DEPARTMENT OF BIOLOGICAL AND ENVIRONMENTAL SCIENCES

THE EFFECT OF LAND MANAGEMENT ON AQUATIC INVERTEBRATES

Christopher Magnusson

Degree project for Master of Science (120 hec) with a major in Biology BIO797 Conservation Biology 60 hec Second cycle Semester/year: Autumn 2019 Supervisor: Johan Höjesjö, Department of Biological and Environmental Science Examiner: Karin Hårding, Department of Biological and Environmental Science

Table of contents Abstract 2 Sammanfattning 2 Introduction 3 Background 3 Focus of the study 4 Aim 4 Material and methods 4 Materials 4 Methods 5 Indexes and selection 6 Statistics 6 Results 7 Novel finds 10 Discussion 10 Conclusion 12 Acknowledgements 12 Reference list 12 Appendix 1. Populärvetenskaplig sammanfattning 15 Appendix 2 16 Appendix 3. 17

Photo on front page: Wetland in municipality of Mariestad Photographer: Christopher Magnusson

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Abstract Wetlands have an important role in the agriculture and can, among other things, elevate the ground water table, clear run-off water from nutrients and mitigate the effects of droughts and floods. They also serve as important hot spots for biodiversity in the landscape. Some insects and molluscs favour grazed shores while others need the shadow that a shoreline covered by canopies offer. This study investigates what type of shores aquatic invertebrates’ favour: covered, grazed or a mixture of both. In total 29 wetlands in the region of Västra Götaland was examined, divided into four categories: (1) grazed and covered, (2) grazed not covered, (3) covered not grazed and (4) no covering or grazing. Macroinvertebrates were collected by netting in the water and most specimens in the samples were identified to either species or genus. Among the 9 556 specimens found in the study 68 genera and two subfamilies were identified. Shannon’s diversity index, ASPT-index, total number of individuals as well as numbers Ephemeroptera, Trichoptera, Asellus, Corixidae and Coenagrionidae were compared between the different categories. ASPT-index seemed to be higher in wetlands both grazed and covered. One wetland had significantly higher drainage area compared to the others. It was therefore removed from the analysis and then there was a difference in the average amount of Ephemeroptera species in favour for grazed ones. Furthermore, 13 wetlands were more distinct and when comparing them a trend was found showing higher values of Shannon and numbers of Trichoptera in covered wetlands. An added value of this study is increased knowledge on the distribution of species in small wetlands, many of them underreported. Future studies should include additional factors such as bottom substrate, water chemistry, abundance and species composition of aquatic macrophytes that can also be important in determining species composition.

Keywords: Wetland, invertebrates, grazing, covered shorelines, freshwater

Sammanfattning Våtmarker är viktiga i jordbrukslandskapet, de påverkar bland annat grundvattennivåerna, renar avrinningsvatten från näringsämnen och minskar effekterna av både torka och översvämningar. De är också viktiga som reservoarer för biodiversitet. Vissa djur behöver betade stränder, medan andra istället vill ha dem skuggade av buskar eller träd. Denna studie syftar till att undersöka vilken strandtyp som akvatiska evertebrater föredrar: skuggade, betade eller en blandning av dessa. Totalt undersöktes 29 små våtmarker i Västra Götaland, uppdelade på fyra kategorier: (1) betad och skuggad, (2) betad, ej skuggad, (3) skuggad, ej betad och (4) varken betad eller skuggad. Våtmarkerna provtogs genom vattenhåvning av makroinvertebrater. Efteråt bestämdes de insamlade individerna till art eller släkte så långt det var möjligt. Bland de 9 556 individer som hittades i studien identifierades 68 släkten och två underfamiljer. Diversitetsindex, ASPT-index, totala antalet individer och antalet av Ephemeroptera, Trichoptera, Corixidae och Coenagrionidae jämfördes mellan de fyra kategorierna. ASPT-värdet verkar bli högre i våtmark med både betning och skuggning. En skillnad syntes i antal Ephemeroptera-arter, där det fanns fler i betade våtmarker. Detta var dock endast om en våtmark med mycket större tillrinningsområde än de övriga räknades bort. Utöver detta valdes 13 stycken våtmarker ut med tydligare kategorisering. När dessa undersöktes fanns en trend mot högre biodiversitet och mer Trichoptera i skuggade våtmarker. En viktig del av studien var att öka kunskapen om utbredningen av arter som trivs i små våtmarker, många underrapporterade. Framtida studier bör inkludera ytterligare andra aspekter som bottenförhållanden, vattenkemi, täckning och artsammansättning av makrofyter vilka kan vara korrelerade till biodiversitet av makroeverebrater. En metod att kategorisera småvattens betydelse för den regionala biodiversiteten kan vara värdefull för naturvården och vid inrättande av biotopskydd. Nyckelord: Våtmarker, invertebrater, bete, skuggade stränder, sötvatten

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Introduction Background Small wetlands have important functions and provide ecosystem services. This study focusses on the biodiversity associated with wetlands. For example, several species of birds use small wetlands during either breeding season, migration or both and need a network of water bodies to prosper (Johnson 2001). Amphibians depend on small wetlands to reproduce and benefit from small isolated ones (Semlitsch & Bodie 1998). The number of insects has declined recently (Hallmann et al. 2017) and many species of insects benefit from water bodies and are dependent on them in one or more stages of their life cycle (Batzer & Wissinger 1996). Insects also constitute prey for e.g. water fowl and have an important role in the wetland ecosystem. Grazed shorelines are important to many species, both plants and animals. Waders, such as the Lapwing (Vanellus vanellus) need the open area that grazing animals provide and benefit from shores free from trees where crows (Corvus corone) and other predators may perch (Berg et al. 1992, Żmihorski et al. 2018). Grazing cattle also provide an increasing amount of organic matter that can serve as food for invertebrates (Scrimgeour & Kendall 2003). This is more important in waters with open shores and especially in running waters. They might however also increase the nutrient load in the wetland. This is an especial concern in small bodies of water. It is therefore important to not overgraze the wetlands. A moderate amount of cattle might improve the biodiversity by creating microhabitats by their trampling and, when allowed to venture out into the water, a blue border (Strand 2019). The blue border is a border of open water between the shoreline and the reed bed. This area can be very high in biodiversity. Grazing is a management method best used with care however. Overgrazing might, as mentioned before, increase nutrient load and also increase turbidity. In some environments grazing might even be detrimental to the biodiversity (Marty 2005). In Sweden, shorelines covered by trees and shrubs is mostly advised against when creating new wetlands and when managing already existing ones (Strand 2019). They might however have an important role as some caddis fly lay their eggs on leaves hanging over water and the shredder feeding group can use fallen branches and leaves as a food source (Dosskey et al. 1997). Trees may also provide shelter for some species and as shade prohibiting the temperatures in the water from rising too much or too fast. Covered shorelines and grazing are not mutually exclusive. With few grazing animals, shrubs and trees might have time to grow big enough to avoid getting eaten. There is also the possibility to manage an open shoreline without animals by cutting down shrubs and mowing grass surrounding the wetlands by manpower. Small wetlands also have a few more important functions and are especially important in agricultural areas (O’Geen et al. 2010). They elevate the ground water table, especially if they are isolated from other bigger sources of water (Mitsch & Gosselink 2000) and prevent both flooding and drought by storing water in the landscape. Wetlands purifies water from nutrients such as nitrogen and phosphorous, especially if they are designed to optimize retention of them (Vymazal 2007). Nitrogen is a bit complicated to remove since the removal processes needs both aerobic and anaerobic environments. Phosphorus is best removed by deep ponds, where the molecules can combine with iron (III) and deposit on the bottom, combined with plant uptake (Vymazal 2007). The emission of the strong greenhouse gas nitrous oxide (N2O) can, according to a new study, be reduced by small wetlands (Webb et al. 2019). The potential to store carbon is also an important function of wetlands, but they can also work as a carbon source (Kayranli et al. 2010). They also provide important refuges for different species of plants and animals that lives on farmland (Ruggiero et al. 2008). They can, however, easily be affected by the neighbouring activities such as fertilising. It is therefore important to have a buffer strip close to the wetland that is not cultivated or fertilised (Dosskey et al. 1997).

