The cruises in Bellingham Bay have been the main focus for my research on hypoxia. So far we have gone on three research trips in the bay in order to collect a large amount of data with the CTD. For these cruises, we perform a transect of ten stations from north to south and eight stations from east to west, as well as CTD casts at eight historic sites in the bay. Water samples are also collected at the surface of each site for chlorophyll a analysis and from deep water at selected sites for dissolved oxygen and nutrient analysis.
Our first cruise was rather long because we had to figure out where exactly to send down the CTD, then create a rhythm in our data collection to make everything go as smoothly as possible. At the fifth station we sent the CTD down at, we found hypoxic conditions in the deep water. From there, we found many other sites also showed evidence of hypoxia in the deep water. All of this was in support of what we believed we would see due to the trends that had been found in the past. First I drew graphs of the data by hand to allow myself to visualize the hypoxic area. Then I made contour plots using a computer program called Surfer, which I will be using to make graphs for the data I collected at later dates as well. Graphing the data in Surfer will allow me to look more accurately at the hypoxic areas in Bellingham Bay and potentially find the volume of the hypoxic water mass.
After finding hypoxic levels on the first cruise, I fully anticipated seeing either the same results or intensified hypoxia on the following two cruises. However, this was not the case at all. The two figures below are the graphs for the concentrations of oxygen for the second research cruise. There was a small hypoxic area higher in the water column, but the concentrations for this cruise fell higher in the 2-4 mg/L range than the hypoxic areas the week prior. Based on all of the wind and mixing that had taken place, we hypothesized that the hypoxic area we had found at the bottom dispersed as a result of the mixing. The most recent cruise we went on, I expected the hypoxic area to return as a result of layers becoming stratified once more. Instead, the water column had the same general trend as the week before and did not have a significant hypoxic area.
These results are quite surprising and it will be interesting to see what we find on our final research trip later this week. I will soon begin analyzing and visualizing my data to calculate the volume of the initial hypoxic area that was found in the first week.