OCEANOGRAPHIC INFORMATION 2 DIVERSITY Snapshots of oceanographic processes in the southern Strait of Georgia reveal a level of diversity that is uncommon for such a small geographic area. Due in part to the freshwater discharge from the Fraser River, the upwelling from Haro Strait, and the varied seabed below, there is a wide range of temperatures, salinity levels, currents and stratification. EXTREMES The southern Strait of Georgia is more than diverse; it is a zone of extremes. For instance, Saanich Inlet, a deep body of water sheltered from the wind, with little current and relatively low levels of fresh water input, is an area of exceptionally high stratification. If the waters could be removed and looked at in profile, there would be clearly defined layers each with different characteristics. In contrast, because of the large volume of water that must squeeze through a tiny, twisting channel, Active Pass has waters that are so highly mixed and churned that the phenomenon is visible from ferry decks above The water in the Strait of Georgia is not much colder than the waters of northern California. IN TERESTING INFO Surface waters move much faster than deeper waters. To travel from the southern Strait of Georgia to the Juan de Fuca Strait, a log at the surface takes only 24 hours; a waterlogged piece of wood 50 metres below takes a full year The Fraser River accounts for roughly 80% of the freshwater entering the Strait of Georgia. 11
PROPOSED SOUTHER N ST R A IT OF GEORGIA NATIONAL MARINE CONSERVATION ARE A RESERV E AT L AS CPTER 2 Supplemental Information Article References Dr. Cliff Robinson, Marine Ecosystem Scientist, Parks Canada http://en.wikipedia.org/wiki/strait_of_georgia http://www.vancouverisland.com/recreation/?id=161 Map Metadata SUMMER SURFACE TEMPERATURE, WINTER SURFACE TEMPERATURE, SUMMER SURFACE SALINITY, WINTER SURFACE SALINITY PHOTO CREDITS Page 11 - Parks Canada, 2009; Page 12: top left - M. Hiebert; top right - Parks Canada / T. Tomascik; bottom left - M. Hiebert; bottom right - Parks Canada / T. Tomascik Fisheries and Oceans Canada, Institute of Ocean Sciences. Base data enhanced with data from: archives of the Marine Environmental Data Service, Ottawa; Institute of Ocean Sciences,, BC; National Ocean Data Service, Washington, DC; and Project Argo. Observations from seasons impacted by severe El Niño and La Niña events were excluded from the analysis. TIDAL CURRENT VELOCITIES Fisheries and Oceans Canada, Institute of Ocean Sciences. Based on Mike Foreman s finite element model for eastern Juan de Fuca Strait and southern Strait of Georgia. 11,697 data points were exported from the current model that averages horizontal velocities over the depth of the water column calculating a horizontal root mean square velocity at each point. The model is further described in the Journal of Geophysical Research, 1995. VERTICAL STRATIFICATION Calculated using the Simpson and Hunter 1974 model. Based on bottom friction and may not be entirely applicable to the deeper portions of the region. Model works on the following equation: S=log10(H/C d U 3 ) where H is the water depth in (cm), C d is the bottom drag taken to be 0.0025 and U is the mean speed of tidal current (cm/s) taken from tidal current velocity data. The stratification parameter is interpreted as: S<1 mixed, 1<S<2 frontal region and S>2 stratified region. 12
