Table of Contents

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

Raw sediment C isotope values.

Methodology from Spivak, AC and J Ossolinski. 2016. Limited effects of nutrient enrichment on bacterial carbon sources in salt marsh tidal creek sediments. Marine Ecology Progress Series. 544:107-130. 10.3354/meps11587

Sediment samples for organic matter composition were collected by placing a hard plastic sleeve around a polyvinyl chloride (PVC) corer (5 cm diameter x 15 cm deep) and then removing the corer. The plastic sleeve remained in place to maintain the integrity of the sediment column and mark the core location. The top 0.5 cm of each core was collected into pre-combusted vials and frozen (-80 deg C) until analysis for total organic carbon content and stable isotopes (d13C). Samples were dried to constant mass (60 deg C), homogenized with a Retsch Mixer Mill 200, and acidified to remove carbonates prior to analysis by the WHOI Organic Mass Spectrometry Facility with a Carlo Erba 1108 elemental analyzer interfaced to Finnigan-MAT DeltaPlus isotope ratio mass spectrometer (IRMS). Isotopic data are reported as d-values in units of per mil (0/00). For sediments from the isotope labeling experiments, resulting d-values were converted to atom % to calculate excess 13C (absolute amount 13C incorporated), using the equations:

where VPDB is the Vienna Pee Dee Belemnite standard (0.011237) and concentrations are expressed in moles carbon per m2, by accounting for sediment bulk density (0.52 g cm-3) and core depth (0.5 cm). Sediment samples collected just prior to application of 13C-labeled NaHCO3 or S. alterniflora detritus served as controls.

BCO-DMO Data Processing Notes:

-reformatted column names to comply with BCO-DMO standards.

Extracted from the NSF award abstract:
This project will address how rates of benthic microalgal production respond to eutrophication and geomorphological changes in human-impacted tidal creeks. Excess nutrient loading increases benthic algal biomass and likely stimulates production rates but the magnitude of nutrient and geomorphological effects on rates of production is unknown. Will changes in benthic algal productivity affect algal-bacterial coupling? Furthermore, how is algal-bacterial coupling affected by geomorphological changes, which may be exacerbated by excess nutrient loading but can also occur in pristine marshes?

This project will take advantage of the infrastructure of the TIDE project, a long-term saltmarsh eutrophication experiment at the Plum Island Ecosystem - Long Term Ecological Research site in Northeastern Massachusetts. Specifically, the PIs will measure benthic metabolism and examine algal- bacterial coupling in fertilized and ambient nutrient tidal creeks in the first field season. The following field season, they will compare sediment metabolism and carbon dynamics on slumped tidal creek walls (i.e. areas where low marsh has collapsed into the tidal creek) to that on the bottom of tidal creeks. In both years, gross and net production will be determined using an innovative triple oxygen isotope technique and traditional dissolved oxygen and inorganic carbon flux measurements. Comparisons between these methods will be useful in informing studies of sediment metabolism. Lipid biomarkers will be used to characterize the sources of organic matter to creek sediments, and stable isotope analysis of bacterial specific biomarkers to identify the sources of organic carbon utilized by sediment bacteria. The biomarkers will reveal whether sediment bacteria use organic matter substrates, such as benthic microalgal carbon, selectively or in proportion to availability. Overall, results from the proposed study will provide important information about how sediment carbon dynamics in shallow tidal creeks respond to long term eutrophication. Furthermore, findings will enhance understanding of the role of tidal creeks in coastal biogeochemistry.