This cruise visited eight stations on the Northeastern U.S. Continental Shelf. Latitudes and longitudes provided per sample in the data, but general station descriptions are below.

• Station 1 - Station 3: Georges Bank near the Gulf of Maine. Approximate location was 41.7 N, 68 W. Samples acquired from 0 m to 25 m depths.
• Station 4: The Great South Channel near the Gulf of Maine. Approximate location was 41.6 N, 69 W. Samples acquired from 0 m to 150 m depths.
• Station 5: Only one CTD profile was taken before this station was aborted due to weather. No data acquired. Station location was 40.8 N, 70.5 W.
• Station 6: Off the coast of Martha's Vineyard. Approximate location was 41.3 N, 70.5 W. Samples acquired from 0 m to 10 m depths.
• Station 7: At the mouth of the Sakonnet River near Newport, Rhode Island. Approximate location was 41.5 N, 71.2 W. Samples acquired from 0 m to 10 m depths.
• Station 8: Hudson Canyon near New York. Approximate location was 39.5 N, 72.3 W. Samples acquired from 0 m to 200 m depths.

Seawater samples between 500 and 2000 ml were vacuum filtered through a 0.45 micron polycarbonate membrane filter. Filter retentate was then stained with Alcian Blue solution. The Alcian Blue solution was made to a concentration of 400 mg/L by mixing dye powder with ultrapure water that was acidified to pH 2.5 with glacial acetic acid. After mixing, the stain was filtered through a 0.22 micron polycarbonate membrane to remove undissolved powder. Stained filters were frozen in Falcon tubes at -20 C for the remainder of the cruise and returned to the lab on dry ice for analysis. In the lab, TEP samples were extracted in 6ml 80% sulfuric acid solution for 2 hrs. The absorbance of this solution was then measured with a spectrophotometer at 787 nm. Concentration of TEP was converted from absorbance to microgram equivalent of Xanthan Gum through a calibration curve. Calibration was conducted following the procedure of Bittar, et al. (2018). A 5-point calibration was performed using dilutions of Xanthan Gum solution with concentrations of 9.37, 18.75, 37.50, 56.25, and 75 micrograms per ml in 1 mL polypropylene tubes. 0.5 ml of the Alcian Blue solution was added to these tubes, which were then mixed for 1 min through manual agitation. These stained aliquots were then poured onto filtration towers and filtered through 0.45 micron polycarbonate filters. The filter retentate was then extracted using the 80% sulfuric acid wash for spectrophotometric quantification. Filters were soaked in the solution for 2-20 hrs with regular agitation. The spectrophotometer (Agilent 8453) was first blanked with ultrapure water prior to measurements. 6 mL of extraction solution was read using 1.0 cm polystyrene disposable cuvettes (Fisher-Scientific).