Influence of invasiveAcer negundoleaf litter on benthic microbial abundance and activity in the littoral zone of a temperate river in Lithuania

Abstract

-Riparian forests are known as important source of allochthonous organic matter entering to water ecosystems via fallen leaves. However, leaf litter, depending on their quality, may create different conditions for benthic microorganisms functioning in littoral zone of water bodies. In order to evaluate the impact of riparian invasive Acer negundo on littoral water zone of the River Neris (Lithuania), we performed physicochemical and microbiological investigations in bottom sediments of three different sites of the river. One sampling site was close by riparian A. negundo, another close by native Alnus glutinosa location and a third zone was near the shore without riparian vegetation. Content of nutrients in the littoral sediments differed between invasive and native trees leaf litter accumulation sites, while not always significantly. The highest microbial densities as well as benthic community respiratory activity (expressed as the rate of organic carbon mineralization) occurred in A. negundo leaves accumulation site. In sediments of this site, the most intensive anaerobic terminal organic carbon mineralization process À sulfate reduction and the highest concentration of hydrogen sulfide were also observed. Differences in the intensity of mineralization processes between sites suggest that the replacement of the riparian native species such as dominant A. glutinosa by invasive A. negundo with higher biodegradability leaves may induce local changes in organic matter processing in the littoral zone of the river. The increase of littoral bioproductivity in the accumulation zone of A. negundo leaf litter can occur due to the inflow of available organic matter and its intensive mineralization.Keywords: leaf litter / benthic microorganisms / river Résumé -Influence de la litière d'Acer negundo invasif sur l'abondance et l'activité microbienne benthique dans la zone littorale d'une rivière en Lituanie. Les forêts riveraines sont connues comme source importante de matière organique allochtone entrant dans les écosystèmes aquatiques via les feuilles tombées. Cependant, la litière, en fonction de sa qualité, peut créer différentes conditions pour que les microorganismes benthiques fonctionnent dans la zone littorale des masses d'eau. Afin d'évaluer l'impact de l'Acer negundo invasif dans la zone d'eau littorale de la rivière Neris (Lituanie), nous avons procédé à des recherches physico-chimiques et microbiologiques dans les sédiments de trois sites différents de la rivière. Un site d'échantillonnage était proche de A. negundo riverain, un autre proche de l'emplacement d'Alnus glutinosa indigène et une troisième zone était près d'une rive sans végétation riveraine. Les contenus en nutriments dans les sédiments du littoral différaient entre les sites d'accumulation de déchets de feuilles d'arbres envahissants et natifs, bien qu'ils ne soient pas toujours significativement différents. Les densités microbiennes les plus élevées ainsi que l'activité respiratoire de la communauté benthique (exprimée en taux de minéral...

Bacterial decomposition of allochthonous organic matter in shallow subtropical lakes

“…The LML exhibited a temperature about 1ºC higher than the HML, a value that appears to have been sufficient to accelerate the microbial activity on allochthonous organic matter. A positive effect of the higher temperature on decomposition rates has also been observed in other studies (Krevš & Kučinskiene, 2017;Silva et al, 2018;Song et al, 2013). The results of the present study, however, differ from those of Rezende et al (2018), who observed similarities in the decomposition of allochthonous debris in shallow lakes with different macrophyte coverage in the Brazilian semi-arid region, attributing this similarity to short geographical distance (~300-m) between the study ecosystems, while the lakes in the present study only had a short distance between them (~200 m).…”

“…Total phosphorus is a limiting factor that can influence the abundance of the main groups in the bacterial community, which favour higher concentrations (Schneider et al, 2012). The results of the present study and those observed in other studies (Krevš & Kučinskiene, 2017;Pascoal & Cássio, 2004) suggest bacteria can make a greater contribution to decomposition in eutrophic systems, especially when fungal activity is restricted.…”

Impact of non-native tree species in Europe on soil properties and biodiversity: a review

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You Can’t See the Woods for the Trees: Invasive Acer negundo L. in Urban Riparian Forests Harms Biodiversity and Limits Recreation Activity

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