Prior research has shown that phytoplankton blooms in the warmer spring months and that causes dissolved oxygen levels in the water to also be higher than that of the colder winter months. The temperature and salinity levels also fluctuate with the seasons with the warmer saltier times being in the summer seasons. Density is driven mostly by the salinity and increases as salinity does. 

Team B sampled on 4/28/2023 between 11:05 AM and 4:30 PM and team A sampled on 4/29/2023 from 10:00 AM to 3:30 PM.

The weather was sunny with minimal clouds and had temperatures ranging in the 60-70's during the sampling periods. There was no rain over the sampling weekend. 

Longitudinal Transect

Triple Cross Transect 

Secchi disk readings showed the depth at which light penetrated the water column. Station 1 had low visibility at 1.75 meters and station 8 had high visibility at 4 meters. This appearss to be most likely linked to the high abundance of phytoplankton in the water during sampling. Also this could mean that at station 1 there was probably a lot more boat traffic being near Elliot Bay and more debris mixed up at the surface from the Duwamish River, as well as a weaker current. At station 8 it was a lot clearer due to less boat traffic in the area, as well as a stronger current due being near the Jensen Transect. The temperature contour plots are showing a small gradient between the warm water at the surface and the cooler water below. At stations 5, 6, and 7, temperature was a bit more stratified than other stations. At all other stations, there was more mixing of water shown by the temperature. Station 5 was sampled when tide was going out, and stations 6 and 7 were sampled when tide was coming in. That means station 5 was getting lots of freshwater during sampling from nearby rivers. It is an estuary that constantly receives freshwater from many different sources nearby such as Lake Washington canal, Duwamish, Puyallup, Skagit, Snohomish, and Stillaguamish river. This is why the salinity contour plots show a lot of freshwater at the surface and saltier water below, it was very stratified during sampling. At station 10, the salinity surfer graph shows the saltier water from the ocean coming in at the very bottom. Density graphs look the same as the salinity graphs because salinity provides mass and makes water denser. The transmissivity contour graph shows that station 5 had a sudden decrease in transmissivity near the surface. This could be due to the Snohomish River plume exiting towards the ocean as the tide was going out. There will be a lot of sediment suspended at the top layer where freshwater meets the saltier water. The fluorescence contour graph shows station 4 had the largest spike in fluorescence near the surface. This usually means there is a higher concentration of phytoplankton in the area. Unfortunately, this doesn't align with results from the abundance table and concentration graphs. Although, Thalassiosira spp. was blooming at station 4, but wasn't the station that had the highest concentration of phytoplankton overall. This could be due to human error during counting of phytoplankton. In general, the fluorescence contour graphs do show a large bloom of phytoplankton. From station 6 to 7, the dissolved oxygen triple transect surfer graph shows a wave of oxygen rich water at the surface. Station 6 had the second highest concentration of phytoplankton at the surface. This could explain the high dissolved oxygen at this station, the phytoplankton were creating a lot of dissolved oxygen in this area.

The Si(OH)4 nutrient concentration graph shows that station 3 thermocline is different than the others, it is lower than the surface when the pattern shows an increase of Si(OH)4 with depth increase. This could be because of phytoplankton eating up the Si(OH)4 in this area. The thermocline concentration graph shows station 3 had a higher concentration of phytoplankton, but there are other stations that have higher concentrations. This could also be due to an error in counting of phytoplankton. Station 6 had really low dissolved inorganic nitrogen (DIN) at the surface. This station also had the second highest concentration of surface phytoplankton out of all the stations. Phytoplankton use DIN for growth through biological processes such as photosynthesis. This could be an explanation for why the DIN is low at the surface, the phytoplankton are using it. 

The sediment size and total organic carbon showed station 3 contained mostly silt and had the highest total organic carbon (TOC). This could be because this station is close to Lake Washington canal and Duwamish River, as well as being close to land. Rivers create fine silt particles due to the erosion and transport of fine-grained materials from upstream areas. This station could be receiving a lot of TOC from upstream sources of the rivers. It is also closer to human activities, which means there is more runoff of agriculture practices, sewage effluent, and industrial discharges. Both being near rivers and human activities can increase TOC. Station 7 had mostly sand. This area is a higher-energy environment where strong waves and currents occur due to being located at the center of the triple junction transect on an underwater plateau. High energy area usually transport and deposit coarser sediments such as sand. The TOC at station 7 is low most likely due to not being near any rivers and being away from human activities, nowhere near the shore. 

The microplastics color frequency shows station 3 having the most clear plastics and station 7 having the most black and white plastics. Station 3 could have the oldest microplastics due to most of them being clear. As microplastics weather and degrade from sunlight and waves, it causes the plastic to fade or change color. Further analysis is needed to actually confirm this. Station 3 was also the cleanest station microplastic wise. There was only 26 microplastics counted compared to the 43 counted at station 7. Station 7 also had the highest diversity of microplastic colors, with 7 different colors. Calculations were done to determine how many microplastics per cubic meter there was, for station 3: 26/81.4 = 0.32 m^3, and for station 7: 43/52.5 = 0.82 m^3.

A previous study examined temporal and spatial variability of physical properties in the Puget Sound (Moore et al. 2008). They looked at patterns in temperature, salinity, and density in different regions of Puget Sound, including Main Basin. Data was collected from 1993 to 2003, which offers a comparison to data we collected more recently. Some of the stations that were sampled in this study are the same as some of the stations sampled in this estuaries class, they are P29, PSB003, P28, P27, and ADM 001. The first thing we noticed is the depths of PSB003 and ADM 001 are not close to being the same between the previous study and our survey. This could just be due to drift, or changes in the bottom environment. P29, P28, and P27 are all close to the same depth. It is harder to compare our surfer graphs to the previous studies surfer graphs because they are looking at monthly temperature and salinity. In the previous study, station ADM 001 still shows the saltier water coming from the ocean at the bottom. It seems like their CTD didn't go as far down as ours, so it didn't capture it very well. 

Master Log

README CTD File

CTD files

Correlation Graphs

Secchi Data

Dissolved Oxygen

Chlorophyll

Nutrients

Phytoplankton Nets & Surface & Thermocline

Zooplankton

Sediments

Microplastics

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