Steve Bollens1,2, Jeffrey Cordell3, Sean Avent1, and Rian Hooff1

1
 Zooplankton Invasions Occurrences, Causes and
Consequences Two Case Studies from the Northeast
Pacific

• Steve Bollens1,2, Jeffrey Cordell3, Sean Avent1,
  and Rian Hooff1
• 1Romberg Tiburon Center for Environmental Studies
  and Department of Biology, San Francisco State
  University
• 2Moss Landing Marine Laboratories, California
  State University
• 3Fisheries Research Institute, School of Aquatic
  and Fishery Sciences, University of Washington

2
Acknowledgements

• Field and Lab Darren Gewant (SFSU), Anne
  Slaughter (SFSU), Dave Purkerson (SFSU), Harmon
  Brown (SFSU), and Alison Sanders (SFSU), Mikelle
  Rasmussen (UW), Olga Kalata (UW), Bill Couch
  (UW), Crew and Scientists of the RV Polaris
  (USGS)
• Discussions and Advice Bruce Frost (UW), Wim
  Kimmerer (SFSU) , Gretchen Rollwagen Bollens (UC
  Berkeley) and Jim Cloern (USGS)
•  
• WA State Sea Grant, LMER, CALFED, EPA, NSF,
  ONR

3
Outline

• Review the current state of research on biology
  of non- indigenous/invasive zooplankton
• Present overview of two on-going research
  projects as case studies
• Pseudiodiaptomus inopinus in Pacific
  Northwest estuaries
• Tortanus dextrilobatus in San Francisco Bay
• III. Recommendations for Future Research

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Terminology
Figure1. The eight colonizer types shown as the
result of the proposed classification scheme.
According to this scheme, Types 1,2 5, and 6 can
be considered successional colonizers, Types 3
and 7 can be considered novel, non-invasive
colonizers and Types 4 and 8 can be considered
novel, invasive Colonizers. It is recommended
that the word invader be used for colonizer Types
4 and 8. From M.A. Davis and K. Thompson (2000).
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
10
Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
12
Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Non-Indigenous Zooplankton ASFA/OA Literature
Review (taxa/publications)
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Pseudodiaptomus Picture
Pseudodiaptomus inopinus
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Abundance of Pseudodiaptomus inopinus in relation
to salinity in seven Pacific northwest estuaries
1000
750
P. inopinus (no. m-3)
500
250
0
0
5
10
15
Salinity (psu)
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Chehalis River Prey Selection Experiments
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Diet of Invertebrate Predators, Chehalis River,
7/98 11/99
Neomysis n 243 predators n 562 prey
Crangon juveniles n 667 predators n 1,272 prey
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Pseudodiaptomus inopinus Vertical
Distribution Chehalis River at 6 PSU Bottom
Salinity
Surface (1)
Mid (2)
Weighted Mean Depth
Bottom (3)
0600
1200
0600
0600
1200
1200
1800
1800
1800
0000
0000
Time
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Percent Contribution (by weight) of Neomysis in
Fish Diets, Chehalis River, 7/98 11/99
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Percent Contribution (by weight) of Neomysis in
Fish Diets, Chehalis River, 7/98 11/99
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Percent numerical composition of copepods across
salinity gradient in fourteen west coast
estuaries without Pseudodiaptomus inopinus
gt 10 psu
0 psu
Paracalanus sp.
E. americana
Cyclopidae
Corycaeus sp.
P. inopinus
Acartiura spp.
Acartia tonsa
E. affinis
Oithona similis
Other Copepods
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Percent numerical composition of copepods across
salinity gradient in fourteen west coast
estuaries without Pseudodiaptomus inopinus
Percent numerical composition of copepods across
salinity gradient in seven west coast estuaries
with Pseudodiaptomus inopinus
gt 10 psu
0 psu
Paracalanus sp.
E. americana
Cyclopidae
Corycaeus sp.
P. inopinus
Acartiura spp.
Acartia tonsa
E. affinis
Oithona similis
Other Copepods
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Percent numerical composition of copepods across
salinity gradient in seven west coast estuaries
with Pseudodiaptomus inopinus
gt 10 psu
0 psu
Paracalanus sp.
E. americana
Cyclopidae
Corycaeus sp.
P. inopinus
Acartiura spp.
Acartia tonsa
E. affinis
Oithona similis
Other Copepods
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Tortanus dextrilobatus
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Prey Selectivity of Tortanus dextrilobatus
Four replicates per treatment (_at_ rep 2
predators and 10 of each prey in 1 L jar)
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Change in Zooplankton Community Composition, 1980
v. 1997
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San Francisco Bay Zooplankton (gt500 µ) Composition
1997
1998
1999
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Summary of Case Studies

• Pseudodiaptomus inopinus
• First observed in the Northeast Pacific in 1990
• Broadly distributed in Washington and Oregon
  coastal river estuaries
• Abundant (lt 800 m-3) in the low salinity zone
  (2-6 psu)
• Predators show neutral selection between this and
  native copepods in experiments
• Vertical distribution is closely associated with
  the bottom during the day
• Important prey item of the bentho-pelagic
  invertebrates, but not pelagic fishes, in the
  Chehalis River
• Suggestive of ecosystem change from pelagic to
  bentho-pelagic production?

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Summary of Case Studies

•  
• Tortanus dextrilobatus
•  
• First observed in San Francisco Bay in 1992
• Broadly distributed in San Francisco Bay
• Abundant (lt 104 m-3) in both North and South Bays
• Selects larger, native copepods over smaller, NIS
  copepods in experiments
• Is one of several other NIS copepods that has
  resulted in a dramatic change in community
• composition in SF Bay in last 20 yrs.
• Implications for higher trophic levels and
  ecosystem productivity currently unknown

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Recommendations for Future Research
Occurrences We need to keep looking (e.g., Evadne
spinifera in Port Hueneme, CA) Causes Wide
variety of vectors and mechanisms of dispersal
under study. Larger role for molecular
genetics. Consequences Impacts at the community
and ecosystem levels are particularly
understudied (or simply absent?)   Modeling
and experimental manipulation (e.g., enclosures)
could be fruitful
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Ongoing Projects
Thin Layers
ONR