Hypoxia and Hydrogen Sulfide (H2S) in Padilla Bay, WA from 2014-07-09 to 2014-09-30 (NCEI Accession 0156596)

The growth rate and photosynthetic efficiency of the eelgrass shoots were monitored weekly for six weeks. After week three, the water columns of six of the tanks were reduced to hypoxic conditions (<2mg L-1). During week 6, the oxygen concentration was dropped further to near anoxic conditions.

After week 6, eelgrass tissue samples were collected for measurement of total sulfur, carbon, and nitrogen. The results indicated that hypoxia had a significant negative effect on Z. marina shoots, which was evidenced by strong reductions in growth rates and photosynthetic efficiencies. These findings indicate that hypoxia in conjunction with sediment organic enrichment harms eelgrass health and enhances the intrusion of sulfide into plant tissues, over a wide range of pore-water sulfide concentrations.