Proposed ern Strait of Georgia National Marine Conservation Area Reserve Summer Surface Temperature PYLADES STUART Chemainus TRINCOMALI Cowichan Ganges Russell PRE VOST AGE Tumbo Mill Rum CORDOVA SIDNEY RO STRAIT < 10 C 10.0-10.5 C 10.5-11.0 C 11.0-11.5 C 11.5-12.0 C 12.0-12.5 C 13.0-13.5 C 13.5-14.0 C 14.0-14.5 C 14.5-15.0 C 15.0-15.5 C 15.5-16.0 C 12.5-13.0 C Institute of Ocean Sciences. Median summer surface temperature of ocean. C denotes degrees Celsius. 13
Proposed ern Strait of GeorgiaVancouver National Marine Conservation Area Reserve Winter Surface Temperature DD DO GABR IOLA PA S ES W D LA O RR PY NA SSAGE CH EL N AN R AI T POR LIE ST S AS R P O F UA ST G EO RT AN CH NE L Chemainus TR IN C RG Ca na da O M AL IC -U.S.A.B NN EL or d er V E E AG NAR R SANSU M OW S SWANS O N C H ANN E S CA P T A IN P A S Ganges A CT I PL UM PE R SO UN D CO WI CH AN BA Y Cowichan E NN L SA UN D Y AR PA SS Rum SAANICH INLET Mill BO GE E C L LIT SATE Russell AS PRE V OS T P Tumbo L IA SI D N AC EL NN OV C RD CO EY N L NE RO IT RA ST < 7 C 7.0-7.5 C 7.5-8.0 C Institute of Ocean Sciences. Median winter surface temperature of ocean. C denotes degrees Celsius. JUA N DE FU CA STR AIT 0 5 10 14 15
Proposed ern Strait of Georgia National Marine Conservation Area Reserve Summer Surface Salinity PYLADES STUART Chemainus TRINCOMALI Cowichan Ganges Russell PRE VOST AGE Tumbo Mill Rum CORDOVA SIDNEY < 19.5 psu 24.50-25.0 psu 19.0-20.0 psu 20.0-20.5 psu 20.5-21.0 psu 25.0-25.5 psu 25.5-26.0 psu 26.0-26.5 psu 21.0-21.5 psu 26.5-27.0 psu 21.5-22.0 psu 27.0-27.5 psu 22.0-22.5 psu 27.5-28.0 psu 22.5-23.0 psu 23.0-23.5 psu 28.0-28.5 psu 28.5-29.0 psu 23.5-24.0 psu 29.0-29.5 psu 24.0-24.5 psu 29.5-30.0 psu RO STRAIT Institute of Ocean Sciences. Median summer surface salinity of ocean. psu denotes practical salinity units. 15
Proposed ern Strait of Georgia National Marine Conservation Area Reserve Winter Surface Salinity PYLADES STUART Chemainus TRINCOMALI Cowichan Ganges Russell PRE VOST AGE Tumbo Mill Rum CORDOVA SIDNEY < 26.5 psu 26.5-27.0 psu RO STRAIT 27.0-27.5 psu 27.5-28.0 psu 28.0-28.5 psu 28.5-29.0 psu 29.0-29.5 psu 29.5-30.0 psu Institute of Ocean Sciences. Median winter surface salinity of ocean. psu denotes practical salinity units. 16
Proposed ern Strait of Georgia National Marine Conservation Area Reserve Tidal Current Velocities PYLADES STUART Chemainus TRINCOMALI Cowichan Ganges Russell PRE VOST AGE Tumbo Mill Rum 0-0.1 m/s CORDOVA SIDNEY 0.1-0.2 m/s 0.2-0.3 m/s 0.3-0.4 m/s 0.4-0.5 m/s 0.5-0.6 m/s RO STRAIT 0.6-0.8 m/s 0.8-1.0 m/s 1.0-1.5 m/s 1.5-2.3 m/s Institute of Ocean Sciences. Tidal Current Velocities obtained from Mike Foreman's finite element model for eastern Juan de Fuca Strait and southern Strait of Georgia. Horizontal velocities averaged over the depth of the water column to calculate a horizontal Root Mean Square velocity at each point. m/s denotes metres/second. 17
Proposed ern Strait of Georgia National Marine Conservation Area Reserve Vertical Stratification PYLADES STUART Chemainus TRINCOMALI Cowichan Ganges Russell PRE VOST AGE Tumbo Mill Rum CORDOVA SIDNEY -2-0 mixed region RO STRAIT 0-1 mixed region 1-2 frontal region 2-4 stratified region 4-8 stratified region 8-16 stratified region Data Source: Fisheries and Oceans Canada. Tidal current velocities from Mike Foreman's finite element model were used to calculate vertical stratification using Simpson and Hunter 1974 model based on bottom friction. Values are shown as a dimensionless mixing parameter. 18