Introduction & Methods

The purpose of this study was to sample some physical and biological elements in a longitudinal course from offshore in the Pacific Ocean and moving into the Straits of Juan de Fuca and then down the length of Puget Sound. Measurements were taken from 20 different locations and included measurements from CTD, core samples, plankton counts, and comparative measurements of dissolved oxygen, chlorophyll and nutrients. Stations #2-7 are considered the Offshore section and are discussed withing this web page. Other results are available by clicking on the UWT icon in the upper left corner.

Two research teams from the University of Washington, Seattle and Tacoma aboard the Research vessel Thomas G. Thompson collected and measured the various samples May 3-7, 2002. Both teams were divided into four rotating shifts for 24 hours and four days of testing. The weather was partly clear with 18 knots southerly winds at first. Within 24 hours, the winds shifted to a NW direction and increased to 26 knots by day two. Intermittent rain fell during this time. By day four the winds decreased and returned to a southerly direction with partial clearing. Stations #2-7 were sampled May 4 and 5. Data was collected and documented on board as well as some later at the university's labs.

Map by Shawn Gilbertson. UWT 2002.

Methods

A 911 CTD plus was used for collection of samples at variousdepths at each station. The CTD recorded conductivity, temperature, depth, salinity, dissolved oxygen (DO), fluorescence and density. The CTD was deployed at each station by use of a crane and and cable. Conductivity, Temperature, Density, Salinity, DO and Fluorescence data was collected electronically.

DO was also determined using a 665 Dosimat meter and Winkler Titration method (Codispoti 1988). DO samples were collected from the Niskin bottles immediately in a 125 volumetric flask washed out three times with sample water. Each flask was filled with sample water, untill the sample water over filled the flask. 1ml each of MgCl2 and NaOH2 * NaI2 was added to each flask and then shaken. The time of sample collected was recorded. After 15 minutes, the samples were shook again and then stored in a dark, cool container until tritrated and standards were determined. Results were converted in percent saturation using the Level of oxygen saturation chart.

Nutrients

Nutrients were collected from the CTD for each station at surface, middle and deep depth. There were three samples taken from each depth. Each sample bottle was washed out three times with the sample water before a sample was taken. Nutrients were frozen and sent to UW Seattle lab for analysis.

Chlorophyll A

Chlorophyll was determined using a Flourometer and sonicator with standards calibrated for each station (Strickland et al. 1972). Sample were taken from selected depth. Depths were surface, middle, deep and any electronically visualized possible spike from recordings of the CTD. A syringe was washed out three times and then filled with sample water to be analyzed.

Plankton Count

Phytoplankton and zooplankton were collected from stations #2, #3 and #6. The depths were not recorded and, therefore were unknown for station #3. Phytoplankton was collected using a 500 micron collection net on a boom pulley computerized apparatus. Zooplankton was collected using a 63 micron closing collection net on the same apparatus. Luval was added to the plankton samples before storing in a refrigerator until analyzed approximately one week later at the University of Washington Tacoma's lab. Counts were taken of phytoplankton, (at least cone count), and zooplankton, (three counts), using a compound scope with a Palmer counting cell and a dissecting scope with a Sedgwick rafter-counting cell respectively. Total number of organisms per meter cubed from each net were calculated by the following formula: organism counted (average 3 times) _____/(1ml) * # ml of sample (filtrate)_____= total # organisms pulled out of water column_____/volume water column (pi)r²* depth_____= total # organisms/m³_____.

Soutar Core

Sediment samples were collected using a Suitar Core, which collected a 1.5-meter sample off the bottom at the varied depths of each station. Taking a pint off the side of the core upon arrival on board, the sediment was stored in the refrigerator until processed back at University of Washington Tacoma's lab. The sample was dried approximately one week in a drying oven and then using a sieve shaker, weighed and compared.