Submarine Groundwater Discharge in the San Juan Archipelago and the Effects of Nitrate Enrichment on Zostera marina L.

Abstract

Submarine groundwater discharge (SGD) can provide vital nutrients to coastal systems. Conversely, it can also lead to eutrophication of coastal waters, especially if the groundwater contains anthropogenic pollutants. This paper presents two studies encompassing this topic: a field study quantifying SGD at four sites in the San Juan Archipelago in the Northeast Pacific and a mesocosm experiment examining the effects of nitrate enrichment (30μM and 150μM added) on local Zostera marina L. SGD rates varied from essentially 0 to 16.7±22.4 cm/day. Results from the mesocosm experiment indicate that Z. marina under nitrate enrichment performs differently than those under control conditions. Under 30μM enrichment, photosynthetic capacity increased, while it decreased under 150μM.