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Focus of the study Macroinvertebrates in freshwater can be divided into four different functional feeding groups (Allan & Castillo 2007). The first group are called grazers, which feeds on algal growth on substrates like tree branches, stones and macrophytes. They include, among others, many different kinds of snails and mayflies of the genus Cloeon. The second group, shredders, break down courser detritus like leaves, branches and other dead organic materials. This group most prominently contains saw bug, Asellus aquaticus and caddisflies from the family Limnephilidae. Third group, predators, feed on other animals. They might even eat other predators, sometimes of the same species. It is a well-represented group, containing for example dragon- and damselflies (Odonata), backswimmers (Notonectidae) and glassworms (Chaoborus). Last group, collectors, can be divided into two subgroups. These are filter feeders and gatherers. They collect food by either filtering small organic particles from the surrounding water or by collecting organic materials laying on the bottom. Mayflies of the genus Ephemera represents the former, while caddisflies (e.g. Limnephilus) and non-biting midges (Chironomidae) constitutes the latter group. These groups are not representing any taxonomical relationship, rather how the invertebrate food web works. More shrubs and trees on the shore can positively increase the number of shredders by providing course detritus and perhaps also predators that hunts the shredders. Macroinvertebrates also serves as important bio indicators. Some groups can survive in more acidic water, whilst others need a higher pH-level to survive. One species thrives in high levels of eutrophication and another one needs pure water. This makes them well suited as bioindicators, an important tool to understand the status of the water. A common measurement to determine the water quality is the ASPT-index (Average Score Per Taxon) (Bydén et al. 2013). In this index, certain taxa (usually family level) gets a score from 1 – 10. The taxa found are given their score, which are then summarized and divided by the number of taxa. ASPT is an overall assessment of the effects from pollution of nutrients and oxygen-demanding pollution with disturbances in the environment. Lower scores indicate a more affected environment. Taxa that gives lower scores are typically Oligochaeta, chironomids, leeches and snails. Mayflies, dragonflies and caddis flies gives, usually, higher scores. Since grazing cattle may increase the nutrient load in the wetlands the ASPT value should be lower in grazed wetlands. Trees and shrubs along the shore might absorbs nutrients and therefore wetlands with covered shorelines should have a higher value. Few studies have shown the effects covered shorelines or grazing animals has on aquatic invertebrates. This will be the main focus of this thesis.

Aim The aim of this study is to determine if grazing cattle or trees/shrubs surrounding small wetlands affect the aquatic invertebrate biodiversity. My hypotheses are that (1) grazing increases aquatic invertebrate biodiversity positively, (2) trees/shrubs surrounding wet-lands affect the biodiversity positively, (3) grazing will have a negative effect on ASPT index-value while (4) covered shorelines will have a positive effect on the same. My predictions are: 1. Grazed wetlands and wetlands with covered shorelines will have a greater biodiversity than wetlands lacking thereof. 2. Wetlands that are both grazed and have covered shorelines will have the highest biodiversity. 3. Grazed and uncovered wetlands will have the lowest ASPT value. 4. Ungrazed and covered wetlands will have the highest ASPT value. An added value of this study will be more knowledge about the distribution of the species in the regions small waters. Material and methods Materials To collect the invertebrates following items were used:

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Two cloth nets with the hole diameter of 1,5 mm, waders, two buckets (ten litres), several small plastic cans with lids, a sieve (hole diameter of 1,5 mm), a trough, a colander, soft pincers, water and ethanol (99,5 %). To determine the invertebrate to species/genus/subfamily level I used: A binocular loupe (15-60 x magnification), petri dishes, pincers, needle, sponge, water, ethanol (99,5 %) and books used to determine taxa (Edington & Hildrew 1981), (Enckell 1980), (Mandahl- Barth 1982), (Nilsson (ed) 2005), (Savage 1989) and (Wallace et al. 1990)

Methods To find which wetlands to sample the “Våtmarksdatabasen” that can be accessed from the website of SMHI through the “Vattenweb” was used (SMHI 2018). A list of all restored wetlands in Sweden that had received funding from the Government was downloaded. Wetlands in the county of Västra Götaland with the size between 0,2 ha - 2 ha were selected. 111 wetlands (see fig. 1) fitted the criteria and their coordinates were put into a GPS and was then visited and examined for suitability for the study. Wetlands that were hard to access was sorted out and the two different study aspects to examine (grazing and trees/shrubs) was noted. After the survey 57 wetlands remained as candidates. 20 of them (see fig. 1) were sorted out because of ambiguities in the categorisation. Because there were few wetlands (7) that were grazed without any trees/shrubs all of them were used and then set the amount on the rest of the wetlands

Figure 1. Map showing the visited (white dots) and selected (black dots) wetlands. to include 15 grazed and 15 with trees/shrubs. These wetlands can be found listed in Appendix 2. Due to the severe drought one of the wetlands without any vegetation or cattle close by was lost. Hence, only 29 wetlands were sampled (see table 1). All wetlands visited was affected by the drought in some capacity. Most were approximately 30 cm below the usual water level.

