EFFECTEFFECT OFOF CLIMATECLIMATE CHANGECHANGE ANDAND ALGALALGAL BLOOMSBLOOMS ONON pHpH ININ THETHE LAGOONLAGOON OFOF THETHE BALTICBALTIC SEASEA

1AtlanticAtlantic ResearchResearch InstituteInstitute ofof MarineMarine FisheriesFisheries andand OceanographyOceanography SergeySergey AleksandrovAleksandrov1 5, Dm. Donskoy Str., Kaliningrad, Russia, e-mail: [email protected] 2 2AtlanticAtlantic BranchBranch ofof P.P.P.P. ShirshovShirshov InstituteInstitute ofof OceanologyOceanology RASRAS JuliaJulia GorbunovaGorbunova 1, Prospect Mira, Kaliningrad, Russia, e-mail: [email protected] 19.5° 20.0° 20.5° 21.0° INTRODUCTION MATERIAL AND METHODS Klaipeda

The Curonian and Vistula Lagoons are the largest lagoons of The researches of hydrological, chemical and 12

the Baltic Sea. The Curonian Lagoon is choke mostly freshwater biological parameters, including primary production (PP), 11 55.5° lagoon, while the Vistula Lagoon is restricted brackish water chlorophyll (Chl), phytoplankton, nutrients, pH and others 13 10 16 9 lagoon. Ongoing eutrophication is one of the most important were carried out monthly in 1981-1982 and 1991-2014 from 8 17 7 problems. The purpose of this research is analysis of long-term March to November at 12 stations in the Curonian Lagoon 14 6 11 10 12 23 18 changes of chemical and biological parameters in the Lagoons and at 9 stations in the Vistula Lagoon Location of this 15 7 6 9 8 5 1 5 2 3 419 1 2 3 55.0° and impact of environmental factors (e.g. climate change), stations corresponds to hydrological and hydrochemical 4 22 Zelenogradsk eutrophication and harmful algal blooms on pH in lagoons. division and covers the Russian waters (fig. 1). Polessk 20 21 Primorsk Kaliningrad 4 Baltiysk 2 1 9 10 3 8,85 200 RESULTS 6 5 RUSSIA pH Chl a, µg/l 7 8,80 54.5° 180 The Curonian Lagoon may be characterized as a hypertrophic water 8,75 body and Vistula Lagoon as a eutrophic-hypertrophic water body. 160 8,70 Climate change in 1990-2000's combined with other factors (high POLAND 8,65 140 nutrients concentrations and their ratio (N:P<7 in summer)), low salinity 8,60 0-5‰) created conditions for summer “hyperblooming” of Fig. 1. Monitoring stations in the Baltic 120 Sea, Vistula and Curonian Lagoons 8,55 Cyanobacteria, eutrophication and increased primary production (360- 100 8,50 668 gC·m-2·year-1). The eutrophication of the lagoons affects at all At present, in these lagoons 8,45 80 trophic levels and primarily the intensity of phytoplankton development. averages for the water area pH 8,40 The annual cycles of primary production, chlorophyll concentrations and 60 change from 8.0-8.1 in winter to 9.2- 8,35 pH are characterized by summer maximum, which corresponds to maximal 40 temperature of water and blooming of Cyanobacteria (Fig. 2). 9.5 in the spring-summer. In 1981- 8,30 20 1982 average for the period April- 8,25 October pH was 8.33-8.37. 8,20 0 8,85 pH 8,85 pH III IV V VI VII VIII IX X XI 8,8 A 8,8 B рН Vistula Lagoon рН Curonian Lagoon 8,75 8,75 Chl Vistula Lagoon Chl Curonian Lagoon 8,7 8,7 8,65 Fig. 2. Seasonal changes of the pH and Chl a 8,65 8,6 8,6 concentrations mean for the period 1991 -2014 8,55 8,55 in the Vistula Lagoon and Curonian Lagoon 8,5 8,5 8,45 8,45 8,4 8,4 I. CURONIAN LAGOON 8,35 8,35 The highest averages for the area pH (9.13-9.55) occur 8,3 8,3 in the Curonian Lagoon during “hyperblooms”, when 1981-1982 1991-1999 2000-2005 2006-2010 2011-2012 1981-1982 1991-1999 2000-2005 2006-2010 2011-2012 chlorophyll amount to 208-904 mg/m3 and primary April-October June-September April-October June-September production 9-16 gC·m-3·d-1. The more intensive water warming in 1990-2000s Fig. 4. The mean for the growing season (April - October) and summer period created favorable conditions for Cyanobacteria. (June-September) pH in the Curonian Lagoons (A) and Vistula Lagoon (B) The local climate warming in the Baltic region is a of the ongoing eutrophication of the Curonian I. VISTULA LAGOON Lagoon. Due to climate change and eutrophication in the Vistula Lagoon, pH average for In the Curonian Lagoon “hyperblooming” of April-October also increased from 8.37 in 1981-1982 to 8.61 in 1991-1999, 8.67 in 2000- Cyanobacteria was observed during 3 years in 2005 and 8.76 in 2006-2010 (fig. 4b). 1980s, while 11 years “hyperblooming” of In the Vistula Lagoon after the invasion of the North American filter-feeding bivalve 2 Cyanobacteria were observed in 1990s and 2000s. Rangia cuneata the benthic biomass increased by 17 times (to 496 g/m ), and Chl Owing to eutrophication and “hyperblooms” of decreased by 2 times (to 20 μg/l) in 2011-2014 (Fig. 5). Water quality is improved from Cyanobacteria, in the Curonian Lagoon average for “poor” to “passable” level in 2011-2014 (Fig. 6). Due to the reduction of eutrophication of April-October pH increased from 8.33 in 1981-1982 water, pH also decreased to 8.58 were observed in 2011-2014 (fig. 4b, 7). to 8.60 in 1991-1999, 8.67 in 2000-2005, 8.76 in 2006- 2010 and 8,71 in 2011-2014 (fig. 4a). 19.5° 20.0° 20.5° 21.0° 19.5° 20.0° 20.5° 21.0°

