Sediment–water interface

The term usually refers to a thin layer (approximately 1 cm deep, though variable) of water at the very surface of sediments on the seafloor.

[8] Microorganisms such as benthic algae can stabilize sediments and keep the sediment-water interface in a more stable condition by building mats.

These microalgal mats' stabilizing effect is in part due to the stickiness of the exopolymeric substances (EPS) or biochemical "glue" that they secrete.

[11] Sedimentation is often the final scavenging process that takes trace chemicals and elements out of the water column.

[2] Sediments at this interface are more porous and can hold a larger volume of pore water in the interstitial sites due to high organic matter content and lack of settling.

[15] While bacteria are present at the interface throughout the lake basin, their distributions and function vary with substrate, vegetation, and sunlight.

And, a functional artifact of heavy vegetation at the interface might be a greater number of Azotobacter, a genus of bacteria that can fix N2 to ionic ammonium (NH4+).

Even though basin morphometry plays a role in the partitioning of bacteria within the lake, bacterial populations and functions are primarily driven by the availability of specific oxidants/electron acceptors (e.g., O2, NO3−, SO4−, CO2).

The flux of oxygenated water into and out of the sediments is mediated by bioturbation or mixing of the sediments, for example, via the construction of worm tubes.
Waves and tidal currents can alter the topography of the sediment-water interface by forming sand ripples, like the ones shown here that are exposed at low tide.
Bioturbation mixes sediments and changes the topography of the sediment-water interface, as shown by time lapse photography of lugworms moving through sediment.
The sulfur cycle is a great example of lake nutrient cycling that occurs via biologically mediated processes as well as chemical redox reactions.