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FINAL REPORT ON THE RELEVANT SYSTEM OF INDICATORS AND CRITERIA FOR EVALUATING THE ECOLOGICAL STATUS OF A VERY LARGE NONSTRATIFIED LAKE AND ITS RIVER BASIN IN WFD CONTEXT Compiled by Tiina Nõges Tartu University Estonia Deliverable D3b July, 2003 Integrated Strategies for the Management of Transboundary Waters on the Eastern European fringe – The pilot study of Lake Peipsi and its drainage basin Title: Final report on the relevant system of indicators and criteria for evaluating the ecological status of a very large nonstratified lake and its river basin in WFD context Authors: Tiina Nõges, Peeter Nõges, Kalle Olli, Meelis Tambets, Markus Vetemaa, Taavi Virro (Tartu University, Estonia) Enn Loigu,Ülle Leisk, Kristjan Piirimäe, Tiiu Alliksaar, Atko Heinsalu (Tallinn Technical University, Estonia) Külli Kangur, Juta Haberman, Marina Haldna, Andu Kangur, Peeter Kangur, Reet Laugaste, Anu Milius, Helle Mäemets, Tõnu Möls, Henn Timm, Rein Järvekülg, Peeter Pall, Malle Viik, Kai Piirsoo, Sirje Vilbaste, Tiiu Trei (Estonian Agricultural University, Estonia) Report No. No. of pages Sponsor Dissemination Contract No. D3b 96 pages level: public +2 The European Commission under the Fifth EVK1-CT-2000- Framework Programme and contributing to the Appendixes implementation of the Key Action ’Sustainable 00076 Management and Quality of Water’ within the Energy, Environment and Sustainable Development ABSTRACT: The ultimate goal of the present work is to establish an indicator system for rivers in L. Peipsi watershed and the lake itself which is in line with the requirements of the WFD. The typificaiton of rivers was based on type of baserock, size of watershed, and flow velocity of the water, giving 20 potential types. Alltogether 41 river samples (108 samples for macrozoobenthos) were considered as in undisturbed state with respect to biological variables. 32 potential biological indicators (quality elements) were evaluated. Reference values were finally proposed for 20 biological indicators. These reference values are interpreted as the demarkation line between high and good status. After intercalibration, which is necessary to find the values for good and satisfacotry classes, the reference values will be assigned a relative value 100%, against which all lower qualtiy classes will be related to find type specific comparison data for some classes of Estonian rivers. The status of rivers is best described by combined hydrochemical subindex system, which, by applying different weights, takes into account biological oxygen demand, pH, oxygen saturation, ammonium, total P and N. The biological indicator systems are more complex and a single index is not available at the moment to summerize the ecological status. Thus, the available data is divided into subchapters, which each gives an overview on the presnent state of art in asessing the ecological status based on individual biological indicators. Following changes of Estonian national river monitoring programme were suggested: (a) implementation of Polluter Pays Principle; (b) better monitoring of small rivers; (c) development of background monitoring; (d) content of dissolved oxygen, content of ammonia, biochemical oxygen demand, total nitrogen and total phosphorus should be constantly measured within the surveillance- monitoring programme aiming at evaluating the ecological status of the water body; (e) monitoring should focus on rivers where chemical quality is below “good”; (f) if changes in significant pollution factors have appeared then additional monitoring is necessary to estimate long-term changes as well as spatial and temporal variability; (g) suggested methodology for monitoring of flux stations would maintain the total number of 12 samples per year but springtime requires 4–6 samples, autumn flood period 3 – 4 while summer and winter time low water periods require only 1 – 2 samples per year; (h) including the routine calculation of nutrient loading into the river monitoring program. For L. Peipsi increased phosphorus loading was considered the most serious anthropogenic pressure to the ecosystem of. To calculate the reference conditions for total phosphorus concentration we used the morpho-edaphic index (MEI). As a quality objective for L. Peipsi we set the reference TP concentration multiplied by 1.5 that corresponded to the lower quartile of long-term TP measurements. Similar approach was used to set the quality class borders for biological quality criteria based on phytoplankton, which were selected on the basis of having significant correlations with TP. According to present hydrochemical and phytoplankton data the ecological quality of L. Peipsi is mainly moderate. According to the macrophyte and fish indices the status is intermediate