The following supplement accompanies the article Phases of microalgal succession in sea ice and the water column in the Baltic Sea from autumn to spring Sara Enberg*, Markus Majaneva, Riitta Autio, Jaanika Blomster, Janne-Markus Rintala *Corresponding author: [email protected] Marine Ecology Progress Series 599: 19–34 (2018) 20 15 25 10 20 5 15 0 -5 10 Percipitation (mm) Air temperature (°C) -10 5 -15 -20 0 X XI XII I II III IV V Month Fig. S1. Mean air temperature (°C, black line) and precipitation (mm, blue bars) throughout the cold-water season from the beginning of October until the end of May at Tvärminne weather station (Finnish Meteorological Institute). 1 Fig. S2. Water temperature (°C) throughout the cold-water season from the beginning of October until the end of May at Krogarviken (site A) in the 0–3-m layer (a) and Storfjärden (site B) in the 0–15-m layer (b). The period from the beginning of January to the end of April represents the ice-covered season. 2 Fig. S3. Water salinity throughout the cold-water season from the beginning of October until the end of May at Krogarviken (site A) in the 0–3-m layer (a) and Storfjärden (site B) in the 0–15-m layer (b). The period from the beginning of January to the end of April represents the ice-covered season. 3 Fig. S4. Seasonal succession of the number (N) of OTUs in ice (a, b), under-ice water (UIW; c, d), the 0–3-m layer (e) and 0–15-m layer at Krogarviken (A) and Storfjärden (B), October−May. 4 Table S1. Nutrient concentrations (mmol m-3) from the ice, under-ice water (UIW) and the 0–3-m layer at Krogarviken (site A) and from the ice, UIW and the 0–15-m layer at Storfjärden (site B). NH4-N NO3+NO2-N Tot-N PO4-P Tot-P SiO4-Si 8.10.2012 A 0–3 M 0.6 1.3 27.8 0.4 0.7 12.3 B 0–15 M 0.8 1.0 27.9 0.4 0.8 12.8 29.10.2012 A 0–3 M 1.5 2.9 27.0 0.5 0.8 19.5 B 0–15 M 1.5 2.6 26.8 0.6 0.9 16.9 19.11.2012 A 0–3 M 0.8 4.5 27.4 0.6 0.9 15.0 B 0–15 M 0.6 4.4 27.0 0.7 0.9 14.8 10.12.2012 A 0–3 M 0.4 6.9 31.4 0.7 0.9 22.1 B 0–15 M 0.1 6.3 27.6 0.8 1.0 18.0 7.1.2013 A ICE 1.4 4.2 33.9 0.2 1.5 8.6 A UIW 1.1 9.8 41.2 0.8 1.1 26.1 A 0–3 M 0.6 10.4 34.2 0.8 1.0 26.3 14.1.2013 A ICE 0.7 3.2 22.9 0.2 1.0 6.5 A UIW 0.6 8.8 39.5 0.8 1.1 27.8 A 0–3 M 0.4 8.5 35.9 0.8 1.1 26.6 B ICE 0.7 3.9 21.0 0.3 0.5 12.1 B UIW 0.8 9.6 36.5 0.8 1.0 30.1 B 0–15 M 0.0 8.0 31.6 0.8 1.1 21.4 21.1.2013 A ICE 1.4 4.0 24.0 0.2 0.7 7.0 A UIW 2.2 17.2 57.4 0.7 1.1 52.8 A 0–3 M 0.9 11.6 41.4 0.8 1.1 35.7 B ICE 0.8 5.7 26.2 0.3 0.6 14.7 B UIW 2.1 25.6 76.7 0.6 1.2 77.0 B 0–15 M 0.2 8.2 34.5 0.8 1.1 26.9 11.2.2013 A ICE 2.2 4.0 23.7 0.2 0.6 8.1 A UIW 2.0 22.1 56.0 0.6 1.0 68.0 A 0–3 M 0.7 13.7 38.4 0.8 1.0 35.3 27.2.2013 A ICE 1.7 5.1 29.1 0.1 0.8 16.1 A UIW 3.3 19.3 60.0 0.6 1.0 71.7 A 0–3 M 1.0 11.2 39.5 0.8 1.1 36.9 B ICE 1.0 3.0 23.7 0.1 0.8 12.4 B UIW 2.4 21.6 60.5 0.5 0.9 72.6 B 0–15 M 0.2 10.2 32.4 0.9 1.1 23.8 11.3.2013 A ICE 1.4 2.6 27.7 0.2 1.0 9.7 A UIW 4.3 12.3 58.3 0.6 1.0 66.6 A 0–3 M 1.1 8.6 38.0 0.8 1.1 34.0 B ICE 1.2 4.0 24.8 0.1 0.5 7.3 B UIW 3.0 15.8 59.3 0.5 0.9 74.6 B 0–15 M 0.2 