Discovering how high the water quality of mountain freshwater actually is

Transcription

1 Discovering how high the water quality of mountain freshwater actually is A study of variation in water quality and its effect on species distribution Authors: Tutor: Fabienne Luong, Theresianum, Ingenbohl, Switzerland Sarah Suleiman, Saint Aloysius College, Birkirkara, Malta Isabelle, Hallgren, ProCivitas Privata Gymnasium, Malmö, Sweden Salome, Steiner Date: June 27,

2 1. Abstract The lakes and rivers distributed along the Swiss Alps are vital sources of freshwater. This together with threats of pollution renders water quality analysis and control very important. The aims of our investigation were to test the varying levels of water quality between running and still streams, as well as the distribution of insect populations among such waters. By comparing results of bioindication to a scale, the water quality of different streams could be derived and by using the Lincoln Peterson index, the population numbers were calculated from a Capture recapture experiment. Through results, it was concluded that running water is of a better quality than still water and that this variation did not directly affect the distribution of insects. The importance of such techniques extends further from the hypothesis analysis, providing the necessary medium for thoroughly analysing the components of the environment and studying life stages of different species populations. 2. Introduction Switzerland possesses 6 % of Europe's fresh water, and is sometimes referred to as the "water tower of Europe" [1]. However, major problems have arisen as regards water pollution from agriculture, such as eutrophication, and have even been recorded to be over the values stated in the Water Protection Ordinance. Water quality is the basis of biodiversity. Thus on a small scale, we aimed to essentially assess the variation in quality of the water through bioindication, which could roughly describe the oxygen and nutrient content of the water through the species present, the latter ultimately being the major factor affecting water quality. Simple projections made by Aqua Viva together with Paul Schiller Stiftung [2] define the quality in terms of species present. Species such as mountain midge, stonefly, Tricoptera and Planaria indicate high quality, mayfly and blackfly larva show medium quality and species such as Diptera indicate low water quality. We specifically aimed to determine whether water quality in the mountain area, where the mountain streams laying close to each other and all of them being close to the source, did change according to whether the water was running or still and if so by what extent. We expected that running water would be of a much higher quality than still water. An interest that arose when working with the multiple species inhabiting the waters was the relative population numbers, which could be studied through the execution of the Capture recapture technique. Therefore, we aimed to use this technique on a small scale, so as to compare the population sizes of mayflies (Ephemeroptera) and stoneflies (Plecoptera) in running water, both being indicators for good water quality. However, the stonefly is known to be highly restricted to good water quality, while the mayfly is also known to tolerate moderately contaminated water. Therefore, we expected the Ephemeroptera species to have a more even distribution along the water areas and therefore a lower, less concentrated population size in relation to the stonefly species. Each species referred to in this article is in the nymph/larval stage. 2

3 3. Materials & Methods 3.1. Environment The field studies were performed in the Swiss Alps in the surrounding of the alp Buffalora in the Val Mustair GR, from 23 rd till 25 th of June. There, six mountain streams were investigated, the altitude and the coordinates of the water areas are: Area 1, 1965 m a.s.l, /169993; Area 2, 2225 m a.s.l., /167630; Area m a.s.l, /167637; Area m a.s.l, /167218; Area m a.s.l.., /166641; Area 6, 1983 m a.s.l, / All these areas can be seen in the Appendix 8.2. The insects in the container were identified and separated according to species. The number and type of species found were noted down and these results were tabulated. This method was repeated for three running streams as well as three still streams Bioindication The method was derived from the GLOBE Swiss project of bioindication [3] to determine water quality. This was done by identifying and counting the several species and morphous forms in a lake and using the numbers in the scale shown in Figure 1 and 2. The vertical axis represents the number of species found, and the horizontal one represents the most superior (one indicating best water quality) leading species. Five stones were turned over from their position and with the net accordingly positioned, the sand and insects displaced by the motion were caught through filtration. The net was emptied in a container of water, and any insect lying on the moved stone were also brushed off into the container. This was repeated five times for five different stones along the same area. An area of small stones was dug through and the sand and insects displaced by the motion were caught once more by the net and emptied as before. This was also repeated five times for five different stony patches. Figure 1. The following scale was used to relate the number of morphospecies and the leading species present (whether superior or inferior) to the water quality. a. Very high quality. b. High quality. c. Moderate quality d. Contaminated. e. Highly contaminated. f. Crucially contaminated. g. Excessively contaminated. N: 2 or more Morfeus species found n: 1 species found Figure 2. Displays the implication of the letters of the scale in figure 1. 3