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The sampling was designed in accordance with the manual from the Swedish Environmental Protection Agency (Havs- och Vattenmyndigheten 2016). The wetlands were sampled with 30 samples each all around the shoreline, roughly evenly distributed to capture different types of shores. The samples were collected in a bucket and sorted out on site or in a lab. Specimens were collected in plastic cans with a 60 % ethanol mixture, labelled and closed. The sampling was done from mid-October to early November which meant that some species living in the wetlands at this time only were present as eggs and therefore not detectable (Havs- och Vattenmyndigheten 2016). Species determination was done with the use of a binocular loupe. Most taxa were determined to species level, but for some it was impossible to go beyond genus or subfamily level. Oligocheates and Platyhelmints were also not examined below respective taxonomical level. This was due to the poor condition in most of those specimens.

Table 1. Number of wetlands before last sorting, after last sorting and number of sampled ones. The last column shows the numbers of the more easily discerned wetlands in each category used in later analyses called distinct wetlands in this paper.

Type of wetland Before After Sampled Distinct

Grazed and trees/shrubs 11 8 8 3

Grazed, no trees/shrubs 7 7 7 3

Trees/shrubs, not grazed 9 7 7 3

Not grazed or trees/shrubs 10 8 7 4

Total 37 30 29 13

Indexes and selection Different kinds of indexes were used in order to examine the wetlands. To evaluate the biodiversity a Shannon’s index was used. Genus-level was used in the index, except for chironomids which instead of genus was assigned to subfamily. An ASPT-index was also used to assess the overall water quality in the wetlands and in the different categories. The results were reported on the Swedish Species Observation System (Artportalen 2019). In addition, a few families were selected to check if some subgroups of animals were affected by the different types of wetlands. The groups used was: number of species and individuals of the families Ephemeroptera and Corixidae and number of species of Coenagrionidae. These were common groups and was present in several wetlands. They also showed a pattern of having a certain disposition towards one of the four categories. All wetlands were included in the comparisons in the beginning of the analyses, but one wetland with a substantially larger watershed was removed from the comparison on Ephemeroptera. To further study the effect of grazing and covered shorelines, some of the more easily discerned wetlands in each category analysed separately. These are called distinct wetlands in this paper (see table 1). The same analysis with Shannon’s diversity index and ASPT-index was done. Also, a visual comparison between the different categories was made. Trichoptera was showing a particular distribution and was analysed statistically.

Statistics Shapiro-Wilk test was done on the sample to control for normality. If normality was found an analysis of variance (ANOVA) was made. In case of no normality in the sample a Kruskal- Wallis test was made instead. To examine the effects grazing and tree/shrubs had on the wetlands an analysis of variance (ANOVA) was used. Number of individuals, ASPT index and Shannon’s diversity index was used

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as dependent variables. Grazing and tree/shrubs were mainly the independent variable, but area, age and the catchment of the wetlands were also considered. When comparing the preferences of different groups, a Kruskal-Wallis test was performed instead of an analysis of variance (ANOVA).

Results In total 9 556 specimens were found, representing 68 genera, 2 subfamilies, 1 family (Annelida) and 1 phyla (Plathyhelminthes) (see table 2). For a complete list see Appendix 3. Most common were Cloeon dipterum/inscriptum 3 682, Asellus aquaticus 1318 and Chaoborus obscuripes 1252.

Table 2. This list shows the average and total individuals of all taxa found in respective category. There is also a total summary at the right end. For a full list see Appendix 3. Grazed with covered Grazed with open Not grazed with Not grazed with open shoreline shorline covered shorline shorline Total Taxa Average Total Average Total Average Total Average Total average Total sum Annelida 0,50 4 0,57 4 1,71 12 0,86 6 0,90 26

Hirudinea Erpobdella octoculata 3,63 29 1,43 10 4,86 34 1,43 10 2,86 83

Erpobdella testacea 0,29 2 0,07 2 Glossiphonia complanata 0,29 2 0,14 1 0,10 3 Helobdella stagnalis 0,38 3 0,14 1 0,14 1 0,43 3 0,28 8 Theromyzon tessulatum 0,29 2 0,71 5 0,14 1 0,28 8

Mollusca Bivalvia Pisidium 8,63 69 1,43 10 3,14 22 0,43 3 3,59 104

Pisidium amnicum 0,38 3 0,29 2 0,14 1 0,21 6 Gastropoda 0,14 1 0,03 1 Myxas glutinosa 0,14 1 0,03 1 Omphiscola glabra (NT) 0,25 2 0,07 2 Radix balthica 1,75 14 2,71 19 3,43 24 0,14 1 2,00 58

Physa fontinalis 0,86 6 0,21 6 Anisus vortex 0,71 5 0,17 5 Bathyomphalus contortus 1,14 8 0,28 8 Gyraulus albus 0,50 4 1,14 8 6,00 42 4,14 29 2,86 83

Gyraulus crista 0,57 4 2,71 19 0,79 23 Platyhelminthes 0,14 1 0,14 1 0,07 2 Araneae Argyroneta aquatica 0,13 1 0,03 1 Amphipoda Gammarus lacustris 0,57 4 0,14 4 Isopoda Asellus aquaticus 49,25 394 18,43 129 73,29 513 40,29 282 45,45 1318

Ephemeroptera Cloeon dipterum/inscriptum 114,00 912 140,71 985 196,57 1376 58,43 409 126,97 3682

Caenis horaria 0,25 2 0,71 5 1,00 7 0,48 14 Ephemera vulgata 0,38 3 0,14 1 3,00 21 0,86 25 Leptophlebia marginata 2,50 20 3,00 21 1,41 41 Odonata Zygoptera 0,50 4 0,14 4

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Coenagrionidae 2,13 17 0,43 3 1,29 9 2,71 19 1,66 48

Coenagrion 0,14 1 0,03 1 Coenagrion armatum 2,38 19 2,29 16 1,21 35 Coenagrion hastulatum 8,00 64 0,57 4 8,86 62 5,71 40 5,86 170

Coenagrion lunulatum 1,14 8 0,28 8 Coenagrion puella/pulchellum 9,25 74 4,43 31 10,14 71 9,86 69 8,45 245 Enallagma cyathigerum 0,38 3 0,71 5 1,29 9 4,14 29 1,59 46 Erythromma najas 0,88 7 0,29 2 0,14 1 0,57 4 0,48 14

Ischnura elegans 0,88 7 0,71 5 2,00 14 0,90 26 Pyrrhosoma nymphula 0,75 6 0,21 6 Anisoptera Aeshna cyanea 0,88 7 0,57 4 0,38 11 Aeshna grandis 0,13 1 0,03 1 Aeshna juncea 0,14 1 0,03 1 Gomphus vulgatissimus 0,14 1 0,03 1 Cordulia aenea 0,50 4 0,14 4 Libellula depressa 0,25 2 0,57 4 0,14 1 0,24 7 Libellula quadrimaculata 0,63 5 0,57 4 0,31 9 Orthetrum cancellatum 0,86 6 0,29 2 0,28 8 Megaloptera Sialis lutaria 3,38 27 1,29 9 1,00 7 1,00 7 1,72 50

