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Title: C-14 as a Tracer of Labile Organic Matter in Antarctic Benthic Food Webs
Authors: Purinton, Brett Leon
Advisors: Carrie Thomas, Committee Co-Chair
Dave DeMaster, Committee Co-Chair
Keywords: Antarctic
organic carbon
Issue Date: 21-Jul-2005
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences
Abstract: 14C measurements were made on surface plankton, surface sediment, benthic invertebrate gut contents and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula shelf between November, 1999 and April, 2001 as part of the FOODBANCS Project (Food for Benthos on the Antarctic Continental Shelf). The 14C contents of the deposit feeder body tissues (-127 +/-13 per mil) were substantially enriched relative to the surface sediment (-234 +/-13 per mil) (Tukeys HSD, p=0.05) and statistically similar to the organic matter collected in plankton tows (-135 +/-10 per mil). Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e., Peniagone sp.) for incorporating labile organic carbon into their tissues as demonstrated by the large difference between surface sediment and gut contents 14C activities (105 +/- 13 per mil). Digestive and/or assimilatory selection was the primary feeding strategy used by irregular urchins and several other holothurians (Protelpidia sp., Bathyplotes sp., and the head-down conveyor belt feeder, Molpadia sp.) for incorporating labile organic carbon into their tissues as demonstrated by large differences (41.9 +/- 6.9 per mil) between their fore gut contents and body tissue 14C activities. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained constant over the 15-month sampling period. Selective assimilatory processes also were evident in 13C and 15N data, but the 14C measurements were a better tool for tracking labile organic carbon during ingestive and assimilatory processes.
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