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A macrophyte is an aquatic plant that grows in or near water and is either emergent, submergent, or floating, and includes helophytes (a plant that grows in marsh, partly submerged in water, so that it regrows from buds below the water surface). In lakes and rivers macrophytes provide cover for fish and substrate for aquatic invertebrates, produce oxygen, and act as food for some fish and wildlife.
Fringing stands of tall vegetation by water basins and rivers may include helophytes. Examples include stands of Equisetum fluviatile, Glyceria maxima, Hippuris vulgaris, Sagittaria, Carex, Schoenoplectus, Sparganium, Acorus, yellow flag (Iris pseudacorus), Typha and Phragmites australis.
- 1 Classification of macrophytes
- 2 Emergent macrophytes
- 3 Floating-leaved macrophytes
- 4 Submerged macrophytes
- 5 Free-floating macrophytes
- 6 As watershed health indicators
- 7 As potential sources of therapeutic agents
- 8 Functions of macrophytes in aquatic system
- 9 Factors affecting the growth of macrophytes
- 10 See also
- 11 References
- 12 External links
Classification of macrophytes
Based on growth form, macrophytes can be classified as:
- Emergent macrophytes
- Floating-leaved macrophytes
- Submerged macrophytes
- Free floating macrophytes
An emergent plant is one which grows in water but which pierces the surface so that it is partially in air. Collectively, such plants are emergent vegetation.
This habit may have developed because the leaves can photosynthesize more efficiently above the shade of cloudy water and competition from submerged plants but often, the main aerial feature is the flower and the related reproductive process. The emergent habit permits pollination by wind or by flying insects.
There are many species of emergent plants, among them, the reed (Phragmites), Cyperus papyrus, Typha species, flowering rush and wild rice species. These may be found growing in fens but usually less well owing to competition from other plants. Some species, such as purple loosestrife, may grow in water as emergent plants but they are capable of flourishing in fens or simply in damp ground.
Floating-leaved macrophytes have root system attached to the substrates or bottom of the lake and stream and with leaves that float on the water surface. Common floating leaves macrophytes are water lilies (family Nymphaeaceae), pondweeds (family Potamogetonaceae).
Submerged macrophytes completely grow under water with root attached to the substrate (e.g. Myriophyllum spicatum) or without any root system (e.g. Ceratophyllum demersum).
As watershed health indicators
A decline in a macrophyte community may indicate water quality problems and changes in the ecological status of the water body. Such problems may be the result of excessive turbidity, herbicides, or salinization. Conversely, overly high nutrient levels may create an overabundance of macrophytes, which may in turn interfere with lake processing.
Macrophyte levels are easy to sample, do not require laboratory analysis, and are easily used for calculating simple abundance metrics.
As potential sources of therapeutic agents
Phytochemical and pharmacological researches suggest that freshwater macrophytes, such as Centella asiatica, Nelumbo nucifera, Nasturtium officinale, Ipomoea aquatica and Ludwigia adscendens, are promising sources of anticancer and antioxidative natural products.
Hot water extracts of the stem and root of Ludwigia adscendens, as well as those of the fruit, leaf and stem of Monochoria hastata were found to have lipoxygenase inhibitory activity. Hot water extract prepared from the leaf of Ludwigia adscendens exhibits alpha-glucosidase inhibitory activity more potent than that of acarbose.
Functions of macrophytes in aquatic system
Macrophytes perform many ecosystem functions in aquatic ecosystems and provide services to human society. One of the important functions performed by macrophyte is uptake of dissolve nutrients (N and P) from water. Macrophytes are widely used in constructed wetlands around the world to remove excess N and P from polluted water. Beside direct nutrient uptake, macrophytes indirectly influence nutrient cycling, especially N cycling through influencing the denitrifying bacterial functional groups that are inhabiting on roots and shoots of macrophytes. Macrophytes promote the sedimentation of suspended solids by reducing the current velocities, impede erosion by stabilising soil surfaces. Macrophytes also provide spatial heterogeneity in otherwise unstructured water column. Habitat complexity provided by macrophytes like to increase the richness of taxonomy and density of both fish and invertebrates.
Factors affecting the growth of macrophytes
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- Hickey, M.; King, C. (2001). The Cambridge Illustrated Glossary of Botanical Terms. Cambridge University Press.
- "Macrophytes as Indicators of freshwater marshes in Florida" (PDF). Retrieved 2014-04-05.
- Swearingen, Jil M. (7 July 2009). "PCA Alien Plant Working Group - Purple Loosestrife (Lythrum salicaria)". National Park Service. Retrieved 24 September 2011.
- Chai TT, Ooh KF, Quah Y, Wong FC (2015) Edible freshwater macrophytes: a source of anticancer and antioxidative natural products—a mini-review. Phytochemistry Reviews 14(3): 443–457
- Ooh KF, Ong HC, Wong FC, Sit NW, Chai TT (2014) High performance liquid chromatography profiling of health-promoting phytochemicals and evaluation of antioxidant, anti-lipoxygenase, iron chelating and anti-glucosidase activities of wetland macrophytes. Pharmacognosy Magazine 10(39): 443-455.
- Brix, H. (1997) Do macrophytes play a role in constructed treatment wetlands?. Water Science and Technology, 35, 11-17
- Vymazal, J. (2013) Emergent plants used in free water surface constructed wetlands: A review. Ecological Engineering, 61, 582-592.
- Hallin, S., Hellman, M., Choudhury, M.I. & Ecke, F. (2015) Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands. Water Research, 85, 377-383.
- Zhu, M.Y., Zhu, G.W., Nurminen, L., Wu, T.F., Deng, J.M., Zhang, Y.L., Qin, B.Q. & Ventela, A.M. (2015) The Influence of Macrophytes on Sediment Resuspension and the Effect of Associated Nutrients in a Shallow and Large Lake (Lake Taihu, China). Plos One, 10.
- Horppila, J., Kaitaranta, J., Joensuu, L. & Nurminen, L. (2013) Influence of emergent macrophyte (Phragmites australis) density on water turbulence and erosion of organic-rich sediment. Journal of Hydrodynamics, 25, 288-293.
- THOMAZ, S. M., DIBBLE, E. D., EVANGELISTA, L. R., HIGUTI, J. and BINI, L. M. (2008) Influence of aquatic macrophyte habitat complexity on invertebrate abundance and richness in tropical lagoons. Freshwater Biology, 53: 358–367. doi:10.1111/j.1365-2427.2007.01898.x