| Macrophytes (vascular plants) can be divided intro three groups. Which? | - emergent
- floating
- submerged |
| Can macrophytes also be non vascular plants? | Yes!
- macroalgae (characeans, chlorophytes)
- mosses |
| Hvordan kan makrofytter optage nærring? | nogle optager gennem rødder fra sedimentet, andre direkte fra vandsøjlen gennem bladene |
| Hvad vil en høj rod:biomasse ratie hos en makrofyt ofte indikere? (i forhold til nærringsoptag) | høj root/biomass ratio betyder de er mere afhængige af sedimentets nutrients end vandsøjlens |
| Hvordan findes størstedelen af uorganisk carbon i en sø? | som bicarbonat |
| Hvad forstås ved hhv. langskudsplanter og grundskudsplanter? nævn eksempler | En vækstformsindeling af submergente makrofytter.
Eksempler
Langskuds: vandaks, vandpest
Grundskuds: strandbo, tvepibede lobeli, brasenføde (lidt sjælden) |
| Hvordan ændrer fordelingen sig af langskudsplanter (elodeids) og grundskudsplanter (isoetids) sig med stigende alkalinitet i en sø? | Generelt: grundskudsplanter vokser ofte i søer med lav alkalinitet (oligotrofe), mens langskuds ofte kan tåle højere alkaliniteter og ofte er meget udbredete i mesotrofe søer¨.
Bonus info: strandbo er altid den sidste iseotids der forsvinder når alkaliniteten (nutrients level stiger) |
| hvad er sammenhængen mellem søstørrelse og artsrigdom? | artsrigdommen øges generelt med arealet (i hvert fald for makrofytter) |
| Decomposition of macrophytes is highly dependent on the C:N and C:P ratio. When is the decomposition rate high? | high decomposition rate when C:N or C:P ratio is low |
| Mention as many roles of macrophytes in lake ecosystems as possible. | h |
| What is meant by the alternative stable state hypothesis? | The Alternative Stable State Hypothesis suggests that shallow lakes can exist in one of two stable ecological states under similar environmental conditions:
Clear-water state dominated by submerged plants
Turbid-water state dominated by phytoplankton (algal blooms) |
| How does macrophyte cover affect the resuspension? | the presence of macrophytes reduces the resuspension and increases the sedimentation of both phosphorus and suspended soilds. |
| What is allelopathy? | Allelopathy is a biological phenomenon where plants/ macrophytes release biochemicals (called allelochemicals) into the environment to influence the growth, survival, or reproduction of other organisms. These chemicals can have positive (stimulatory) or negative (inhibitory) effects on neighboring plants, microorganisms, or aquatic organisms. |
| Is allelopathy common among submerged macrophytes? | Yes! but not all macrophytes have allelopathic effects |
| Mention a group of macrophyte with an often low allelopathic potential. | Potamogeten spp. (vandaks) |
| Mention two ways (not allelopathy) where macrophytes can affects zooplankton | - by creating refuge to zooplankton
- by favouring piscivorous fish |
| Hvordan undgår zooplankton prædation i hhv. lavvandede og dybe søer? forklar ud fra de to figurer | Lave søer = horisontal flytning mellem dag og nat
Dybe søer = vertikal flytning mellem dag og nat |
| How does fish community change with presence and absence of macrophytes? | Presence of macrophytes = more of the good stuff (perch)
Absence of macrophytes = more of the bad stuff (Roach and Bream) |
| What role do macrophytes play on macroinvertebrates? | Positive impacts to invertebrates (both benthic and epiphytic).
can seve as a habitat, a refuge from predators and as substrate for food colonisation |
