Seasonal oxygen, nutrient, Mn, and Fe data for intertidal pore waters and adjacent seawater of Spiekeroog Island North Beach (Germany)

Concurrently, coastal seawater nutrient and organic matter composition change seasonally due to variations in pelagic productivity. To assess seasonal changes in organic matter degradation in the intertidal zone of a high energy beach (Spiekeroog Island, southern North Sea, Germany), we analyzed shallow pore waters for major redox constituents (oxygen (O2), manganese (Mn), iron (Fe)) and inorganic nitrogen species (nitrite (NO2-), nitrate (NO3-), ammonium (NH4+)) in March, August, and October.

Surface water samples from a local time series station were used to monitor seasonal changes in pelagic productivity. O2 and NO3- were the dominating pore water constituents in March and October, whereas dissolved Mn and Fe were more widely distributed in August. Seasonal changes in seawater temperature as well as organic matter and nitrate supply by seawater were assumed to affect microbial rates and respective pathways.