Development of Tools for Ecological Quality Assessment in Polish Marine Areas According to the Water Framework Directive
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Oceanological and Hydrobiological Studies International Journal of Oceanography and Hydrobiology Vol. XXXVIII, No.3 Institute of Oceanography (87-99) University of Gdańsk ISSN 1730-413X 2009 eISSN 1897-3191 Received: February 14, 2009 DOI 10.2478/v10009-009-0037-1 Original research paper Accepted: July 17, 2009 Development of tools for ecological quality assessment in Polish marine areas according to the Water Framework Directive. Part I – Nutrients Elżbieta Łysiak-Pastuszak1, Włodzimierz Krzymiński, Łukasz Lewandowski Institute of Meteorology and Water Management – Maritime Branch ul. Waszyngtona 42, 81-342 Gdynia, Poland Key words: nutrients, eutrophication, response curves, ecological quality assessment, Baltic Sea Abstract Assessment of the ecological status of an aquatic environment according to the European Union Water Framework Directive (WFD) requires the determination of a link between the observed status of the marine ecosystem and catchment loading as well as the establishment of criteria for ecological status definitions. This article presents the results of a study identifying links between environmental pressures in the Polish sector of the Baltic Sea and state parameters applied in the assessment of eutrophication. Strong, statistically significant correlations were found between riverine loads of nutrients and their marine concentrations even in relatively short time data series. 1 Corresponding author: [email protected] Copyright© by Institute of Oceanography, University of Gdańsk, Poland www.oandhs.org 88 E. Łysiak-Pastuszak, W. Krzymiński, Ł. Lewandowski INTRODUCTION The Water Framework Directive (WFD) aims to achieve a good ecological status in all European rivers, lakes and coastal marine waters and demands that the ecological status is quantified based on biological indicators, i.e. phytoplankton and benthic flora and fauna (Anon. 2000). Nutrient concentrations, oxygen conditions or water transparency, the parameters traditionally applied to assess eutrophication, are treated as supportive ones. To implement the WFD it is necessary to develop and test methods that allow assessment of reference conditions, establish criteria for ecological status classification, and establish links between ecological status and catchment loading. In other words, it is necessary to develop a tool which, for a particular quality element, describes the correlation between environmental impact or anthropogenic pressure and effect, i.e. it is necessary to identify relevant environmental pressures for the construction of response curves or functional relations (Nielsen et al. 2002, Nielsen et al. 2003, Andersen et al. 2004). The implementation of WFD also requires an assessment of reference conditions as pristine, i.e. representing “the period without anthropogenic influence” (Schernewski&Neumann 2005), or, alternatively and more pragmatically, the best attainable conditions. By 2015 water bodies identified and categorized typologically (Schernewski&Wielgat 2004, Krzymiński et al. 2004) have to meet the standards of good ecological quality unless the area is heavily modified by human physical activity. This would require loading reduction, estimated in an action plan elaborated for the catchment area. Therefore, a classification of good, high, moderate, poor or bad status compared to reference conditions is essential for future planning and development of strategies for managing the environmental quality of groundwaters and surface water, including transitional and coastal marine waters. This series of contributions presents the results of a study identifying the links between environmental pressures in the Polish sector of the Baltic Sea and state parameters applied in the assessment of eutrophication. MATERIALS AND METHODS Assessment areas Traditionally eutrophication assessments of the Polish sector of the southern Baltic Sea focused on the characteristic regions (HELCOM 1987, 1990, 1993; Trzosińska&Łysiak-Pastuszak 1996, Łysiak-Pastuszak et al. 2004): the bays – the Gulf of Gdańsk in the east and the Pomeranian Bay in the west, the Copyright© by Institute of Oceanography, University of Gdańsk, Poland Tools for ecological quality assessment. Part I – Nutrients 89 off-shore area - with distinguished regions of the Gdańsk Deep and SE Gotland Basin, and a coastal strip (delimited by 20 m bathyline according to the HELCOM definition of coastal areas (HELCOM 1997)) along the central Polish coast. Locations of the areas selected for the analyses in this study are shown in Fig. 1. The areas discussed in the present assessment are as follows (with codes for each station listed in parentheses): - Vistula River mouth section2 (ZN2), - internal Gulf of Gdańsk (NP, P114, P115, P110), - outer Puck Bay2 (KO, P102, P104), - Gdańsk Deep (P1, P116), - SE Gotland Basin (P140, P63), - central Polish coast (Z, L7, P16, K6, M), - open Pomeranian Bay (B13, B15, SK), - Oder River mouth section2 (Sw3). Assessment data Nutrient reference values in the off-shore areas were determined on the basis of scarce historical data from the years 1938-1960 (Kijowski 1938, Głowińska 1962, Piątek 1962, Wiktor&Wiktor 1962, Trzosińska 1978) and the data collected in the oceanographic database of the Institute of Meteorology and Water Management in Gdynia between 1959 and 2004 (Łysiak-Pastuszak et al. 2004). The regular monitoring activities within the Polish sector of the southern Baltic Sea, related to HELCOM BMP, started in 1979 in the off-shore region, and were succeeded by the present HELCOM COMBINE programme in 1999 (IMGW, 1987-1999, 2000-2001). Since 1991 the HELCOM COMBINE in Poland has been included in the National Environmental Monitoring Programme. The data prior to that time were collected at random occasions within various scientific oceanographic projects (Majewski&Lauer 1994). The methodology regarding sampling and chemical determination of nutrients was carried out according to international marine chemistry guidelines (Grasshoff et al. 1976) and following the HELCOM manuals (HELCOM 1997; ICES 2004). The data on riverine nutrient loads - monthly mean values of riverine flows and nutrient concentrations between 1990 and 2005 - were supplied for the present assessment by Ośrodek Monitoringu Jakości Wód in Katowice (Katowice Branch of the Institute of Meteorology and Water Management). The measurements were carried out within the National Monitoring Programme of surface waters according to Polish Standard methods. 2 The areas form presently transitional water bodies according to WFD typology (Krzymiński et al. 2004). www.oandhs.org Fig. 1. Location of monitoring stations and assessment areas in the Polish sector of the Baltic Sea. Tools for ecological quality assessment. Part I – Nutrients 91 RESULTS AND DISCUSSION Reference conditions Reference conditions for eutrophication indicators in the marine environment have been determined for 1950 (HELCOM 2000). In the off-shore areas, the central Polish coast and the Gulf of Gdańsk, reference concentrations of dissolved phosphate (DIP) during winter were determined on the basis of scarce historical data (Łysiak-Pastuszak et al. 2006). In the cases of inorganic nitrogen (DIN = NO3 + NO2 + NH4), total nitrogen (TN) and total phosphorus (TP), the reference values have been determined by extrapolation of temporal trends (Łysiak-Pastuszak et al. 2004, HELCOM 2006), mainly for the data prior to 1985. Steep positive trends (statistically significant by t-Student test) in winter concentrations of oxidised nitrogen forms (TOxN) and dissolved phosphate (DIP) were discerned in the surface water layer (0-10 m) in the Polish bays between the end of the 1960s and 1988-1990; e.g.: Gulf of Gdańsk - DIP (<1984) tg α = +0.04 mmol m-3 a-1 (R2 = 0.24, p<0.05, n = 1 048); TOxN (<1984) tg α = +0.78 mmol m-3 a-1 (R2 = 0.35, p<0.02, n = 962); Pomeranian Bay - DIP (<1985) tg α = +0.12 mmol m-3 a-1 (R2 = 0.79, p<0.05, n = 188); TOxN (<1988) tg α = +1.39 mmol m-3 a-1 (R2 = 0.73, p<0.02, n = 189); tg α - slope of the regression curve (Łysiak-Pastuszak et al. 2004). The coastal (central Polish coast) and off-shore waters showed a significant increase in winter nutrient concentrations, though the detected trends were not statistically significant. In this case the reference values were derived using expert judgement by comparison of the medians and averages, utilizing the lower number as the reference value. Unfortunately, gaps in the data occur due to weather conditions, ship machinery or sampling gear break-downs, etc., and the data series on total nitrogen and phosphorus forms are much shorter in certain areas, starting only in 1999. This unevenness of data series has made the determination of temporal trends and functional relations difficult and sometimes impossible. The combined set of reference3 nutrient concentrations – DIP and DIN for the winter and TP and TN for the summer as proxies of productivity – are shown in Table 1. Although the presented reference values have been determined by a simplified statistical analysis, they are in good agreement with the Baltic-wide values established by more advanced modelling techniques 3 The determination of reference nutrient concentrations was carried out under various projects: WFD implementation in Poland (IMGW 2005), HELCOM EUTRO (HELCOM 2006) and EUTRO PRO, a project on thematic assessment of eutrophication in the Baltic Sea (HELCOM 2009). www.oandhs.org 92 E. Łysiak-Pastuszak, W. Krzymiński, Ł. Lewandowski Table 1 Reference conditions of nutrient concentrations