USING A TEMPERATURE-BASED GIS MODEL TO IDENTIFY POTENTIAL HABITAT FOR Zostera japonica IN HUMBOLDT BAY, CA Andrew E. Weltz Humboldt State University Department of Biological Sciences

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USING A TEMPERATURE-BASED GIS MODEL TO IDENTIFY
POTENTIAL HABITAT FOR Zostera japonica IN
HUMBOLDT BAY, CAAndrew E. WeltzHumboldt State
University Department of Biological Sciences
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Background on Non-Native Species

• What are they?
• Invasive species
• How do they get here . . . or anywhere?
• Potential impacts on native ecosystems
• Importance of predicting their spread

Image Sunluck International Shipping Ltd.
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Ecosystem Services

• Biodiversity
• Productivity
• Economics

• A very conservative and now old estimate of the
  economic value of seagrass beds is 20,000 ha-1
  year-1 (Costanza et al. 1997)
• Costanza, R., R dArge, R de Groot, S Faber, M
  Grasso, B Hannon, S Naeem and K Van den Belt.
  1997. The value of the worlds ecosystem services
  and natural capital. Nature 387 253-260

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Predicting Spread of Non-Native Species

• Understanding of
• Intrinsic properties of organism
• Properties of the environment/landscape

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Zostera japonica
Comparison between Z. marina and Z. japonica
Z. japonica growing on mudflat
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Non-Native Range and Spread
Map from Shafer et al. 2007
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What Have Local Managers Done So Far?

• Recent management decisions in Pacific North West
  (BC, WA, OR)
• Humboldt Bay eradication effort 2002-2011(CA)
• Bathymetry-based prediction for Humboldt Bay
  (Kauffman et al. 2006)

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Beyond BathymetryZ. japonica temperature vs.
growth
Shafer, D.J., S. Wyllie-Echeverria, and T.D.
Sherman. 2008. The potential role of climate in
the distribution and zonation of the indroduced
seagrass Zostera japonica in North America.
Aquatic Botany. 89 297 302.
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Approach Prediction Based on Temperature and Z.
marina Distribution

• Determine the spatial distribution of Z.
  japonicas optimal temp. range (20-30ºC) on
  Humboldt Bay mudflats
• Compare that distribution to current Z. marina
  range in Humboldt Bay to determine potential
  future Z. japonica habitat
• Nomme, KM and PG Harrison. 1991. Evidence for
  interaction between the seagrasses Zostera marina
  and Zostera japonica on the Pacific coast of
  Canada. Canadian Journal of Botany. 69
  2004-2010.

Z. japonica
Z. marina
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Methods

• Randomly selected
• temp. logger sites
• -Stratified by bay

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Dividing the Bay Into Areas of Optimal Habitat

• Determine proportion of time spent between 20-30
  C during 2010 for each temperature logger site
• Using ordinary kriging, interpolate proportions
  across mudflats to determine relative habitat
  optima for Z. japonica.

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Representative Temperature Curves
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Percent time within optimal temperature range and
Z. marina distribution
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Water Quality Monitoring Data

• 2009

• 2010

Data courtesy of
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• Warm Scenario ( 2 C)
• Percent time within optimal temperature range and
  Z. marina distribution

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Summary

• Warmer temperatures in North Bay provides most
  optimal habitat in both scenarios
• Cooler temperatures in South Bay are consistent
  with current absence of Z. japonica there
• Potential optimal habitat area in both bays is
  reduced by the presence of Z. marina

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Management Implications

• Local
• Current survey methods need to expand beyond
  perimeter of North Bay
• Surveys should be more inclusive of South Bay
  mudflat
• General
• Method adaptation

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Acknowledgements
Humboldt State University Dept. of Biological
Sciences, CA Dept. Fish and Game, U.S. Fish and
Wildlife Service, CA Sea Grant, HSU CeNCOOS, Dr.
Frank Shaughnessy, Dr. Erik Jules, Dr. Steven
Steinberg, Dr. Rob VanKirk, Dr. Michael Mesler,
Annie Eicher, Susan Schlosser, Dr. Deborah
Shafer, Megan Mach, Kirsten Ramey, Liz Weaver,
Steve Monk, Roxanne Robertson, Kirby Morejohn,
Chris Steenbock, Simona Augyte, Bethany Baibak,
Greg OConnell, Jose Montoya... and thanks to all
of you for coming!