Michelle Rau

2014 Mouth of the Columbia River Deep Water Site and Shallow Water Site Monitoring Series, Part 2 of 4: Grab Sampling

Part 2 of our Oregon adventure series describes the grab sampling effort that was part of the June and October surveys.  During the two surveys the team collected benthic samples at 40 locations in and around the drop zones of the DWS .  During the October survey, the team collected sediment samples from 45 locations for physical and chemical analysis.  We used a Gray O’Hara modified box corer to collect samples at water depths ranging from 178 to 279 feet.

The objectives of the study were to:

  • Provide a physical characterization of the benthic habitat
  • Assess levels of chemicals of concern
  • Characterize the benthic invertebrate community

 

Michelle pic 1

Deploying the grab sampler. The ropes helped keep the sampler from swinging and ensured that it reached the water surface safely. The sampler weighed 600 lbs.

 

 

Michelle pic 2

Emptying a sample into a decontaminated stainless steel pan.

 

 

michelle pic 3

An intact sample in the box core.

 

 

michelle pic 4

Washing the benthic sample through a 0.5-mm-mesh sieve box.

 

 

michelle pic 5

The remaining material (organisms plus coarse sediment) was decanted into a jar and fixed with 10% buffered formalin solution.  Sample organisms were later taxonomically determined at the lab.

 

 

michelle pic 6

Homogenizing a sediment sample prior to containerizing in glass sample jars.

 

 

michelle pic 7

An unlucky Dungeness crab caught in the box corer. 

 

 

michelle pic 8

The box corer stand also makes a nice throne.

 

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