Plecoptera Nemoura flexuosa 0,38 3 0,10 3 Heteroptera Ranatra linearis 0,38 3 0,29 2 0,57 4 0,31 9 Corixinae 0,25 2 1,43 10 0,29 2 0,48 14 Arctocorisa germari 0,29 2 0,07 2 Callicorixa praeusta 0,25 2 0,29 2 0,29 2 0,21 6 Corixa dentipes 0,38 3 0,14 1 0,14 4 Corixa punctata 0,43 3 1,00 7 0,14 1 0,38 11

Hesperocorixa linnaei 0,50 4 1,86 13 0,14 1 0,62 18 Hesperocorixa sahlbergi 0,25 2 1,00 7 0,31 9 Paracorixa concinna 0,57 4 0,57 4 0,28 8 Sigara 3,75 30 13,14 92 1,00 7 0,14 1 4,48 130 Sigara distincta 5,13 41 2,57 18 1,14 8 1,71 12 2,72 79 Sigara dorsalis 1,00 8 3,57 25 1,43 10 6,86 48 3,14 91 Sigara falleni 5,13 41 4,71 33 0,57 4 1,14 8 2,97 86 Sigara fossarum 28,13 225 2,00 14 2,00 14 14,57 102 12,24 355

Sigara iactans 0,29 2 0,43 3 0,17 5 Sigara lateralis 2,63 21 7,57 53 1,57 11 3,71 26 3,83 111

Sigara limitata 0,13 1 0,03 1 Sigara longipalis 0,63 5 0,71 5 0,14 1 2,14 15 0,90 26

Sigara nigrolineata 2,75 22 0,76 22 Sigara scotti 1,38 11 2,86 20 1,07 31 Sigara semistriata 0,38 3 0,14 1 0,14 4 Sigara striata 0,13 1 0,71 5 0,71 5 0,38 11

Cymatia bonsdorffii 0,63 5 9,14 64 1,43 10 0,14 1 2,76 80 Cymatia coleoptrata 0,13 1 11,71 82 3,00 21 0,14 1 3,62 105

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Notonecta glauca 3,00 24 0,71 5 3,43 24 0,86 6 2,03 59

Plea minutissima 4,00 28 0,97 28

Coleoptera 0,13 1 0,14 1 0,07 2 Agabus 1,50 12 0,41 12 Ilybius 1,50 12 3,71 26 0,57 4 0,71 5 1,62 47

Platambus maculatus 0,29 2 0,07 2 Colymbetes 0,14 1 0,43 3 0,14 4 Rhantus 1,43 10 0,29 2 0,41 12 Acilius canaliculatus 0,13 1 0,14 1 0,07 2 Acilius sulcatus 0,57 4 0,14 4 Hydroporus 0,14 1 0,03 1 Porhydrus lineatus 0,50 4 0,14 1 2,57 18 0,79 23 Hygrotus 0,13 1 0,14 1 0,57 4 0,21 6 Hygrotus inaequalis 0,13 1 0,14 1 1,43 10 0,41 12 Hyphydrus ovatus 1,13 9 0,31 9 Laccophilus 0,14 1 0,03 1 Laccophilus hyalinus 0,14 1 0,03 1 Laccophilus minutus 0,29 2 0,14 1 0,10 3 Haliplus 0,25 2 0,29 2 0,43 3 0,43 3 0,34 10

Noterus clavicornis 0,14 1 0,03 1 Trichoptera 0,14 1 0,29 2 0,10 3 Cyrnus trimaculatus 0,14 1 0,03 1 Holocentropus dubius 2,00 16 0,71 5 0,71 5 0,90 26 Limnephilidae 0,63 5 0,17 5 Limnephilus 6,38 51 4,00 28 2,57 18 3,34 97 Nemotaulius punctatolineatus 0,25 2 0,07 2 Phryganeidae 0,86 6 0,21 6 Agrypnia 0,50 4 0,57 4 0,28 8 Agrypnia obsoleta 0,13 1 0,14 1 0,14 1 0,10 3 Oligotricha striata 0,13 1 0,03 1 Phryganea bipunctata 0,29 2 0,14 1 0,10 3 Diptera Serromyia 0,13 1 1,29 9 0,14 1 0,14 1 0,41 12

Chironominae Chironomini 12,63 101 8,14 57 3,86 27 6,14 43 7,86 228 Tanypodinae 2,75 22 2,71 19 2,71 19 2,71 19 2,72 79

Chaoborus crystallinus 0,29 2 10,71 75 2,66 77 Chaoborus flavicans 0,50 4 1,00 7 8,14 57 0,71 5 2,52 73 Chaoborus obscuripes 19,75 158 9,00 63 43,71 306 103,57 725 43,17 1252

Anopheles (Anopheles) 0,14 1 0,03 1 Anopheles maculipennis 0,13 1 0,03 1 Coquillettidia richiardii 0,13 1 0,03 1 Limoniidae 0,13 1 0,43 3 0,14 4 Dicranoptycha fuscescens 0,29 2 0,07 2 Pediciidae 0,14 1 0,03 1 Tipula (Arctotipula) 0,14 1 0,03 1 SUM 322,13 2577 242,38 1939 372,38 2979 257,63 2061 329,52 9556 Shannon’s diversity index 1,76 – 1,20 – 1,41 – 1,47 – 1,47 – ASPT index 5,05 – 4,17 – 4,23 – 4,55 – 4,52 –

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Initially there seemed to be no differences in Shannons biodiversity index between the different groups (p>0,1). However, after selecting the most typical site for each category a trend was shown (see fig. 2) were the covered wetlands tended to have higher biodiversity (p=0,056; F=4,801; df=1). Similarly, ASPT index tended to be higher (p=0,058; F=3,948; df=1) when the wetland was both covered and grazed (See fig. 3). The distinct sample set however did not show the same trend at all (p>0,1). Here, there was a slight trend for higher ASPT-index at covered wetlands however (p=0,106; F=3,231; df=1).

Among the different subgroups, Trichoptera and Asellus aquaticus stood out showing preferences for covered wetlands. The former had very few findings in uncovered wetlands and in the group containing both open and grazed wetlands only one specimen could be found (see table 2). The latter was only found at two sites in the same category. Trichoptera was analysed within the selected wetlands and showed a clear trend being more abundant in wetlands with covered shores (p=0,088; Mann-Whitney U=20; df=1). The number of species of Figure 2. Average diversity index in open and covered wetlands. Ephemeroptera tended to be more Standard error bars denote 95 % confidence interval of group means. abundant in grazed wetlands (p=0,076; Kruskal-Wallis H=3,148; df=1). The wetland in Trollhättan was standing out in the ungrazed group and when compared to the other wetlands it had a much higher catchment area of 50 km2. The average area was 2,99 km2 with Trollhättan and just 1,31 km2 without. When removing the large wetland in Trollhättan, there were significantly more Ephemeroptera species in grazed wetlands (p=0,022; Kruskal- Wallis H=5,282; df=1). This was not found when comparing the distinct grazed Figure 3. Average ASPT index in grazed and not grazed wetlands cross-examined by coverage. Standard error bars denote 95 % wetlands however (p=0,148; Kruskal- confidence interval of group means. Wallis H=2,089; df=1).

