Bridging GLEON sites with Gloeotrichia echinulata

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Bridging GLEON sites with Gloeotrichia echinulata

• Cayelan Carey1
• Kathleen Weathers2
• Kathryn Cottingham3
• Irene Karlsson-Elfgren1

1Uppsala University, Sweden 2Institute of
Ecosystem Studies, USA 3Dartmouth College, USA
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Gloeotrichia echinulata

• Toxic N-fixing cyanobacterium
• Discrete benthic and planktonic life stages
• Impact of blooms on a lake ecosystem

(1-2 mm)
(Istvanovics et al. 1993, Pettersson et al. 1993,
Jacobsen 1994, Forsell and Pettersson 1995,
Pettersson 1998, Hyenstrand et al. 2001,
Karlsson 2003, Karlsson-Elfgren et al. 2003,
Karlsson-Elfgren et al. 2005)
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Lake Erken, Sweden

• Long history of G. echinulata blooms in Lake
  Erken
• Documented relationships between light,
  temperature, stratification and G. echinulata
  recruitment

Lake Erken
Pierson et al. 1992, Forsell and Pettersson 1995,
Hyenstrand et al. 2001, Karlsson 2003,
Karlsson-Elfgren et al. 2003, Karlsson-Elfgren et
al. 2004, Karlsson-Elfgren et al. 2005
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Lake Sunapee, USA

• Recent G. echinulata outbreaks across the
  northeastern United States
• gt 27 oligotrophic lakes have exhibited blooms
  since 2002

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My questions

• What factors are causing G. echinulata to bloom
  in oligotrophic lakes? Do these mechanisms
  operate in eutrophic systems? Invasion or
  re-emergence?
• How do G. echinulata blooms impact an
  oligotrophic lake ecosystem?
• Lake phosphorus cycling, toxicity, phytoplankton
  and zooplankton community structure, and trophic
  status

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The role of sediment P in triggering G. echinulata

• G. echinulata is dependent primarily on P in the
  sediments, not water column
• Used field monitoring, lab experiments, and an in
  situ nutrient-diffusing experiment to examine the
  role of TP at the sediment-water interface on
  recruitment

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Lake monitoring results
2005 2006
G. echinulata recruitment rate is correlated with
pore water TP, lagged by 25 days (r 0.53).
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2005 Sediment TP and G. echinulata pulses
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2005 Sediment TP and G. echinulata pulses
Germination (1 week)
Phosphorus Absorption (2.5 weeks)
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Nutrient-diffusing experiment
P-diffusing tile
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Nutrient-diffusing experiment
Experimental P addition significantly increased
the rate of G. recruitment 22 days after the
start of the experiment (Matched pairs t-test,
one-sided P 0.0097).
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G. echinulata and eutrophication
Increased watershed development
G. echinulata increases lake eutrophication
processes
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Future Erken/Sunapee GLEON research

• Use routine monitoring data at both sites to
  evaluate other factors triggering G. echinulata
  recruitment (i.e. light, temperature, etc.)
• Can P pulses trigger G. echinulata blooms in
  Erken?
• Examine long-term database at Erken
• Toxicity analyses
• Comparing Swedish/U.S. G. echinulata phylogeny

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Acknowledgments

• U.S. Swedish Fulbright Commission
• Lake Sunapee Protective Association
• Northeast Aquatic Plant Management Society
• Jim Haney, Center for Freshwater Biology,
  University of New Hampshire
• Andrew W. Mellon Foundation
• National Science Foundation

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Questions?
Photo Karen Moore
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G. echinulata toxicity

• First toxicity study conducted on G. echinulata
  in Lake Sunapee produces 0.10 0.01 µg MC-LR
  g-1 dry wt. colonies
• At peak bloom conditions in Sunapee, MC-LR
  toxicity was 6 orders of magnitude below the WHO
  guideline
• In Lake Erken, however up to 5000 colonies L-1
  in 2004 (Eiler et al. 2006), toxicity may be
  within 2 orders of magnitude of water safety
  guideline
• Other toxicity effects