4 3.3. Capture recapture The Capture recapture method, with the Lincoln-Petersen index [4], was used to estimate three different insect species populations abundance in running water found along the mountains. A known number of a population was captured by turning over and digging through stones (done by three people) for 20 minutes in a region of 5 m length in Area 1. The captured insects were marked by a waterproof red colour (Marabu GmbH & Co. KG, Bietigheim-Bissingen, Germany). They were then released back into their habitat. This was done for three insect species present in the same area. 24 hours later another portion of a population was captured using the same method as before. The number of recaptures as well as those coloured was noted and the results tabulated. The recaptures were released back into the water. The mathematical equation (the Lincoln-Petersen index) used for the calculation of the total species population number in the tested area (N) was N = Mc/r. M representing the total number of captures, C representing the total number of recaptures and r representing the total number of coloured recaptures. 4. Results 4.1. Better water quality in running streams than in still streams As shown in Table 1, a general pattern could be noted. The three running streams were rated at moderate and high quality, while the still streams were rated as being contaminated, except for one which was noted as moderate (Area 5). The still water areas had a higher temperature than the running ones as shown in Table 2. The ph-values were all more or less the same Larger population of Ephemeroptera than Plecoptera in running stream The population of the stonefly (Plecoptera) in the region tested was considerably lower than that of the mayfly (Ephemeroptera) as seen in Table 3. Furthermore, the Ephemeroptera was completely absent in still water streams, as seen in the raw material for still water quality tests in the Appendix 8.1. Table 1. Water Quality data of the different water areas. Type of area Running water Still water Areas Water quality Moderate High Moderate Moderate Crucially contaminated Excessively contaminated Table 2. Measurements and data noted from water areas. Measurements/Water area PH Temperature ( C) Velocity (m/s) Riverbed Stone Stone Pebbles/sand Grass Sand Sand 4

5 Table 3. Data of the Capture recapture experiment. Baetis alpinus (Ephemeroptera) Rhithrogena alpestris (Ephemeroptera) Dictyogenus fontinum (Plecoptera) 13 2/ Total Species Captured Recaptured Total recaptured population size in the area Figure 3. Rhithrogena alpestri (Ephemeroptera) Figure 4. Dictyogenus fontinum (Plecoptera) Figure 5. Baetis alpinus (Ephemeroptera) 5. Discussion The above results were based on the number of morphospecies present and also the types of species. By knowing their oxygen requirements they could be used as an index for water quality. The running streams contained, among many, the Tricoptera, Planaria, Plecoptera and mountain midge, all species that can only thrive in highly oxygenated environments. The still streams on the other hand held species such as the Diptera Nematocera Family Chironomidae, Limnodrilus hoffmeisteri [5] and many Pupae of Culex (as seen in Appendix 8.3.). These are tolerant to low levels of oxygen and indicate an inferior quality. With such evidence and the results from the GLOBE bioindication index allow us to accept the hypothesis. Nonetheless, the running streams were expected to have a higher quality of water due to the mountainous location. The presence of errors (discussed below) must be considered. Despite this, Area 2 was shown to have a high quality. This was the river of the fastest velocity, through which we can conclude that a faster velocity promotes a higher water quality. This may indicate that even though certain streams are running, their velocities may not be sufficient enough so as to retain as high a quality as we would expect from such areas. Another contradiction lies in still water Area 4, which was actually rated at the same level as most of the running streams (moderate), due to the presence of stoneflies and Tricoptera (both superior leading species) in one region. This result is rather anomalous, due to the fact that stoneflies and Tricoptera are associated with high 5

