Measurements of ethylene production (using the acetylene reduction assay) as a proxy for nitrogen fixation of epiphytes on seagrass in West Falmouth Harbor during July from 2005 through 2019.

West Falmouth Harbor (West Falmouth, MA, USA) has been experiencing a dramatic increase in nitrogen loading from an upgradient municipal wastewater treatment facility since the early 2000’s. As part of a long-term study into the effects of this nitrogen enrichment, we have measured nitrogen fixation rates of seagrass-associated epiphytes using the acetylene reduction technique. Samples were taken annually in July at two sites, one in the well-flushed outer basin (OH) and one in the inner basin closer to the dominant groundwater N source (Snug Harbor, SH). Additional data are presented in 2019 at 18 sites spatially distributed through the seagrass bed to assess spatial heterogeneity. Individual replicate data are presented. These data are in support of a manuscript submitted to the journal Biogeochemistry by Marino et al, submitted for publication (12/2022).