Use of native macrophytes for recovery of the habitat structure and complexity of a lowland stream affected by river engineering works: Implications for management

Abstract

Macrophytes were transplanted into a lowland stream affected by river engineering works. The aim was to analyse the feasibility of their reintroduction and potential to be used for the recovery of the structure and complexity of the lotic habitat. Macrophytes contribute heterogeneity to streams, modify the current velocity, affect sediment and nutrients dynamics, and provide a substrate for epiphytic biofilm. We transplanted specimens of Ludwigia peploides, Gymnocoronis spilanthoides, and Egeria densa into a stream located in the Pampean plain (Buenos Aires, Argentina). The growth and coverage of the transplanted macrophytes and the changes in the structure of the epiphytic biofilm were assessed. The results show that specimens of G. spilanthoides were negatively affected by the transplant and new conditions, E. densa decreased its coverage after the transplant, and L. peploides endured the transplant and adapted to the dredging site with successful establishment and expansion. There were no significant differences between the biofilm developed in L. peploides and G. spilanthoides. Additionally, the biofilm had similar features between the transplanted macrophytes and those from a site with no dredging. Considering this result, the selection between these macrophytes in relation to biofilm production is indifferent. However, as L. peploides adapts better to the new conditions generated by the river engineering works, its use in the rehabilitation project is recommended.Moreover, it is important to consider the ability of different species of macrophytes to survive the transplant and grow under new environmental conditions in order to include them in rehabilitation projects.

Selection of macrophytes by a generalist invertebrate herbivore and potential impacts for stream rehabilitation

“…This study complements a previous study carried out on a lowland stream to analyse the feasibility of the reintroduction of macrophytes for recovery of the structure and complexity of the stream (Paz et al 2018). Our results will be useful in determining less affected macrophyte species by a generalist herbivore.…”

“…Field sampling was performed in the Martín stream (34°52'5.38"S; 58° 4'9.80"W), a second order lowland watercourse located in the Buenos Aires province of Argentina, which was dredged and channelized before the experiment began. Three beds of the study macrophyte species were transplanted into a section of the Martín stream immediately after dredging and channelization (Paz et al, 2018) so the only macrophytes present in that section at the time of the experiment were the transplanted beds from where the samples were taken. The three beds of each macrophyte were identified and numbered.…”

“…Because of the numerous benefits they provide, the transplant of macrophytes into stream channels is a useful technique in recovering the loss of ecological services due to anthropogenic activities (Paice et al, 2015;Paz et al, 2018). Macrophytes play an important…”

Observaciones sobre algunas características ecológicas de las plantas que habitan los bañados de desborde fluvial afectados por la urbanización y las prácticas agrícolas

“…Por lo tanto, es posible disponer de un conjunto de especies nativas en estos ambientes para implementar medidas correctivas en bañados que requieran rehabilitación o restauración contribuyendo así a mejorar la calidad del agua de los sistemas fluviales. Estudios recientes con Ludwigia peploides, también dan cuenta del éxito de esta planta en experiencias de trasplantes, para mejorar rápidamente el hábitat de arroyos intervenidos por dragados (Paz et al, 2018). En cuanto a la conservación de estos ambientes, también sería importante promover bancos de semillas de plantas vasculares que habitan en estos humedales, ya que han sido una herramienta útil en los programas de restauración de comunidades vegetales en ambientes estacionalmente inundados (Liu et al, 2005;Espeland et al, 2010), sencillamente porque presentan estrategias adaptativas como lo es la producción de semillas capaces de sobrevivir enterradas en los sedimentos y mantenerse latentes hasta que las condiciones ambientales sean propicias para su germinación (Leck, 2003).…”

Las diatomeas del biofilm fluvial como indicadores ambientales a corto plazo en el seguimiento de la recuperación de la calidad del agua de sistemas acuáticos pampeanos

“…Asimismo los cuerpos de agua de la región han sido fuertemente modificados con el fin de evitar inundaciones. Tales modificaciones implican canalizaciones, rectificaciones, desviaciones y entubaciones de los cursos agua resultando en una fuerte simplificación ecológica del hábitat (Paz et al, 2018). Además, el gran crecimiento de la población en muchos casos no fue acompañado por inversiones en infraestructura sanitaria, por lo que los ríos y arroyos de la región tienen un alto impacto debido al vuelco de aguas residuales y efluentes domésticos sin tratar (Cirelli y Ojeda 2008), con altos niveles de materia orgánica y contaminación microbiológica (Vilches et al 2011).…”