Role of small-plankton communities in the diet oftwo Antarctic octocorals (Primnoisis antarcticaandPrimnoella sp.)

• Published in: Marine Ecology Progress Series
• Main Authors: Orejas, Covadonga, Gili, Josep Maria, Arntz, Wolf E.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Inter Research 2003
• Subjects: Antarctic gorgonians; Small plankton communities; Suspension feeders; Feeding ecology; Antarctic; Weddell; Weddell Sea; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10261/184218; https://doi.org/10.3354/meps250105

12 pages, 7 figures, 4 tables The diet composition of 2 Antarctic octocorals, Primnoisis antarctica and Primnoella sp., from the shelf of the eastern Weddell Sea (Antarctica) is studied here for the first time. Although mesozooplankton is very scarce in the diet of these organisms, it seems to be important because of its high carbon content. Feeding experiments showed that components of the seston, including the finer fraction of suspended organic matter (ciliates, dinoflagellates and phytoplankton), are also an important part of the octocoral diet. In P. antarctica, the diatom Pragillariopsis spp. accounted for 77% of the total number of cells captured, followed by dinoflagellates (20%), Nitzschia spp. (2%) and ciliates (1%). In Primnoella sp., dinoflagellates were consumed preferentially (92%), followed by ciliates (6%) and centric diatoms (2%). Biomass consumed, however, was low (1.11 × 10-5 mg C polyp-1 d-1 for P. antarctica and 1.34 × 10-4 mg C polyp-1 d-1 for Primnoella sp.). In P. antarctica, small plankton food covers approximately 49% of the daily energy demand. The ability of these suspension feeders to capture small cells at lower concentrations may allow them to remain seasonally active for considerably longer periods than previously thought Peer Reviewed