Diatom/Dinoflagellate Index N. Wasmund, J. Gbel, A. Jaanus, M. - - PowerPoint PPT Presentation

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Diatom/Dinoflagellate Index N. Wasmund, J. Gbel, A. Jaanus, M. - - PowerPoint PPT Presentation

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Diatom/Dinoflagellate Index N. Wasmund, J. Gbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz Silicate consumption as proxy for diatom growth in spring Diatoms Smoother & confidence interval Smoother Upper limit Low er

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SLIDE 1

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

1 15.1.2015

Changes also in zooplankton and fish, also North Sea  „Regime Shift“ Wanted: Indicator for changes in the ecological state

5 10 15 20 25 30

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

Si [mmol/m³] Year

Bornholm Sea (c)

5 10 15 20 25

79 80 81 82 83 84 87 88 89 90 92 93 94 95 96 97 98 99

Si [mmol/m³] Year

Si conc. before the bloom Si consumption by the bloom

Mecklenburg Bight (a)

Smoother & confidence interval Smoother Upper limit Low er limit 1999 1997 1995 1993 1991 1989 1987 1985 1983 1981 3 2 1 Smoother & confidence interval Smoother Upper limit Low er limit 1999 1997 1995 1993 1991 1989 1987 1985 1983 1981 3 2 1

Diatoms

In spring, Gotland Sea

Dinoflagellates

In spring, Gotland Sea

Wasmund, N. et al. (1998), J. Plankton Res. 20: 1099-1117. Wasmund, N. und Uhlig, S. (2003), ICES J. Mar.Sci. 60: 177-186. Alheit et al. (2005), ICES J. Mar. Sci. 62: 1205-1215.

Silicate consumption as proxy for diatom growth in spring

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SLIDE 2

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

2

Red Line = winter-minimum temperature

Wasmund et al. (2013): Journal of Plankton Research 35: 393-406; doi: 10.1093/plankt/fbs101

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SLIDE 3

3

Are changes in diatom and dinoflagellate spring blooms relevant for the ecosystem? Can they be used as indicators ? Approach: The indicator shows whether diatoms or dinoflagellates dominate in spring 𝐄𝐣𝐛/𝐄𝐣𝐨𝐩 𝐣𝐨𝐞𝐟𝐲 =

𝐂𝐣𝐩𝐧𝐛𝐭𝐭 𝐩𝐠 𝐞𝐣𝐛𝐮𝐩𝐧𝐭 𝐂𝐣𝐩𝐧𝐛𝐭𝐭 𝐩𝐠 𝐞𝐣𝐛𝐮𝐩𝐧𝐭 + 𝐂𝐣𝐩𝐧𝐛𝐭𝐭 𝐩𝐠 𝐞𝐣𝐨𝐩𝐠𝐦𝐛𝐡𝐟𝐦𝐦𝐛𝐮𝐟𝐭

If Dia/Dino index = 0 → only dinoflagellates If Dia/Dino index = 1 → only diatoms

Advantage:

  • Diatoms and dinoflagellates are the dominating groups (Baltic and world-wide)

 High biomass, therefore high relevance, high statistical confidence

  • Tax. Identification on group level easy, no errors

However: Differentiation autotrophic/mixotrophic versus heterotrophic dino‘s difficult. We want only„autotrophe/mixotrophe“, but heterotrophs not bloom-forming. Importance: Food for zooplankton (and zoobenthos). Question: Which group is the better food?  Dia/Dino-Index is more a foodweb indicator (D5) than a biodiversity indicator (D1), It may also serve as eutrophication indicator (if change from N- to Si-limitation)

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SLIDE 4

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

4

Practical problems and solutions:

  • Sampling: from the upper mixed layer (different strategies are accepted)
  • Unit of phyto biomasse optional (wet weigt or carbon), low influence as quotient is calculated.

Problems with large diatoms due to their high ww/C-ratio, will be discussed below. Perhaps different GES borders for wet weight and carbon.

