Week 9 - November 16th

November 16th observations

Josie Wood

From my observations I found that there was more diversity in stratification in the control and 4% salinity columns. From this, it is clear that an increase in salinity can affect what organisms are able to grow. I also found that that there was more stratified layers and colors on the side of the column that is facing the window at all times (see table 1).

For the control column the bottom layer appears to just be sediment, but the thickness of this layer differs depending on if it was on the light or dark side (6.5 cm vs. 9.1 cm respectively). The dark red-brown band is most likely anaerobic bacteria, however on the light side this band is thicker and specked with light green, possibly anoxygenic photosynthetic bacteria. Darker green bands on both dark and light sides are most likely communities of cyanobacteria and nonsulfur bacteria. The green water most likely contains both diatoms and cyanobacteria.

The 4% salinity column contains less stratification than seen in the control column. Again, the sediment is occupying the bottom 9.2-9.7 cm of the column. The dark side of the column then has a 1.2 cm band of dark green, most likely cyanobacteria, and then the water. The light side has a yellow band with pink spots between the sediment and the green band of cyanobacteria. This yellow/pink band may contain purple and nonsulfur photosynthetic bacteria.  

Both the 8% and 12% salinity columns had less stratification and did not show any changes between the dark and light sides. For both these columns the sediment occupies most of the space with a thin layer of dark green/black at the top of the sediment and then the water. These observations are similar to those that were made on week 8 although the green/black layer seems to be slowly gaining thickness. Approximately .2 cm to .7 cm in 8% salinity and from less than .1 cm to approximately .1 cm in the 12% salinity column.  

Figure 1. Control (left = dark side, right = light side)

Figure 2. 4% salinity (left = dark side, right = light side)

Figure 3. 8% salinity

Figure 4. 12% salinity

Figure 5. Top view (control on left with increasing salinity to the right)

Table 1. Recorded observations and band widths taken on Nov 16th. Columns with 8% and 12% salinity did not exhibit any differences between the light and dark sides.