Novel finds One of the most interesting species found was the Pygmy back-swimmer Plea minutissima. It was the northernmost record in Sweden to that date. However, in the spring 2019 a few more specimens were found in the nearby area (Artportalen 2019). Other rarely reported species found was Sigara iactans and Oligotricha striata.

Discussion Wetlands with covered shorelines had higher values of Shannons biodiversity index than those lacking trees and shrubs. This finding supports my hypothesis that covered shorelines

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increase the biodiversity in small wetlands. This was only found when the more distinct wetlands in my study was examined, thus having a smaller sample size. The ASPT-index showed an interesting, clearly discernible trend for higher values in wetlands both grazed and with covered shorelines. The latter was expected in the hypothesis, but not the grazing. The picture is complicated by the fact that this trend was non-existent in the sample set with more distinctly categorized wetlands. However, here we found a very weak trend towards higher values of ASPT in wetlands with covered shorelines. Trichopetra-species also showed a trend towards wetlands with covered shorelines. The species found in this study belongs in the families Polycentropodidae, Limnephilidae and Phryganeidae. The first family do not build cases and should therefore not need course materials to build nests (Nilsson (ed) 2005). They were also only found in six (four distinct) wetlands and hard to say anything about. The two latter families however build cases out of mainly plant parts (in some cases also shells from snails and sand grains). They were also more abundant in wetlands with covered shorelines and is probably a result of more plant materials to build their cases of. One wetland with a much larger catchment area than the other wetlands was removed. That led to a significant result showing that number of Ephemeroptera genera increases if the wetlands are grazed. The reason for removing it was that the catchment area might affect the number of species in the wetlands. There was however no significant difference when comparing the more distinct sites (in which the aforementioned wetland was not included). Other similar studies have shown different results, but mostly that grazing has a positive impact on species richness (Davis & Bidwell 2008). Previous studies done on Odonates, which Coenagrionidae belongs to, indicated that they might be affected negatively from grazing cattle (Lee Foote & Rice Hornung 2005). They need vegetation emerging from the water to lay eggs and to climb up on when they are ready to fly. Feeding animals might graze upon that type of vegetation. Curiously, a significant result when all wetlands was considered could vanish when the more distinct wetlands was examined. Likewise, a clear trend in the distinct wetlands could be nowhere to be seen when all sites was compared. Only the caddisflies showed a consistent pattern. One reason for that could be the lack of distinct wetlands (just 13). More unmistakable types of shorelines should be used. The intensity of grazing and share of tree/shrub coverage of the wetlands should also been noted. The experience from the field is that other aspects such as bottom conditions and aquatic macrophytes play a huge role in the composition and abundance of invertebrates. The appearance of the wetlands is important too, as physical factors such as small islands, depth and laciniated shorelines contribute to the heterogeneity of the wetlands. That increases the amount of microhabitat and thus the amount of species. This should have been included into this study during the site election to compare similar-looking areas. Other factors that are very important include water chemistry (Bydén mfl 2003). Oxygen, pH, nutrients and pollution are all limiting the environment for different groups of aquatic invertebrates. The wetlands in this study were located in an agricultural landscape and therefore nutrients such as nitrates and phosphates should have a significant impact on the chemistry from manure and animal droppings. They can also have a cascading effect by stimulating algae growth and in the long run deplete oxygen when dead algae decompose. The pH in eutrophic wetlands is rarely a problem. Water from the different site were sampled, but due to time constraints not analysed. The wetlands surveyed in this study were most likely eutrophic, however a chemical analysis could have helped by pointing out differences in nutrient levels. The time of this survey was in late autumn. It is a good time for assessing the ASPT-value (Havs- och Vattenmyndigheten 2018), but the best time to investigate the biodiversity is in early spring when more species are abundant (Havs- och Vattenmyndigheten 2016). However, the results should still be relevant since the aim of this study was to compare the different wetlands rather than evaluate the biodiversity in itself. The summer preceding this study was also unusually dry and hot with little to no rain from the middle of May to the middle of August. Because of this most wetlands

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were approximately 30 cm below the usual water level. This have probably affected the study in a negative way. The study also contributes new knowledge of the biodiversity and distribution of common macroinvertebrates in the region, and also new findings of rare species such as the Pygmy backswimmer (Plea minutissima), known from primarily Skåne and Gotland. My finding on Orust, Bohuslän led to another finding in the near area. Other species include the different Chaoborus species. C. obscuripes for example are have been reported five times in the Swedish Species Observation System (Artportalen 2019). They have been observed in twelve wetlands in this study. They are clearly underreported and thus this study has helped with more knowledge of our invertebrates. Climate warming is likely to contribute to a gradual northward expansion of the southern species.

Conclusion To summarize the findings, covered shorelines seem to host increased biodiversity of aquatic invertebrates. These types of wetlands also have a more diverse fauna of caddisflies, Trichoptera. Greater values of ASPT might be expected in wetlands with both grazed and covered shorelines, however further studies from more wetlands are needed. The same goes for mayflies, Ephemeroptera, which seems to favour grazed shorelines. Further studies should focus on wetlands with more similar conditions and clear differences in the different land use categorizations. These should also include a gradient in cover and grazing intensity. A north-south gradient can reveal changes in macroinvertebrate fauna through time with climate change.

Acknowledgements Many thanks to:

Professor Johan Höjesjö, Department of Biological and Environmental Science, Gothenburg University for excellent supervising and many good advices.

Magnus Lovén Wallerius for help with identification, methods and layout.

Arash Toormagiyoun, Maria Eriksson Andin, Josefina Pehrson, Viktor Åström, Moa Pettersson and Peder Winding for help with sampling.

Professor Donald Blomqvist for help with statistics.

Associate professor Karin Hårding for help with framing questions to work with.

Olof Persson, Oskar Gran and people in the Facebook groups “Halvvingarnas liv (Hemiptera)” and “Skalbaggarnas liv (Coleoptera)” for help with identification.

A special thanks to the land owners on whose estate I did my surveys.

