18 July 2008 R/V Wecoma cruise - Estuary South Channel

We left the dock this morning at 5:30 am and headed down estuary to our first sampling station. Our goal today was to collect water samples at a range of salinities and make sure those samples do not have a lot of particles in them. This estuary has very strong Estuarine Turbidity Maxima (ETM) in its north and south channels. ETM are hydrodynamic phenomena in which river-borne particles are trapped and concentrated in the estuary as the freshwater moves through. These particles are resuspended by the tides and settle back to the bed during slack tides. While we were sampling these particle-free "background" water samples, Joe Needoba on the R/V Barnes was stationed in the region of the ETM collecting particle-filled water samples to assess microbial activity and diversity. We spent most of the day near River Mile 11 waiting for the tides to bring the right salinity water to the ship.