Climate impacts on Puget Sound circulation and ecology

1. Climate impacts on Puget Sound circulation and ecology Jan Newton University of Washington

3. PNW estuaries have strong influence from climateGlobal influence on:ocean conditions watershed conditions local weather NASA SeaWiFS Image

4. Estuaries receive the “triple whammy” when climate varies: • Variation from ocean • Variation from local weather • Variation from rivers

5. “thermocline” or “pycnocline” temperature salinity determine density + FRESH WARM less dense SALTY COLD more dense

6. Density structure can be two different ways: “stratified” “mixed” WARM FRESH COLD SALTY

7. { CO2 + H2O  C(H2O) + O2 } sunlight nutrients Organic (primary) production: Lo nutrient Hi oxygen Phytoplankton present Phytoplankton present Hi nutrient Lo oxygen No phytoplankton No phytoplankton

8. Oxygen structure can be two different ways: “stratified” “mixed” HIGH OXYGEN WELL-MIXED OXYGEN LOW OXYGEN

9. 1. Variation in coastal ocean: Downwelling Upwelling N NO3- NO3- NO3- S NO3- NO3- NO3- NO3- NO3- NO3- NO3-

10. 1. Variation in ocean: seasonal, interannual Downwelling Upwelling WIND WIND Temperature Temperature

11. Downwelling Upwelling WIND WIND Chlorophyll Chlorophyll 1. Variation in ocean: seasonal, interannual

12. 110 m Depth (m) April 1998 10 m Depth (m) April 1999 Distance from shore (km) 1. Variation in ocean: thermocline depth  nutrient availability The depth of the thermocline off Oregon coast was much deeper following El Niňo than La Niňa. This affects not only the temperature but also the nutrients available at the surface. Will affect nutrient-limited phytoplankton biomass and species in coasts and estuaries. Smith et al. 2000

13. 2. Variation in local light availability: Light availability in PNW can vary significantly in both magnitude and timing. Much of PNW phytoplankton prod’n is light-limited. Variation in primary prod’n will affect trophic transfer and water quality. NCDC Sea Tac data

14. N NO3- NO3- S NO3- NO3- NO3- NO3- NO3- NO3- Downwelling Upwelling

15. El Niño versus La Niña primary prod’n Newton & Horner, 2003

16. Local and large-scale climate forcing of Puget Sound oceanographic properties on seasonal to interdecadal timescalesMoore et al., 2008 Abstract- The influence of climate on Puget Sound oceanographic properties is investigated on seasonal to interannual timescales using continuous profile data at 16 stations from 1993 to 2002 and records of sea surface temperature (SST) and sea surface salinity (SSS) from 1951 to 2002. Principal components analyses of profile data identify indices representing 42%, 58%, and 56% of the total variability at depth-station combinations for temperature, salinity, and density, respectively, and 22% for water column stratification. Variability in the leading pattern of Puget Sound water temperature and salinity profiles is well correlated with local surface air temperatures and freshwater inflows to Puget Sound from major river basins, respectively. SST and SSS observations are informative proxies for the leading patterns of variations in Puget Sound temperature and salinity profiles. We find that Puget Sound’s oceanographic properties also have significant correlations with Aleutian Low, El Niño-Southern Oscillation, and Pacific Decadal Oscillation variations in winter that can persist for up to three seasons or reemerge the following year. However, correlations with large-scale climate variations are weaker compared to those with local environmental forcing parameters.

17. 3. Variation in regional river flow: • Anticipated changes in annual precipitation due to climate change. • Signal from drought/flood years • Much of PNW phytoplankton prod’n is light-limited. • How will this affect stratification, circulation, growth conditions, and species composition ? USGS & Env Canada data Mote, CIG

18. 2000-2001 Drought “Second worst in Washington State recorded history.” Driest since 1976-77 One of five driest in past 100 years WA Ecology website

19. Reduced regional river flows evident: Fraser River Snohomish River Skagit River Willapa River USGS & Env Canada data

20. Core station Rotational station Washington State’s Long-term Marine Waters Monitoring Program

21. Density (sigma-t) depth Surface salinity Bottom salinity Salinity (PSU) Year Year Stratification: Stratification: what is driving this reduction? Southern Hood Canal Delta Sigma-t Year WA Ecology data Newton et al., 2003

22. 4.Commencement Bay 1.Bellingham Bay Stratification (delta sigma-t) vs. time: 5.Budd Inlet 2.Possession Sound 1 2 6 3 3.Elliott Bay 6.N. Hood Canal 4 5 WA Ecology data

23. Percent change instratification (10-y mean – Oct 00-Sep 01) / 10-y mean) <0% 0-30% 30-49% 50-69% >70% Mean = 56% Grays Harbor = 52% Willapa Bay = 49% Newton et al., 2003

24. Density stratification affects: • Water quality (e.g., hypoxia) • Phytoplankton bloom timing (with impacts on pelagic food-web • Circulation and flushing (e.g., transport of organisms, pollution)

25. Joint Effort to Monitor the Strait (JEMS) JEMS line JEMS Partners: MEHP WA Dept. Ecology King County UW PRISM NOAA Friday Harbor Labs

26. Flow in Strait of Juan de Fuca: North Canada South U.S.A. fresher, warmer water from Puget Sound and Georgia Basin flowing out colder, salty water from Pacific Ocean flowing in Thomson, 1994

27. Compare Sept 2000 with Sept 2001: JEMS data Temperature Why is there cooler saltier water in 2000 ?? Salinity Newton et al., 2003

28. N S Cross-Channel Density Gradient Cooler, saltier water drives a weaker density gradient during Sep 2000 than in Sep 2001 Lo Hi Newton et al., 2003

29. Low River Flow Weak Density Gradient Decreased Outflow Velocity Water stays in Puget Sound longer (this means how fast the water flows out the Strait) Geostrophic Velocity (cm/sec) Four-fold difference in speed of inland water outflow. Newton et al., 2003

30. Conclusions • Puget Sound, an estuary, integrates climate-related impacts from the ocean, atmosphere, and watershed. • While predominantly forced by oceanic influence, there is a significant affect from freshwater input, with measurable impacts on stratification and circulation.

31. Conclusions • Drought period increased salinity of the estuarine waters, leading to higher density surface layer and weaker stratification. • Higher salinity waters with a weaker density gradient result in decreased outflow velocity and longer residence time in estuary. • Implications of both of these effects on oxygen, phytoplankton blooms, trophic transfer, and transport or retention of larvae, species, and pollutants need further investigation.

32. Conclusions • Assessment of the various climate-related impacts on Puget Sound physics is complex but must be addressed together. • Only then can the chemical and biological implications be evaluated. • While multi-disciplinary evaluations on estuaries is complicated, in light of climate change, this needs regional attention.