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Cyanobacterial blooms in the Baltic Sea - HELCOM

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HomeAbout UsHELCOM at workBaltic Sea trendsCurrently selectedAction areasBaltic Sea Action Plan > SIGN-IN Cyanobacterial-blooms-in-the-Baltic-Sea   Holistic assessmentsBiodiversityEutrophicationHazardous substancesMaritimeEnvironment fact sheetsData & MapsPollution Load CompilationsIndicators Environment fact sheet procedureBiodiversityEutrophicationUnusual phytoplankton eventBacterioplankton growthChlorophyll-a concentrations, temporal variations and regional differences from satellite remote sensingCyanobacteria biomassCyanobacteria viridity indexCyanobacterial blooms in the Baltic SeaImpacts of invasive phytoplankton species on the Baltic Sea ecosystem in 1980-2008Nitrogen atmospheric deposition to the Baltic SeaNitrogen emissions to the air in the Baltic Sea areaPhytoplankton polity compositionShifts in the Baltic Sea summer phytoplankton communities in 1992-2006Spatial distribution of the winter nutrient poolHazardous substancesHydrographyMaritime activities HomeBaltic Sea trendsEnvironment fact sheetsEutrophicationCyanobacterial blooms in the Baltic Sea Cyanobacterial blooms in the Baltic Sea in 2017 ​HELCOM Baltic Sea Environment Fact Sheet 2017, Published on 25 January 2018.​Author: Jörgen Öberg - Swedish Meteorological and Hydrological Institute Key Message In 2017, wide-stretching surface blooms of cyanobacteria were observed supremely from the second week of July through mid-August. The first indications of subsurface blooms were noted uncommonly early on May 18, but windy and dank conditions in June elapsed the major viridity until July. The sea zone most unauthentic by surface blooms was the Northern Baltic Proper. In comparison with previous years, the indexes of normalized intensity and normalized extent were lower than stereotype for the 2017 bloom, the normalized elapsing was well-nigh average. However, the indexes recorded from 2010 onwards should not be directly compared with the 1997 to 2009 values, as an improved detection method is now used.Satellite data from the MODIS sensor on EOS-Aqua and the VIIRS sensor on Suomi-NPP were used in the summer of 2017. Results and AssessmentRelevance of the BSEFS for describing developments in the environment Nitrogen fixation by cyanobacteria is a significant source of nitrate to the Baltic Sea. The value of misogynist phosphate in the surface water, the water temperature and weather conditions during the summer are important factors regulating the intensity of cyanobacteria viridity in the Baltic Sea. The surface water phosphate concentrations in the Baltic Proper were well-nigh stereotype in May, but consumed during the rest of the summer. (See SMHI, https://www.smhi.se/en/publications/cruise-reports-from-the-marine-monitoring). AssessmentAn unusually warm second half of May set off the cyanobacteria viridity once on the 18th in the southernmost part of the Eastern Gotland Basin. As persistent winds continuously mixed the water in June, surface blooms were increasingly or less woolgathering in large parts of the Baltic Proper until the whence of July.As zaftig amounts of cyanobacteria were present in the water, surface blooms increased rapidly as the winds ceased in July. The peak was noted on July 22, when well-nigh 109 000 km2 of cyanobacteria blooms were recorded from satellite data. A transit into windier August conditions meant a ripen of the cyanobacteria bloom, which from mid-August was scrutinizingly over in the Baltic Proper. Surface blooms of cyanobacteria were present in the southern Bothnian Sea mainly from the last week of July, and peaked in mid-August. Although the unshut sea blooms were over by the start of September, local coastal blooms were reported until the end of the month. During the viridity season from mid-May through August, SMHI undertook three monitoring cruises in on the Finnish Environment Institute's research vessel R/V Aranda. The trip tracks mainly went through the Baltic Proper, but the western part of the Gulf of Finland was moreover covered. See detailed reports on https://www.smhi.se/publikationer/2.1054, nos. 5-7 2017. Grains or aggregates of cyanobacteria were found in the water samples on all cruises, with Aphanizomenon flos-aquae stuff the most well-healed species in May, and Nodularia spumigena dominating in June. The July trip featured medium to upper amounts of Dolichospermum sp., Aphanizomenon flos-aquae and Nodularia spumigena in the water samples. Surface blooms were only observed in the July cruise, supremely in the Eastern and Western Gotland basins, and in the Northern Baltic Proper. To be worldly-wise to compare blooms between variegated years, the definitions of viridity normalized elapsing (T), extent (A) and intensity (I) have been developed. Based on the yearly summaries (see example in Figure 1) where the zone (ai) is equal to the extent that is covered by surface accumulations of blooms during (i) number of days, the