between good and moderate while zooplankton and benthic macroinveretbrates indicate ‘good’ ecological status. The following suggestions for adjustment of L. Peipsi monitoring program should be made: (a) including the monitoring of macrovegetation; (b) including the monitoring of abundance, biomass and age structure of all fish species; (c) the current monitoring program of macrozoobenthos in open-water areas should be continued. It gives valuable data for estimation of fish food and enables to watch year- to-year variability of abundance and biomass that is not possible to achieve in another way. A simple reorganisation of open-water sampling sites could give us both the data of fish food (at the same level), and also the estimation of ecological quality of different parts of lake. Studies of shallow areas with handnet samples are recommended for the last purpose. 3 CONTENTS 1. REVIEW OF THE REQUESTS OF EC WATER FRAMEWORK DIRECIVE (P. NÕGES).............5 2. SHORT REVIEW OF ENVIRONMENTAL INDICATORS APPLIED IN LAKES AND RIVERS (T. NÕGES)............................................................................................................................................................8 3. ASSESSMENT OF THE REFERENCE CONDITIONS .......................................................................11 3.1. ASSESSMENT OF REFERENCE CONDITIONS FOR THE RIVERS IN LAKE PEIPSI REGION (E. LOIGU, K. PIIRIMÄE, Ü. LEISK)........................................................................................ 11 3.2. ASSESSMENT OF THE REFERENCE CONDITIONS FOR LAKE PEIPSI (P. NÕGES) .......12 3.3. PALEOLIMNOLOGICAL STUDIES OF LAKE PEIPSI (A. HEINSALU & T. ALLIKSAAR)14 4. INDICATORS AND CRITERIA TO ASSESS THE ECOLOGICAL STATUS OF RIVERS IN THE LAKE PEIPSI CATCHMENT AREA (K. OLLI, E. LOIGU, Ü. LEISK, K. PIIRIMÄE, H. TIMM)........18 4.1. TYPOLOGY OF THE RIVERS IN LAKE PEIPSI REGION....................................................18 4.2. INDICATORS AND CRITERIA FOR ASSESSMENT OF ECOLOGICAL STATUS OF RIVERS..................................................................................................................................................................20 4.2.1. CRITERIA OF CHEMICAL AND HYDROMORPHOLOGICAL STATUS.........22 4.2.2. CRITERIA OF ECOLOGICAL STATUS...................................................................24 5. ECOLOGICAL STATUS OF RIVERS IN L. PEIPSI BASIN ACCORDING TO THE REQUESTS OF WFD (K. OLLI, E. LOIGU, Ü. LEISK, K. PIIRIMÄE, H. TIMM)................................................................29 5.1.HYDROCHEMISTRY.....................................................................................................................30 5.1.1. POINT SOURCES................... .................. .................. .................. .................. ..........30 5.1.2. NON-POINT SOURCES......... .................. .................. .................. ............................ 33 5.1.3. SOURCE APPORTIONMENT.....................................................................................34 5.1.4. CHEMICAL STATUS....................................................................................................35 5.1.5. POLLUTION LOAD TO L. PEIPSI.............................................................................36 5.2. BIOLOGICAL STATUS OF L. PEIPSI RIVER BASIN.............................................................37 5.2.1. BACTERIA.....................................................................................................................37 5.2.2. PHYTOPLANKTON AND CHLOROPHYLL...........................................................38 5.2.3. BENTHIC DIATOMS...................................................................................................39 5.2.4. MACROZOOBENTHOS..............................................................................................39 5.2.5. MACROVEGETATION................................................................................................41 6. INDICATORS AND CRITERIA FOR ASSESSMENT OF ECOLOGICAL STATUS OF LAKE PEIPSI...................................................................................................................................................................42 6.1. CHEMICAL AND PHYSICAL PROPERTIES AND PHYTOPLANKTON (P. NÕGES, R. LAUGASTE, T. NÕGES)... ...............................................................................................................................42 6.2. ZOOPLANKTON (T.VIRRO & J.HABERMAN)......................................................................46 6.3. ZOOPLANKTON/PHYTOPLANKTON RATIO (J. HABERMAN & R.LAUGASTE)........48 6.4. MACROPHYTES (H. MÄEMETS).............................................................................................50 6.5. BENTHIC INVERETEBRATES