WINTER ECOLOGY 2005

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WINTER ECOLOGY 2005

• Field Course in Winter Ecology 21.02-24.02 at
  Mekrijarvi Research Station

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Lake Ecosystem in Winter

• Instructor Matti Leppanen
• Group Anna Arnkil
• Elisabeth Heigl
• Eva Pier
• Magdalena Madalinska
• Tarja Kainlauri
• Stefan Gerdes
• Tom Nagawiecki
• Jordi Canals

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The goal

• Proper water sampling
• Analize physical, chemical and biological
  parameters of lakes
• Compare both lakes over time

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Terrain of studies

• The terrain of studies comprised Iso-Suokko and
  Mekrijarvi Lakes
• The lakes are situated close to each other near
  Ilomantsi
• The lakes studied were different in depth and size

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Characteristic

• Iso-Suokko Lake
• The lake has small surface area-26 ha and 7m
  depth(max.depth 15m)
• Mekrijarvi Lake
• The lake has big surface area-894 ha and 1.7m
  depth(max.depth 3m)

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Physical chemical measurements

• DO (mg/L)
• pH
• Conductivity
• Colour
• Water temperature

• Water depth
• Secci
• Ice thickness
• Snow thickness

Mentionable material or methods used Ruttner
sampler, Kajak sampler, Secci disc and Winkler
method
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Physical and chemical measurements- Iso-Suokko -
22.02.2005 24.02.2005 Mean Surface
Bottom Surface Bottom
Surface Bottom
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Physical and chemical measurements- Mekrijärvi -
21.02.2005 23.02.2005 Mean
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Physical chemical measurements - Results

• both Lakes are cloudy (mean secci-depth is 0.34 m
  (IS)/0.37 m (M))
• both Lakes are acidic (pH about 5.5)
• both Lakes have a low ion concentration (gt soft)
• Iso-Suokko Lake is significant deeper than Lake
  Mekrijärvi (about 10 m / 2 m)
• both water bodies show humic features (typical
  for Finnish lakes)

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Physical chemical measurements - Results

• bottom oxygen-saturation-difference in comparison
  to 2003 in Iso-Suokko Lake
• longer fall in 2004 might be the explanation by
  longer influence of wind mixture

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Physical chemical measurements - Results
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Zoobenthos
animal life associated with substrate
of water bodies
Oligochaeta
Chaoboridae
Chironomidae
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Zoobenthos

• more taxa and higher number of individuals in
  Lake Mekrijärvi
• (most common Chironomidae (M IS) and
  Chaoboridae (IS)
• BUT Shannon-Weaver index analysis implies higher
  biodiversity at Lake Iso-Suokko
• Mekrijärvi 1.03 with maximum of 2.40
• Iso-Suokko 1.02 with maximum of 1,61
• (the higher the difference the less biodiv.)

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Zoobenthos summer/winter

• little number of samples and difference in years
  those were taken lower comparison reliability
• table indicates higher biodiversity in summertime
• some families present in both seasons (e.g.
  Chironomidae, Chaoboridae) while others (e.g.
  Oligochaeta) were absent or rare in winter

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Zooplancton

• most abundant taxa in
• Mekrijärvi Rotifera
• Iso-Suokko Copipoda
• according Lake Iso-Suokko there are more
  organisms at the surface compared to the bottom
• similar numbers in amount of individuals let
  doubt about data collection process (reliability)
  if difference in characteristica of both lakes is
  taken into account (trophic status, depth... )

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Zooplancton

• high deviation in Shannon-Weiner-index indicates
  little biodiversity in both lakes
• (dominant abundance of one/two taxa)
• same index shows more diversity for bottom
  compared to surface
• little data processed by many single persons has
  to be considered as arguable

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Zooplancton summer/winter

• general dogma about differences in summer/winter
  zooplancton populations
• higher input of sunlight -gt warmer water -gt
  better conditions for photosynthesis -gt higher
  population
• higher numbers of Cladocera in winter can be
  explained by life cycle of it (males not present
  in winter and also female breeding in summer)

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Zoobenthos - discussion

• Lake Iso-Suokko with more stable living
  conditions than Mekrijärvi due to depth and thus
  more stable oxygen and temperature stratification
• compared to earlier years higher biodiversity
  level (also because of late winter initiation?)

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Zooplancton - discussion

• lesser abundance of Chironomidae in summer is due
  to higher primary production and thus lesser
  oxygen content
• summer species diversity was higher in more
  shallow lake Mekrijärvi resulting from higher
  primary production and thus higher food supply
  for invertebrate organisms

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References

•   (1)           Huttunen, M. A. (ed.) 2004
  Field Course in Winter Ecology 2004 University
  of Joensuu, Department of Biology
  http//bio.joensuu.fi/winter/w2004.doc
• (2)                       Huttunen, M. A. (ed.)
  2003 Field Course in Winter Ecology 2003
  University of Joensuu, Department of Biology
  http//bio.joensuu.fi/winter/w2003.doc
• (3)                       Huttunen, M. A. (ed.)
  2002 Field Course in Winter Ecology 2002
  University of Joensuu, Department of Biology
  http//bio.joensuu.fi/winter/w2002.doc
• (4)                       Huttunen, M. A. (ed.)
  2001 Field Course in Winter Ecology 2001
  University of Joensuu, Department of Biology
  http//bio.joensuu.fi/winter/w2001.doc
• (5)                       Wetzel, R.G., 2001.
  Limnology, 3rd edition, Saunders College
  Publishing
• (6)                       Baumgartner, Albert
  Liebscher, Hans-Jürgen 1996 Allgemeine
  Hydrologie, Quantitative Hydrologie 2nd
  edition Gebrüder Borntraeger-Berlin-Stuttgart
• (7)                       Hütter, Leonhard A.
  1992 Wasser und Wasseruntersuchung 5th
  edition. Frankfurt am Main Otto Saale Verlag
  Verlag Sauerländer
• (8)                       Homepage of Mekrijärvi
  field station www.joensuu.fi/mekri/mekri.htm
• (9)                       Moss, Brain Ecology
  of Freshwaters 1980 Blackwell Scientific
  Publications
• (10)                       Lerman, Abraham (ed.)
  Lakes Chemistry, geology, physics 1978

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End of presentation Questions?