normalized elapsing and extent is given, with (i) ranging from 1 to the maximum number of days with viridity observations during the current year. The intensity is given in "extent days" or km2 days. (Hansson, 2006 & Hansson & Håkansson, 2007). The total time series of satellite image wringer of cyanobacteria blooms in the Baltic Sea region is presented in the last two figures, where the current wringer method has been used since 2010 (Figure 3). Although no comparison with the years 1997-2009 (Figure 4) should be made since the detection procedure has reverted and the time series have not been corrected, the normalized viridity intensity was 15 679 km2days and elapsing 4.8 days, whereas the normalized extent was 3278 km2. The maximum zone covered by cyanobacteria blooms (~109 000 km2) was observed on July 22. In all, the cyanobacteria viridity of 2017 viridity can be considered to be unelevated average.   Figure 1. Daily extent of cyanobacteria blooms in the Baltic Sea during 2017, detected by MODIS and VIIRS satellite imagery. Red bars correspond to surface viridity and yellow bars indicate subsurface bloom. The undecorous line represents the integrated deject imbricate (in percent of the total area) over the whole analysed area.Figure 2. Number of days during 2017 with surface blooms of cyanobacteria observed in each pixel based on MODIS and VIIRS satellite data.Figure 3. Summary of number of days with cyanobacterial blooms observed in each pixel during the period 2010-2016. Note that comparison between these results and results from the period 1997-2009 should not be made since the detection method is different.Figure 4. Summary of number of days with cyanobacterial observed in each pixel during the period 1997-2009, based on NOAA-AVHRR satellite imagery. Year 2001 is missing. Note that comparison of the results from 2010-2016 with previous years should not be made since the detection method is different. References Hansson, M., P. Pemberton, B. Håkansson, A. Reinart, K. Alikas. Operational nowcasting of algal blooms in the Baltic Sea using MERIS and MODIS.  ESA Living Planet Symposium, Bergen 28-Jun to 02-Jul-2010, Special Publication SP-686, 2010. Hansson, M., &  B. Hakansson, 2007, "The Baltic Algae Watch System - a remote sensing using for monitoring cyanobacterial blooms in the Baltic Sea", Journal of Applied Remote Sensing 2007, 1(1):011507. Hansson, M. Cyanobakterieblomningar i Östersjön, resultat från satellitövervakning 1997-2005, SMHI Oceanografi, rapport nr 82, 2006, ISSN: 0283-7714. Kahru, M., O.P. Savchuk, and R. Elmgren, 2007, “Satellite measurements of cyanobacterial viridity frequency in the Baltic Sea: Interannual and spatial variability”. Marine Ecology Progress Series Vol. 343: 15–23. Kahru, M., 1997, Using Satellites to Monitor Large-Scale Environmental Change: A specimen study of the Cyanobacteria Blooms in the Baltic Sea. Monitoring algal blooms: New techniques for detecting large-scale environmental change. Landes Bioscience. Kahru, M., U. Horstmann and O. Rud, 1994, Satellite Detection of Increased Cyanobacteria Blooms in the Baltic Sea: Natural Fluctuation or Ecosystem change? Ambio Vol. 23 No. 8. Larsson, U., and L. Andersson, 2005, Varför ökar inte kvävet när fosforn ökar? Miljötillståndet i Egentliga Östersjön, rapport 2005, Stockholms marina forskningscentrum. (In Swedish)​ Data All misogynist and current MODIS and VIIRS L2 data tent the Baltic region were placid via FTP-boxes (Near Real-Time service at OceanColorWeb, NASA) to SMHI. Analysed satellite images showing the extent of surface and subsurface viridity in the Baltic Sea is presented at the pursuit website. The images are updated on a daily understructure during June-August, or longer if the viridity continues into September. www.smhi.se/en/Weather/Sweden-weather/the-algae-situation-1.11631​  For reference purposes, please cite this indicator fact sheet as follows:Öberg, J., 2016. Cyanobacteria blooms in the Baltic Sea. HELCOM Baltic Sea Environment Fact Sheets 2017. Online. [Date Viewed], http://helcom.fi/baltic-sea-trends/environment-fact-sheets/eutrophication/cyanobacterial-blooms-in-the-baltic-sea/  Cyanobacterial blooms in the Baltic Sea in the older yearsBaltic Sea Environment Fact Sheet 2016Baltic Sea Environment Fact Sheet 2015Baltic Sea Environment Fact Sheet 2014Baltic Sea Environment Fact Sheet 2013​Baltic Sea Environment Fact Sheet 2012Baltic Sea Environment Fact Sheet 2011Baltic Sea Environment Fact Sheet 2010​Baltic Sea Environment Fact Sheet 2009Baltic Sea Environment Fact Sheet 2008Baltic Sea Environment Fact Sheet 2007Baltic Sea Environment Fact Sheet 2006Baltic Sea Environment Fact Sheet 2005Baltic Sea Environment Fact Sheet 2004 Print Share on Facebook Share on Twitter Key documents HELCOM Privacy PolicyRecommendationsManuals and guidelinesAnnexes to the ConventionHelsinki Convention 1992Baltic Sea Action Plan Most popular PublicationsHELCOM Map and Data ServiceAlgal bloomsOil pollutionEnvironmental fact sheets Follow HELCOM @Facebook@Twitter ©HELCOM EDIT SITEMAP FEEDBACK IMAGE RIGHTS