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

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, 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 limit In spring, Gotland Sea (a) Si conc. before the bloom 25 Mecklenburg Bight Si consumption by the bloom 20 Si [mmol/m³] 3 15 10 5 2 0 79 80 81 82 83 84 87 88 89 90 92 93 94 95 96 97 98 99 Year 1 (c) 30 Bornholm Sea 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 25 Si [mmol/m³] 20 Dinoflagellates Smoother & confidence interval 15 Smoother Upper limit Low er limit In spring, Gotland Sea 10 5 0 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 3 Year Changes also in zooplankton and fish, also North Sea  „Regime Shift “ 2 Wanted: Indicator for changes in the ecological state Wasmund, N. et al. (1998), J. Plankton Res. 20: 1099-1117. Wasmund, N. und Uhlig, S. (2003), ICES J. Mar.Sci. 60: 177-186. 1 Alheit et al. (2005), ICES J. Mar. Sci. 62: 1205-1215. 15.1.2015 1 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz Red Line = winter-minimum temperature 2 Wasmund et al. (2013): Journal of Plankton Research 35: 393-406; doi: 10.1093/plankt/fbs101

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 𝐂𝐣𝐩𝐧𝐛𝐭𝐭 𝐩𝐠 𝐞𝐣𝐛𝐮𝐩𝐧𝐭 𝐄𝐣𝐛/𝐄𝐣𝐨𝐩 𝐣𝐨𝐞𝐟𝐲 = 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) 3

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz 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 4

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz 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 5

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz Which areas to be separated? Coastal waters to be included? • 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 ? 6

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz 7

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz Addition of Polish data (1996-2013) without coastal data: • • Good agreement between calculation based Similar tendency of the phytoplankton data based on mean values and on maximum values. on wet weight and those based on carbon. • • Similar tendency of the phytoplankton data Good agreement since 2002 when probably and the data based on silicate consumption. diatom cells were smaller. 8

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz The Diatom/Dinoflagellate Index in spring (Feb-April) in historical and more recent years, according to Wasmund et al. (2008). Year Date of Date of dinoflagellate Dia-Dino index Original data diatom maximum source maximum 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 Dia/Dino indices in Kiel Bight, separated into open sea water and coastal water, for 2006-2010. 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 No need to separate open and coastal waters ? Where to define GES? At Dia/Dino index = 0.7 ? 9

Diatom/Dinoflagellate Index N. Wasmund, J. Göbel, A. Jaanus, M. Johansen, I. Jurgensone, J. Kownacka, K. Piwosz 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 Interpretation (example): If diatom bloom  „GES“ If no diatom bloom No diatoms grown, Diatoms grown but immediately grazed, → no Si consumption. → Si consumption. → alternative groups ( Dino‘s ) may grow → less nutrients for alternative phyto groups → problem for zoobenthos (and zooplankton ?) → good for zooplankton  very lowDia/Dino-Index, also after control → onla problem for zoobenthos ?  lowDia/Dino-Index, but correction after control by Si consumption data  „ bad state “ by Si consumption data  „ good state “ 15.1.2015 EuNäP-Sitzung 10