Due to a battery malfunction, the CTD did not record data for Station 50, so it was not included in the CTD profile section, nor was it included in the correlation graphs. However, discrete field samples were taken from Station 50 (DO, chlorophyll, nutrients, and both phytoplankton surface and net samples). It was unclear as to the reason for this event, as the subsequent stations (50 was sampled first) were all recorded normally. It is possible this could have been due to Station 50 being the deepest station sampled that day (Table 1). 

Both the morning and afternoon team had fine weather during sampling, with partial sun and calm water conditions. Stations 50, 51, 52, and 53 all occurred during an ebb tide, while Stations 54, Dockton, 55, and 56 occurred during a flood tide (Fig. 5). Secchi data (Fig. 18) display an increase in visibility for the inner harbor stations (54, 55, 56, and Dockton), while the outer stations had a decrease in visibility from the Secchi readings. The fact that the Secchi could be seen deeper into the water column is indicative of the water having less particulates—such as suspended sediments or phytoplankton. Shallower Secchi readings could be an indication of phytoplankton blooms or the Puyallup River plume. The fact that the outer harbor stations showed decreased visibility could be attributed a phytoplankton bloom that had been flushed out of the surface of Quartermaster Harbor and/or to their placement closer to main body of the Main Basin, receiving mixing from the current pushing ocean water clockwise around Vashon as well as outflow from the Puyallup River. 

When comparing Quartermaster Harbor to the other regions sampled by the research team, Quartermaster had some of the highest concentrations of dissolved oxygen and fluorescence (Fig. 9 and 10). The highest dissolved oxygen reading was 9.5 mL/L at Station 52. Dissolved oxygen being so high is notable, as in previous years there was concern over the low dissolved oxygen levels at Quartermaster (DeGasperi and Ferguson 2012, Beachcomber 2014). While follow-up studies would have to be conducted to confirm this, it would seem that mitigation efforts that have been put forth have been effective in reversing Quartermaster’s previous low dissolved oxygen levels. Data from 2024 (Fig. 14) also shows that the summer months average around 7 mL/L, while winter months average around 5 mL/L. 

Interestingly, Station 56 had a lower total organic carbon (TOC) content than station 54 despite higher concentrations of phytoplankton at 56. This may be due to station 56 being the shallowest station. However, this TOC reading is still quite high, which is probably due to the inner harbor’s long flushing times (Albertson 2013), which allows organic content to accumulate.

Fluorescence readings (Fig. 10) being high and following the trends seen for dissolved oxygen supports increased phytoplankton activity, as phytoplankton largely contain chlorophyll.  Data for nitrate (NO₃⁻) (Fig. 21) emphasizes this high phytoplankton activity near the surface, as surface concentrations for nitrate are practically at zero, while nitrate concentrations deeper into the water column are higher; nitrate is an important nutrient for phytoplankton to thrive, and in oceanic and coastal ecosystems, dissolved nitrate is the most commonly available form of nitrogen (Kramer and Roesler  2014). Dockton’s surface nitrate readings are low at both the surface and near the bottom, though this could be attributed to it being one of the shallowest stations (Table 1). However, Fig. 19 reveals a huge concentration of phytoplankton at the surface— with nearly 900,000 cells/L, when compared to the second highest—Station 52—with almost 500,000 cells/L. Orthosilicic acid (Si(OH)₄) which includes silicate, a necessary building block for diatoms (Amo and Brzezinski 1999), is also depleted at the surface (Fig. 20), though not nearly as much as nitrate. 

The most prominent species found at Dockton was Chaetoceros spp., which was also the most prominent at all other stations, with the exception of 52, in which Thalassiosira spp. had the majority. It’s important however to keep in mind that due to the limited magnification of the compound microscopes (100x), that these are identified by genus only and not species, so those identified as either Chaetoceros or Thalassiosira could be any species within that genus. This skews the data heavily towards these genera, as some other phytoplankton are identified at the species level and therefore more difficult to say for certain the species in many cases. However, the high concentration of phytoplankton found in the surface samples reveals that Quartermaster Harbor is an ideal blooming ground for them, likely due to its partially enclosed and shallow bathymetry. Alexandrium catenella was present at Stations 55 and 50, though it is considered rare in both areas. This lines up with previous research done in the area (DeGasperi 2010) which characterized Quartermaster Harbor as a common blooming ground for A. catenella. A. catenella can cause paralytic shellfish poisoning (PSP) and this finding highlights the need for continued monitoring for blooms. 

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