| Mention some pressures on Danish streams | Overview |
| Hvordan har udviklingen af udledningen af N og P fra forskellige punktkilder udviklet sig? | Massiv reduktion i udledningen fra samt alle disse kilder - særligt renseanlæggene er blevet meget meget bedre! |
| Så hvor stammer størstedelen af udledningen af N og P fra i dag? | Landbruget naturligvis! men vi skal jo have noget at spise! så husk vi er et stolt landbrugsland, som har brug for alle 30 mio grise i vores indutri <3 |
| Hvordan har koncentrationerne af N og P i vandløb ændret sig fra 1990'erne? og hvad skete der for peaket i 2019? | N koncentrationerne er faldet med omkring 40% fra 1990. De sidste 5-10 år har N konc. været uændret med et stort peak i 2019. Dette skyldes dårlig høst i 2018 pga. tørke, der ledte til at meget N ikke blev optaget af afgrøderne, men blev i jorden også efterfølgende skyllet ud med regnen i 2019.
P koncentrationer er faldet med ca. 34% siden 1990. Særlig stor reduktion i lvandøb, som tidligere har været meget påvirket af punktudledninger fra rensningsanlæg og fiskefarme. |
| Hvordan har koncentrationerne af N og P udviklet sig i kystnære farvande siden 1990'erne? | Tendensen er faldende koncentrationer for begge nærringsstoffer. |
| Hvordan tror du, at udviklingen ser ud, hvis man kigger på organisk materiale i vandløb? | Her er der også faldende udledning og deraf faldende koncentrationer af organisk materiale i danske vandløb. |
| What is meant by channelization of streams? | refers to the process og modifying a natural stream or river by straightening, deepenig, widening, or otherwise altering its course |
| What is the pupose of channalization? | - Flood control
- Agricultural drainage
- Urban Development |
| How can drainage of agricultural fields or urban areas affect groundwater recharge and water table? | Increased drainage reduces natural groundwater recharge and can lower the water table affecting the overall hydrology of the area. |
| What is the purpose of weed cutting and is it a normal practice in Danish streams? | Weed cutting is a way to maintain efficient drainage of channelised streams. It is conducted in most Danish streams twice or more per year. |
| Water abstraction is another hydro-morphological disturbance in streams. What can the consequences of this be? | - Lower water levels
- Stream sections drying out |
| How will increasing pressures impact the biological communities in streams? | With relativly low stress there are primarily changes in the frequency of species occurence and only minor species loss. As pressures increases, sensitive species will disappear and replaced by tolerant species. |
| Explain the figure. | h |
| How will eutrophication affect the macrophyte species composition in streams? | Species with apical growth and species tolerant of low light will benefit. |
| How have habitat due to channelisation changed? | Loss of 43% stream lenght and loss of 48% wetland areas |
| How is the velocity changed with channelisation? | The average flow velocity increases |
| What negatvie consequences are assosiated with weed cutting? | - Removing of habitats for many organisms
- Removing of breeding grounds for fish
- Decline in plant diversity
- Disturb sediments and lead to increased turbidity in the water |
| Any plants who benefit from weed cutting? | Species with basal growth - like Pindsvineknop |
| How does discharge affect the biological communities? | Principle 1: high flow rates are cucial for the physical habitats in streams
Principle 2: species have developed life-history strategies as a direct response to the dynamics og natural flow regimes
Principle 3: longitudinal and lateral connectivity in streams is essential for the viability of many populations
Principle 4: there is a greater risk of invasive species when flow dynamics are altered |
| Med hvilket vandløbsindeks er der flest samlede samlede vandløb, som når miljømålene? | vandløbsfaunaindeks (DVFI) med 58% - det betyder at den økologiske status for macroinvertebrater i vandløb faktisk er nogenlunde |
| Hvilken type vandløb målt med hvilken parameter klarer sig dårligst? | Dansk fiskeindeks for ørred (DFFVø) for mellemstore vandløb - fiskene er generelt presset i vandløb |
| The measurements of the five categories of oraganisms can be used as indicators for different pressures. What organism group can be used as a indicator for most pressures? | macrophytes |
| Explain how these stressors can change macrophyte trait characteristics | h |
