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

PNW estuaries have strong influence from climate Global influence on: ocean conditions watershed conditions local weather NASA SeaWiFS Image

Estuaries receive the “triple whammy” when climate varies: 1. Variation from ocean 2. Variation from local weather 3. Variation from rivers

WARM COLD temperature salinitydeterminedensity FRESH SALTY + less dense more dense “thermocline” or “pycnocline”

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

Lo nutrientHi oxygen Phytoplankton present Hi nutrientLo oxygen No phytoplankton Organic (primary) production: Phytoplankton present No phytoplankton { CO 2 + H 2 O  C(H 2 O) + O 2 } sunlight nutrients

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

N S NO 3 - DownwellingUpwelling 1. Variation in coastal ocean: NO 3 -

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

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

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. 1. Variation in ocean: thermocline depth  nutrient availability Smith et al April 1999 April m 10 m Depth (m) Distance from shore (km)

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

N NO 3 - S DownwellingUpwelling

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

Local and large-scale climate forcing of Puget Sound oceanographic properties on seasonal to interdecadal timescales Moore 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 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.

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 3. Variation in regional river flow:

Drought “Second worst in Washington State recorded history.” Driest since One of five driest in past 100 years WA Ecology website

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

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

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

1. Bellingham Bay Stratification ( delta sigma-t ) vs. time: 2. Possession Sound Budd Inlet 4. Commencement Bay 6. N. Hood Canal3. Elliott Bay WA Ecology data

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

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)

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

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

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

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

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

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.

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.

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.