Effects of climate change on water quality in the Ilperveld Jiske van der Wiele 0564958 Master Biological Sciences programme Limnology & Oceanography University of Amsterdam, IBED Master thesis, 50 ECTS Supervisors: Wilko Verweij (RIVM), Esther van der Grinten (RIVM) Examiner: Michiel Kraak (UvA) September 2009 - May 2010 Contents page Summary 4 Introduction 6 1. The Ilperveld 7 1.1 Location 7 1.2 History 8 1.3 Water management 9 1.4 Current water quality 11 1.4.1 Chemical water quality 11 1.4.2 Ecological water quality 12 2. Natura 2000 and the Ilperveld 17 2.1. Introduction Natura 2000 17 2.2 Aquatic goals 18 2.2.1 Oligo-mesotrophic water with Chara spp. vegetation 18 2.2.2 European Bitterling 18 2.2.3 Spined Loach 19 2.2.4 Bullhead 19 2.3 Current distribution 20 2.3.1 Oligo-mesotrophic water with Chara spp. vegetation 20 2.3.2 European Bitterling 21 2.3.3 Spined Loach 22 2.3.4 Bullhead 23 3. Environmental requirements for the Natura 2000 species 24 3.1 Abiotic conditions macrophytes 24 3.1.1 Abiotic conditions plant communities 26 3.1.1.1 Najadetum marinae 26 3.1.1.2 Ruppietum maritimae 26 3.1.1.3 Nitellopsidetum obtusae 26 3.1.1.4 Charetum hisipidae 26 3.2 Biotic conditions macrophytes 27 3.3 Environmental conditions fishes 27 3.4 Effect indicator Natura 2000 32 4. Climate change in Noord-Holland 33 4.1 Introduction 33 4.2 Direct effects 33 4.2.1 Temperature 35 4.2.2 Precipitation 37 4.2.3 Extreme precipitation 39 4.2.4 Wind, sunshine and sea level rise 41 4.2.5 Increase atmospheric carbon dioxide concentration 41 4.2.6 Water quantity 42 4.2.7 Water quality 44 4.3 Indirect effects 45 4.3.1 Salinization 45 4.3.2 Recreation 45 4.3.3 Nature (aquatic ecosystems) 46 2 5. Influence of climate change on ecosystems 47 5.1 Introduction 47 5.2 Western Peat District 48 5.3 Ilperveld 49 5.3.1 General 49 5.3.2 Floods 50 5.3.3 Droughts 50 5.3.4 Eutrophication 52 5.3.5 Salinization 53 5.3.6 Recreation 54 6. Influence of climate change on species 56 6.1 Changes in abiotic conditions 56 6.1.1 Increase in water temperature 56 6.1.1.1 Macrophytes 56 6.1.1.2 Fish 58 6.1.2 Slight increase in chloride concentration 59 6.1.2.1 Macrophytes 59 6.1.2.2 Fish 60 6.1.3 Eutrophication 60 6.1.3.1 Macrophytes 60 6.1.3.2 Fish 61 6.1.4 Decrease in water transparency 61 6.1.4.1 Macrophytes 61 6.1.4.2 Fish 62 6.1.5 Low water level 62 6.1.5.1 Macrophytes 62 6.1.5.2 Fish 63 6.1.6 Decline oxygen concentration 63 6.1.6.1 Fish 63 6.2 Changes in biotic conditions 64 6.2.1 Macrophytes 64 6.2.2 European Bitterling 64 6.2.3 Spined Loach 65 6.2.4 Bullhead 65 6.3 Migration 67 7. Conclusions 69 7.1 Conclusions 69 7.2 Measures 69 7.2.1 Oligo-mesotrophic water with Chara spp. vegetation 69 7.2.2 European Bitterling 71 7.2.3 Spined Loach 71 7.2.4 Bullhead 71 7.3 Future perspectives 72 Acknowledgements 74 References 75 Appendix 1 81 Appendix 2 84 3 Summary In this study, the effects of climate change on the aquatic Natura 2000 goals of the Ilperveld were investigated. The Ilperveld is a brackish peat land area in the province of Noord-Holland. The Ilperveld is designated to preserve habitat type 3140, which is nutrient-poor water with Chara spp. vegetation. In addition, populations and habitats of the fish species European Bitterling ( Rhodeus amarus ), Spined Loach (Cobitis taenia ) and Bullhead ( Cottus perifretum ) need to be preserved. In general, the effects of climate change on a local scale (Ilperveld) differ from the effects that are described on a national scale. On a national scale, big issues that can increase due to climate change are an increase in harmful cyanobacterial blooms and salinization of the surface waters. For the Ilperveld these issues seem no threat because the surface water already has a relatively high chloride concentration. In general, from this study it appears that dry periods in summer combined with an elevated temperature is the main threat for the Ilperveld, because this combination increases peat oxidation. For the water quality, an increase in eutrophication and water turbidity are the main threats. Eutrophication increases due to an increase in water inlet during dry periods, and increased nutrient run-off from the peat soils during wet periods. The predicted alternation between dry periods and intense rainfalls in summer, can lead to temporary peak concentrations of nutrients in the surface water. The turbidity of the water increases due to more recreation in summer, peat degradation, and an increase in benthivorous fish. Oligo-mesotrophic water with Chara spp. vegetation The water quality that is required for oligo-mesotrophic water with Chara spp . vegetation is currently not reached in most parts of the Ilperveld. However, the brackish variant (vegetations