  • Seasonal mean or maximum for calculation ?

Has surprisingly little influence (discussed below)

  • Differentiation autotrophic/mixotrophic versus heterotrophic Dino‘s difficult.

Little influence as bloom are mostly autotrophic, e.g.Peridiniella catenata, Gymnodinium corollarium

  • Besides of dinoflagellates, Mesodinium rubrum, may be dominant in the Baltic Proper.

We decided to neglect Mesodinium to keep the indicator simple.

  • Low sampling frequency. Especially diatom blooms can be overlooked.

Solution: Check on the basis of Si-consumption data.

Si in µM. Biomass of Dino‘s in carbon [µg/l]. If dinoflagellate biomass is given in wet weight, conversion to carbon units by factor 0.13

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SLIDE 5

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

5

General problems still to be solved Main problem: What is the „good state“ (GES) ? Are diatoms or dinoflagellates „good“ ? Does the ecosystem tolerate strong changes ? Preliminary solution: The „historical“ condition is „good“, strong (and sudden ?) changes are bad. Further problem: No measures possible to mitigate adverse changes

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SLIDE 6

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

6

  • Data from mean or max. similar, max. slightly higher
  • Index extends from 0 to 1, strong fluctuations
  • Expected decrease at end of 1980s visible
  • GES –border at 0,5 ?

Which areas to be separated? Coastal waters to be included?

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SLIDE 7

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

7

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SLIDE 8

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

8 Addition of Polish data (1996-2013) without coastal data:

  • Good agreement between calculation based
  • n mean values and on maximum values.
  • Similar tendency of the phytoplankton data

and the data based on silicate consumption.

  • Similar tendency of the phytoplankton data based
  • n wet weight and those based on carbon.
  • Good agreement since 2002 when probably

diatom cells were smaller.

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SLIDE 9

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

9 Year Date of diatom maximum Date of dinoflagellate maximum Dia-Dino index Original data source 1905 12.4.1905 12.4.1905 0.99 Lohmann (1908) 1906 11.4.1906 11.4.1906 0.87 Lohmann (1908) 1912 3.4.1912 3.4.1912 0.97 Busch (1916-1920) 1913 7.3.1913 13.2.1913 0.95 Busch (1916-1920) 1950 19.3.1950 30.3.1950 0.94 Gillbricht (1951) 2001 13.3.2001 26.3.2001 0.97 Göbel 2002 18.3.2002 2.4.2002 0.92 Göbel 2003 17.2.2003 17.2.2003 0.91 Göbel The Diatom/Dinoflagellate Index in spring (Feb-April) in historical and more recent years, according to Wasmund et al. (2008). Year Open sea water Coastal water 2006 0.94 0.95 2007 0.97 0.99 2008 0.86 0.97 2009 0.87 1.00 2010 0.99 0.99 Dia/Dino indices in Kiel Bight, separated into open sea water and coastal water, for 2006-2010.

No need to separate open and coastal waters ? Where to define GES? At Dia/Dino index = 0.7 ?

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SLIDE 10

Diatom/Dinoflagellate Index

  • N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz

10 EuNäP-Sitzung 15.1.2015

Interpretation (example): If no diatom bloom

No diatoms grown, → no Si consumption. → alternative groups (Dino‘s) may grow → problem for zoobenthos (and zooplankton ?)  very lowDia/Dino-Index, also after control by Si consumption data  „bad state“ Diatoms grown but immediately grazed, → Si consumption. → less nutrients for alternative phyto groups → good for zooplankton → onla problem for zoobenthos ?  lowDia/Dino-Index, but correction after control by Si consumption data  „good state“

Main problem: What is the „good state“ (GES) ? Are diatoms or dinoflagellates „good“ ? Does the ecosystem tolerate strong changes ? Preliminary solution: The „historical“ condition is „good“, strong (and sudden ?) changes are bad. Further problem: No measures possible to mitigate adverse changes

If diatom bloom

 „GES“