Table of Contents

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

High-resolution sampling via Dataflow was performed along the lower York River estuary during a Margalefidinium polykrikoides bloom in early August, an Alexandrium monilatum bloom in early September, and following disappearance of the bloom in mid-September for determinations of pCO2, salinity, temperature, pH, Chla, CDOM, turbidity, DO, and location (lat/long). Cruises were on 24ft Carolina skiffs. Concurrent with the DataFlow sampling, grab sampling was performed at 5 stations within bloom patches (as determined by levels of chlorophyll a), and at 5 stations outside of bloom patches for determinations of DIC, DOC, active Chla (extractable), nutrients (DIN, DON, DIP, DOC), TSS, and CDOM. Locations listed in the dataset were those recorded when grab samples were taken. Data shown are averages and standard errors per station.

High-resolution sampling was performed with a Dataflow system modified from Madden and Day (1992) and as described in Crosswell et al, (2017). The pCO2-DataFlow system is instrumented with a pCO2 analyzer, a multi-parameter datasonde (YSI 6600V2), Wet Labs CDOM sensor, Garmin global positioning system (GPS MAP 546S), and data acquisition system. The system continuously samples surface water (approximately every 30 m at an average speed of 20 knots) from a stern-mounted water intake located 0.5 m below the water surface with a pump, which delivers water in parallel to (1) a showerhead equilibrator and (2) a flow-through cell attached to the YSI which is configured to measure water temperature, salinity, chl-a fluorescence, DO, pH, and turbidity. pCO2 in the equilibration chamber is determined by recirculating a carrier gas at a flow of approximately 1.5 L min-1 through the equilibrator chamber and a nondispersive infrared absorbance detection analyzer (LI-COR, LI-840).

Instruments:
Laboratory analyzed CDOM and chl-a were used to calibrate in situ CDOM and chl-a measurements made during the DataFlow surveys, as described by Anderson et al. (2013). Water column analyses (NO3, NO2, NH4, PO4) were performed with a Lachat QuikChem 8000 automated ion analyzer (Lachat Instruments,Milwaukee, WI, USA); detection limits for NO3−,NH4+, and PO43− are 0.20, 0.36, and 0.16 μM, respectively. DIC was analyzed on an Apollo, model AS-C3 (Apollo SciTech, Newark DE); DOC on a Shimadzu TOC-VCSN combustion analyzer, and extracted chla on a Beckman Coulter DU800 Spectrophotometer.

Known problems/issues:
Missing pCO2 data for August 11 cruise because of instrument failure.

BCO-DMO Processing:
- changed date format to YYYY-MM-DD;
- renamed fields.

NSF Award Abstract:
Estuaries, coastal water bodies where rivers mix with ocean water, are hotspots for the processing of carbon and nutrients moving from land to the coastal ocean. Within estuaries land-based nutrient inputs can cause intense blooms of single-celled algae called phytoplankton, which can have significant impacts on the ecosystem. As blooms move down-estuary some of the phytoplankton material is buried on the bottom, and some is decomposed, resulting in low oxygen conditions (hypoxia), harmful to marine life, and production of carbon dioxide (CO2), the major greenhouse gas, which can exchange with the atmosphere. The remaining phytoplankton material can be exported to the ocean. The type and amount of carbon exported from the estuary depend both on its biological activity and physical factors such as fresh water discharge, temperature, and light availability. If phytoplankton production is greater than decomposition, the estuary will take up atmospheric CO2 and export phytoplankton carbon to the coastal ocean. On the other hand, if decomposition is greater than production the estuary will be a source of CO2 to the atmosphere and dissolved CO2 to the coastal ocean. The investigators expect that intense phytoplankton blooms will greatly amplify carbon exchanges with the atmosphere, coastal ocean, and bottom sediments. As intense phytoplankton blooms increase in the future due to increased nutrient inputs and temperature, low oxygen events may become more frequent with potential negative impacts on fisheries and increased export of carbon to the coastal ocean and atmosphere. This study will fill critical gaps identified by the Coastal Carbon Synthesis Program in knowledge of how microtidal estuaries transform and export C to the atmosphere, benthos, and coastal ocean. In addition, there will be a strong teaching and training component to this project, with support for graduate and undergraduate students. The graduate student will be partnered with secondary teachers to gain teaching experience and enrich the middle school educational programs. Summer undergraduate interns will be recruited for a summer program from Hampton University, a historically Black college. There will be public outreach through participation in existing programs at VIMS.

Estuaries serve as critical hotspots for the processing of carbon (C) as it transits from land to the coastal ocean. Recent attempts to synthesize what is known about sources and fates of C in estuaries have noted large data gaps; thus, the role of estuaries, especially those that are microtidal, as important sources of carbon dioxide (CO2) to the atmosphere and total organic carbon (TOC) and dissolved inorganic carbon (DIC) to the coastal ocean, or as a C sink in bottom sediments, remains uncertain. Intensive phytoplankton blooms are becoming increasingly frequent in many estuaries and are likely to have important and yet unknown impacts on the C cycle. The trophic status of an estuary will determine in large part the species of C exported to the atmosphere, bottom sediments, and coastal ocean. The overarching objective of this project is to identify the impacts of intense phytoplankton blooms on C speciation, net C fluxes and exchanges in the Lower York River Estuary (LYRE), a representative mesotrophic, microtidal mid-Atlantic estuary. Metabolic processes are hypothesized to be spatially and temporally dynamic, driving the speciation, abundance, and fates of C in the LYRE. High spatiotemporal resolution sampling in the LYRE will capture rates of C cycling under both baseline conditions throughout most of the year, and during periods when the estuary is perturbed by widespread and intense, but patchy, late summer phytoplankton blooms. The short-term effects of physical drivers (wind, temperature, salinity, fresh water discharge, nutrient and organic carbon loads) and biological drivers (metabolic rates, bacterial and phytoplankton abundances and composition) on C transformations, speciation, and exchanges will be assessed. Expected longer term variations in the C cycle due to anthropogenic and natural disturbances will be predicted through use of modeling. In addition, laboratory manipulations will examine the impacts of specific organisms dominating intensive phytoplankton blooms on benthic metabolism, processing of organic C by the microbial community, and C fluxes to the water column.