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Berg, Å., Lindberg, T., & Källebrink, K. G. (1992). Hatching success of lapwings on farmland: differences between habitats and colonies of different sizes. Journal of Animal Ecology, 469- 476. Bydén, S., Larsson, A. M., & Olsson, M. (2003). Mäta vatten: undersökningar av sött och salt vatten. Institutionen för miljövetenskap och kulturvård, University of Gothenburg. Davis, C. A., & Bidwell, J. R. (2008). Response of aquatic invertebrates to vegetation management and agriculture. Wetlands, 28(3), 793-805. Dosskey, M. G., Schultz, R. C., & Isenhart, T. M. (1997). How to design a riparian buffer for agricultural land. Edington J M, Hildrew A G (1981) A key to the caseless caddis larvae of the British Isles: with notes of their ecology. Ambleside: Freshwater Biological Association Enckell P H (1980) Kräftdjur. Lund: Signum Hallmann, C. A., Sorg, M., Jongejans, E., Siepel, H., Hofland, N., Schwan, H., ... & Goulson, D. (2017). More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PloS one, 12(10), e0185809. Havs- och vattenmyndigheten (2016) Bottenfauna i sjöars litoral och vattendrag 1:2, 2016-11-01 https://www.havochvatten.se/download/18.2a9deb63158cebbd2b44e924/1481197150482/b ottenfaunasjoarslitoralovattendragm42oberoende.pdf Havs- och vattenmyndigheten (2018) Bottenfauna i sjöar vägledning för statusklassificering 2018- 12-03 https://www.havochvatten.se/download/18.670c3c9a16786bb1262409d3/1544453985458/r apport-bottenfauna-sjoar-vagledning-for-statusklassificering.pdf Johnson, D. (2001). Habitat fragmentation effects on birds in grasslands and wetlands: a critique of our knowledge. Great Plains Research: A Journal of Natural and Social Sciences, 568. Kayranli, B., Scholz, M., Mustafa, A., & Hedmark, Å. (2010). Carbon storage and fluxes within freshwater wetlands: a critical review. Wetlands, 30(1), 111-124. Lee Foote, A., & Rice Hornung, C. L. (2005). Odonates as biological indicators of grazing effects on Canadian prairie wetlands. Ecological Entomology, 30(3), 273–283. Mandahl-Barth G, (1982) Småkryp i sötvatten. 4 edition. Fältbiologerna förlag. Marty, J. T. (2005). Effects of cattle grazing on diversity in ephemeral wetlands. Conservation Biology, 19(5), 1626–1632. Mitsch, W. J., & Gosselink, J. G. (2000). The value of wetlands: importance of scale and landscape setting. Ecological economics, 35(1), 25-33. Nilsson A (ed), (2005) The Aquatic Insects of North Europe vol. 1&2. Stenstrup: Apollo Books Aps. O'Geen, A. T., Budd, R., Gan, J., Maynard, J. J., Parikh, S. J., & Dahlgren, R. A. (2010). Mitigating nonpoint source pollution in agriculture with constructed and restored wetlands. In Advances in agronomy (Vol. 108, pp. 1-76). Academic Press. Ruggiero, A., Céréghino, R., Figuerola, J., Marty, P., & Angélibert, S. (2008). Farm ponds make a contribution to the biodiversity of aquatic insects in a French agricultural landscape. Comptes Rendus Biologies, 331(4), 298-308. Savage, A A (1989) Adults of the British Aquatic Hemiptera Heteroptera: A key with ecological notes. Ambleside: Freshwater Biological Association. Scrimgeour, G. J., & Kendall, S. (2003). Effects of livestock grazing on benthic invertebrates from a native grassland ecosystem. Freshwater biology, 48(2), 347-362. Semlitsch, R. D., & Bodie, J. R. (1998). Are small, isolated wetlands expendable?. Conservation biology, 12(5), 1129–1133. SMHI (2018) Våtmarksdatabasen 2017 http://vattenwebb.smhi.se/wetlands/ 2019-05-15 Strand, J. (2019). Gynna mångfalden vid vatten. Jordbruksverket Wallace I D, Wallace B, Philipson G N (1990) A key to the Case-bearing Caddis larvae of Britain and Ireland. Ambleside: Freshwater Biological Association

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Webb, J. R., Hayes, N. M., Simpson, G. L., Leavitt, P. R., Baulch, H. M., & Finlay, K. (2019). Widespread nitrous oxide undersaturation in farm waterbodies creates an unexpected greenhouse gas sink. Proceedings of the National Academy of Sciences, 116(20), 9814-9819. Vymazal, J. (2007). Removal of nutrients in various types of constructed wetlands. Science of the total environment, 380(1-3), 48-65. Żmihorski, M., Krupiński, D., Kotowska, D., Knape, J., Pärt, T., Obłoza, P., & Berg, Å. (2018). Habitat characteristics associated with occupancy of declining waders in Polish wet grasslands. Agriculture, ecosystems & environment, 251, 236–243.

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Appendix 1. Populärvetenskaplig sammanfattning Små våtmarker är mycket viktiga för både ekosystemet och oss människor. Bland annat utgör dessa våtmarker livsmiljöer för en mängd olika livsformer. För att främja vissa fåglar som tofsvipa brukar våtmarkerna i Sverige ofta betas och stränderna rensas från buskar och träd. Våtmarkerna kan annars växa igen och träden fungerar som utkiksplatser för kråkfåglar som gärna plundrar vipornas bon. Några andra som gillar våtmarker är insekter och andra småkryp. Många insekter har olika livsstil under olika stadier av sina liv. Vissa grupper, som trollsländor och myggor, lever som larver eller nymfer under vattenytan, ibland under flera år. När de senare blir vuxna återvänder de bara till vattnet för att lägga sina ägg där. Andra grupper som skalbaggar och buksimmare lever i vattnet som både larver/nymfer och vuxna. De senare kan dock ofta flyga och lämna vattnet för att hitta nya områden. Förutom insekter finns även en hel del snäckor, kräftdjur och iglar som trivs i vattenmiljö. Vad som är osäkert är hur insekter och andra småkryp påverkas av bete och stränder utan buskar. Till exempel lägger vissa arter av nattsländor ägg på blad som hänger över vatten. Buskar och träd kan även tillföra näring genom att tappa löv och grenar i vattnet som vissa av småkrypen äter. Betande boskap kan både vara en fördel och nackdel. Om de får gå ut och beta i vattnet kan en så kallad blå bård skapas. Det är en yta med öppet vatten mellan vassbältet längre ut och stranden. Denna kan vara väldigt rik på liv. För mycket bete kan dock medföra för mycket näringstillskott i form av avföring vilket kan påverka systemet kraftigt. För att undersöka detta valdes 29 våtmarker ut utifrån kategorierna (1) betat utan buskar på stränderna, (2) betat med buskar, (3) obetat utan buskar och (4) obetat med buskar. Dessa ligger spridda i Västra Götalands län. Dessa våtmarker håvades under hösten och de småkryp som hittades artbestämdes sedan. Därefter gjordes beräkningar på biologisk mångfald och även ett index (ASPT) där vissa grupper av djur får mer eller mindre poäng beroende på hur känsliga de är för dålig vattenkvalité. Därefter gjordes statistiska undersökningar för att hitta skillnader mellan de olika kategorierna av våtmarker. Vissa grupper av småkryp studerad extra noga för att se om de föredrog någon typ av våtmark. Totalt hittades 9 556 individer i de våtmarker som undersöktes. Resultatet av de olika statistiska undersökningarna var först lite otydliga, men genom att ta fram 13 våtmarker där kategoriseringen var tydlig kunde vissa trender hittas. I våtmarker med träd- och buskbevuxna stränder fanns en tydlig trend mot större biologisk mångfald. När ASPT undersöktes fanns först en tydlig trend där våtmarker som både var bevuxna och betades hade bättre värden. Denna trend fanns märkligt nog inte när bara de tydligaste våtmarkerna granskades. Nattsländor och vattengråsuggor trivdes bra i våtmarker med bevuxna stränder medan fler arter dagsländor fanns i betade våtmarker. Förmodligen hade våtmarkernas stränder behövt vara mer typiska, fler och mer lika i övrigt för att statistikt signifikanta variabler som förklarar artdiversiteten skulle kunna påvisats. Till exempel bör man kontrollera provtagningen med avseende på dominanta vattenväxter, bottenmaterial och vattenkemi. Denna studie visar dock att flera arter gynnas av högre vegetation runt våtmarker. En rekommendation är därför att behålla eller släppa upp en mindre mängd träd och buskar kring vissa våtmarker där målet är att gynna insektsfaunan.