of N. marina and R. maritima ) of this habitat type is able to survive at slightly higher nutrient and chloride concentrations, and from this study it became clear that these brackish macrophytes are neutral in response to temperature. A shift towards the brackish variant of this habitat type is favorable. The largest threats for this habitat type (both variants) are a decline in water transparancy and increased eutrophication. At elevated eutrophication and salinization levels, the plant communities that belong to the habitat type oligo-mesotrophic water with Chara spp. vegetation (Nitellopsidetum obtusae and Charetum hispidae) shift to other communities. In bad case, it is likely that the water vegetation develops in vegetations of Ceratophyllum demersum, Potamogeton pectinatus, Zannichellia palustris , and Azolla filiculoides . However in the worst case, the vegetation disappears completely and the water is going to be dominated by algae. European Bitterling The European Bitterling (Rhodeus amarus) has a unique spawning relationship with freshwater mussels. A decline in freshwater mussel numbers, results also in a decline in European Bitterling numbers. An increase in muddy conditions and a decrease in the oxygen concentration of the water are disadvantageous for both mussel and fish. The fish is also sensitive for high chloride concentrations, low water levels and a decline in macrophyte abundance. An increase in water temperature seems no threat, because the European Bitterling is a thermophilic species. This fish is currently abundant in the isolated compartments. But when due to climate change, the environmental conditions in the compartments become unfavorable; the fish are unable to migrate. Unfavorable conditions that can occur in the compartments for the European Bitterling are expected mainly in summer. The chloride concentration can 4 become too high, and the water level too low. So, many negative effects of climate change are expected for the European Bitterling. Spined Loach The influence of climate change on the Spined Loach ( Cobitis taenia ) is not totally clear; this is partly due to the unknown distribution of this species in the Ilperveld. An advantage for the Spined Loach is that the fish can survive at low oxygen concentrations and low water levels. An increase in water temperature seems no threat. The fish is just like the European Bitterling a freshwater fish, which means that an increase in the chloride concentration and especially fluctuations in choride levels could be negative. There is also not much known about predators and dispersal distances. From this small amount of information, it seems that climate change is not a threat for the Spined Loach in the Ilperveld. Bullhead The Bullhead ( Cottus perifretum ) is distributed in the open water of the Ilperveld. Here, chloride and sulphate concentrations are higher, and the pH is slighty higher than in the compartments. Bottlenecks for the Bullhead are decreasing oxygen concentrations and increasing water temperatures. However, warming of the open water occurs slower compared with the compartments. When alien crayfish are introduced in the Ilperveld, this is a risk for the Bullhead. The risk consists of direct predation or competition for habitat with the crayfish. In addition, other predators like fish-eating birds can also increase in the future. Migration is not hindered by obstacles, but the fish itself is unable to cross large distances. An increase in muddy conditions is disadvantageous for Bullhead. In contrast, salinization seems no threat. Probably, climate change has little influence on Bullhead in the Ilperveld. Future It can be concluded from this study that the effects of climate change make it more diffcult to achieve the aquatic Natura 2000 goals of the Ilperveld. In addition, there are many inconsistencies round the Natura 2000 goals and the different functions of the area. The species approach of Natura 2000 conflicts with the preservation of the unique brackish character of the Ilperveld. 5 Introduction Climate change is nowadays a hot subject. Global climate scenarios predict an increase in air temperature, changing precipitation patterns and sea level rise. These changes will influence water systems (water quantity and quality), and subsequently agriculture, economy and the human population. Climate change will also affect nature via changes in abiotic conditions and (corresponding) changes in biotic conditions. In addition, for some nature areas in the Netherlands it is expected that climate change will form an extra problem for the achievement of the nature goals (van Rooij et al., 2009). The exact direction and extent of climate change is still uncertain.