Seafloor nutrient biogeochemistry and benthic fluxes in the Northeastern Mediterranean sea

Abstract

The coastal ecosystem of the Northeastern (NE) Mediterranean Sea has been affected by nutrient inputs originated from regional rivers and wastewater discharges. Sediment porewater nutrient fluxes into the deep waters are strongly associated with eutrophic and suboxic/anoxic conditions. There was only limited number of studies performed on the porewater and sediment biogeochemistry in the NE Mediterranean Sea having oxic conditions in the deep waters. In this study, therefore, sediment porewater nutrient (Si, N, P) and sediment organic matter biogeochemistry were studied. The study results indicated a series of redox reactions as well as remarkable contribution of porewater diffusive nutrient fluxes to the total nutrient budget in the NE Mediterranean Sea. Lower Si/N and higher N/P molar ratios in the total nutrient inputs are very likely to modify phytoplankton composition and abundance in the phosphorus deficient NE Mediterranean productive shelf waters leading to development of mesotrophic/eutrophic conditions in the NE Mediterranean Sea.