Benthic diatoms from Potter Cove, 25 de Mayo (King George) Island, Antarctica: mucilage and glucan storage as a C-source for limpets

HERNAN SACRISTÁN; RODRIGUEZ MARÍA CECILIA; YASMIN DAGLIO; MARTIN ANSALDO

Polar Science

Elsevier

Lugar: Oxford; Año: 2018

1873-9652

Biofilms were allowed to develop on ceramic tiles placed in closed containers26 on the shore of Potter Cove, 25 de Mayo (King George) Island. Water pumping27 from the cove inside the containers extended for 25 days. Diatoms were the28 dominant microalgae in these biofilms, which were removed from a set of tiles to29 a) characterize the extracellular mucilage, b) carry out floristic determination and30 c) perform grazing experiments with the limpet Nacella concinna. Biofilms31 mucilaginous matrix consisted of proteins and carbohydrates. Room temperature32 aqueous extraction of the freeze-dried material rendered a fraction enriched in the33 storage glucano chrysolaminarin, its identity confirmed by methylation structural34 analyses. Hot water extracted products showed greater heterogeneity in35 monosaccharide composition, including glucose, mannose, galactose, fucose,36 xylose and rhamnose. Diatom identification revealed that Pseudogomphonema37 kamtschaticum was the dominant species followed by several Navicula species,38 Nitzschia pellucida and Synedra kerguelensis. Photographical survey of colonized39 tiles placed in glass flasks together with a specimen of Nacella concinna exhibited40 between 5-30% removal of the biofilms coverage after 24 h of exposure to the41 limpet, suggesting that EPS and chrysolaminarin constitute a C-source for the42 gastropod.