Thursday, July 29, 2010

July Aerial Survey

The NBEP crew had our third aerial survey Monday July 12th. As expected, many areas of the bay were cloudy with hypoxia and macroalgae was seen just about everywhere. When oxygen levels drop in marine waters sulfur precipitates out, causing the water to become cloudy. The Seekonk River was streaked red with phytoplankton which may be a dinoflagellate or diatom (like the dinoflagellate Gynodinium we found in May), however we were not able to obtain a sample to identify it.
The wrack line at Conimicut was loaded with a filamentous Ulva.
Ground truthing showed expected results: Ulva is heavily coating the northern parts of the Bay, however, the species are changing. While in the past we have seen the big sheets of Ulva (commonly known as sea lettuce) covering beaches, the filamentous Ulva was found in big mats along the shores of Conimicut.

Also, this time last year we were seeing the brown seaweed Punctaria mixed into the Ulva, but this year the red seaweed Grinnellia has taken its place.

Punctaria latifolia. Image: Carol Thornber, URI

Grinnellia americana. Image:

Sunday, July 11, 2010

Seafloor (Benthos) Survey

On June 21, in collaboration with the University of Rhode Island’s Cell & Molecular Biology department, we completed a videotaping survey throughout six different locations in Narragansett Bay.  We will be surveying six locations throughout Greenwich Bay. Click on the map below to see our locations marked in yellow.[googlemaps,-71.435667&spn=0.02943,0.021252&output=embed&w=425&h=350]

Liquid Nitrogen Storage Tank.
Sediment samples
A GPS, in correlation with the program Chartview Pro, was used to track the exact locations that we surveyed so we can return to them each time. At each of the six locations, we used the SeaViewer Underwater camera to capture video clips of the benthic regions in the Bay. We used a YSI to measure temperature, salinity, dissolved oxygen (DO), and chlorophyll at surface and bottom depths (click on yellow icons above to see our readings).  A Niskin water sampler was used to take water samples at the bottom, as well as a sediment grab which plunges into the ground to collect sediment samples. The sediment samples were preserved in a liquid nitrogen storage tank. Both sediment and water samples will be tested by the molecular biology students.

Aghardiella (a red branching seaweed) with
Ulva (green "sea lettuce) underneath.
After viewing the video footage, we found a plethora of interesting marine life living in the sediment in the Bay.  For instance, single-celled algae was found, as well as the red algae Aghardiella species and Gracilaria species. Ctenophores, commonly referred to as “comb jellies” were also abundant at the surface and benthic regions in the Bay.  Amphipods, tunicates, and crabs were among the other species found within the sediment.
Aghardiella (a red branching seaweed)
Aghardiella (a red branching seaweed)