Print”, an estimate of the relative proportions of HBIs from each algal source can also be made. Although H-Print analysis of animal tissues in the Arctic is starting to provide such information, it has not yet been established to what extent H-Prints in animals provide a true reflection of the content of their algal food source. Here it is demonstrated that the H-Print determination can yield reliable estimates of mixed sympagic/pelagic algal content both within a food source of known composition, and in a primary consumer fed on it. In doing so, the utility of the H-Print is extended towards providing quantitative estimates of the relative importance of sympagic algae to animal diet. To achieve this, a series of 5 algal samples were prepared with known %sympagic algal content ranging from 0 to 100%. Analysis of these samples led to a comparison of different regression models based upon H-Prints using 4 different combinations of individual HBIs. A linear model comprising 3 HBIs (2 sympagic and 1 pelagic) provided the most accurate estimates of the sympagic content (− 1%, 50% and 101%) for samples containing 0%, 50% and 100% sympagic algae. This linear model was then used to estimate the proportion of sympagic algae in Artemia sp. (− 3%, 44% and 101%) fed on the same algal mixtures in the laboratory. The similarity between H-Prints in mixed algae and Artemia sp. suggested that H-Prints were not altered substantially by grazing, and this was also confirmed by analysis of the remaining water (containing ungrazed algae and faecal ...