Article

Estuaries and Coasts

, Volume 37, Issue 1, pp 46-62

Impacts of Climate-Related Drivers on the Benthic Nutrient Filter in a Shallow Photic Estuary

  • Iris C. AndersonAffiliated withVirginia Institute of Marine Science, College of William & Mary Email author 
  • , Mark J. BrushAffiliated withVirginia Institute of Marine Science, College of William & Mary
  • , Michael F. PiehlerAffiliated withInstitute of Marine Sciences, The University of North Carolina
  • , Carolyn A. CurrinAffiliated withNational Oceanic and Atmospheric Administration, National Ocean Service, National Centers for Coastal and Ocean Science
  • , Jennifer W. StanhopeAffiliated withVirginia Institute of Marine Science, College of William & Mary
  • , Ashley R. SmythAffiliated withInstitute of Marine Sciences, The University of North Carolina
  • , Johnathan D. MaxeyAffiliated withVirginia Institute of Marine Science, College of William & Mary
  • , Meaghan L. WhiteheadAffiliated withVirginia Institute of Marine Science, College of William & Mary

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

In shallow photic systems, the benthic filter, including microphytobenthos and denitrifiers, is important in preventing or reducing release of remineralized NH4 + to the water column. Its effectiveness can be impacted by climate-related drivers, including temperature and storminess, which by increasing wind and freshwater delivery can resuspend sediment, reduce salinity and deliver nutrients, total suspended solids, and chromophoric dissolved organic matter (CDOM) to coastal systems. Increases in temperature and freshwater delivery may initiate a cascade of responses affecting benthic metabolism with impacts on sediment properties, which in turn regulate nitrogen cycling processes that either sequester (via microphytobenthos), remove (via denitrification), or increase sediment nitrogen (via remineralization, nitrogen fixation, and dissimilatory nitrate reduction to ammonium). We conducted a seasonal study at shallow stations to assess the effects of freshwater inflow, temperature, wind, light, and CDOM on sediment properties, benthic metabolism, nitrogen cycling processes, and the effectiveness of the benthic filter. We also conducted a depth study to constrain seasonally varying parameters such as temperature to better assess the effects of light availability and water depth on benthic processes. Based on relationships observed between climatic drivers and response variables, we predict a reduction in the effectiveness of the benthic filter over the long term with feedbacks that will increase effluxes of N to the water column with the potential to contribute to system eutrophication. This may push shallow systems past a tipping point where trophic status moves from net autotrophy toward net heterotrophy, with new baselines characterized by degraded water quality.

Keywords

Shallow photic estuary Benthic filter Climate Microphytobenthos Benthic metabolism Remineralization Nitrogen fixation Denitrification