Seabird Responses to Variability in Coastal Upwelling at Multiple Time Scales J

PRBO Conservation Science

Seabird responses to variability in coastal upwelling at multiple time scales J. Jahncke, J.E. Roth, M.L. Elliott, R.W Bradley, B.L. Saenz, P. Warzybok, C.L. Abraham, N.J. Karnovsky PRBO Conservation Science Outline

• Brief overview

• Long time scales - Ocean conditions - Seabird responses

• Short time scales - Upwelling forcing - Ecosystem responses

Photo: Jan Roletto PRBO Conservation Science Upwelling in the California Current has increased

• Bakun’s (1990)

Increase upwelling

• Snyder et al. (2003) predictions (SF – North)

Further increases in upwelling intensity

Delay in upwelling PRBO Conservation Science Long term changes in upwelling (Bakun revisited)

300 • Significant increase trend 250 in upwelling from 1946 to 200 150 2007 100 r2 = 0.13 Upwelling Index 50 p = 0.004 0 1946 1956 1966 1976 1986 1996 2006 Year 300 250 • Slight decrease in 200 upwelling from 1972 to 150 100 r2 = 0.03

2007 Upwelling Index 50 p = 0.35 0 1972 1977 1982 1987 1992 1997 2002 2007 Year

Roth et al. (in prep) PRBO Conservation Science Stable temperature and earlier spring transitions

• Slight increase in sea 13 surface temperature 12

SST 11 from 1972 to 2007 r2 = 0.03 10 p = 0.34 9 1972 1977 1982 1987 1992 1997 2002 2007 Year 140 • Significant change 120 100 towards earlier spring 80 60 r2 = 0.14 transitions from 1972 to Date Julian 40 20 p = 0.02 2007 0 1972 1977 1982 1987 1992 1997 2002 2007 Year

Roth et al. (in prep) PRBO Conservation Science Long time scales

Are seabirds responding to changes in ocean conditions?

Modeled median egg-laying dates and breeding success as a function of upwelling, temperature and spring transition date. PRBO Conservation Science Cassin’s auklets

Small birds (23 cm; 150-200 g)

Max dive ~ 40 m Zooplanktivorous (80% krill)

Breeding success correlates with krill abundance (Abraham and Sydeman 2004) PRBO Conservation Science Cassin’s auklets – A Good Sentinel Species

Cassin's Auklet Median Laydate 180 160 r2 = 0.03 140 p = 0.29 120 100 Julian Date Julian 80 60 1970 1980 1990 2000 2010 Year

1.4 CAAU Breeding Success r2 = 0.02 1.2 p = 0.39 1 0.8 0.6 0.4 0.2

Numb. of chicks Numb. 0 1970 1980 1990 2000 2010 Year

Roth et al. (in prep) PRBO Conservation Science Temperature important to auklet timing

Variable Variable Sign Importance

UI 0.47 + 140

2 UI 0.13 + 130 LATE Breeding

SST 0.99 + 120

110 SST2 0.32 + 100

DATE 0.62 - 90 WARM CAAU predicted laydate predicted CAAU

DATE2 0.34 + 80 -2 -1 0 1 2 Sea surface temperature anomaly SST x UI 0.38 -

Roth et al. (in prep) PRBO Conservation Science Upwelling and date important to breeding success

Variable Variable Importance Sign UI 0.99 + UI2 0.31 + SST 0.70 + SST2 0.43 - DATE 0.87 + DATE2 0.78 - UI x SST 0.47 +

1.6 1 HIGH Success HIGH Success 1.2 0.8

0.8 0.6 success

0.4 0.4 STRONG CAAU predictedCAAU breeding Window Optimal 0 0.2 -40 -20 0 20 40 60 45 65 85 105 125 Upwelling anomaly Spring transition date Roth et al. (in prep) PRBO Conservation Science Summary – LONG TIME SCALES

1. Earlier spring transitions and slight weakening of upwelling and warming ocean from 1972 – 2007.

2. Egg-laying date related to sea surface temperature.

3. Breeding success related to spring transition date and upwelling. PRBO Conservation Science At short time scales

What are the mechanisms that lead to changes in egg-laying date and breeding success?