6.8 33.4 0.8 1.1 22.7 8.4.2013 A ICE 1.5 2.2 22.2 0.2 0.9 5.8 A UIW 2.4 32.6 50.5 0.5 1.0 68.1 A 0–3 M 0.8 19.1 34.1 0.7 1.1 29.5 B ICE 0.9 5.4 20.0 0.1 0.6 6.9 B UIW 0.5 38.9 54.3 0.3 1.0 62.5 B 0–15 M 0.0 7.1 28.0 0.6 1.0 19.5 15.4.2013 A ICE 1.3 1.4 23.7 0.2 0.8 4.3 A UIW 0.3 10.0 45.0 0.2 1.8 31.9 A 0–3 M 0.1 5.3 34.0 0.3 1.5 21.6 B 0–15 M 0.1 4.2 24.6 0.4 1.0 15.9 29.4.2013 A 0–3 M 0.0 0.0 24.6 0.1 0.8 9.3 B 0–15 M 0.0 0.0 22.2 0.2 0.7 9.9 8.5.2013 A 0–3 M 0.1 0.0 34.8 0.1 0.6 5.9 B 0–15 M 0.0 0.0 34.1 0.1 0.6 6.5 13.5.2013 A 0–3 M 0.1 0.0 24.4 0.0 0.7 3.1 B 0–15 M 0.0 0.0 20.2 0.1 0.5 4.5 5 Table S2. List of encountered species and taxa. Site A Site B Cyanobacteria: 0-3 m UIW Ice 0-15 m UIW Ice Anabaenopsis sp. V.V.Miller, 1923 x Aphanizomenon sp. A.Morren ex Bornet & x x x x x x Flahault, 1888 Aphanocapsa sp. Nägeli, 1849 x Cuspidothrix sp. Rajaniemi, Komárek, x Willame, Hrouzek, Ka, 2005 Dolichospermum sp. Thwaites, 1850 x x Lemmermanniella sp. Geitler, 1942 x Limnothrix sp. Meffert, 1987 x Merismopedia sp. Meyen, 1839 x x Nodularia spumigena Mertens ex Bornet & x x x Flahault, 1886 Nodularia sp. Mertens ex Bornet & Flahault, x x x 1886 Planktothrix sp. Anagnostidis & Komárek, x x 1988 Planktolyngbya sp. Anagnostidis & Komárek, x x x x x 1988 Pseudanabaena sp. Lauterborn, 1915 x x x x x x Snowella sp. Elenkin, 1938 x x x Spirulina sp. Turpin ex Gomont, 1892 x Woronichinia sp. Elenkin, 1933 x x x x x Charophyta: Klebsormidiophyceae Elakatothrix sp. Wille, 1898 x Klebsormidium flaccidum (Kützing) x x x x x P.C.Silva, K.R.Mattox & W.H.Blackwell, 1972 Prasinophyceae Pyramimonas sp. Schmarda, 1849 x x x x x Zygnematophyceae Closterium sp. Nitzsch ex Ralfs, 1848 x Cosmarium sp. Corda ex Ralfs, 1848 x Chlorophyta: Chlorophyceae Chlamydomonas caudata Wille, 1903 x x x x Chlamydomonas sp. Ehrenberg, 1833 x x x x x x Desmodesmus sp. (R.Chodat) S.S.An, x T.Friedl & E.Hegewald, 1999 Monoraphidium cf contortum (Thuret) x x x x Komárková-Legnerová, 1969 Monoraphidium sp. Komárková-Legnerová, x x x x x x 1969 Pyrobotrys sp. Arnoldi, 1916 x x Scenedesmus sp. Meyen, 1829 x x x Tetraëdron minimum (A.Braun) Hansgirg, x 1888 6 Trebouxiophyceae Crucigenia quadrata Morren, 1830 x x Crucigenia tetrapedia (Kirchner) Kuntze, x 1898 Oocystis sp. Nägeli ex A.Braun, 1855 x x Planctonema sp. Schmidle, 1903 x x x Choanozoa: Choanoflagellatea Parvicorbula socialis (Meunier) Deflandre, x 1960 Unidentified choanoflagellate x x x x x x Cryptophyta: Cryptophyceae Unidentified cryptophytes x x x x x x Telonemea Telonema sp. Griessmann, 1913 x x x x x x Euglenozoa: Euglenoidea Anisonema sp. Dujardin, 1841 x Euglena sp. Ehrenberg, 1830 x x x x x x Eutreptiella sp. A.da Cunha, 1914 x x x x Trachelomonas sp. Ehrenberg, 1835 Haptophyta: Prymnesiophyceae Chrysochromulina birgeri Hällfors & Niemi, x x x x x x 1974 / Prymnesium sp. Massart, 1920 Myzozoa: Dinophyceae Cladopyxis sp. Stein, 1883 x Dinophysis sp. Ehrenberg, 1839 x x Gonyaulax sp. Diesing, 1866 x Gymnodiales Gyrodinium sp. Kofoid & Swezy, 1921 x x Heterocapsa arctica subsp.