Response of eichhornia crassipes (pontederiaceae) to water level fluctuations in two lakes with different connectivity in the Paraná river floodplain
Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia cras sipes (Mart.) Solms (one of the most frequent aquatic plant) was studied in two floodplai...
Guardado en:
| Autores principales: | , , |
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| Formato: | Artículo |
| Lenguaje: | Inglés |
| Publicado: |
Universidad de Costa Rica
2022
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| Materias: | |
| Acceso en línea: | http://repositorio.unne.edu.ar/handle/123456789/48644 |
| Aporte de: |
| Sumario: | Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its
location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia cras sipes (Mart.) Solms (one of the most frequent aquatic plant) was studied in two floodplain lakes with different
flooding regimes. Samples were taken between March 1997 and December 2001 on 13 different hydrologic
conditions during prolonged hydrologic connection and prolonged hydrologic isolation. Leaf height, leaf den sity, biomass and nutrient content of the mature leaves of E. crassipes were measured and related to water level
fluctuation and the hydrologic connectivity. The lake more connected with the main channel had a long lasting
inundation phase. In this condition the surface area covered by water increased more than three times compared
to prolonged hydrologic isolation condition. As river water entered the floodplain lakes, dissolved inorganic
nitrogen increased to high values, especially NO3
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, whereas the isolation condition was characterised by a
decrease in NO3
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concentrations to undetectable levels. Compared to plants growing in the more isolated lake,
those growing in the more connected lake had a significantly lower leaf density, longer leaves, less root biomass
and lower ratio between below-ground and above-ground biomasses. However, total and leaf biomasses were
not significantly different between sites. In each lake, differences in leaf height, leaf biomass and root biomass
between prolonged hydrologic connection and isolation, as well as the insignificant relationship between leaf
size and leaf density, indicate that the morphological traits of E. crassipes respond to pluri-annual water level
fluctuations. The highest nutrient concentration in mature leaves was registered at the end of the prolonged
hydrologic connection in the more connected lake. During the prolonged isolation, leaves had more lignin and
a higher L:N ratio than at high waters, at the same sites. The success of E. crassipes in occupying habitats sub jected to wide and erratic fluctuations in water level, such as the Paraná River floodplain, appears to be related
to its ability to modify morphological traits according to water level. |
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