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Appendix 2. Visited wetlands. Site number 30 not sampled due to low water level.

Site N E Municipality Area (ha) Catchment (km2) Year of construction Comment Categories ID Grazed: Yes 1 6458350 414020 Falköping 1,15 2,9 2012 Covered: Yes 31635187-e6aa-459a-a97f-48e8c0b4f61c Grazed: Yes 2 6477280 376120 Lidköping 0,34 0,5 2011 Covered: Yes 25d8d3e7-47f9-402d-9ae2-58599dd9f614 Grazed: Yes 3 6465460 400840 Skara 1,3 2,5 2009 Covered: Yes d295ad17-0788-4504-90da-19ce779bf213 Grazed: Yes 4 6481900 422940 Skövde 1,07 1,1 2014 Distinct Covered: Yes 85939312-b9fe-4761-931b-6bfa62d4a7e0 Grazed: Yes 5 6483350 428860 Skövde 0,28 0,1 2010 Covered: Yes 59f346b0-e52c-44f5-9786-a07eeab34aad Grazed: Yes 6 6461720 297530 Uddevalla 0,88 1,1 2013 Distinct Covered: Yes 65e5a4d6-9fdb-4d3c-88c1-4a2ff3ef8a26 Grazed: Yes 7 6412830 413580 Ulricehamn 0,42 0,15 2008 Covered: Yes f8a9379d-77fa-4597-9549-bc2f2dd7aa3e Grazed: Yes 8 6418220 403450 Ulricehamn 0,37 0,07 2011 Distinct Covered: Yes 45824435-19f4-4cf2-8888-c41dfaf7ce81 Grazed: Yes 9 6460300 428810 Falköping 1,32 0,6 2011 Distinct Covered: No 8c79f2d7-4585-4506-b3f7-43447a704721 Grazed: Yes 10 6440940 412920 Falköping 1,26 0,28 2012 Distinct Covered: No 7de90c41-71ca-44a6-9edd-4e1370de40bd Grazed: Yes 11 6444480 424790 Falköping 1 0,3 2010 Covered: No 52e89561-d632-4510-b7f7-2244a8d91bc5 Grazed: Yes 12 6487230 383930 Lidköping 1,64 0,75 2014 Covered: No 3715827e-c919-4124-9b48-b1a620fc3bc6 Grazed: Yes 13 6455100 294980 Orust 1,2 2 2008 Distinct Covered: No 662d8e72-4110-4e66-a4c4-f6991fda453b Grazed: Yes 14 6420230 402740 Ulricehamn 1,54 0,6 2013 Covered: No dc74c80f-cd30-48b3-917d-df3ee2d74210 Grazed: Yes 15 6453680 385320 Vara 0,36 2 2009 Covered: No 394033fe-fef9-494d-9893-3beb9e05ac9e Grazed: No 16 6451050 368240 Essunga 1 12 2013 Covered: Yes 3d275fb3-6ef6-48fc-bd81-47979b3d07a3 Grazed: No 17 6461060 426730 Falköping 0,97 1,2 2013 Covered: Yes 32545ee2-32cc-4f6c-a838-544e6e314e83 Grazed: No 18 6484340 417730 Götene 1,15 1,5 2013 Covered: Yes 53a4dd4f-dbe3-4554-aab2-e62758e7038c Grazed: No 19 6510790 439970 Mariestad 1,48 0,14 2010 Distinct Covered: Yes 0dfb4820-856d-468c-a1b5-037e838b9d7c Grazed: No 20 6506530 314750 Munkedal 1,18 0,5 2008 Covered: Yes 80aa7f5f-c361-4575-a3a4-5c48d0bde855 Grazed: No 21 6471430 443210 Skövde 1,61 4,5 2015 Distinct Covered: Yes 46a6855b-5595-44cc-915b-f0fd7b1e1876 Grazed: No 22 6438760 432670 Tidaholm 1,61 0,5 2015 Distinct Covered: Yes fd87f919-5b05-4be4-8b52-04ab0c69fd0e Grazed: No 23 6447300 410000 Falköping 0,72 0,1 2011 Distinct Covered: No ae271fb1-60cc-4219-97ea-57a4d9ac4fa3 Grazed: No 24 6447390 406400 Falköping 1,72 0 2013 Covered: No 31798a83-0da7-4ce3-a1e2-9ff4b475c4dd Grazed: No 25 6439020 422840 Falköping 1,67 0 2010 Distinct Covered: No f74dac9d-0ccb-42c0-b46b-4cb311866613 Grazed: No 26 6439910 423080 Falköping 0,97 0,5 2007 Distinct Covered: No 8e414a39-5976-426b-adc7-a51c6de9704e Grazed: No 27 6467420 399690 Skara 0,5 0,4 2011 Covered: No ec709518-a384-41b6-844e-19e21f3e19e7 Grazed: No 28 6458770 352420 Trollhättan 0,82 50 2012 Covered: No 55cdf580-b557-49d7-863c-0a6c036d62fe Grazed: No 29 6430870 360080 Vårgårda 0,99 0,5 2012 Distinct Covered: No 56ce8513-182d-43d1-8894-83563f46988d Grazed: No 30 6453070 407080 Falköping 1,8 6,5 2015 Not sampled Covered: No cb6e229a-2e6a-4f3c-b583-3e3fc2891d0f

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Appendix 3. A complete list of all specimens and where they were found.