6 water quality. This result may be due to the fact that this region was closest to the running water upstream, leading to a movement of the stoneflies and Tricoptera from higher water quality areas. These results lead to the understanding that the still stream, due to lack of movement, allows an accumulation of nitrates and phosphates (eutrophication) [6]. This favours plant growth and aerobic decay, which depletes the water of oxygen. Such nutrients may arise from excretory products as well as contamination through the agricultural pressure present in the area. The slower running streams may still be able to accumulate such compounds, a reason behind their moderate rating. Further to this, running water was cooler. This is because the water is not in one position, constantly exposed to the sunlight, but moving and losing its heat to the surrounding air. The opposite is true for still water. Being cooler, it has a higher oxygen capacity than the still water [7]. The running streams have a flushing system, so the above nutrients are constantly being swept away and do not accumulate. This results in high level of Dissolved Oxygen (DO), supporting our hypothesis [8]. However, the second set of results for Capture recapture was contrary to our hypothesis due to the mayfly (Ephemeroptera) being of a larger population size than the stonefly (Plecoptera), which was not expected. This may possibly be because of the difference in lifecycles. Although both show incomplete metamorphosis, the mayfly adult only lasts one day while that of the stonefly adult may last up to four weeks. Having a shorter lifecycle means reproductive rate is higher, allowing it to be more numerically common than the stonefly. Thereby, the hypothesis is clearly rejected. Another possible reason for this is the difference in the position of the two species in the food chain. While the mayflies are herbivorous, the stoneflies are found further along the chain as predators. According to the common ecological pyramid, the latter would tend to be in fewer numbers, as each individual requires a large number of prey individuals for feeding. So in a given system, there are more of the prey species further down the pyramid supporting less predator individuals. The lack of mayflies in other regions could be because of interspecific competitive displacement between the mayfly nymphs and those of other species, which thrive in such areas. The mayfly may have not competed successfully and died out in such areas, leading them to be present only in the running water with sufficient oxygen and healthy conditions for the growth of many individuals [9]. Another reason may be their intolerance to disturbance of the habitat, thus any case of this may have led to the elimination of the species in such areas [10]. It is important to note that the Baetis alpinus was, by a large gap, more abundant than the Rhitrogena alpestris. This may be due to the difference in structure of the two types of species. The Baetis alpinus is more adapted to the running water by having a more streamlined body (resulting in a higher efficiency in swimming to areas of nutrients and away from threatening conditions, such as pursuit by a predator) and its population numbers may flourish [11]. It is important to note that assumptions are being made on approximate results. Certain inaccuracies did lie in both tests. The time period of study only al- 6

7 lowed a limited number of tests as regards areas of a stream and different number of streams. Further to this, as regards Capture recapture, this was only performed in one area for one stream and therefore its results only give a mere indication of the population differences. Having a larger array of results would have been more accurate. Having said that, the tests made carry a high amount of significance. Mark and recapture, on a larger and more accurate scale continues to grow as an important tool in population studies. It is used to examine different species as well as estimate transition probabilities among lifestages from capture histories of marked individuals by the method known as multistage mark-recapture (MSMR) [12]. Banking (ESB) or newly developed strategies as the Multi-Markered Bioindication Concept (MMBC) are well established monitoring programmes. These may, with others, continue to be developed so as to reach leading goals of precision, accuracy and calibration, in international quality studies. This integration implies quality control of biological, physical and chemical components of ecosystems for human health aspects or environmental protection purposes, such as the monitoring of the destructive pollution, which is becoming a growing issue [13]. 6. Acknowledgements First of all we wish to thank the Swedish Federation of Young Scientists, the Foundation Swiss Youth in Science and the National Student Travel Foundation (Malta) for giving us the opportunity to have a formidable experience during the International Wildlife Research Week and to accomplish this project. We also wish to thank our supervisor Salome Steiner for her guidance throughout this project. 7. References 1. Swiss Agency for the Environment, Forest and Landscape. National report of Switzerland on the role of ecosystems as water suppliers. Convention on Protection and Use of Transboundary Watercourses and International Lakes December. 2. Aqua Viva. Wir zeigen die Gewässergüte von deinem Bach an. Available at Accessed June Gingins F. Schluep R. Vogel J. Bioindikation im Lebensraum Bach und Fluss. GLOBE Schweiz. May Fujiwara M. Mark-recapture statistics and demographic analysis. Massachusetts Institute of Technology Engelhardt W. Martin P. Rehfeld K. Pfadenhauer J. Was lebt in Tümpel, Bach und Weiher. Franckh-Kosmos Verlags-GmbH & Co. KG National Academy of Sciences (U.S.). Eutrophication: Causes, Consequences, Correctives; Proceedings of a Symposium. National Academies United States Environmental Protection Agency. 5.2 Dissolved Oxygen and Biochemical Oxygen Demand. Available at Accessed June The Global Water Sampling Project. Dissolved Oxygen. Available at Accessed June

