Inferences for Biological Transport:
Results from a West Coast Drift
Card Study
Vanessa M. Howard & Mark Sytsma
Portland State University
Alternative Ballast Water Exchange Areas Workshop
June 21, 2006 – Seattle, Washington
Outline
• Background
• Methods
• Results
– Return rates & recovery time
– Recovery patterns - spatial & seasonal
• Summary
Schwartzlose 1963
Background
• Circulation patterns/currents
www.noaanews.noaa.gov
(Schwartzlose 1963, Heath 1969, Dewees & Strange 1984)
• Situation of marine protected areas
(Klinger & Ebbesmeyer 2001)
• Sewage outfall (Crone et al 1998, Sauers et al 2001)
• Floating materials
– hypothetical oil spill (NOAA’s 2005 Safe Sancuary Drill in FL
Keys NMS)
– floating pollutants (NOAA’s 2002-04 Hawaii Drift Card
Study)
Objectives
Photo courtesy of NRCS
• Understand potential seasonal
&/or spatial patterns of ocean
dispersal from three heavily
infested bays
• Understand relative risk posed
by various Spartina species
• Identify common debris
collection zones
• Education & outreach
Methods – Card Design
• Buoyant plywood cards
(10 cm x 15 cm)
• Biodegradable - designed to
persist 3-6 months
• Coded for release date and
location
• NOAA specifications (Oahu,
Hawaii Drift Card Study
2002-2004)
Methods – Releases
• Three release locations
• September 2005 through
August 2005
• 200 cards
• Within two hours
of high tide
Willapa Bay
Humboldt Bay
San Francisco
Willapa
Humboldt
San Fran
Aug-05
Jul-05
70%
Jun-05
80%
May-05
Apr-05
Mar-05
Feb-05
Jan-05
Dec-04
Nov-04
Oct-04
Sep-04
# recovered/total released
Results – return rates
100%
90%
Willapa 41.8%
60%
50%
40%
30%
20%
10%
0%
Willapa
Humboldt
San Fran
Aug-05
Jul-05
Jun-05
70%
May-05
80%
Apr-05
Mar-05
Feb-05
Jan-05
Dec-04
Nov-04
Oct-04
Sep-04
# recovered/total released
Results – return rates
100%
90%
Humboldt 26.2%
60%
50%
40%
30%
20%
10%
0%
Willapa
Humboldt
San Fran
Aug-05
Jul-05
Jun-05
May-05
70%
Apr-05
80%
Mar-05
Feb-05
Jan-05
Dec-04
Nov-04
Oct-04
Sep-04
# recovered/total released
Results – return rates
100%
90%
San Francisco 43.8%
60%
50%
40%
30%
20%
10%
0%
Recovery time
1.0
% of total recovery
0.8
0.6
0.4
San Francisco
Humboldt Bay
Willapa Bay
0.2
0.0
0
50
100
150
200
250
300
Days after release
350
400
450
500
Results – bay vs. coast
# cards
1000
800
600
400
200
0
WB
HB
SF
bay
78
7
288
ocean
925
622
763
Results – near vs. long distance
1.00
0.90
0.80
0.70
>100 km
50-100 km
25-50 km
< 25 km
0.60
0.50
0.40
0.30
0.20
0.10
0.00
WB
HB
SF
WB releases
 Max North ~ 2,000 km
(129 days)
 Max South ~ 300 km
(227 days)
WB releases
Seasonal Patterns
Willapa:
Estimated velocities
mean (range)
SOUTH (km/d) NORTH (km/d)
Fall
4.13
(0.18-12.99)
2.75
(0.03-12.73)
Winter
---
6.51
(0.08-36.86)
Spring
2.58
(0.09-6.78)
2.11
(0.04-12.77)
Summer
2.88
(0.23-7.80)
2.84
(0.08-12.75)
HB releases
 Max North ~ 2,800 km
(214 days)
 Max South ~ 530 km
(45 days)
HB releases
Seasonal Patterns
Humboldt:
Estimated velocities
mean (range)
SOUTH (km/d) NORTH (km/d)
Fall
0.48
(0.02-5.28)
1.59
(0.02-13.46)
Winter
3.41
(0.02-11.15)
9.01
(0.02-24.52)
Spring
1.29
(0.02-6.17)
3.54
(0.05-12.47)
Summer
0.80
(0.02-4.91)
2.44
(0.04-10.49)
SF releases
 Max North ~ 630 km
(56 days)
 Max South ~ 400 km
(151 days)
SF releases
Seasonal Patterns
Known S. alterniflora x foliosa hybrid
San Francisco:
Estimated velocities
mean (range)
SOUTH
NORTH
Fall
1.41
(0.03-6.69)
2.02
(0.18-14.55)
Winter
1.19
(0.05-5.37)
2.95
(0.08-16.06)
Spring
1.45
(0.02-14.0)
2.61
(0.01-11.38)
Summer
1.51
(0.09-16.06)
1.95
(0.11-3.04)
Discussion
Limitations:
• Simulates surface transport only
• Does not account for life history
or behavior
• May underestimate velocities
• Does not account for inter-annual variation
Applications:
•
•
•
•
Knowledge of near-shore, coast-wise transport
Emphasizes seasonal nature of dispersal
Identifies likely collection zones
Inexpensive - allowing greater numbers of replicates
Summary
• Drift from these three locations has a large seasonal
component, generally following known patterns of
ocean currents
• Highest northward velocities & transport seen in WB & HB
winter releases
• Lower velocities & transport from SF
• Local deposition more likely than distant, although
rapid long-distance transport seen in certain instances
• Question of transport into estuaries?
• Additional releases of drift cards may help identify
collection zones
Acknowledgements
Funding
San Francisco Estuary Institute
Oregon Department of Agriculture
Washington Department of Fish & Wildlife
Collaborators
Kristen Ward, Golden Gate National Recreation Area (NPS)
Travis Haring, Russell Nunez, Les Holcomb and David Heimer, WDFW
Bill Pinnix, USDFW - Arcata office
Volunteers
Beachwatch (CA)
COOAST (WA & OR)
SOLV (OR)
Beachcombers, tourists, children & many others
Questions ?
700
Recoveries North
of release site
600
Willapa
Humboldt
San Fran
# of cards
500
400
300
200
100
0
< 25
25-50
50-100
distance (km)
>100
300
Recoveries South
of release site
250
Willapa
Humboldt
San Fran
# of cards
200
150
100
50
0
< 25
25-50
50-100
distance (km)
>100