1991-2000 Klaipeda 45 2001-2010 Klaipeda 650 2 41 55.5 55.5 3 350 55 40 3 4 5 4

2 50 55 3 300 48 45 37 4 5 3 5 250 40 114 112 85 4 5 115 90 5 112 107 80 77 5 103 136 111 110 35 5 55.0 55.0 5 5 200 30 92 94 89 82 93 80 87 80 70 3 25 Zelenogradsk Zelenogradsk 150 Polessk Polessk 20 Kaliningrad Kaliningrad 46 37 100 15 46 41 39 38 Chlorophyll µg/la, 29 41 46 26 34 36 10 35 44 25 36 Biomass of benthos, g/m ofbenthos, Biomass 50 37 RUSSIA 25 RUSSIA 5 54.5 54.5 0 0 POLAND POLAND 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Year Rangia cuniata Benthos Chlorophyll 19.5° 20.0° 20.5° 21.0° Fig. 6. Water quality in the Vistula Lagoon,

Fig. 5. Long-term change biomass of benthos and Chl 2011-2014 Klaipeda Curonian Lagoon, South-Eastern Baltic Sea “a” concentrations in the Vistula Lagoon in 1991-2013 2 (based on the average for year Chl а) 55.5 3 650 (Data on Chl in the Lithuanian part in 1991-2000 3 4 from “Baltic sea phytoplankton database”) 3 5 4 350 8,90 4 5

2 8,85 3 5 300 4 5 79 74 Classification of water 8,80 5 5 81 103 110 126 quality in the Baltic 5 5 250 8,75 55.0 5 68 74 72 111 Sea (Vuoristo, 1998) 3 200 8,70 Zelenogradsk Po lessk 8,65 pH Kaliningrad 150 22 8,60 20 19 13 17 19 8,55 12 17 CONCLUSION 100 17 RUSSIA CONCLUSION 8,50 54.5 Thus, in lagoons the increase

Biomass of benthos, g/m benthos, of Biomass 50 8,45 eutrophication and primary production 0 8,40 POLAND due to climatic changes can significantly increase the pH, but 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Rangia cuniata Benthos pH Year biological invasions can promote improvement of quality of waters and Fig. 7. Biomass of benthos and pH in the Vistula Lagoons in 1991-2013 decrease in pH. Considerable water exchange The waters of the Baltic Sea on the concentration of nutrients, chlorophyll between the lagoons and sea can and phytoplankton biomass can be characterized as mesotrophic, promote to maintain of stable state of especially in offshore part. the pH in coastal areas of Baltic Sea For the Baltic Sea in 2005-2006 average for the growing season surface despite of global processes of ocean pH was 8.07-8.10 that correspond to the average pH in the world’s oceans. acidification