8 9. EcoSpark. Scientific name: Plecoptera. Available at Accessed June Mathooko J. M. The effect of continuous physical disturbance on mayflies of a tropical stream: an experimental approach. Hydrobiologia NEWTON Home Page. Mayflies. Available at Accessed June Fujuwara M. Caswell H. Estimating Population Projection Matrices from Multi-Stage Mark-Recapture Data. Ecology. Dec Vol 83. No Holt E. A. Miller S. W. Bioindicators: Using Organisms to Measure Environmental Impacts. Nature Education

9 8. Appendix 8.1 Data of experiments The following tables show the data derived from the two experiments. Table 4. Species found in water area 1. Specie Region A Region B Region C 1. Diptera Nematocera Family Tipulidae 2. Diptera Brachycera Family Tabanidae 3. Diptera Nematocera Family Culicidae 4.Rhithrogena (Ephemeroptera) alpestris 5. Dictyogenus fontium (Plecoptera) 6. Mountain midge 7. Baetis alpinus (Ephemeroptera) 8. Blackfly Total different species Table 5. Species found in the water area 2. Species Region A Region B Region C 1. Baetis alpinus 2. (Ephemeroptera) 3. Rhithrogena alpestris (Ephemeroptera) 4. Planaria 5. Blackfly 6. Trichoptera family Phryaneidae ciever) (with 7. Trichoptera family Limnephilidae (with ciever) 8. Dictyogenus fontium (Plecoptera) 9. Dictyogenus alpinum (plecoptera) Total different species

10 Table 6. Species found in water area 3. Species (larvae) Region A Region B Region C 1. Dictyogenus fontium (Plecoptera) 2. Diptera Nematocera family Tipulidae 3. Blackfly 4. Diptera Nematocera Puppe of Anopheles 5. Diptera Nematocera Family Chironomidae Total different species (larvae) Table 7. Species found in still water area 4. Specie Region A Region B 1. Dictyogenus fontium (Plecoptera) 2. Dictyogenus alpinum (plecoptera) 3. Diptera Nematocera family Tipulidae 4. Coleoptera Family hydrophilae 5. Trichoptera family Sericostomaticae (with ciever) Total different species 4 2 Table 8. Species found in still water area (the highest area). Specie Region A Region B Region C 1. Coleoptera family Mydrophilidae 2. Diptera Nematocera family Culicidae 3. Diptera Nematocera Puppe of Anopheles 4. Coleoptera family hydrophilae 5. Coleoptera family Dystiscidae (Fabcicius) 6. Lepidoptera Total different species

11 Table 9. Species found in running stream 3. Specie Region A Region B Region C 1. Dragonflylarva 2. Pothamantus luteus 3. Blackfly larva 4. Diptera family chironomidae 5. Limnodrilus hoffmeisteri 6. Diptera family psychodidae 7. Crustacea family sididae 8. Diptera Nematocera family Tipulidae Total different species Table 10. The water quality results for all regions within the different water areas Area Region A Region B Region C Best result 1 c c c c 2 e f g e 3 c c c/d c 4 c d - c 5 g f f f 6 c b b b 11

12 8. 2. Areas studied The following figures show the environment and coordinates of the different areas. Figure 6. Displays the different water areas on a map Area 1 Area 1 Area 2 Area 3 Area 4 Area 5 Area 6 Figure 7. Displays pictures of the six different water areas, where the experiments were performed. 12

13 8.3. Insects studied The following figure shows the different insects present in the water areas. Mountain midge Diptera Coleoptera Figure 8. Displays different insects. Pupa of Culex Diptera Anopheles Larvae 13