Limnol. Oceanogr., 44(6), 1999, 1359–1369

The effects of a major storm event (Hurricane Gordon) on the biogeochemistry of Atlantic coastal and Gulf Stream waters were investigated during a research cruise in November 1994. Prestorm, NH , NO , and PO 1 2 23 4 3 4 concentrations were consistently well below 1 mM, whereas after the storm, nutrient concentrations were higher in the surface-water samples: .2 mM, in some instances. Primary and secondary (bacterial) production were stimulated by factors of 5 and 2, respectively, up to 4 d following the storm. Bioassay experiments showed that additions of inorganic N stimulated chlorophyll a (Chl a) concentrations, CO2 fixation, and stable isotope fractionations both before and after the storm, but the addition of phosphate had a greater impact in post-storm experiments. The d15N of particulate nitrogen (PN) varied from 15 to 11.5‰ before Gordon, then afterward attained a consistent value of 13.0‰. Sedimentary organic d15N values were similar to water-column organic N, and the d15N of dissolved NH from surface sediments (14.0‰) almost matched the d15N of water-column particulates. These results indicate 4 that storm-generated winds mixed sediments along with dissolved nutrients into surface waters, which supported a rapid increase in water-column primary production. Interactions between atmospheric processes and primary production in the world’s oceans are striking during and after major storm events over continental shelf regions. N, a lim-