We are working with Dr. Mark Martin and his Microbiology students to identify the microbial community that make up the bacterial mats.  We will be using microscopy and genetic sequencing methods to identify the bacteria.  At this point we have tentatively identified the dominant bacterial type as the sulfide-oxidizing bacterium Beggiatoa spp.  These bacteria are some of the largest known, and mats of Beggiatoa observed at the surface of sediments have been regarded as an indicator of organic enrichment from either natural or anthropogenic sources (see general information on The Prokaryotes webpage).  Our research in Commencement Bay shows that white bacterial mats on the sediment surface are associated with areas where there are high levels of hydrogen sulfide in the sediments.  These areas correspond to sites where large amounts of wood waste were released into the nearshore area from historic pulp mills that lined the Ruston Way shoreline (Elliott, Spear and Wyllie-Echeverria. in press.  Mats of Beggiatoa bacteria reveal that organic pollution from lumber mills inhibits growth of Zostera marina.  Marine Ecology).  In Hood Canal, the presence of the mats at the sediment surface are likely a result of the low oxygen levels in the water column and high sulfide levels in the sediments.  Further research is needed to determine the factors causing the large visible surface mats of the bacteria in Hood Canal and other locations in Puget Sound.

The images below are from the bacterial mats in Hood Canal.  The images of the bacteria are from core tube samples collected by the Skokomish tribe divers and benthic grab and core samples taken by UPS students.

Core tube with bacterial mat just after it was brought to the surface.

Close-up of bacterial mat in the core tube.

Image of the bacterial mat taken with a dissecting scope at approx. 30X.

Image of the mat taken with a dissecting scope at approx. 30X.

Image of the bacteria taken at approx. 40X with a dissecting microscope. 

This is the large form of the bacteria in the mats.

This is the large form (approx. 120 μm in diameter) of the bacteria in the mats.  Image taken by Dr. Mark Martin (UPS microbiologist) on a compound scope at 100X.

This is the small form (approx. 20 μm in diameter) of the bacteria in the mats.  Image taken by Dr. Mark Martin (UPS microbiologist) on a compound scope at 100X.

Webpage and project content by:

Dr. Joel Elliott, University of Puget Sound, Department of Biology
 

Please contact Dr. Joel Elliott for use of videos and images.  Thank you.

This project is funded by the Northwest Academic Computing Consortium and the University of Puget Sound

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