Spatially coherent intermittent stratification and hypoxia in disparate

sub-regions of an estuary.

Jamie Vaudrey & Jim KremerDepartment of Marine Sciences, University of Connecticut

Dan CodigaGraduate School of Oceanography, University of Rhode Island

courtesy of R.L. Wilke

Funded by the NOAA Coastal Hypoxia Research Program (CHRP), 2005

Field and Lab Work Supported By…

Kaitlyn Shaw (UCONN) – Profiler and Sonde maintenance and deployment, assistance with data processing

Gary Grenier, Dennis Arbige, Bob Dziomba (UCONN) – technical and mechanical support for the profilers

Dr. Candace Oviatt’s Lab group (URI) – boat rides to the field sites, maintained the deep water buoys

~ Edwin Requintina Sr., Heather Stoffel, Taylor Crockford, Leslie Smith

Autonomous Profiler - Grover

1 profile every 3 hours

deployment = 2 to 3 weeks

samples every 8 seconds

~ 12cm intervals

max depth = 5m

Bullock Reach

Field’s Point

Warwick Neck

Rumstick Neck

Northern Narragansett Bay, RI

2007, Rumstick Neck

2007, Rumstick Neck

2007, Rumstick Neck

2007, Rumstick Neck

Similar patterns seen at the stations…Dissolved Oxygen, July 2006

Similar patterns seen at the stations…Density, July 2006

Similar patterns seen at the stations…Dissolved Oxygen, August 2006

Similar patterns seen at the stations…Density, August 2006

Hypoxia linked to stratification, but…Is tidal stage (spring/neap) an adequate predictor of stratification?

Bottom DO vs. the Neap Tide Prediction

July

August

Sept.

Conclusions

• NNB shows a certain synchronicity to stratification / hypoxic events for the stations surveyed.

• Bottom water hypoxia is linked with stratification.

• There is a high probability that the water will be stratified during and just following a neap tide.

• However, hypoxia (and stratification) also occur at other stages of the monthly tidal cycle.

Rumstick July 2006

Warwick July 2006

Bullock Reach Aug 2006

Warwick Neck Aug 2006

Rumstick Neck Aug 2006

Warwick Neck Sept 2006

Rumstick Neck Sept 2006

Field’s Point Sept 2006