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NW Georges Bank Salinity Anomaly (0-30m) 0.5 0.0 -0.5 -1.0 1975 1980 1985 1990 1995 2000 Broad Scale Chlorophyll vs Salinity – Ted Durbin 2 Jan 1.5 Feb Chlorophyll 1 Mar Apr 0.5 May June 0 -0.5 -1 y = -36.961x + 0.000 r 2 = 0.180 -1.5 -0.015 -0.01 -0.005 0 Salinity 0.005 0.01 0.015 Normalized deviations of Georges Bank monthly mean salinity vs chlorophyll. The slope is significantly different from zero, p<0.01. There was no significant relation between temperature and chlorophyll, or between temperature and salinity (p>0.05). Broad-scale copepod summary – Ted Durbin Interannual Variability: All of the dominant copepods on Georges Bank show similar patterns of variability between years. 3 Mean Seasonal mean Georges Bank normalized deviations of the total population of each of the dominant copepods for each year together with the overall mean for the total Mean Normalized Deviation Calanus Pseudocalanus 2 Centropages Oithona copepod population. Temora 1 Metridia 0 -1 1994 1995 1996 1997 1998 1999 2000 Larval Growth Rates vs Prey – Larry Buckley & Ted Durbin Pseudocalanus Prey for 7 mm Cod Cod Haddock 96 98 95 97 99 R esidual Grow th d( - 1) 0 .0 2 0 .0 1 0 .0 0 -0 . 0 1 -0 . 0 2 Haddock 4.5 –7 mm -0 . 0 3 r2 = 0.58 p<0.01 -0 . 0 4 -1 . 0 0 -0 . 6 0 -0 . 2 0 0 .2 0 0 .6 0 Normalized Residual Prey 1 .0 0 Broad-scale larval analyses: 12 10 Haddock Cod 8 Early larval mortality rate (ppd) 6 4 2 0 1994 1995 1996 1997 1998 1999 2000 10 8 Early Larval Mortality Early larval mortality rate (cod and haddock) vs Salinity anomaly 6 4 2 0 -1.2 -1.0 -0.8 -0.6 Salinity Anomaly (…and survivorship correlated with recruitment) -0.4 -0.2 0.0 GB Salinity Anomaly vs Gulf Stream Position 250 0.5 300 0.0 350 400 -0.5 450 -1.0 -1.5 1992 500 1994 1996 1998 2000 2002 (Gulf Stream position from Tom Rossby) Connections from: Physical conditions to Chlorophyll to Zooplankton to Larval growth and survival to Recruitment Physical conditions reflecting the ocean’s response to climate scale forcing GLOBEC! No dynamics yet – go back to the beginning: what’s up with the salinity? 0.5 0.0 -0.5 -1.0 1990 1992 1994 1996 1998 2000 2002 Gulf of Maine Inflows 44.5 44.5 44 44 43.5 43.5 43 43 42.5 42.5 42 42 41.5 41.5 41 41 40.5 40.5 40 -71 40 -71 -70.5 -70 -69.5 -69 -68.5 -68 -67.5 -67 -66.5 -66 -65.5 -65 1976-1979 -64.5 -70.5 -70 -69.5 -69 -68.5 -68 -67.5 -67 -66.5 -66 -65.5 -65 -64.5 -64 -64 1993-1996 More inflow of water from the Scotian Shelf (…lower in salinity) during the 1990’s (i.e., not originating locally – but coming from outside the region) GoM Salinity Anomaly (0-30m) 1 0 -1 GBas 1975 1980 1985 1990 1995 2000 1980 1985 1990 1995 2000 1985 1990 1995 2000 1985 1990 1995 2000 1 0 -1 JBas 1975 1 0 -1 WBas 1975 1980 1 0 -1 GBnk 1975 1980 Wilkinson Basin Temperature 150-200m 8 7 MARMAP – filled circles 1990’s – open circles 6 5 4 0 100 200 300 Calendar Day Low surface layer salinities shut down winter convective cooling Temp Anomaly (150-200m) 3 2 1 0 R2 = 0.68 -1 -1.5 -1.0 -0.5 0.0 0.5 1.0 Salinity Anomaly (0-30m) (Taylor and Mountain, submitted) April Chlorophyll in Wilkinson Basin (from SEAWIFS, courtesy of J. O’Reilly) 3.4 3.2 3.0 April Chlorophyll 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 -1.5 -1.0 -0.5 Surface Salinity Anoamly 0.0 0.5 OK, still – where is it coming from? NW Georges Bank Salinity Anomaly (0-30m) Salinity Anomaly 1.0 0.5 0.0 -0.5 -1.0 1975 1980 1985 1990 1995 2000 Year O18 analysis indicates the low salinity in the 1990’s is from high latitude. NW Georges Bank Salinity Anomaly (0-30m) Salinity Anomaly 1.0 0.5 0.0 -0.5 -1.0 1975 1980 1985 1990 Year 1995 2000 Labrador Current Transport (shifted one year) And Georges Bank Salinity Anomaly 0.5 ds 0.0 3.0 -0.5 3.2 -1.0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 lctsmooth 2.8 Could the changes we have seen on Georges Bank be related to the changes in the Arctic and in the large-scale North Atlantic Ocean? A direct connection between climate change and the Georges Bank ecosystem (?) 3 Questions: Is influence of the low salinity through: physics (i.e., stratification/mixing)? nutrients? resident plankton populations? some combination of these? Where is the influence of the low salinity occurring: in the Gulf of Maine and result transported to GB? on Georges Bank itself? both in the GoM and GB? What is the origin of the low salinity event? Is it related to changes in the Arctic? Was it progressive & episodic through the 90’s (connection to the Arctic gives us a seat at the Climate Change table)