Working on a baseline for the Kongsfjorden food web: production and properties of macroalgal particulate organic matter (POM)

• Published in: Polar biology Vol. 39; no. 11; pp. 2053 - 2064
• Main Authors: Buchholz, Cornelia Maria, Wiencke, Christian
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2016; Springer; Springer Nature B.V
• Subjects: Alaria esculenta; Algae; Biomass; Biomedical and Life Sciences; Ecology; Food; Food chains; Food chains (Ecology); Hiatella arctica; Laminaria digitata; Leaching; Life Sciences; Microbiology; Microorganisms; Mollusks; Mysis oculata; Oceanography; Original Paper; Particulate organic matter; Photosynthesis; Plant Sciences; Saccharina latissima; Stable isotopes; Thallus; Zoology; Arctic region; PNE, Norway, Svalbard, Spitsbergen, Ny-Aalesund, Kongsfjorden; Phlorotannin; Spitsbergen; Kongsfjorden; Macroalgal detritus; C/N ratio; Particulate organic matter; Arctic; Stable isotope baseline
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-015-1828-3

Macroalgae, in particular kelps, produce a large amount of biomass in Kongsfjorden, which is to a great extent released into the water in an annual cycle. As an example, the brown alga Alaria esculenta loses its blade gradually, 3 ± 0.8 % of the blade area per day (August 2012), thereby adding to the pool of particulate organic matter (POM) in the fjord. Upon release small thallus pieces are “aging” in that they are prone to leaching and serving as substrate for microorganisms, thus turning into palatable food for suspension and bottom feeders. In order to define a macroalgal baseline for the Kongsfjorden food web, stable isotopes δ 14 C and δ 15 N were measured in individuals of A. esculenta , Saccharina latissima and Laminaria digitata directly sampled after collection and in artificially produced POM (aPOM) of A. esculenta that was allowed to age under experimental conditions. In aPOM from this species sampled in August 2012 the C/N ratios decreased between d1 and d8 of a 14-day culture period in parallel to the fading photosynthetic activity of the algal fragments as demonstrated by use of an Imaging-PAM. Microscopic observations of the aPOM in August 2012 and 2013 revealed the frequent occurrence of small brown algal endo- and epiphytes. First feeding experiments with Mysis oculata (Mysids) and Hiatella arctica (Bivalves) showed that these species can ingest macroalgal POM. The importance of kelp-derived POM for the food web is subject of the current research.