Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Fatty acid data from infauna in sediment cores collected at the “Jetty” dive site, Hutt Point, McMurdo Station, Antarctica.  Seasonal sampling took place in September, November and February 2012-2013.

Methodology: 
Sample collection and field treatment: Sediment cores were collected at the “Jetty” dive site location in September, November and February 2012-2013.  These were sieved on a 300-micron sieve to collect macrofauna and members of the abundant species Spiophanes tcherniai (a spionid polychaete) and Edwarsia spp.  (a sand anemone) were picked under a dissecting microscope and placed in filtered seawater overnight to allow gut evacuation. At this point, individuals were frozen separately at -80 C prior to lipid extraction.

Sampling and analytical procedures:
Samples were freeze-dried and their lipids extracted using one-step extraction-transesterification procedure of Lewis et al. (2000) as used in Thurber (2014). In brief, individuals were placed in pre-cleaned and extracted sample vials, heated to 90 deg. C for one hour in a solution of methanol, chloroform, and hydrochloric acid (10:1:1 by volume) before cooling and water added to break the phase.  Fatty acid methyl esters (FAMEs) were extracted in sequential addition of hexane:chloroform (4:1) and water further removed through the addition of sodium sulfate.  The FAMEs were then ready for quantification on a GC-FID. 

Isotopic analysis was measured on a Thermo 1310 gas chromatograph with a Flame Ionization detector using a TR-WaxMS column (30mx 0.32mm x 0.25 um).  Peak identification was by comparison to known standards (for example the Supulco 32 FAME mixture).

Peak identity and area were manually checked and we report concentration as a percentage of total FAMEs for those that make up more than 1 percent of the total integrated area of the chromatogram.  We have been conservative in peak identification, with multiple unidentified FAs indicated, however, these are comparable across the samples (i.e. Unident. FA # 2 is the same in all individuals analyzed).

BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* parameter names modified for clarity: Fatty_Acid -> Fatty_Acid_ID ; Concentration -> Fatty_Acid_Concentration ;  Replicate -> Core_Replicate
* updated coordinates in data for hutt point sample site based on correspondence with data contributor.

The biota of the world's seafloor is fueled by bursts of seasonal primary production. For food-limited sediment communities to persist, a balance must exist between metazoan consumption of and competition with bacteria, a balance which likely changes through the seasons. Polar marine ecosystems are ideal places to study such complex interactions due to stark seasonal shifts between heterotrophic and autotrophic communities, and temperatures that may limit microbial processing of organic matter. The research will test the following hypotheses: 1) heterotrophic bacteria compete with macrofauna for food; 2) as phytoplankton populations decline macrofauna increasingly consume microbial biomass to sustain their populations; and 3) in the absence of seasonal photosynthetic inputs, macrofaunal biodiversity will decrease unless supplied with microbially derived nutrition. Observational and empirical studies will test these hypotheses at McMurdo Station, Antarctica, where a high-abundance macro-infaunal community is adapted to this boom-and-bust cycle of productivity. The investigator will mentor undergraduates from a predominantly minority-serving institution, in the fields of invertebrate taxonomy and biogeochemistry. The general public and young scientists will be engaged through lectures at local K-12 venues and launch of an interactive website. The results will better inform scientists and managers about the effects of climate change on polar ecosystems and the mechanisms of changing productivity patterns on global biodiversity.