Conducted cruises to examine how ocean processes influence the ecology of Cassin’s auklets. PRBO Conservation Science Research cruises around Farallon Islands

L2 RV John H. Martin

SE Farallon L6 Island NOAA McArthur II PRBO Conservation Science Surveys include predators, prey and ocean

• Birds/mammals (standardized strip and line transects) • Zooplankton/fish (hydroacoustics and nets) • Oceanography (CTD casts and continuous CT and fluorometry) PRBO Conservation Science Great variability in ocean conditions

0.5 NOAA Buoy Data - Bodega 1982 – 2008

0.0 2004 -0.5 2005 -1.0 2006 Alongshore Wind (Cumulative, m/s) -1.5 2007 1151101151 51 101 151 2008 15 13 11 9

Sea Surface 1 51 51 101 101 151 151 201 201 Temperature (C°) Julian day PRBO Conservation Science Less acoustic krill available in upper 200-m ) 2

40 ~1 inch

0 Mean biomass (g/m Mean biomass cells identified as krill cells identified July July July Feb Oct Oct Oct May May May May June June June Sept Sept April

2004 2005 2006 2007 Upper 200 m PRBO Conservation Science Large and densely aggregated flocks of auklets

2004 PRBO Conservation Science Small and loosely dispersed flocks of auklets

2005 2006

2008 2007 PRBO Conservation Science Cassin’s auklets feed on krill – mostmost ofof thethe timetime

1 Other Pices Amphipods 0.5 Mysids Euphausiids Proportion by number 0 1970 1975 1980 1985 1990 1995 2000 2005 2010 PRBO Conservation Science Cassin’s auklets on the rebound

1.5 Mean productivity = 0.67 1.0

0.5

Number of Number of 0.0 Chicks raised 1970 1975 1980 1985 1990 1995 2000 2005 2010 PRBO Conservation Science Summary – SHORT TIME SCALES

1. Variability in ocean conditions can lead to rapid changes in zooplankton communities and decrease in krill.

2. Dense layers of krill and aggregated flocks of auklets in 2004. Thin layers of krill and scattered flocks of birds in other years (2005-2008). PRBO Conservation Science

Even finer scales… Time-Depth-Recorders on auklets

70-85% of dives are less than 10 m

0.8 0.7 May 0.6 June 0.5 0.4 0.3 0.2 0.1

Frequency of dive depths dive of Frequency 0 1.5-5 5.0-10 10.0- 15.0- 20.0- 25.0- 30+ 15 20 25 30 Depth (m)

Karnovsky et al. (in prep) PRBO Conservation Science Further warming of the ocean will affect auklets

Karnovsky et al. (in prep) Photo: Glen Tepke Photo: Glen PRBO Conservation Science Conclusion

1. Earlier spring transition, slight weakening of upwelling and slight warming of the ocean.

2. Ocean conditions affect timing of breeding and productivity of auklets on the Farallon Islands.

3. Ocean conditions lead to decreased prey availability and low auklet breeding success.

4. Deepening of upper mixed layer may further reduce krill availability with negative consequences for the auklets. PRBO Conservation Science Acknowledgements

PRBO staff, interns, volunteers.

Gerry McChesney, United States Fish and Wildlife Service

Lisa Etherington, Cordell Bank National Marine Sanctuary Jan Roletto, Gulf of the Farallones National Marine Sanctuary

Moira Galbraith, Institute of Ocean Sciences, Canada Rachel Fontana and John Largier, Bodega Marine Laboratory Zachary Brown, Charlotte Chang, Andre Cavalcanti, Pomona College

Nancy Kachel and Carol Ladd, Pacific Marine Environmental Lab. Pacific Fisheries Environmental Lab.

Resources Legacy Fund Foundation National Fish and Wildlife Foundation Moore Family Foundation California Sea Grant