Hydrobiologie I Englisch (Fach) / Prüfungsfragen (Lektion)

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• What promotes summer stagnation? Wind impact only on the uppermost layer of the waterbody, the "Epilimnion". Whereas the layers beneath (Metalimnion and Hypolimnion) are not influenced by the "mixing process"
• What does the "Secci-Disk" show? The visible depth - thumb rule secci-disk depth x 2,5 = the compensation level
• Whats the name oft he layer with digested sludge? This layer is call Sapropel -orginates on the bottom eutropher – low in oxygen – waterbodies; anaerobic depletion (=Abbau) causes hydrogen sulphide – and methanogenesis
• Where is Endorheism present? In arid areas, meaning the evaporation (Verdunstung) is higher than the precipitaion (Niederschlag)
• What does it depend on wether plankton floats in the water? On the temperature and the density of the water body
• Which animal species are most frequent in mud? Sludge worms (tubifex) or "Schlamm-Röhrenwürmer"
• Which plants disappear first, after a falling carbon dioxide content? The fontinalis type, because it only absorbs the dissolved CO2
• At which point of the aquatic food chain can you find the pike (Hecht)? On the top of the food-chain because he is a „following-consumer“ (Carnivore)
• Where can you find a stratified O2 saturation? In eutrophic (=nährstoffreichen) lakes
• Where does zooplankton live? In the Pelagical (midwater, also "Freiwasserkörper")
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• How does the O2-content behave in potamals (Tieflandflüssen)? Depends on the time of the day. At night there is high consumption by dissimliation, destruction and respiration. However the O2 entry from the atmosphere is the highest at night. At daytime with the light (photosynthesis) O2 is produced in the river Concluding it is changing through the day -> amplitude
• Which factors influence the density of water? Temperature, hydrostatic pressure (every 100m Water temperature of max. density decreases by 0,1), and salt content
• What does salinity mean? The salt content in water bodys, in lakes usually ranging from 0,01‰ to 1‰ (Promille)
• Which plants are not common or don´t exist in the Rhithral? Riverplankton or Phytoplankton, attached algae (periphyton), macrophytes
• What is the compensation level? The layer between the light saturated eutrophic/trophpgenic zone and the aphotic/trophplytic zone without light. At the compensationlevel 1% of the original light radiation remains
• How do you call the light unexposed layer in lakes? Aphotic or tropholytic
• What are the specific features from metalimnion? The temperature change is the greatest, decrease of temperature with increasing depth (thermocline)
• Which circulation type posses most austrian lakes? Dimictic/Holomictic and Dimitic/Meromictic
• How did most Austrian lakes originate? By glacier movements in the ice age; exogenous forces
• What does meromixis mean? Only partial mixing of the water. The mixed part then is called Mixolimnion. On the opposite the untouched part of the water is called Monimolimnion. You can differ three reasons for Meromixie: 1) morphologically induced Meromixie: Lake is too deep for total mixing 2) topographically induced Meromixie: lakes are well shelterd from wind 3) chemically indulced Meromixie: dissolved chemical substances (electrolytes) increase the deep water body density so much that even in the state of homothermie ("Temperaturgleichheit"), the specific weight of the depth water body remains unchanged
• On what factors does the critical loading depend on? mean depth and retention period (of water)
• Which species lay “permanent eggs”? Crustacea (crayfish): Cladocera (water fleas), Copepoda (copepds) and Rotatoria (rotifers)
• Which characteristics do groundwater inhabitants have? With no exposure to light groundwater inhabitants have no pigments and no sight organs They are also exposed to a low seasonal fluctuation (over the year)
• Who lives in extreme habitats/ raised moors? Only few populations. However in massive populations
• What does “Henry`s law“ state? The solubility decreass along with increasing temperature and decreasing pressure. Cs = Ks x Pt (When the amount of gas dissolved in the water corresponds to the solution equilibrium, 100% saturation is reached)
• Which measure counteracts the eutrophication? Outside the water: keeping it free from wastewater, riparian protection stripes/buffer stripes (Uferschutzstreifen), less fertilisation Inside: suction oft he hypolimnion with pipes, insertion of organic suspenden sediment
• Why ist he temperature regulation of water so good/acceptable? Because oft its high specific warmth
• In which part oft he river are the most ramificatons (Verzweigungen)? In the delta of the riverIn the potamal, which is (longitudinal) the lowerreaches of a river, the ramificated area is called furcation
• Where ist he allochtonous entry main carbon source? In nutrient poor rithral waters
• What does the “Beer-Lambert Law“ define? As the depth increase, the light attenuation (Verminderung increases exponentially
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• On what does the heat balance in runnign waters depend on? Volume, evaporation, the waters mass distribution, the absorbed and reflceted radiation and the air ground heat exchange
• What is mainly responsible for warming up of lakes? The long waved red heat radiation
• When does homothermy occur? In Spring and Autumn
• What is trophitiy? The intensity of primary production i.e. the supply of an ecosystem with organic matter
• What is saprobity? The intensity of degradation of organic matter
• Up to which area does primary production take place in standing waters? Up tot he compensation level which is the bottom border oft he trophgenic/eutrophic zone
• Where do Zoobenthos live? In the Benthal/benthic region (lake bottom)
• The production in the pelagic region (mid water) occurs through…? Phytoplankton
• How is the sediment with brown mud called? Dy It is typical of dystrophic lakes (nutrient-content low, huminacid content high ->low pH value, pH usually at 4) and includes predominantly coarse plant remains.
• How is the sediment with grey sludge called? Gyttja Itis a fine particulate sediment with different high organic contents. It is produced in oxygenic oligotrophic and eutrophic waters. The color varies depending on the organic content: in oligotrophic lakes, the sediment is light due to the mineralization, the oxygen saturation is at least 50%. In eutrophic lakes, organic material that did not decompose is still present and is responsible for the dark brown to black coloring.
• The model of the “Critical loading“ provides information about what? The “Critical loading“ from Vollenweider provides information on the load-carrying capacity and critical phosphorous exposure of lakes.
• At which level of the food-chain are “decomposers“ standing? At the end of the food-chain
• The oxygen distribution in a lake shows a characteristic profile over the year. Where can you find an orthograde oxygen distribution? In Oligotrophic lakes (nutrient-poor leading to little organic production)
• Which communities are predominant in the rhithral rivers? In rhithral rivers, benthic invertebrates and fish are the predominant communities.
• What do you know about the O2 ration in rhithral rivers? The turbidity is very high in rithral waters causing in vast O2 enrichening of the water (close to the saturation level)
• How is the light-flooded layer in lakes called? Eutrophic or throphogenic layer
• Which type of plants cannot be found in alpine streams? Plants with floating leaves, Periphytons (= a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems)
• Which plant-type is typical for oligotophic alpine streams? Fontinalis antipyretica / Common water moss
• How does Zooplankton swim? With vacuoles filled with oil
• On the compensation level are… Assimilation and dissimilation balanced. Assimilation: (foreign inorganic and organic substances from the environment are used for the production of organic material) Dissimilation (Organic material is used to produce energy, ATP)

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