Grazed with covered shorelines Grazed with open shorelines Not grazed with covered shorelines Not grazed with open shorelines Taxa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Annelida 2 1 1 2 2 5 4 1 2 1 4 1 1

Hirudinea Erpobdella octoculata 4 21 4 1 3 1 5 1 20 6 7 10 Erpobdella testacea 2 Glossiphonia complanata 1 1 1 Helobdella stagnalis 1 2 1 1 2 1 Theromyzon tessulatum 2 2 1 2 1

Mollusca

Bivalvia Pisidium 11 10 43 3 2 2 4 4 9 3 1 8 1 1 2 Pisidium amnicum 2 1 1 1 1

Gastropoda 1 Myxas glutinosa 1 Omphiscola glabra (NT) 2 Radix balthica 14 1 8 3 7 24 1 Physa fontinalis 6 Anisus vortex 5 Bathyomphalus contortus 8 Gyraulus albus 4 6 2 39 3 11 17 1 Gyraulus crista 4 6 13

Platyhelminthes 1 1

Araneae Argyroneta aquatica 1

Amphipoda Gammarus lacustris 1 3

Isopoda Asellus aquaticus 20 5 78 113 14 41 108 15 30 99 6 211 38 26 1 111 120 16 239 18 8 1

Ephemeroptera Cloeon dipterum/inscriptum 183 29 198 110 5 67 149 171 250 94 7 1 256 55 322 345 452 229 31 261 58 67 140 136 11 44 7 4 Caenis horaria 1 1 2 1 2 7 Ephemera vulgata 1 2 1 12 9 Leptophlebia marginata 13 6 1 19 2

Odonata

Zygoptera 4 Coenagrionidae 6 1 1 9 2 1 6 3 19 Coenagrion 1 Coenagrion armatum 8 11 6 10 Coenagrion hastulatum 11 10 3 21 19 4 14 45 3 40 Coenagrion lunulatum 8 Coenagrion puella/pulchellum 16 4 40 14 7 2 15 7 13 35 1 2 15 5 21 46 2 Enallagma cyathigerum 3 5 3 6 8 10 11 Erythromma najas 5 2 1 1 1 2 2 Ischnura elegans 3 4 1 4 14 Pyrrhosoma nymphula 6

Anisoptera Aeshna cyanea 1 1 2 3 3 1 Aeshna grandis 1 Aeshna juncea 1 Gomphus vulgatissimus 1 Cordulia aenea 1 3 Libellula depressa 2 1 2 1 1 Libellula quadrimaculata 1 1 3 2 2 Orthetrum cancellatum 6 2

Megaloptera Sialis lutaria 2 13 4 8 2 7 1 3 3 7

Plecoptera Nemoura flexuosa 3

Heteroptera Ranatra linearis 1 1 1 2 2 2

Corixinae 2 10 2 Arctocorisa germari 2 Callicorixa praeusta 2 2 1 1 Corixa dentipes 2 1 1 Corixa punctata 1 2 2 1 2 1 Hesperocorixa linnaei 2 2 13 1 Hesperocorixa sahlbergi 2 3 1 1 1 Paracorixa concinna 2 2 4 Sigara 24 4 2 20 72 5 1 1 1 Sigara distincta 16 1 24 4 1 11 2 5 3 7 5 Sigara dorsalis 1 4 1 2 2 23 7 1 2 16 32 Sigara falleni 14 23 4 6 8 3 3 13 1 1 2 6 2 Sigara fossarum 2 3 7 2 211 12 1 1 1 13 34 58 10 Sigara iactans 2 3 Sigara lateralis 21 49 4 1 10 2 24 Sigara limitata 1 Sigara longipalis 5 5 1 1 14 Sigara nigrolineata 3 1 18 Sigara scotti 1 10 3 1 16 Sigara semistriata 3 1 Sigara striata 1 5 5

Cymatia bonsdorffii 5 1 63 8 2 1 Cymatia coleoptrata 1 1 81 17 4 1

Notonecta glauca 9 3 4 2 6 1 4 1 2 1 14 6 1 1 4 Plea minutissima 28

Coleoptera 1 1 Agabus 10 2 Ilybius 1 6 5 26 1 2 1 1 4 Platambus maculatus 2 Colymbetes 1 3 Rhantus 10 2 Acilius canaliculatus 1 1 Acilius sulcatus 4 Hydroporus 1 Porhydrus lineatus 4 1 18 Hygrotus 1 1 1 1 1 1 Hygrotus inaequalis 1 1 10 Hyphydrus ovatus 9 Laccophilus 1 Laccophilus hyalinus 1 Laccophilus minutus 2 1 Haliplus 1 1 2 1 1 1 2 Noterus clavicornis 1

Trichoptera 1 2 Cyrnus trimaculatus 1 Holocentropus dubius 15 1 4 1 4 1 Limnephilidae 5 Limnephilus 1 6 28 9 3 4 2 1 1 21 3 14 2 2 Nemotaulius punctatolineatus 2 Phryganeidae 6 Agrypnia 4 4 Agrypnia obsoleta 1 1 1 Oligotricha striata 1 Phryganea bipunctata 2 1

Diptera Serromyia 1 3 4 2 1 1 Chironominae Chironomini 2 15 13 15 1 51 2 2 15 1 8 9 20 4 12 2 1 1 8 2 1 2 1 9 31 Tanypodinae 5 8 5 3 1 4 4 1 5 5 13 3 3 1 1 1 16 Chaoborus crystallinus 2 1 36 38 Chaoborus flavicans 1 3 4 1 1 1 2 1 42 12 4 1

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Chaoborus obscuripes 2 9 145 2 52 11 196 6 104 705 6 14 Anopheles (Anopheles) 1 Anopheles maculipennis 1 Coquillettidia richiardii 1 Limoniidae 1 3 Dicranoptycha fuscescens 1 1 Pediciidae 1 Tipula (Arctotipula) 1

Sum 276 173 449 326 51 275 523 504 389 335 10 100 498 93 514 462 1070 378 230 9 613 214 103 1159 225 142 247 90 95

Shannon's diversity index 1,44 1,90 1,86 1,70 1,75 2,29 1,78 1,33 1,30 1,77 0,80 0,49 1,55 1,16 1,35 1,08 1,76 1,27 2,27 0,35 1,83 1,29 1,23 1,17 1,19 1,28 2,11 2,46 0,85

ASPT 5,21 4,70 4,69 4,50 5,11 5,38 4,80 6,00 4,20 4,27 3,00 4,00 4,00 4,83 4,87 3,67 4,53 4,54 4,94 2,50 4,27 5,17 3,90 4,06 5,43 5,14 4,00 6,31 3,00

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