Title: Habitat features and zooplankton community structure of oxbows in the limnophase: reference to transitional phase between flooding and stabilization
Abstract: espanolDebido a su origen, morfometria e hidrodinamismo, los meandros abandonados representan un tipo de ecosistema lacustre particular, especialmente si se comparan con lagos de origen glaciar. El funcionamiento de los meandros abandonados, esta directa o indirectamente relacionado con las fluctuaciones temporales del nivel del agua del rio. Las inundaciones periodicas de los habitats de la llanura fluvial aportan minerales y compuestos organicos a los productores primarios, crean refugio a los organismos acuaticos frente a perturbaciones en el canal del rio y contribuyen al incremento de la biodiversidad en todo el sistema fluvial. Con el objetivo de conocer los predictores de la comunidad de zooplancton, asi como de las especies de rotiferos y crustaceos, comparamos la composicion taxonomica con algunos parametros ambientales: tipo de habitat, usos del suelo, sombra en la superficie del lago y presencia de peces. El estudio se realizo en meandros abandonados durante la limnofase. A pesar de que la estructura de la comunidad en estos sistemas pudiera ser sencilla, se encontro que la complejidad del habitat favorecia la riqueza de especies y la diversidad de Shannon-Weaver del zooplankton. Esto confirma el hecho de que durante la limnofase, estos habitats son ecotonos entre el periodo de inundacion y el de estabilizacion. A diferencia de lo que ocurre en otros tipos de cuerpos de agua de menor tamano, el uso del suelo (bosque vs campo), que determina la calidad de los compuestos organicos y minerales aportados, junto con la presencia de peces, no afectaron notablemente ni la diversidad ni la abundancia de la comunidad de zooplancton en los sistemas estudiados. Algunas especies de zooplancton mostraron una segregacion de habitat de acuerdo a su grupo ecologico (especies pelagicas vs especies litorales) o a su afiliacion taxonomica (rotiferos vs crustaceos). Las especies litorales, relacionadas con la presencia de macrofitos, prefieren lagunas con un alto grado de sombra. Dentro de las especies pelagicas de zooplancton, que prefieren permanecer en la zona de aguas abiertas, se registraron una gran cantidad de especies eutroficas, debido a la alta carga de nutrientes y materia organica. La gran diversidad de zooplancton de los ecosistemas estudiados y las caracteristicas abioticas revelan el estado de inestabilidad y perturbacion de estos sistemas y su papel como zona de transicion. Estos resultados pueden complementar el conocido Flood Pulse Concept EnglishDue to their origin and their morphometric and hydrodynamic parameters, oxbow lakes represent a distinct type of aquatic ecosystem, especially compared with post-glacial lakes. The functioning of oxbows is directly and indirectly connected with temporal fluctuations of the water level in rivers. Periodic inundation of floodplain habitats provides primary producers with access to mineral and organic compounds, creates refuge conditions for aquatic organisms against disturbances in the river channel, and contributes to the increase of biodiversity in the whole river system. To determine the best predictors of zooplankton community indices, as well as those of rotifer and crustacean species, we examined them with respect to the following environmental parameters: the type of habitat, the type of land uses, the shading of the lake’s surface and the presence of fish. The study was performed on oxbows during limnophase. Despite the fact that the biotic structure in oxbows may be simplified, it was found that a high level of habitat complexity positively influences zooplankton species richness and the Shannon-Weaver index of diversity. This would support the fact that during limnophase, oxbows are in an ecotonal phase – between the flooding and the stabilization period. In contrast to other types of small water bodies, the type of land uses (forest vs. field) that affected the quality of the supplies of organic and mineral compounds, along with the presence of fish, did not have a pronounced effect on either zooplankton diversity or their community abundance. Particular zooplankton species also exhibited habitat segregation in accordance with their ecological group (pelagic vs. littoral species) or taxonomic affiliation (rotifers vs. crustaceans). Littoral species, attributed to elodeids, preferred oxbows with a high degree of overshading. Among the pelagic zooplankton, which preferred to remain in the open water zone, a large representation of eutrophic species was recorded due to the overload of the water by mineral nutrients and organic matter. The high zooplankton diversity of the studied aquatic ecosystems and the abiotic features, which revealed an unstable and disturbed status, confirmed the fact that oxbows during the limnophase reflect an ecotonal phase. This may be a complementation to the river flood pulse concept.
Publication Year: 2016
Publication Date: 2016-01-01
Language: es
Type: article
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Cited By Count: 9
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