Through a subcontract with the Hood Canal Salmon Enhancement Group (HCSEG), PSI staff Mary Middleton and Aimee Christy analyze phytoplankton samples collected as part of the Hood Canal Dissolved Oxygen Monitoring Program (HCDOP).
This project addresses medium priority 2015 goal 6.1.4, "Collect information about virulent species, abundance, and presence. Build a comprehensive database for phytoplankton occurrences."
Task 1 involved routine marine water phytoplankton analysis. For this task phytoplankton samples from the HCDOP weekly monitoring program were analyzed by PSI staff. Sample sites were Potlatch, Sister’s Point, Bamban Cove, and Sund Rock. One net tow sample and one whole water or discrete sample was collected at each monitoring site. Samples are taken at the depth of the chlorophyll maximum. Whole water and net tow samples were preserved in 1% Lugol’s iodine solution and transported to PSI. Whole water phytoplankton samples were allowed to settle overnight prior to being concentrated 10-fold and viewed under an Olympus® inverted microscope using a 0.1 ml Palmer-Maloney counting chamber. Net tow samples were not used for quantification, but rather screened for species presence. A complete species list was generated and each species was classified as dominant (1-2 species that comprise approximately 40-50% of species composition), prominent (2-3 species that comprise of sub blooms) or present (majority of species that are found in smaller quantities) for each sample.
Task 2 involved emergency response marine water phytoplankton analysis. For this task PSI was part of the HCDOP-IAM emergency response (ER) phone tree. The HCDOP developed an emergency response team that responds to reports of algal blooms and fish kills. The ER mechanism is set in motion by a call to the Washington Department of Ecology (WADOE). The WADOE then contacts representatives from HCDOP-IAM to develop an appropriate response for the situation. For these situations, PSI processed water samples quickly, within 1-2 days, in order to provide immediate information feedback on the status of the water conditions. PSI was not called on to respond to any bloom events in 2007-2008. During 2009, PSI was called on to respond to 2 phytoplankton blooms. Both of these blooms were dominated by the dinoflagellates Noctiluca scintillans, over 3 million cells/L in May and over 500,000cells/L in June.
PSI has analyzed over 300 phytoplankton samples from Hood Canal. In addition, PSI has been monitoring plankton in Puget Sound for about 8 years at sites on Eld and Totten Inlets as part of NOAA/Sea Grant Oyster Disease Program, and in Willapa Bay since 2001 as a part of the Olympic Region Harmful Algal Bloom (ORHAB) program. In comparison to Puget Sound and Willapa Bay sites, plankton cell counts in Hood Canal appear to remain high later in the year. In 2005 phytoplankton cell counts in Hood Canal remained high through December, and in 2006 there was a large plankton bloom in November, over 6 million cells/L. We did not see this same pattern in 2007, during this year counts dropped off in July and remained low for the remainder of the year.
Few areas in Puget Sound have such a detailed account of phytoplankton blooms and species composition. This sampling program has allowed us to begin to see patterns in the cycle of phytoplankton in Hood Canal. Comparing data from 2005-2008 we do see the typical cold water trend of large spring blooms, with a decrease in the number of cells during mid summer, and then smaller fall blooms followed by decreasing numbers in late fall and early winter. When looking at individual years we see variations from this trend. The first two years of this project showed phytoplankton counts remaining high into early winter, but this was not seen in 2007. Typically we would expect to see the spring blooms composed mostly of diatoms and the fall blooms dominated by dinoflagellates. This pattern was observed in Hood Canal during 2005 and 2006, but in 2007 the entire year was dominated by diatoms. With more data we may be able to determine if these differences were anomalous for these years or if there is a difference in the patterns of phytoplankton in Hood Canal than typical cold temperate regions.